JPH03139675A - Destaticizer of copying machine - Google Patents

Abstract

PURPOSE:To reduce the size of the device and to make the contour of a destaticization area clear by providing a light emitting element cover made of a transparent plate which is fitted in the light-irradiation-directional opening of a light emitting element house. CONSTITUTION:The destaticizer is equipped with a printed board 11 which has respective components of the destaticizer arranged and also has linear end surfaces, a driver IC 12 for driving a light source selectively, the LED house 13 which is fitted to the printed board 11 and has the opening in a surface formed on the linear end surface side perpendicularly to the printed board 11 and split and cuts off luminous flux from respective chip LEDs constituting the light source, the chip LEDs 14a - 14b which are arranged on the printed board 11 and irradiate the printed board surface, and the LED cover 15 which is made of the transparent plate and fitted to the opening part of the LED house 13 so as to protect the chip LEDs from toner staining. Then the LED cover 15 is fitted between the ceiling plate of the LED house 13 and the printed board 11. Consequently, size is reduced and the contour of the destaticization area is made clear.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a static eliminator for erasing charges on a photosensitive drum of an image forming apparatus such as an electronic copying machine.

(Background of the Invention) An image forming apparatus such as an electronic copying machine exposes a charged photoreceptor (hereinafter, a photoreceptor drum will be explained as an example) to light according to document information to form an electrostatic latent image. This is a device that uses toner to visualize the toner image, and then transfers and fixes the toner visible image onto transfer paper.

In recent years, this type of image forming apparatus has been used in all fields of industry.

Incidentally, the static eliminator used in this type of image forming apparatus is a device that applies light to the non-image area of the photoreceptor drum to prevent toner from adhering to the non-image area (area outside the document range) and unnecessary pixel areas. This is a device for erasing the charge on the photoreceptor drum by irradiating it. For this purpose, the light emitting device is composed of a plurality of light emitting elements, and can be turned on and off in accordance with the size of the document area. As this light emitting element, a light emitting diode (hereinafter referred to as LED) is generally used.

FIG. 15 is a configuration diagram showing the configuration of an image forming apparatus around a conventional static eliminator from a side direction. Reference numeral 1 designates a photoreceptor drum constituting an image carrier; 2 a charging electrode that charges the photoreceptor drum 1 by corona discharge; and 3 a static eliminator that erases the electric charge on a non-image area of the photoreceptor drum 1. Note that this static eliminator 3 has a plurality of LEDs arranged in a direction perpendicular to the paper surface.

FIG. 16 is a block diagram showing the structure of the static eliminator 3 in detail. 3a is a printed circuit board on which each component of the static eliminator is arranged; 3b is a driver IC for selectively driving the light source;
3c is a lamp house that holds a plurality of LEDs constituting the light source and separates the luminous flux from each LED. Although it cannot be seen in this diagram, paired chip LEDs are placed in the area surrounded by the lamp house on the printed circuit board.

(Problems to be Solved by the Invention) Incidentally, in recent years, there has been a demand for smaller copying machines. For this reason, photoreceptor drums, which occupy a considerable portion of the interior of copying machines, are becoming smaller.

However, various parts are crowded around the photosensitive drum of a copying machine. As the diameter of photoreceptor drums has become smaller,
It is expected that the area will become even more crowded.

Therefore, the static eliminator also needs to be made smaller.

However, the conventional static eliminator that irradiates light perpendicularly to the printed circuit board requires a space equivalent to the size of the ED support substrate for holding the LED.

Therefore, miniaturization has been extremely difficult.

Therefore, even if it is desired to use a photosensitive drum with a small diameter, the size of the static eliminator becomes a problem, and a compact image forming apparatus cannot be realized.

It is also conceivable to use paired chip LEDs in order to downsize the static eliminator, but there are also problems in this case.

FIG. 17 is a diagram of a static eliminator using paired chip LEDs viewed from the light irradiation direction. This figure shows a case where paired chip LEDs with a gate angle of 0.4 are used. This paired chip LED is arranged on the cathode side electrode of the printed circuit board, and the anode side is connected to the anode side electrode via a wire (the electrode on the printed circuit board is omitted). When manufacturing such a static eliminator, a pair of chip LEDs is mounted (wire bonding) on a printed circuit board, and then a lamp house 3c is attached. Therefore, when installing the lamp house 3c, it is sometimes impossible to make the opening (window) of the lamp house small in order to avoid contact with the wires of the paired chip LEDs.

Furthermore, since the photoreceptor drum has a cylindrical shape, if the window portion of the lamp house is large, there is also a problem that the boundary of the static elimination area becomes unclear. That is, as shown in FIG. 18, due to the broadening of the irradiation angle, the angle of incidence on the drum surface becomes larger at the edge of the irradiation light. As a result, the contours between the image area and the non-image area become vague. This becomes a problem especially when creating a binding margin (binding margin mode). FIG. 19 is an explanatory diagram showing the result when copying is performed in the binding margin mode. There is a charge-eliminating area A at the edge of the transfer paper and at the center in the direction perpendicular to the direction of drum movement (this is referred to as the sub-scanning direction), and the rest of the area is the area where the charge is not removed (image area).
B and C. In such a case, due to the above-mentioned drum shape and spread of the irradiation angle, blurring occurs in the sub-scanning direction between the charge-eliminating area and the non-charge-eliminating area. This fading is
This may cause deterioration of image quality.

FIG. 20 is an explanatory diagram showing a state in which a transparent sheet 3s for protecting the static eliminator 3 from toner contamination is removed. Therefore, it is necessary to perform positioning accurately, which causes a decrease in work efficiency.

Furthermore, if the alignment is not performed accurately, a gap may occur, and toner may adhere to the chip LED through this gap.

Further, as shown in FIG. 21, a lens array 3d having light condensing properties may be attached in order to efficiently block light from a plurality of adjacent LEDs. In this case, it is necessary to accurately align the center of each lens with the optical axis from the LED, which causes a decrease in work efficiency.

The present invention has been made to solve the above-mentioned problems, and its purpose is to construct a compact static eliminator suitable for small-diameter photoreceptor drums, to make the outline of the static neutralization area clear, and to provide The purpose is to realize a static eliminator with high work efficiency.

(Means for Solving the Problems) The present invention, which solves the above problems, is arranged so as to face the surface of the photoreceptor drum, and by illuminating the photoreceptor drum, unnecessary charges on the photoreceptor drum are removed. In a copying machine static eliminator for erasing, LED driving IC and LE
A printed circuit board on which D is arranged and whose linear end face faces the photoreceptor drum, a plurality of LEDs arranged linearly on the printed circuit board parallel to the linear end face, and a plurality of LEDs arranged on the linear end face side of the printed board. The present invention is characterized by comprising an LED house having an opening and a partition wall at a predetermined position, and an LED cover made of a transparent plate fitted into the opening of the LED house in the light irradiation direction.

(Function) In the static eliminator of the present invention, the irradiated light from the LED illuminates the photosensitive drum in a direction parallel to the printed circuit board surface, so that the area occupied by the static eliminator in the image forming apparatus is reduced. In addition, since the irradiation light from the LED is emitted parallel to the substrate surface, the opening area of the LED house becomes smaller.
The static eliminator becomes smaller and the spread of the emission angle is suppressed.

Therefore, the outline of the static elimination area becomes clear. And since a transparent LED cover is fