DE69414643T2 - Process unit and imaging device - Google Patents

Description

The invention relates to an image forming apparatus and a removable processing unit therefor.

The image forming apparatus may be in the form of an electrophotographic copier or a printer which uses a developer.

The electrophotographic image forming apparatuses are widely used as copying machines or the like. In such an apparatus, a photosensitive drum 1 is uniformly charged and selectively exposed to form a latent image. The latent image is visualized with a developer, and the visualized image is transferred to a recording material. In such an apparatus, a photosensitive drum and a developing device having a developer container or the like are combined in a process unit. The process unit is arranged on a main assembly of the image forming apparatus. The latent image formed on the photosensitive drum is developed using a developer which is stored in the developer container in the process unit.

As described in patent document EP-A-0330225, in order to prevent the developer from leaking out of the container during transportation, the opening of the developer container is sealed by a sealing member. Before starting use, the operator removes the sealing member to open the developer container, through which the developer contained in the container is supplied to the developing roller or the like through the opening.

However, if the operator incorrectly opens the container by pulling the sealing element at an angle, the opening action is not carried out as desired, and as a result a desired opening area is not guaranteed.

It is the object of the present invention to improve the handling of removing the sealing member while effectively preventing the leakage of developer.

According to one aspect of the present invention, there is provided a process unit detachably mounted on a main assembly of an electrophotographic image forming apparatus, the process unit comprising: an electrophotographic photosensitive member capable of bearing a latent image, a first frame having a developer container for accommodating a developer, a second frame having a developer carrying member for carrying the developer supplied from the developer container to develop the latent image, and a sealing member for sealing an opening for supplying the developer from the developer container to the developer carrying member, the sealing member being able to be pulled off between the first and second frames in a pulling direction to expose the opening, characterized by: an end seal disposed downstream of the opening with respect to the pulling direction, and a pair of projections disposed between the first and second frames on respective transverse sides of the sealing member with respect to the pulling direction and extending through holes in the end seal to restrict the pulling direction of the sealing element.

A specific embodiment of the present invention will now be described by way of example with reference to the accompanying drawings.

Fig. 1 is a sectional view of an image forming apparatus according to an embodiment of the present invention,

Fig. 2 shows a sectional view of a process unit according to an embodiment of the present invention,

Fig. 3 shows a sectional view of the image forming apparatus, when it is opened,

Fig. 4 shows an arrangement element of the photosensitive drum,

Fig. 5 shows a sectional view of a second conductive element of the arrangement element,

Fig. 6 shows the dimensions of the arrangement element,

Fig. 7 is a perspective view in which a toner container, an opening restricting member and a cover member are disassembled,

Fig. 8A shows a sectional view of a cover seal,

Fig. 8B shows a sectional view of a tear tape,

Fig. 9 shows a tear tape according to another embodiment,

Fig. 10 shows a sectional view of a cover element, which has a cover seal and a tear strip in one piece,

Fig. 11 shows a cover element which is curled,

Fig. 12 shows the welding of a cover element with an opening limiting element,

Fig. 13 shows a relationship between the cover seal and the tear tape,

Fig. 14 shows the arrangement of a development device frame on a toner container with a sealing element,

Fig. 15 shows the pressure force acting on the cover seal due to an internal pressure of the toner container,

Fig. 16 shows a pulled out cover seal,

Fig. 17 shows a sectional view of an embodiment having an end seal,

Fig. 18 shows a limiting projection for limiting the tension of the tear tape,

Fig. 19 shows a table of test results of the tensile resistance of the tear tape,

Fig. 20 shows a table of test results of the resistance to opening of the process unit,

Fig. 21 shows a table of test results of the resistance to opening of the process unit and a tensile resistance of the tear tape,

Fig. 22 shows a table of the test results of the resistances of the toner container and the process unit in the pressure test and the drop test,

Fig. 23 shows a table of the test results of the tearing elongation of the cover seal and the tearing stability when pulling the tear tape,

Fig. 24 shows a table of the test results of the remaining sealing material and the improper image formation when the tear tape was pulled out,

Fig. 25 shows a conventional sealing element in which a cover film and a tear tape are completely welded,

Fig. 26 shows the curling of the sealing element,

Fig. 27 shows a sealing element in which a cover film and a tear tape are heat-sealed in overlapping edge areas,

Fig. 28 shows a sealing element in which a cover film and a tear tape are heat-sealed at locations in a longitudinal edge,

Fig. 29 shows a sealing element, wherein the heat seal is omitted on one of the short sides at the overlapping portion of the cover film and the tear tape,

Fig. 30 shows a sealing element in which the heat seal is only carried out on the inner edge of the overlapping section between the cover film and the tear tape,

Fig. 31 shows a sealing structure according to a first embodiment in which the sealing element is sealed in a raised structure on an opening limiting element,

Fig. 32 shows a conventional sealing structure in which the sealing member in the form of a frame is sealed on the opening limiting member,

Fig. 33 shows a conventional sealing structure in which a sealing member in the form of a protrusion is sealed on an opening restricting member and a sealing width is uniform,

Fig. 34 shows a toner container having a sealing member on which a developing device frame is arranged,

Fig. 35 shows a sectional view with an end seal,

Fig. 36 shows a table of the test results with regard to the degree of curling, the tearing stretch width and the tear stability in a heat-sealing structure of the cover film and the tear tape,

Fig. 37 shows a table of the sealing structure dimensions for heat sealing the sealing element in Experiment 2-1,

Fig. 38 shows results of the puncture resistance and the drop test in test 2-1,

Fig. 39 shows a table of the sealing structure dimensions for heat sealing the sealing element in Experiment 2-2,

Fig. 40 shows a table of the results of the puncture resistance and a drop test in test 2-2,

Fig. 41 shows a table of the sealing structure dimensions for sealing the sealing element in test 2-3,

Fig. 42 shows a table of the puncture resistance and the drop test in test 2-3,

Fig. 43 shows a table of sealing structure dimensions for heat sealing the sealing element, and

Fig. 44 shows a table of the results of the puncture resistance and the drop test in Experiment 2-4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment of the present invention will now be described with reference to the accompanying drawings.

Embodiment 1

Fig. 1 is a sectional view of an image forming apparatus with a loaded process unit according to an embodiment of the present invention. Fig. 2 is a sectional view of the process unit.

(General description)

An image forming apparatus A, as shown in Fig. 1, projects photoimage information from an optical system 1 onto a photosensitive drum which is an embodiment of the image bearing member, and a developed image is formed on the photosensitive member. In synchronism with the toner image formation, a recording material 2 is fed by a feeder 3, and in an image forming station which is in the form of a cassette (process unit B), the toner image is transferred from the photosensitive drum to a recording material by a transfer device 4. The recording material 2 is fed to a fixing device 5 in which the toner image is fixed on the recording material, and the recording material is discharged to a discharge station.

A process unit B constituting the image forming station, as shown in Fig. 2, is such that the photosensitive drum 7 is rotated while the surface thereof is uniformly charged by a charger 8 and the light image from the optical system 1 is projected onto the photosensitive drum 7 through an exposure station 9 so that a latent image is formed. The latent image is developed into a toner image by a developing device 10. The toner image is transferred therefrom to the recording material 2 by the transfer device 4, and thereafter the residual toner remaining on the photosensitive drum 7 is removed by a cleaning device. Various parts such as the photosensitive drum 7 or the like are arranged in a casing so as to constitute a process unit.

The description will be made below with respect to various parts of the image forming apparatus A and the process unit B. The description will also be made with respect to an arrangement member 15 for arranging the photosensitive Drum 7 on a cleaning container 12c and a sealing element which is arranged on a toner container 12a around an opening.

(image forming device)

The description will be made below with respect to an optical system, a feeding device, a transfer device, a fixing device and a process unit arranging device in this order.

(Optical system)

The optical system generates the light beam directed to the photosensitive member 7, which includes the image information provided by an external device or the like. As shown in Fig. 1, it comprises an optical unit 1a having a laser diode 1b, a polygon mirror 1c, a scanning motor 1d and an image forming lens 1e.

When an image signal is output from an external device such as a computer or a word processor, the laser diode 1b emits light in response to the image signal, and the emitted light is projected as the image forming beam onto the polygon mirror 1c which is rotated at a high speed by a scanning motor 1d. The image forming beam reflected by the polygon mirror 1c is projected by the image forming lens 1e and is directed by the mirror 1f onto the photosensitive drum 7, the surface of which is selectively exposed. As a result, a latent image is formed on the drum in accordance with the image information.

(Recording material feeder)

The description will be made below with regard to the structure of the feed device 3 for feeding the recording material (e.g. recording sheet, OHP film, Ge In this embodiment, two cassettes 3a and 3b are usable so that two types of recording material 2 can be selectively fed. In addition, single-sided or double-sided printing is possible.

When either the cassette 3a or the cassette 3b is selected, the top sheet is fed by a pickup roller and a separation roller pair 3d in the selected cassette. Then, it is fed to a registration roller pair 3e. The registration roller pair 3e is driven in synchronization with the image forming operation to feed the recording material 2 to an image transfer position where the photosensitive drum 7 and the transfer roller 4 come into contact.

The recording material 2 having received the toner image is fed to the image fixing device 5, in which the toner image is fixed. In the case where a single-side printing mode is selected, the recording material is fed by an intermediate feed roller pair 3f along a discharge path 3g and is then discharged by a discharge roller pair 3h with the recording side facing downward into a discharge section 6.

In the case of duplex printing (double-sided printing), a deflector plate 3i swings so that the recording material after taking an image on one side is fed to a repeat feed path 3j by an intermediate feed roller pair 3f and then temporarily stored in a repeat feed station 3k1 and 3k2. When it is to be fed again, the deflector plate 3n swings to allow the recording material stored in the repeat feed station 3m to be fed to the registration roller pair 3e by a pickup roller 30 and the feed roller pair 3p. Then, the back side of the recording material is subjected to image formation.

(Transfer facility)

The transfer device 4 transfers the toner image formed on the photosensitive drum 7 to a recording material. The transfer device 4 of this embodiment, as shown in Fig. 1, is formed by a transfer roller 4. The transfer roller 4 presses the recording material 2 against the photosensitive drum 7 in the process unit B while supplying a voltage having a polarity opposite to that of the toner image formed on the photosensitive drum 7 to the transfer roller 4, so that the toner image is transferred from the photosensitive drum 7 to a recording material 2.

(Fixing device)

The fixing device 5 is operative to fix the toner image transferred by the voltage applied to the transfer roller 4. As shown in Fig. 1, the fixing device 5 comprises a drive roller 5a and an internal heater 5b, and a fixing roller 5c which is driven by the pressure contact acting from the drive roller 5a. When the recording material with the toner image passes through a nip formed between the drive roller 5a and the fixing roller 5c, the pressure in the nip between the rollers 5a and 5c becomes effective while being exposed to the heat generated by the fixing roller 5c, thereby fixing the toner image on the recording material 2.

(Process unit arrangement device)

In the image forming apparatus A, a process unit arranging means for reliably accommodating the process unit B is provided. As shown in Fig. 3, the mounting or dismounting of the process unit B relative to a main assembly 13 is effected after opening an opening member 14. The upper part of the main assembly 13 is equipped with an opening member 14 which can be operated by a rotary joint 14a. When the opening member 14 is opened, a process unit guide member (not shown) is provided on the left and right inner surfaces of the opening member 14. These guide members act as a guide for inserting the process unit B. The process unit B is inserted along the guide, and then the opening member 14 is closed, thereby arranging the process unit B in the image forming apparatus A.

(process unit)

The description will be made below with respect to the processing unit B arranged in the image forming apparatus A.

This process unit B comprises an image bearing member and at least one process device. The process device comprises: a charger for charging the surface of the image bearing member, a developing device for forming a toner image on the image bearing member, a cleaning device for removing the residual toner from the image bearing member surface, and the like. The process unit B of this embodiment comprises an electrophotographic photosensitive drum 7 as the image bearing member, a charger 8, an exposure device 9, a developing device 10 and a cleaning device 11, the photosensitive drum 9 being surrounded by them, as shown in Fig. 2. This process device is integrally arranged in a housing, thus forming a replaceable process unit which can be loaded into or removed from the main assembly of the apparatus.

The parts of the process unit B are described in the order of photosensitive drum 7, charging device 8, exposure device 9, developing device 10 and cleaning device 11.

(Photosensitive drum)

The photosensitive drum 7 in this embodiment has a cylindrical drum base made of aluminum and an organic photoconductive layer coated thereon. The photosensitive drum 7 is rotatably mounted in the casing 12. A flange gear mounted at a longitudinal end of the photosensitive drum 7 is driven by a driving force from a driving motor mounted in the main assembly, by which the photosensitive drum 7 is rotated in a direction shown by an arrow in Fig. 2 in accordance with the image forming operation.

(Charging device)

The charging means is effective to charge the surface of the photosensitive drum 7 uniformly, and in this embodiment, it is a so-called contact charging type in which a charging roller 8 is rotatably mounted on a cleaning container 12c. The charging roller 8 has a metal roller shaft 8a, an electrically conductive elastic layer disposed thereon, a high-resistance elastic layer, and a surface protective layer. The electrically conductive elastic layer comprises an elastic rubber layer made of EPDM or NBR or other elastic rubber layer having carbon dispersed therein. It is effective to apply a bias voltage through the roller shaft 8a. The high-resistance elastic layer is made of urethane rubber or the like and comprises, for example, a small amount of an electrically conductive fine powder. It is effective to limit the leakage current to the photosensitive drum 7 to prevent the sudden drop in bias voltage even when the charging roller comes into contact with a highly electrically conductive portion such as a pin hole of the photosensitive drum 7. The protective layer is made of N-methylmethoxynylon, so that plastic material in the elastic layer of high resistance or in the electrically conductive elastic layer can be directly is in contact with the photosensitive drum 7 to deteriorate the surface of the photosensitive drum 7.

The charging roller 8 is in contact with the photosensitive drum 7, and for image formation, the charging roller 8 is driven by the rotation of the photosensitive drum 7, and the superimposed application of the DC voltage and the AC voltage to the charging roller 8 is effective to uniformly charge the surface of the photosensitive drum 7.

(Exposure device)

The exposure station 9 is operative to expose the surface of the photosensitive drum 7 uniformly charged by the charging roller 8 according to the light image supplied from an optical system 1 and thus to form an electrostatic latent image on the surface of the photosensitive drum 7. An opening 9 for introducing the light image, which is formed in the upper surface of the housing 12, constitutes the exposure means.

(Development facility)

As shown in Fig. 2, the developing device 10 has a toner container 10a for containing toner and a toner supply member 10b which is reciprocally movable in the direction shown by an arrow to supply the toner in the toner container 10a. A non-rotatable magnet 10c is arranged therein. By rotating therearound, a developing drum 10d carrying a thin toner layer is supplied to a developing zone in which the developing drum 10d is spaced from a photosensitive drum 7 by a narrow gap.

When the toner layer is to be formed on the surface of the developing drum 10d, the toner and the developing drum 10d come into contact with the triboelectric charge of the Toner in sufficient amount to develop the latent image on the photosensitive drum 7. To regulate the layer thickness of the toner, a blade 10e is arranged as shown.

(cleaning device)

The cleaning device 11 shown in Fig. 2 comprises a cleaning blade 11a for scraping the toner from the photosensitive drum 7 by contact with the surface thereof, a receiving pad 11b arranged under the blade 11a in light contact with the surface of the photosensitive drum 7 for receiving the toner scraped by the cleaning blade 11a, a member 11c for supplying the residual toner thus received into a rear part of the container, and a residual toner container 11d for receiving the removed residual toner.

(Photosensitive drum arrangement element)

The description will be made below with respect to the arranging member for rotatably arranging the photosensitive drum to the casing 12. As shown in Fig. 4, a flange gear 7a is arranged at one end of the cylindrical aluminum base of the photosensitive drum 7. The flange gear 7a is made by injection molding an insulating plastic material such as polycarbonate resin or polyacetal resin or the like. It is arranged at the end of the drum base by press fitting or is fixedly arranged using an adhesive. The support member 15 is inserted into a hole 7b which is created in the flange gear 7a to rotatably support the photosensitive drum 7.

As shown in Fig. 4, the arrangement element 15 has a first conductive element 15b which protrudes from one side surface of the base body 15a, and a second conductive element 15c which protrudes from the other side of the base body 15a. An extension 15d extends from the base body 15a. A cylindrical element 15e made of plastic material is arranged at one end of the second conductive element 15c.

The first conductive member 15b is an electrical contact for electrically grounding the photosensitive drum 7. When the process unit B is arranged in the main assembly 13, the first conductive member 15b comes into contact with a ground contact (not shown) of the main assembly 13.

On the other hand, the second conductive member 15c is inserted into a hole 7b of the flange gear 7a to rotatably support the photosensitive drum 7. As shown in Fig. 5, a base portion 15c1 received by a hole 12c1 of the cleaner 12c and an axle portion 15c2 received by the hole 7b of the flange gear 7a are integrally formed by a step portion 15c3. One end of the axle 15c2 is merged into the hole 7b toward the end for easy insertion.

When the second conductive member 12c is inserted into the hole 7b of the flange gear 7a, its end is brought into contact with a contact 7c (Fig. 4) in the photosensitive drum 7, and the photosensitive drum 7 is electrically connected to the electrical ground of the main assembly 13 through the second conductive member 15c and the first conductive member 15b. For this purpose, the first conductive member 15b and the second conductive member 15c are made of electrically conductive material. It can be, for example, steel, stainless steel, brass, aluminum or the like, with a chromium nickel coating. In this embodiment, the base body 15a and the extension 15d are formed integrally with the first conductive member 15b and the second conductive member 15c.

The plastic cylindrical member 15e is made of a material having sufficient sliding properties with respect to the flange gear 7a. Examples include polyacetal, polybutylene terephthalate, polycarbonate and the like. It may be molded onto the shaft portion 15c2 of the second conductive member 15c or a cylindrical member 15e is fixedly mounted onto the shaft portion 15c2 by press-fitting. Further, it may be optionally bonded by an adhesive. When the cylindrical member 15e is inserted into the hole 7b of the flange gear 7a, it comes into contact with the inner peripheral surface of the hole 7b to support the photosensitive drum 7. Therefore, when image formation is carried out using the assembled process unit B, the flange gear 7a is in sliding contact with the cylindrical member 15e made of resin of the arranging member 15, and therefore the sliding properties are improved.

For this reason, the scraping of the flange gear 7a made of the plastic material is prevented by the sliding contact with the metal axis, in contrast to the prior art. In addition, the generation of noise can be prevented.

Since the cylindrical member 15e is made of insulating material, the current to be supplied to the electric ground is prevented from flowing into the other path such as the flange gear 7a or the like.

Referring to Fig. 6, the dimensions of various parts of the arranging member 15 in this embodiment are given. Fig. 6A shows a front view of the arranging member 15 as seen from the second conductive member 15c. Fig. 6A shows a sectional plan view.

A diameter D1 of the first conductive element 15b is approximately 8 mm.

A protruding length L1 of the first conductive element 15b from the base body 15a is about 12 mm.

A diameter D2 of the base body portion of the second conductive element is about 12 mm.

A diameter D3 of the axial portion of the second conductive member 15c is approximately 10 mm.

A protruding length L2 of the second conductive element 15c from the base body 15a is approximately 25 mm.

A diameter D4 of a hole 15a1 for the screw of the extension is approximately 4 mm.

A diameter D6 of a slot 15d2 is approximately 4 mm.

In order to arrange the photosensitive drum 7 by the arranging member 15 on the cleaning frame 12c, as shown in Fig. 4, the shaft portion 15c2 of the arranging member 15 is inserted into the hole 7b of the flange gear 7a arranged on the photosensitive drum 7 through a hole 12c1 of the cleaning container 12c. At this time, an end portion of the shaft portion 15c2 is brought into contact with a ground contact 7c in the photosensitive drum 7. A slot or slit 15d2 in the extension 15d is operatively connected to a positioning projection 12c2 of the cleaning container 12c, and a screw 16 is threaded through the holes 15a1 and 15d2, which are respectively created in the base body 15a and the extension 15d, whereby the arranging element 15 is fixedly arranged on the cleaning container 12c.

Similarly, at the other longitudinal end of the photosensitive drum 7, the axis portion of the locating member is inserted into a hole of the flange which is arranged at the end of the drum. In this case, the similar supporting manner can be carried out using the locating member 15. However, in the case of this end, the provision of the cylindrical element 15e made of plastic material is not unavoidable.

(Sealing element for the toner container)

The sealing member disposed on the toner container 12a will be described below. As shown in Fig. 7, the toner container 12a is provided with an opening 12a1 through which the toner contained in the container is supplied to a developing drum. However, when the process unit B is not used, the toner in the container may leak out or may become damp during storage or transportation of the process unit B if the opening 12a1 is open. A sealing member S is disposed to close the opening for the purpose of hermetically sealing the opening 12a1 before use and allowing it to be opened during use.

The sealing member S comprises a cover seal 17a and a flexible tear tape 17b which are integrally formed by welding or the like to form a cover member 17. The cover member 17 is arranged on the opening restricting member 18 by welding or the like. The opening restricting member 18 is arranged adjacent to the opening 12a1 of the toner container 12a, thereby hermetically sealing the opening 12a1.

(cover seal)

As shown in Fig. 8A, the cover seal 17a has a base body member 17a1 and a sealing material layer 17a2.

The material of the base member 17a1 is such as to allow sufficient maintenance of the sealing property of the opening of the container and to have the tearing tendency effective in one direction. Examples thereof include uniaxially oriented film material or sheet material, such as uniaxially oriented polyethylene, uniaxially oriented polypropylene, uniaxially oriented foam polypropylene material or the like.

By using such a film, the force required to tear open the cover element 17 can be reduced, and in addition, the width of the toner opening created by the tearing can be made uniform.

With respect to the material of the base member 17a, which has durable longitudinal tear properties and substantial film strength, stretched foam polypropylene film or the like having a film thickness of about 120 - 140 µm and an average density of about 0.6 g/cm³ - 0.9 g/cm³ is preferable. The sealing layer 17a2 is preferably a polyethylene gasket to allow easy welding on the sealing layer of the tear tape 17b by heat sealing (heat fusing) which will be described below. Other examples are vinyl acetate resin and ionomer resin. In addition, pulse welding or high frequency welding devices are applicable if appropriate materials are selected. When a polyethylene sealing material containing several percent to several tens of percent of ethylene-vinyl acetate copolymer material is used, the film thickness is preferably 10-30 µm in consideration of the adhesive strength, and more preferably the film thickness is about 15-25 µm.

(tear tape)

The tear tape, as shown in Fig. 8B, has a base material 17b1 and a sealing material layer 17b2 on its front and back sides.

The material of the base body element 17b1 must have sufficient strength to enable the cover seal 17a to be torn open, in particular its tensile strength must preferably be approximately three times the tensile strength of the cover seal 17a. Examples of the Usable materials are biaxially oriented polyester, biaxially oriented polypropylene, polystyrene, biaxially oriented nylon or other film or sheet material. In particular, biaxially oriented polyester film with a film thickness of approximately 20-40 µm is preferred.

The material of the sealing material layer 17b2 is similar to that of the sealing material layer 17a2 of the cover gasket 17a. When the sealing material layers 17a2 and 17b2 are welded for the purpose of combining the cover gasket 17a and the tear tape 17c, they are similar materials in order to better seal them together. When the sealing material layer 17b2 is a polyethylene sealing material containing several percent to several ten percent of ethylene-vinyl acetate copolymer, the layer thickness thereof is preferably about 20-40 µm in consideration of the adhesive strength. More preferably, the layer thickness is about 25-35 µm.

With respect to the tear tape 17b, as shown in Fig. 9, a nylon layer N may be arranged to provide a buffer property in heat sealing between the base material 17b1 and the sealing material layer 17b2. The nylon layer N preferably has a layer thickness of about 10-20 µm, and more preferably about 13-17 µm.

In this embodiment, the cover seal 17a and the tear tape 17b, as shown in Fig. 8, are integrally formed by heat sealing as shown in Fig. 10 to produce a cover member 17. At this time, a longitudinal end of the tear tape 17b extends from a cover seal 17a and forms a free end. The free end portion functions as a gripping member for peeling off the cover seal 17a.

If the heat shrinkage of the base material 17a1 of the cover seal 17a is large during the heat-sealing between the cover seal 17a and the tear tape 17b, the cover member 17 may curl due to the heat-sealing, as shown in Fig. 11 If this occurs, the cover member 17 is no longer able to be precisely positioned on the opening restricting member 18. In order to reduce the degree of curling, the preferred heat shrink ratio of the base material 17a1 in the cover seal 17a is about 1-10% in the tensile direction and about 0.1-3% in the non-tensile direction.

The heat shrinkage ratio is measured when the cover member 17 is placed in a hot air circulating oven at 120ºC for 15 min.

(Opening limiting element)

The cover member 17 is arranged at the opening portion of the opening restricting member 18 as shown in Fig. 7. The opening restricting member 18 is effective to restrict the width of the opening when the toner is supplied from the toner container 12a to the developing sleeve 10d. The opening restricting member 18 has a thickness of 0.3-2 mm and is a polyester plate, a polystyrene plate, a nylon plate, an ABS plate or the like which is formed as a sheet-like member. The opening 18a is formed by punching or molding. The opening restricting member 18 is arranged on the flange 12a2 around the opening 12a1 of the toner container by ultrasonic welding or the like, and therefore it is preferably made of the same material as the container 12a. If the container 12a is made of polystyrene material, the opening limiting element 18 is also made of polystyrene material.

The above-described cover member 17 is arranged to cover the opening 18a of the opening restricting member 18 by welding or the like to hermetically close the opening 18a. When sealing is effected by the hot-press contact as shown in Fig. 12, the corona discharge treatment or the like is carried out as desired for facilitating the bonding.

With regard to the heat sealing conditions, sealing is carried out with a welding stamp 19a of a horn 19 at about 110°C-130°C, a pressure of about 1.5 kgf/cm²-5 kgf/cm² [0.15 MPa-0.49 MPa] for about 1-3 seconds. In this case, the short side overlap portion 17c where the cover gasket 17a and the tear tape 17b of the cover member 17 overlap has a thickness larger by the thickness of the tear tape 17b, and therefore a recess 19a1 corresponding to the thickness is formed in a portion corresponding to the welding stamp 19a. When the thermocompression welding is carried out using the welding stamp 19a, the opening restricting member 18 and the welding stamp 19a are arranged parallel to each other and are brought into uniform pressure contact. If this is not uniform, the sealing surface 17d of the cover member 17 is subjected to an additional stress to such an extent that in the event that the process unit B is subjected to an impact or a drop shock, the film is torn off from an inner edge 17d1 of the sealing surface 17d, which may possibly cause the toner to leak out of the toner container 12a.

As shown in Fig. 13, an overlap area (dotted portion) between the cover seal 17a and the tear tape 17b excluding the sealing surface 17d of the cover seal 17a for sealing the opening 18a (hatched portion in Fig. 13) is preferably about 50-99%, more preferably about 70-90%. The reason for this is that the stress on the edge portion covered only by the cover seal 17a is reduced with the increase of the area in which the cover seal 17a and the tear tape 17b overlap against the internal pressure by the toner in the toner container during transportation. Therefore, the toner leakage due to the tearing of the seal can be reliably prevented.

In order to effectively prevent the removal of the seal, the length of the short side of the tear tape 17b is preferably approximately 0.5-2 mm longer than the length of the short Side of the opening 18a of the opening limiting member 18, since then the pressure which acts directly on the sealing surface 17d of the cover seal 17a during transportation due to the fall or the pressure change or the like is reduced.

(Sizes of the cover seal and the like)

The dimensions of various elements that make up the sealing element S are as follows (Fig. 7):

a length of the long side of the cover seal 17a: approx. 237 mm;

a length of the short side of the cover seal 17a: approx. 51.5 mm;

Length of the long side of the tear tape 17b: approx. 574 mm;

Length of the short side of the tear tape 17b: 38.5 mm;

Length of the long side Y1 of the opening 18a of the opening limiting element 18: approx. 220 mm;

Length of the short side Y2 of the opening 18a of the opening limiting element 18: approx. 36.5 mm;

Length of the long side Y3 of the opening limiting element: approx. 278.5 mm;

Length of the short side Y4 of the opening limiting element 18: approx. 77.5 mm;

Length of the long side X1 of an opening 12a1 of the toner container 12a: approx. 221.5 mm;

Length X2 of the short side of the opening 12a1 of the toner container 12a: approx. 63.5 mm.

(Arranging the sealing element)

The opening restricting member 18 with which the cover member 17 is used is arranged on the flange 12a2 of the toner container 12a, by which the toner container 12a is hermetically sealed. In this arrangement, the toner supply member 10b is fitted into the toner container 12a, and then the arranging is carried out. As shown in Fig. 7, a tool not shown is inserted through a positioning hole 18b at an end of a short side of the opening restricting member 18 and a positioning hole 12a3 of the toner container 12a to align the holes, and the opening restricting member 18 is positioned relative to the flange 12a2, in this positioning state, the ultrasonic welding or the like is carried out to complete the welding.

Subsequently, a developing device frame 12b shown in Fig. 14 is connected to the toner container 12a. The developing drum 10d or a developing blade 10e is arranged on the developing device frame 12b. Into the positioning hole 12a3 of the toner container 12a with the sealing member S arranged thereon and in which the tear tape 17b is reversed and into the positioning hole 12b1 formed in the developing device frame 12b, a tool not shown is inserted to align the holes to accurately position the developing device frame 12b with respect to the container 12a. In this positioning state, the ultrasonic welding or the like is carried out to weld the frame 12b to the opening restricting member 18, thus combining the frame 12b, the sealing member S and the toner container 12a. As shown in Fig. 14 and Fig. 7, the tear tape 17b is reversed. More specifically, the tear tape 17b has a first portion 17b3 which extends along one surface of a cover seal 17a, and a second portion 17b4 which is arranged on the other side of the cover seal 17 and extends from one end of the first portion 17b3 in a reverse direction.

In order to perform positioning between the toner container 12a and the frame 12b, as shown in Fig. 14, positioning projections 12b2 are arranged on both sides of the frame 12b. The toner container 12a is provided with holes 12a5 which engage with the projections 12b2. In Fig. 14, a wall 12b3 is arranged at a longitudinal end of the frame 12b for arranging a drive unit for driving the toner supply member or the like. Reference numeral 18d denotes a positioning hole which becomes effective when the opening restricting member 17 is arranged on the toner container 12a. A tongue having positioning holes 12a3, 12b1 and 18b usable for positioning the developing device frame 12b or the like becomes unnecessary when the three parts are combined, and therefore the tongue is subsequently removed.

In this way, the toner is supplied through an unillustrated inlet opening into the toner container 12a disposed on the developing device frame 12b, and the opening is closed. Then, the photosensitive drum 7 is disposed therein, thus forming the process unit B. Then, the process unit B is shipped from the factory. During transportation, the cover member 17 is subjected to a stress due to a fall, impact or pressure change to which the process unit is subjected, as shown in Fig. 15. Then, there is a possibility that an inner edge portion 17d1 of the sealing surface 17d is torn off (20) as shown in Fig. 16. This is because the cover gasket 17a is made of a uniaxially oriented material, and therefore the direction of the stress in the thermocompression using the welding punch 19a is aligned with the tearing longitudinal direction, and therefore the inner edge portion is relatively easily torn, as opposed to the non-tensile direction.

To avoid this possibility, the resistance to tearing of the base material 17a1 of the cover seal 17a is important. It is preferably approximately 1.0-3.0 kgf/mm [9.81-29.42 N/mm] in the non-tension direction, and more preferably 1.3-3.0 kgf/mm [12.75-29.42 N/mm]. The layer thickness of the base material 17a1 of the cover gasket 17a is about 130-150 µm.

In the case of the above-described process unit B, the tear tape 17b is pulled out so that the cover seal 17a is torn, thereby opening the sealing member S before use. In order to prevent the leakage of the toner between the toner container 12a and the developing device frame 12b, end seals 21 made of foamed polyurethane material or the like are fixedly arranged on the rear side of the developing device frame 12b adjacent to the longitudinal ends of the developing film 12b.

The end seal 28 usually has a thickness of about 2-5 mm, and after the connection between the frame 12b and the toner container 12a, it is compressed to a thickness of about one-half or one-third so that the leakage of the toner after opening is prevented.

However, the force required to pull the tear tape 17 at the beginning of use is increased by the end seal 21, and in addition, the tear end of the cover seal 17a becomes shaggy or uneven due to friction with the end seal 21. The reason for this is as follows: If the welding between the sealing material layer 17a2 of the cover seal 17a and the sealing material layer 17b2 of the tear tape 17b is not complete, the cover seal 17a is torn approximately 2-3 mm wider than the tear width of the tear tape 17b. This is the reason for the unevenness. Therefore, the material of the sealing material layer 17a2 of the cover seal 17a is the same as or similar to that of the sealing material layer 17b2 of the tear tape 17b.

If the pulling direction of the tear tape 17 is not correct when the tear tape 17b is pulled by an operator before starting to use the process unit and the pulling force is increased significantly, even to the maximum level, it becomes impossible to pull out the tear tape 17b.

In view of this, in this embodiment, as shown in Fig. 14 and Fig. 18, projections 22a and 22b acting as regulating members for pulling are arranged at a pitch slightly larger than the width of the tear tape 19b. The projections 22a and 22b are inserted into the holes 18c and 12a4 created in the opening restricting member 18 and the toner container 12a when the frame 12b and the toner container 12a are connected. In this embodiment, the pitch between the projections 22a and 22b is about 41.5 mm, and they are each spaced about 1-3 mm from the side ends of the tear tape 17b. As is clear from Fig. 14 and Fig. 34, the end seal 21 is provided with holes 21a and 21b, and the projections 22a and 22b are in operative relationship with the holes 21a and 21b.

By providing the projections 22a and 22b as shown in Fig. 18, even if the operator erroneously pulls the tear tape 17b in an oblique direction, the projections 22a and 22b act as guides of the side ends of the tear tape 17b to allow the smooth pulling in the opening direction. When the tear tape 17b is pulled at an angle, the frictional resistance acts between the tear tape 17b and the projections 22a and 22b, and therefore the operator is alerted to the pulling of the tear tape 17b in the wrong direction.

In this embodiment, the projections 22a and 22b are arranged on the frame 12b, and the holes 12a4 are formed in the toner container 12b. Conversely, however, the toner container 12a may be provided with projections and the frame 12b is provided with holes operatively associated with them, with the same advantageous effects.

(Test results)

The test results regarding the resistance to tension or the like after the manufacture of various cover seals and tear tapes are explained.

(Experiment 1)

Two kinds of cover seals 17a are produced. The base materials 17a1 are 120 µm and 140 µm thick, respectively. They are coated with the sealing material layer 17a2 of ethylene-vinyl acetate copolymer (EVA) of the same material by dry coating to a thickness of 20 µm. As shown in Fig. 9, it is bonded to the tear tape 17b by heat sealing, thereby producing two kinds of cover members 17.

The tear tape 17b has a base material 17b1 made of biaxially oriented polyester film with a thickness of 38 µm, a sealing material layer 17b2 (EVA) with a thickness of 30 µm and a stretched nylon layer N with a thickness of 15 µm as a cushioning layer.

The heat sealing conditions are 115ºC, 2.8 kg/cm² and 3 seconds. The size of the cover seal 17a is 48.0 mm x 237 mm, and the size of the tear tape 17b is 37.5 mm x 575 mm.

The cover members 12 of each of the two types of cover members 17 are heat-sealed onto a sealing surface of the opening restricting member 18 made of a polystyrene plate having an opening 18a of 36.5 mm x 220 mm and a thickness of 0.5 mm after corona discharge treatment. In this way, the sealing member S of the toner container 12a is produced. The heat-sealing conditions are 140°C, 3.0 kg/cm² and 5.5 seconds. After it is confirmed that the parallelism between the welding die 19a and the sealing surface of the opening restricting member 18 is precisely ensured, heat-sealing is then carried out.

Then, the opening limiting element 18 with the cover element 17 is attached to the flange 12a2 of the toner container 12 by ultrasonic welding. In this way, two types of toner containers 12a are manufactured. These are referred to as Embodiment 1 and Embodiment 2.

As a comparative example, instead of the cover seal 17, a conventional easily peelable film is used, and the opening restricting member 18 is sealed thereby. Then, the opening restricting member 18 is fixed by ultrasound welding. In this way, a toner container of Comparative Example 1 was manufactured. The easily peelable film comprises a first base material having a thickness of 16 µm, a second base material having a thickness of 25 µm, a cushion layer having a thickness of 20 µm, and an EVA sealing material layer having a thickness of 30 µm. The first base material and the second base material are made of polyethylene terephthalate, and the cushion layer is made of low molecular weight polyethylene having an average molecular weight of about 10,000.

With respect to the three toner containers, the force required to peel off the tear tape, i.e. the resistance to pulling, was measured in the direction of 180º. The pulling speed is approximately 3000 mm/min.

As is clear from Fig. 19, the tensile force is low in the Embodiments 1 and 2 and is quite high in the Comparative Example 1.

In addition, each of the three toner containers is connected to a developing device frame 12b provided with pulling direction restricting projections 22a and 22b by ultrasonic welding, so that three process units are manufactured.

An end seal 21 made of foam polyurethane material is set in the process unit after it is opened. This prevents the toner from leaking out of the process unit. after it is opened, e.g. when the process unit is taken out when trouble occurs such as paper jam or the like. In view of the balance with this effect and the tensile force, its thickness is 3 mm.

Fig. 20 shows the results at a pulling speed of approximately 3000 mm/min for the respective process unit.

As is clear from Fig. 20, the required force is very small in the embodiments 1 and 2, and therefore, the operability is good. On the other hand, in the case of the process unit of the comparative example 1 using the easily peelable film, a very large force is required, and therefore, the operability is poor even to such an extent that an operator is unable to open it.

(Experiment 2)

The embodiments 1 and 2 are used with the modification in which the size of the opening is 60 mm x 220 mm, the size of the cover seal 17a is 71.5 mm x 237 mm, and the size of the tear tape 17b is 61.5 mm x 575 mm. Similarly to the experiment 1, the toner containers 12a and the process units B are manufactured. They are referred to as embodiment 3 and embodiment 4, respectively.

As a comparative example 2, instead of the cover member 17, the easily peelable film used in the comparative example 1 is used, with the size change to adjust the size of the opening of the opening restricting member 18. In a similar manner, the toner container and the process unit are manufactured.

Using the three types of toner receiving containers and processing units, the tensile strength test and the pressure resistance test are carried out, and after 550 g toner are loaded, the drop test is carried out. Fig. 21 and Fig. 22 show the results.

In the pressure resistance test, the conditions are as follows: The pressure is increased by 0.05 kgf/cm2 [4.90 kPa] at a time, with a pressure hold time of 5 seconds, and the test is carried out until the cover member is pierced by the internal pressure. The conditions of the drop tests are as follows: Three are dropped from a height of 60 cm in two ways, i.e., 1-corner-3-edge and 6-side mode, and 6-side-4-corner mode. Ten drop tests are carried out for one lot, and the toner leakage from the cover member is checked.

As is clear from Fig. 21 and Fig. 22, the record of the tear tape pulling resistance and the opening resistance in the embodiments 3 and 4 are satisfactory, and no problem occurs even if the width of the opening 18a of the opening restricting member 18 is increased to about 60 mm. In the comparative example 2, however, the operability is very poor so that an ordinary operator is unable to open.

With respect to the pressure resistance and the drop tests, the pressure resistance in Embodiments 3 and 4 is high enough, and no problem occurs in the drop test. In Comparative Example 2, the adhesive strength of the seal is not sufficient, resulting in toner leakage when the width of the opening 18a is increased as in this case.

With respect to Embodiments 3 and 4, as is clear from the foregoing results, the sealing properties of the cover seal 17a are good enough, and the tear tape 17b has a width which is larger than the opening width of the opening restricting member 18, and therefore the pressure directly acting on the sealing surface of the cover seal 17a is reduced, that is, there are significantly advantageous effects from the standpoint of pressure reduction. durability, drop resistance or other transport influences.

(Experiment 3)

This is a modification of Embodiments 3 and 4. The size of the opening of the opening restricting member 18 is 60 mm x 220 mm, and the size of the cover seal 17a is 71.5 mm x 237 mm, as in Embodiments 3 and 4. The size of the tear tape 17b is 37.5 mm x 575 mm. Similarly to Embodiments 3 and 4, the toner containers and the process units are manufactured. They are respectively referred to as Embodiment 5 and Embodiment 6.

These investigations were carried out to check whether the opening width can be reliably limited by the tear tape 17b when the opening width 17a of the opening limiting member 18 is larger than the opening width of the developing device.

The tear tape is pulled at a speed of about 3000 mm/min, and the tear elongation of the cover gasket 17a after opening, the unevenness on the end face of the cover gasket 17a at opening, i.e., the stability of tearing, are checked. The results are shown in Fig. 23.

As is clear from Fig. 23, the tear elongation of the cover seal 12a when opened is not more than 1 mm for both of them, and therefore the opening width to the developing device is sufficiently limited and the tear stability is satisfactory.

The process unit is mounted in the main assembly of the machine, and the influence on the image is checked. It is confirmed that the toner discharge characteristics are very good and there is no problem related to the image.

In the foregoing description, it has been confirmed that even if the opening width of the opening limiting member 18 is larger than the opening width of the developing device, the width of the opening of the developing device frame to the developing device is reliably limited by the tear tape 17b.

When the conventional easy-peel film is used, the opening width to the developing device cannot be limited by the sealing element.

(Experiment 4)

For each of the three types of process units manufactured according to Embodiments 1 and 2 and Comparative Example 1, 100 process units are produced. The tear tape is pulled at a pulling speed of about 3000 mm/s, and the process unit is disassembled after opening. The sealing surface on the opening restricting member 18 is checked whether the residual seal remains or not.

The opened process unit is placed in the main body, and it is checked whether or not improper image formation with white streaks or the like occurs by the introduction of the remaining sealing material into the toner. The results are shown in Fig. 24.

As shown in Fig. 24, no residual sealing material or improper image formation is observed with respect to Embodiments 1 and 2, but in Comparative Example 1, 5 process units out of 100 process units have the residual sealing material. Among five process units, the improper image formation caused thereby occurs in 3 process units.

Further embodiments will be described with reference to Figs. 25-44. First, a seal structure will be explained.

When the cover film 17a and the tear tape 17b are combined, the entirety of the overlap portion between the cover film 17a and the tear tape 17b (dotted portion) S2 is sealed except for the sealing portion (hatched portion) S1 corresponding to the opening portion of the sealing member 17 in a conventional embodiment, as shown in Fig. 25. However, since the heat shrinkage ratio of the film material of the cover film 17a and the tear tape 17b is different, the sealing member 17 may curl significantly in the longitudinal direction and the width direction after sealing, as shown in Fig. 11.

As shown in Fig. 26, when the curl degree, particularly that in the width direction k1, is about 2-3 mm, no problem occurs. However, when it is several tens of millimeters, the next step of positioning the sealing member 17 against the opening in the sealing operation becomes difficult, possibly resulting in deviation.

As a result of investigations and experiments, it was found, as shown in Fig. 27, that in the case where a sealing structure portion S3 which is an outer edge of the conventional sealing portion S2 is sealed, it is possible to manufacture the sealing member 17 substantially without curling without deteriorating the peeling properties.

The sealing width W1 of the sealing structure S3 is preferably about 2-7 mm. Particularly, with respect to the two short sides of the sealing structure S3, if the peeling sealing member 17 is reliably combined, the tearing properties are deteriorated even to the worst extent so that the cover film 17a becomes uneven after it is removed. Particularly for this reason, in the case of the toner container having an opening width of not less than 20 mm, the sealing width W1 of the two short sides is preferably about 5-7 mm.

As shown in Fig. 28, the sealing structure S3 may be exposed only on the two long sides or, as shown in Fig. 29, the sealing structure S3 may not be sealed in a short side portion corresponding to an end of tearing of a tear tape 17b (channel-shaped formation).

As shown in Fig. 30, sealing only an inner portion S4 (point portion) of the conventional sealing portion (S2 in Fig. 25) is effective to prevent curling, but since the short side portion corresponding to the tearing start is not sealed and therefore the tearing property is not good, thus generating an uneven portion of the cover sheet 17a, this is not preferable.

The following is a description of how to arrange the sealing element.

(Arranging the sealing element on the opening limiting element)

When arranging the sealing element 17 on the opening limiting element 18, the sealing element 17 is welded to the opening limiting element 18 and thus the opening 18a is hermetically sealed.

As shown in Fig. 31A, the sealing structure of the heat sealing is such that the portion corresponding to the front end and the rear end when the tear tape 17b is pulled, that is, the portion P2 (short side sealing structure) corresponding to the short side of the opening 18a is narrowed as much as possible with respect to the portion corresponding to the middle part, that is, the portion corresponding to the long side P1 (longitudinal sealing structure), taking into account the length of the short side (opening width) Y2 of the opening restricting member 18 and the amount of toner therein, so that the toner does not leak out of the container 12a upon falling, impact or the like. The short side sealing structure P2 is in the shape of a protrusion having an apex angle θ.

The longitudinal sealing structure P1 has an outer gap or an inner gap of sealing the sealing member 17 in consideration of the sealing deviation relative to the width Y5 of the longitudinal flange portion. The gaps are about 1-2 mm. The sealing width T1 of the longitudinal sealing structure is preferably about 2-5 mm. When the dimension of the short side of the opening 18a (Y1) is about 20-100 mm, it is about 3-5 mm.

The short side sealing structure P2 has an outer gap of the sealing of the sealing member 17, that is, the difference of the distance from the longitudinal end of the opening limiting member 18 of about 1.0-3.0 mm in consideration of the sealing deviation relative to a width Y6 of the short side flange of the opening limiting member 18. The sealing width T2 is about 1.5-3.5 mm. When the short side length Y2 of the opening 18a is 20 mm long, the sealing width T2 is preferably about 2.0-3.5 mm.

As described above, the sufficient pressure resistance is ensured even if the sealing width T2 of the short side sealing structure P2 is narrower than the sealing width T1 of the longitudinal sealing structure P1. When the same force is evenly applied to the long side sealing structure P1 and the short side sealing structure P2 upon falling or impact, the seal normally bulges in the longitudinal direction because the short side length Y2 of the opening 18a is shorter than the long side length Y1. From the viewpoint of the pressure resistance, the force applied to the short side sealing structure P2 is smaller than the force applied to the longitudinal sealing structure P1. Therefore, the short side sealing structure width T2 can be smaller than the longitudinal sealing structure width T1, and the pressure resistance is still sufficient.

When the developing device frame 12b is connected to the toner container 12a having the opening restricting member 18 disposed thereon by ultrasonic welding or the like, the portion of the short-side sealing structure P2 is sealed by the end seal telement 21 made of foamed polyurethane or the like, which is arranged adjacent to the frame 12b (Fig. 23), and therefore the sealing width T2 is narrower (about 1-2 mm) than the longitudinal sealing structure width T1.

The sealing element 17 sealed using the sealing structure is removed by pulling the tear tape 17b. The maximum force felt by the operator when pulling is proportional to the maximum sealing width T shown in Fig. 31B. That is, when the maximum sealing width T is large, the required pulling force is also large, and it is small when the maximum width is small. The maximum sealing width T when the peak angle of the projection is used is given by:

T = 2 · [T2/cos(θ/2)]... (1).

Accordingly, the opening resistance (the required tensile force) is proportional to the sealing width T2 of the short-side sealing structure P2. When the sealing structure is linear, as in the case of the frame structure, versus the maintaining structure, the sealing width G and the maximum sealing width T are equal, as shown in Fig. 32. When the usable sealing width G is set in consideration of the short-side length Y2 of the opening 18a, the opening resistance reaches the maximum value.

Even if the short-side sealing pattern P2 has protrusions as shown in Fig. 33A and Fig. 33B, the maximum sealing width is large as compared with the case of this embodiment (T1 > T2), as is clear from the above-mentioned equation (1) when the short-side sealing pattern width T2 is equal to the longitudinal sealing pattern width T1 (T1 = T2).

Thus, the opening resistance of the sealing element 17 is minimized by applying the raised shape in the short side sealing structure P2 and by making the sealing width T2 smaller than the longitudinal sealing structure width T1, and accordingly a significant reduction in opening resistance is achieved.

As is clear from the equation (1), the opening resistance is reduced as the apex angle θ is reduced. However, if the apex angle θ is reduced beyond 90°, the toner in the toner container 12a may enter between the sealing member 17 and the opening restricting member 18 in the bump portion, thus scattering the toner which is thus introduced when the sealing member 17 is removed. In addition, if the angle θ becomes smaller than 90°, the seal in the end portion of the bump shape (hatched portion in Fig. 31B) may come off when the toner container 12a or the process unit B is dropped or impacted, resulting in a larger pressure and thus the toner tends to leak out.

Accordingly, the short side sealing structure P2 is in the bump shape, but the apex angle is not less than 90°, whereby the scattering of the toner at the time of opening can be reduced and the printing durability can be ensured. In addition, the opening resistance can be reduced. In this case, the preferable apex angle is 90-170°, and more preferably 130-120°. The short side width Y6 of the opening restricting member 18 is preferably 3-12 mm, and more preferably 5-12 mm.

(Dimensions of the sealing element)

The dimensions of the sealing element S in this embodiment are as follows (Fig. 7 and Fig. 31):

Length of cover foil 17a: 237 mm;

Dimension of the short side of the cover film 17a: 51.5 mm;

Length of tear tape 17b: approx. 574 mm;

Length of the short side of the tear tape 17b: approx. 38.5 mm;

Longitudinal dimension Y1 of the opening 18a of the opening limiting element 18: approx. 220 mm;

Dimension Y2 of the short side of the opening 18a of the opening limiting element 18: approx. 36.5 mm;

Longitudinal dimension Y3 of the opening limiting element 18: approx. 278.5 mm;

Dimension Y4 of the short side of the opening limiting element: approx. 77.5 mm;

Longitudinal dimension Y5 of the opening limiting element 18: approx. 15 mm;

Dimension Y6 of the short side of the opening limiting element 18: approx. 11 mm;

Longitudinal sealing structure width T1: approx. 3.5 mm;

Short side sealing structure width T2: approx. 2 mm;

Tip angle θ: approx. 160°;

Longitudinal dimension X1 of the opening 12a1 of the toner container 12a: approx. 221.5 mm;

Short side length X1 of the opening 12a1 of the toner container 12a: approx. 63.5 mm.

(Arranging the sealing element)

The opening restricting member 18, which is welded to the cover member 17, is arranged on the flange 12a2 of the toner container 12a, thereby hermetically sealing the toner container 12a. In this arrangement, the toner supply member 10b is installed in the toner container 12a, and then the arranging is carried out. As shown in Fig. 34, a tool not shown is positioned by a position lation hole 18b at one end of a short side of the opening restricting member 18 and through a positioning hole 12a3 of the toner container 12a to align the holes, and the opening restricting member 18 is positioned relative to the flange 12a2, in this positioning state, the ultrasonic welding or the like is carried out to complete the welding. In this way, the toner container is assembled.

(Development Facility Framework)

Subsequently, a developing device frame 12b shown in Fig. 34 is connected to the toner container 12a. The developing drum 10d or the developing blade 10e is arranged on the developing device frame 12b.

Adjacent to the toner supply opening of the developing sheet 10e, a radiator line 12b4 which acts as an electrode for detecting the toner remaining amount change as an electrostatic capacity change is fixedly arranged.

The emitter line 12b4 is arranged in a recess formed in the developing device frame 12b, and an arranging member 12b5 is fixedly arranged in the recess by means of an adhesive, and one end 12b6 is exposed to the outside as an electrode. A toner stirring rod 12b7 is arranged next to the emitter line. The toner stirring rod 12b7 rotatably supports a wire end curved in a channel shape, and the driving force is transmitted to a gear (not shown) arranged at one of the ends, by which the toner stirring rod 12b7 is rotated to stir the toner supplied through the toner supply opening of the developing drum 10d.

The developing device frame 12b is provided with the members 22a, 22b or the like for restricting the pulling direction of the end sealing member 21 or a tear tape 12b in a predetermined position.

In the positioning hole 12a3 of the toner container 12a with the sealing member S arranged thereon and in which the tear tape 17b is deflected, and the positioning hole 12b1 formed in the developing device frame 12b, a tool not shown is inserted to align the holes and accurately position the developing device frame 12b with respect to the toner container 12a. In this positioning state, the ultrasonic welding or the like is carried out to seal the frame 12b with the opening restricting member 18, thus combining the frame 12b, the sealing member S and the toner container 12a. The description will be made with reference to the structure which is different from that shown in Fig. 14.

In this embodiment, when the toner container 12a and the frame 12b are joined, the end sealing member 21, as shown by hatching lines A in Fig. 34, presses the longitudinal end portion of the cover film 17a and the return end portion of the tear tape 17. The reason is as follows.

Since the tear tape 17b is folded back (reversed) when the pulling of the tear tape 17b (second portion 17b4) is performed, the cover film 17a is torn from the folded back end (tear end) so that it is removed. At this time, the width of the tear tape 17b is small and there is no problem. However, if the opening 18a of the opening restricting member 18 has a large width, thus the width of the tear tape 17b is large, the width of the overlap between the cover film 17a and the tear tape 17b increases in the short side sealing structure P2 (Fig. 31). Therefore, when the tear tape 17b is pulled, the force required to peel off the cover film 17a of the opening limiting member 18 becomes larger than the force (adhesion force by the short-side sealing structure P2) with which the cover film 17a adheres to the opening limiting member 18. In this case, before the cover film 17 is torn, the tear end of the cover film 17a is peeled off and lifted by the pulling force of the tear tape 17b so that it can be removed from the opening limiting member 18. so that the force required to remove the tear tape 17b becomes extremely large. In this embodiment, the tear end of the cover film 17a is limited by the end seal 21 so that the peeling and lifting of the tear end when the tear tape is pulled is prevented and therefore the cover film 17a is reliably torn off.

If the urging force of the tear end of the cover film by the end seal member 21 is too small, the peeling prevention effect is not expected. If it is too large, the opening resistance of the tear tape 17b becomes large. In view of this, the urging force is preferably 1.0 kgf-3.0 kgf [9.81 N-29.42 N], and more preferably 1.2 kgf-2.0 kgf [11.77 N-19.61 N].

When foam polyurethane, foam polyethylene, foam polypropylene or the like is used as the material for the end seal 21, and when a distance between the developing device frame 12b and the opening restricting member 18 disposed on the toner container 12a is 1-2 mm, the end seal 21 is compressed from 2-5 mm in thickness to approximately 1/2-1/3 of the thickness.

In this embodiment, the distance between the frame 12b and the opening restricting member 18 is 1 mm, and the end sealing member 21 made of foamed polyurethane having a thickness of 2 mm is arranged, and it is compressed to about half the thickness, thereby pressing the tearing end of the cover sheet 17a by the force of about 1.5 kgf [14.71 N].

(Sealing prevention structure)

In this way, the pulling direction of the tear tape 17b is regulated. However, when the tear tape 17b is pulled out, there is a possibility that the end seal member 21 is partially peeled off by the tear tape 17. When the end seal 21 is peeled off, the pulling force increases significantly to 7-8 kg, although it is usually 5 kg. In this embodiment, as shown in Fig. 34, a projection 23 is arranged in a portion of the end seal 21 adjacent to the tension side of the tear tape 17b, by which the peeling off of the end seal 21 is prevented.

As shown in Fig. 34 and Fig. 35, the projection 23 is in contact with an upstream end of the end seal 21 with respect to the tear tape pulling direction. In this embodiment, as shown in Fig. 35, the projection 23 has a height H of about 0.3-0.5 mm and a width W of about 3-5 mm. It is formed integrally with the developing device frame 12b (separate polystyrene members of similar shape may be arranged on the developing device frame 12b). At one end of the projection 23, the upstream end of the end seal member 21 is in contact, and the end seal 21 is sealed. The dimension of the projection, measured in the width direction of the tear tape 17b (perpendicular to the drawing base of Fig. 35), is preferably larger than the width of the tear tape 17b, but is not necessarily larger than the width of the tear tape 17b, or it may be provided intermittently.

It is desirable to form the corner of the projection 23 rounded (R) in order to reduce the resistance to pulling the tear tape 17b.

Due to the arrangement of the projections 23 as shown in Fig. 35, in the case where the tear tape 17b is pulled in an arrow direction, the projections 23 come into contact with the ends of the sealing member 21, so that the peeling off of the sealing member 21 and the lifting by the tear tape 17b are prevented. Therefore, the continuous peeling action can be carried out without increasing the required pulling force of the tear tape 17b.

The projections 23b may be formed integrally with the developing device frame 12b or may be separate elements.

In the above-described embodiments, an opening restricting member 18 is arranged to restrict the opening area of the toner container 12a, and the sealing member 17 is arranged on the opening restricting member 18, but the provision of the opening restricting member 18 is not mandatory, but the sealing member 17 may be arranged directly on the opening of the toner container.

In the embodiment described above, the cover film 17a and the flexible tear tape 17b are integrally formed , and the cover film 17a is torn by the tear tape 17b, but the sealing member may be in the form of a so-called easy-peel film.

Hereinafter, description will be made regarding the easy-peel film used as a sealing member 17. The preferred embodiment of the easy-peel film comprises a first body member, a second body member, a damping layer and a sealing material layer. However, this does not limit the present invention.

With respect to the first body member, stretched polypropylene film or the like has been conventionally used. However, due to the possibility of film tearing problem or the like, biaxially oriented polyethylene film having higher film strength is used.

Regarding the second base member, a nylon layer is used to impart strength (toughness) to the film, but the nylon has a property of very high moisture absorption, as a result of which curling easily occurs, and therefore biaxially oriented polyester film similar to the first base member is preferably used.

The second base body element may have an arrow or the like printed on it to guide the operator to inform about the opening direction of the toner container or the like.

If printing is not performed, the first base body element and the second base body element can be used as a single-layer base body. The single-layer base body has better welding performance and the printing is clear.

In this case, a biaxially oriented polyester film is used with a film thickness corresponding to that of the first and second base body elements.

After printing is performed on the second base body element, the first base body element and the second base body element are laminated to form a base body material.

The adhesive strength between the first base member and the second base member of the laminate is higher than the adhesive strength between the sealing material layer and the toner container, since otherwise the first base member and the second base member are peeled off from each other when opened. Therefore, a bonding method that gives high adhesive strength is used, such as by using polyester adhesive material that uses a binder similar to the film base.

The lamination is carried out so that no curling occurs in the first and second base body elements and that no air or the like is introduced therebetween.

A polyethylene layer is used for the cushioning layer. To increase the cushioning effect during heat sealing, low molecular weight polyethylene (approximately 10,000) is preferably used.

For the sealing material layer, for example, ethylene-vinyl acetate copolymer sealing material is used, preferably it is a material which contains approximately 1-20 wt.% vinyl acetate copolymer.

The sealing material layer comprises material having adhesive properties or sliding properties or the like to ensure well-adjusted and balanced easy peelability. The easy peeling function, as specified in JIS, when peeling at 15mm width and 30mm, the force is approximately 1kg/15mm-3kg/15mm. This is the value when the sealing film, which is heat-sealed at the lowest sealing pressure on a flat plate made of mainly polystyrene or the like, is peeled in the 180º direction.

Actually, the adhesive strength and the opening resistance changes depend on how much the cushion layer and the sealing material layer collapse or how much the sealing surface of the toner container deforms (squeezes) by the heat and pressure in the heat sealing operation, depending on the heat sealing conditions with respect to the toner container.

The film thickness of each layer of the easy-peelable film having the four-layer structure is determined as follows from the standpoint of the balance between the adhesive strength and the opening force. The first base member has a thickness of 10-30 µm, the second base member has a thickness of 10-30 µm, the cushion layer has a thickness of 10-30 µm, and the sealing material layer has a thickness of 30-50 µm. More preferably, the first base layer has a thickness of 10-20 µm, the second base layer has a thickness of 20-30 µm, the cushion layer has a thickness of 20-30 µm, and the sealing material layer has a thickness of 40-50 µm. Regarding the manufacturing method of the easy-peelable film, the first and second base members are laminated, and the base layers and the sealing material layer are bonded by the bonding agent. molten damping layer, and then they are cooled and wound up.

The opening can be sealed with such an easily peelable film.

(Test results)

The description is made with regard to the tests with the sealing element 17. In the first test, various cover films 17a and tear tapes 17b are produced, and the curling degree and tear resistance of the sealing element 17 with various sealing structures are examined. In the second test, the sealing element 17 is sealed on the opening limiting element with various sealing structures, and the opening resistance and pressure resistance are demonstrated.

(Experiment 1-1)

The cover film 17a is produced by dry laminating a sealing material layer 17a2 of ethylene vinyl acetate (EVA) material of 20 µm thickness on a base body 17a1 of uniaxially oriented expanded polypropylene of 140 µm thickness. The tear tape 17b has a base body 17b1 of biaxially oriented polyester film of 38 µm thickness, an EVA sealing material layer 17b2, a stretched nylon layer N as a cushioning layer of 15 µm thickness, with the layer structure shown in Fig. 9. The sealing element 17 is produced by heat sealing these.

The size of the cover film 17a is 53.5 mm x 237 mm, the size of the tear tape 17b is 38.5 mm x 575 mm, and the heat sealing condition is 120ºC, 5.0 kg/cm², and 3 seconds. The sealing structure for combining the cover film 17a and the tear tape 17b is as shown in Fig. 27, and the sealing width W1 is 5 mm.

Fig. 36 shows results of measurements of the curling degree of the sealing member 17 in the width direction as shown in Fig. 26. It is understood that in the case where the width of the tear tape 17b is very large, such as about 40 µm, the curling degree can be reduced to a very low level, i.e., 2 mm.

Such a sealing member 17 is heat-sealed on the sealing surface of the opening limiting member 18 with a thickness of 0.5 mm, an opening of 36.5 mm x 220 mm and made of a polystyrene plate after corona discharge treatment. At this time, the curling degree of the sealing member 17 is so small that there is no problem, therefore, no sealing deviation occurs on the sealing surface of the opening limiting member 18 and furthermore, the automation of production is considered possible.

The heat sealing condition is 140ºC, 3.0 kg/cm² and 5.5 seconds. The sealing surfaces between the welding die 19a and the opening restricting member 18 are detected to be exactly parallel, and thereafter heat sealing is carried out.

Then, on the flange surface of the toner container 12, the opening restricting member 18 on which the sealing member 17 is arranged is fixedly arranged by an ultrasonic welding process, whereby the toner container 12 is manufactured. Using the toner container 12a, the process unit B is manufactured.

The end sealing member 21 made of foamed polyurethane material has a dimension of 2 mm to prevent the leakage of the toner from the belt removing section of the opened process unit B when the process unit is removed from the main assembly in the event of a malfunction such as a sheet jam or the like, and thus to ensure the balance in terms of the opening resistance.

The process unit B is opened at a speed of approximately 3000 mm/min, and a tearing stretch width of the Cover film 17a after opening and the unevenness (tear resistance) of the final surface of the cover film 17a during opening are present.

The results are shown in Fig. 36. As can be seen from these results, the tear stretch width is not more than 1 mm, and therefore the opening width of the developing device is sufficiently limited and the tear stability is good.

(Experiment 1-2)

Similar to Experiment 1-1, the sealing structure for combining the cover film 17a and the tear tape 17b is made of dots as shown in Fig. 28, and the sealing width W1 is 5 mm.

The curling degree K1 of the sealing member 17 is very small as shown in Fig. 36. In addition, the sealing deviation with respect to the opening restricting member 18 does not occur. The automation of the heat sealing process is considered possible. In addition, a process unit B is manufactured similarly to the experiment 1-1, and the test is carried out on the tearing stretch width and the tearing stability of the cover film 17a. As shown in Fig. 36, the results are very satisfactory.

(Experiment 1-3)

Similar to Experiment 1-1, the sealing structure for combining the cover film 17a and the tear tape 17b as shown is in the form of a channel as shown in Fig. 29. The sealing width W1 is 7 mm.

The curling degree K1 of the sealing element 17 is very small, as shown in Fig. 36, there is no sealing deviation from the opening limiting element 18, and the automation of the sealing process is considered possible. Similar to the experiment 1-1, a process unit B is produced. and the tear stretch width and tear stability of the cover film 17a after opening are tested. As Fig. 36 shows, the results are very satisfactory.

(Experiment 1-4)

This test is the same as Test 1-1, except that the sealing material layer 17b2 is applied only to one side of the tear tape 17b, as shown in Fig. 8B.

The curling degree K1 of the sealing element 17 is very small, as shown in Fig. 36, and the sealing deviation relative to the opening limiting element 18 does not occur. The automation of the sealing process is considered possible.

Similarly to Experiment 1-1, a process unit B is prepared, and the tear stretch width and tear stability of the cover film 17a after opening are checked. The results are shown in Fig. 36 and are very satisfactory.

(Experiment 1-a)

The cover film 17a and the tear tape 17b are made of the same material and under the same sealing conditions as in the experiment 1-1. However, the sealing structure is as shown in Fig. 25, that is, the entire surface 54 in which the cover film 17a and the tear tape 17b overlap, except for the sealing portion of the sealing member 17 corresponding to the opening, that is, the entire surface of the sealing structure S3 in Fig. 27 including the non-sealing portion.

The curl degree of the sealing element 17 is 15.5 mm as shown in Fig. 36, which is very large, so that positioning the seal to the opening limiting element 18 is not easy, and consequently a seal deviation often occurs. occurs and the automation of the sealing process is considered impossible.

(Experiment 1-b)

The cover film 17a and the tear tape 17b are made of the same materials as in Experiment 1-1, and they are combined under the same heat sealing conditions but with the sealing structure in Fig. 30, i.e., the non-sealing portion in the sealing structure S3 in Fig. 27 is also sealed (S4).

The curl degree of the sealing member 17, as shown in Fig. 36, has a size of 10.3 mm, and therefore, the positioning of the seal against the opening restricting member 18 is not good, as a result, the seal deviation often occurs, and therefore, the automation of the sealing process is considered to be impossible.

Similarly to Experiment 1-1, a process unit B is prepared, and the tearing stretch width and tearing stability of the cover film 17a after opening are checked. The results are shown in Fig. 36, and the tearing stretch width is 4.5 mm. Therefore, the tearing is not steady, and furthermore, the cover film 17a becomes uneven.

The reasons for this are as follows. Since the combination of the section of the tear start is not ensured, the friction with the end seal 21 with the tension section occurs, whereby the cover film 17 is peeled off from the tear tape 17b and the unevenness or a rough surface is present, the tear width increases.

(Experiment 2-1)

The sealing element 17 and the opening limiting element 18 are used as in Experiment 1-1, and the heat sealing condition of the sealing element on the opening limiting element 18 is 140ºC, 5.0 kg/cm² and 5.5 seconds. After confirming the precise parallelism between the welding die 19a and the sealing surface of the opening restricting member 18, heat sealing is carried out. Thereafter, the opening restricting member 18 is sealed by the sealing member 17 to the flange surface of the toner container 12a by ultrasonic welding, thus manufacturing the toner container.

Two sealing structures for sealing the sealing member 17 on the opening restricting member 18 are used, as shown in Fig. 31. Samples 1 and 2 are manufactured with the structure dimensions as shown in Fig. 37.

As a comparative example, the seal structures shown in Fig. 32 and Fig. 33 are used as samples a and b.

The four kinds of toner containers 12a are joined by ultrasonic welding to the developing device frame 12b which is provided with a projection for opening direction support, so that four kinds of process units are produced.

The distance between the opening restricting member 18 and the developing device frame 12b is 1 mm, and the end sealing member 21 made of foamed polyurethane has a thickness of 2 mm.

The process unit B is opened at a speed of about 3000 mm/min. The opening resistance (the force required for opening) is shown in Fig. 37. As can be seen, no toner scattering occurs when the sealing member 17 is opened in four embodiments. However, the opening resistance is very low in samples 1 and 2, and the handling during opening is very good.

On the other hand, in the case of samples a and b (comparative examples) there is a very high opening resistance, and therefore the handling when opening is poor, even to the extent that opening by an operator is impossible.

Using the four types of toner containers 12a and the process unit, the puncture resistance is tested and the drop test (after 550 g of toner is filled) is carried out.

With regard to the puncture resistance, the pressure resistance is measured until the sealing member 17 is removed and the puncture occurs by the internal pressure when the pressure is repeatedly increased by 0.05 kgf/cm² [4.9 kPa] and the pressure is maintained for 5 seconds each. In the drop test, three process units are dropped together from a height of 90 cm. The process unit is subjected to 10 drop tests for a group in the one-corner-3-edge-6-surface mode and the 6-surface-4-corner mode, and the toner leakage is checked.

The results are shown in Fig. 38. As is clear from the results, even if the short-side sealing pattern width T is reduced by 1 mm-1.5 mm compared with the longitudinal sealing pattern width T1, the sufficient resistance to puncture and drop impact is ensured.

The above tests have confirmed that using the sealing structure of the embodiments, the toner container has low opening resistance, good opening handleability and high pressure resistance.

(Experiment 2-2)

An easily peelable film is used for the sealing element for sealing the opening 18a of the opening limiting element 18. The easily peelable film has a first base body element made of biaxially oriented polyester film with a thickness of 16 µm, a second base body element ment made of biaxially oriented polyester film with a thickness of 25 μm, a damping layer made of low molecular weight polyethylene film with a thickness of 20 μm, and an EVA sealing material layer with a thickness of 30 μm (four-layer structure). The film size of the easy-peel film is 46 mm x 574 mm.

The sealing member is heat-sealed to the opening 18a of the opening restricting member 18 as in Experiment 2-1. The sealing conditions are 150ºC, 5.0 kg/cm² and 2.5 seconds. After confirming the precise parallelism between the welding die 19a and the sealing surface of the opening restricting member 18, the heat-sealing operation is carried out. Thereafter, the opening restricting member 18 is sealed by such a sealing member to the flange surface of the toner container 12a by ultrasonic welding, thus manufacturing the toner container.

Two kinds of sealing structures for arranging the sealing member on the opening restricting member 18 are produced as shown in Fig. 31, and the structure dimensions are as shown in Fig. 39. The samples are referred to as samples 3 and 4.

As comparative examples, sealing structures shown in Fig. 32 and Fig. 33 with the structure dimensions shown in Fig. 39 are used. The samples are referred to as samples c and d.

The four kinds of toner containers 12a are joined by ultrasonic welding to the developing device frames 12b having a projection for opening direction support, thereby producing four kinds of process units.

The distance between the opening restricting member 18 and the developing device frame 12b is 1 mm, and the end sealing member 21 made of foamed polyurethane has a thickness of 2 mm.

Fig. 39 shows the opening resistance when the process unit B is opened at a speed of about 3000 mm/min. As can be seen from these results, the scattering of the toner does not occur when the sealing member 17 is opened in the four types of process units. However, in Samples 3 and 4, the opening resistance is very small, and therefore the handling during opening is very satisfactory.

On the other hand, in samples c and d (comparative examples), the opening resistance is very high and the handling when opening is poor, even to the extent that opening by an operator is impossible.

Using the four types of toner containers 12a and the process unit B, the puncture and drop tests are carried out under the same conditions as in Experiment 2-1. The results are shown in Fig. 40. As the results show, even if the short-side seal pattern width T2 is reduced by 1-1.5 mm compared with the long-side seal pattern width T1, the sufficient durability in the puncture and drop tests is ensured.

As is clear from the above description, even when the easily peelable film is used as the sealing member, the toner container has low opening resistance, good opening handleability, and high pressure resistance by using the sealing structure explained above.

(Experiment 2-3)

Using the cover film 17a similar to the cover film 17a used in Experiment 2-1, a tear tape 17b of the four-layer easy-peel film is heat-sealed, and three kinds of the tear seal member 17 of different sizes are produced as Samples 5, 6 and Sample e.

The tear tape 17b comprises a biaxially oriented polyester film having a thickness of 16 µm, a biaxially oriented nylon layer having a thickness of 25 µm, a low molecular weight polyethylene layer having a thickness of 30 µm, and an EVA sealing material layer having a thickness of 40 µm. The heat sealing condition of the tear tape 17b is 120ºC, 5 kg/cm², and 3 seconds.

The size of the cover film 17a of sample 5 is 44.0 mm x 310 mm, the size of the tear tape 17b is 32.0 mm x 700 mm, the size of the cover film 17a of sample 6 is 44.0 mm x 320 mm, the size of the tear tape 17b is 32.0 mm x 700 mm, the size of the cover film 17a of sample e is 44.0 mm x 348 mm, and the size of the tear tape 17b is 32.0 mm x 700 mm.

The sealing member 17 is heat-sealed to the sealing surface of the toner container 12a having an opening of 30.0 mm x 301 mm with the sealing structure of Fig. 31 and with the structural dimension shown in Fig. 41 after the corona discharge treatment. After confirming the precise parallelism between the welding stamp 19a and the flange surface of the toner container 12a, the heat-sealing is carried out. Three kinds of toner containers 12a are joined to the developing device frames 12b having opening direction support projections by ultrasonic welding, thus producing three process units.

The clearance between the toner container 12a and the frame 12b is 1 mm, and the end seal 21 made of foam polyurethane has a thickness of 2 mm.

Fig. 41 shows the results of the opening resistance when the process unit B is opened at a speed of about 3000 mm/min. As can be seen from the results, the opening resistance of the sealing element of each of the three types is very small, and therefore the handling during opening is very good. In particular, in the case of the Er In the raised-type seal structure with a tip angle θ of not more than 90º in sample e, the opening resistance is the lowest.

However, in samples 5 and 6, the scattering of toner does not occur when the sealing member is opened, but in sample e, the toner exists between the sealing member 17 and the flange of the toner container 12a due to the large width Y6 (24 mm) at the end of the flange, and therefore the toner is scattered when the sealing member is opened, resulting in the contamination of the environment.

Using the three kinds of toner containers 12a and the process units B, the puncture and drop tests are carried out under the same condition as in Experiments 2-1. The results are shown in Fig. 42. As can be seen from these, sufficient pressure resistance, puncture resistance and drop resistance of Samples 5 and 6 are ensured.

However, in sample e, the seal adjacent to the apex of the seal structure is loose due to the large width Y6 (24 mm) at the ends of the flange, and therefore the seal is peeled off from the apex of the bump seal structure in both the puncture test and the drop test. The leakage of the toner occurs in the same position.

From the above explanation, it is clear that the angle θ and the width Y6 are preferably in certain ranges .

(Experiment 2-4)

The sealing member 17 uses an easily peelable film to hermetically seal the opening 12a1 of the toner container 12a. The easily peelable film has a first base body member made of biaxially oriented polyester film with a thickness of 16 µm, a second base body member made of biaxially oriented polyester film with a thickness of 25 μm, a cushioning layer made of low molecular weight polyethylene with a thickness of 20 μm and an EVA sealing material layer with a thickness of 50 μm (four-layer structure). The size of the easy-peel film is 39.0 mm x 700 mm.

Such an easily peelable film is heat-sealed on the sealing surface of the toner container 12a having an opening 12a1 of dimensions 30.0 mm x 301 mm with the sealing structure shown in Fig. 31, the heat-sealing conditions being 180°C, 5.0 kg/cm² and 2.5 seconds.

The heat sealing structure dimensions are as shown in Fig. 33, and samples 7, 8 and f are manufactured as three kinds of toner containers 12a. After confirming the accurate parallelism between the welding stamp 19a and the sealing surface of the flange of the toner container, heat sealing is carried out. Three toner containers 12a are joined to the developing device frames 12b having opening direction support projections by ultrasonic welding, and thus the three kinds of process units are produced.

The clearance between the toner container 12a and the frame 12b is 1 mm, and the foam polyurethane end sealing member 21 has a thickness of 2 mm.

The opening resistance when the process unit B is opened at a speed of about 3000 mm/min is shown in Fig. 43. As can be seen from these results, the opening resistance of the sealing member is very low for all of the three types, and therefore the opening operability is very satisfactory. In particular, the opening resistance is lowest for sample f, which has a bump-shaped sealing structure with a tip angle of not more than 90°.

Although scattering of toner when removing the sealing member is not observed in Samples 7 and 8, but in Sample f, toner exists between the sealing member and the flange of the toner container 12a in the bump-shaped sealing portion, the toner is scattered when the sealing member is removed, and the environment is contaminated.

For the three kinds of toner containers 12a and the process units B, the puncture test and the drop test are carried out under the same conditions as in Experiment 2-1. The results are shown in Fig. 44. It is clear and confirmed that Samples 7 and 8 ensure sufficient pressure resistance in the puncture test and the drop test.

However, in the case of sample f, the seal adjacent to the apex of the bump shape is loose due to the large end width Y6 (24 mm) of the flange, the seal is peeled off in the puncture and drop tests adjacent to the apex, and the toner leakage occurs at the same position. From the above explanation, in the case where the easily peelable film is used as a sealing member, the angle θ of the bump seal structure and the end width Y6 of the flange are preferably within the predetermined range.

In the above-described embodiments, the material of the toner container 12a is preferably shock-resistant polyethylene material or the like to which butadiene rubber is added for the purpose of preventing cracks from falling or impact during transportation. Further, the addition of bromine- or phosphorus-based flame retardant is preferable.

(Other embodiments)

The process unit B of this embodiment is not limited to black and white image formation, but is Process unit for multi-color image formation (two colors, three colors or full colors) using a variety of developing devices.

In the above-described embodiment, the photosensitive layer of the image bearing member is an organic photoconductor (OPC), but the present invention is not limited to this case. For example, it may be amorphous silicon (A-51), selenium (Se), zinc oxide (ZnO) or cadmium sulfide (CdS) or the like. The shape of the image bearing member is not limited to a drum but may be a belt.

As the development method, a known two-component magnetic brush development method, a cascade development method, a touch-down development method, a cloud development method or another development method is applicable.

In the above-described embodiment, a so-called contact type charging method was used for the charging means, but another known structure is usable. For example, a metal shield made of aluminum or the like is arranged to enclose three sides of a tungsten wire to which a high voltage is applied, whereby positive or negative ions are moved to the surface of the photosensitive drum to uniformly charge the surface of the drum.

The loading device can be a blade type (loading blade), a cushion type, a block type, a rod type or a wire type.

For the cleaning process for the toner remaining on the photosensitive drum, a sheet, a fur brush, a magnetic brush or the like can be used.

In the above description, the image forming apparatus was in the form of a laser beam printer, but the present invention is not limited to this and is applicable to a LED printer, electrophotographic copier, facsimile machine, word processor or other image forming device.

As explained above, according to the present invention, the handling ability when removing the sealing member is improved while the leakage of developer is prevented.

Claims (9)

1. A process unit which is detachably arranged on a main assembly of an electrophotographic image forming apparatus, the process unit comprising: - an electrophotographic photosensitive element (7) capable of carrying a latent image, - a first frame with a developer container (12a) for holding a developer, - a second frame (12b) with a developer carrying member (10) for carrying the developer supplied from the developer container to develop the latent image, and - a sealing element (17b) for sealing an opening for supplying the developer from the developer container to the developer carrying element, wherein the sealing element between the first frame and the second frame (5) can be pulled off in a pulling direction to expose the opening, marked by: - an end seal (21) which is arranged on the outlet side of the opening with respect to the pulling direction, and - a pair of projections (22a, 22b) arranged between the first frame and the second frame on the respective transverse sides of the sealing element with respect to the pulling direction and extending through holes in the end seal to restrict the pulling direction of the sealing element. 2. Process unit according to claim 1, wherein the projections are arranged on the second frame and protrude from the second frame toward the first frame. 3. Process unit according to claim 2, wherein the first frame is provided with openings which receive the projections. 4. Process unit according to one of the preceding claims, wherein the projections are in the form of elevations. 5. Process unit according to one of the preceding claims, wherein a separate hard plate is arranged between the first frame and the second frame and the sealing element is arranged on the hard plate. 6. Process unit according to one of the preceding claims, wherein the projections are spaced 1 mm-3 mm from the pulling path. 7. Process unit according to one of the preceding claims, wherein the sealing element comprises a sealing film and a flexible band with a first portion extending along one surface of the sealing film and a second portion on the other surface of the sealing film, wherein the sealing film can be torn open along the first portion of the flexible band by pulling the second portion of the flexible band. 8. Process unit according to one of the preceding claims, wherein the first frame and the second frame are connected by ultrasonic welding. 9. An image forming apparatus having a process unit according to any one of the preceding claims, which is detachably mounted thereon.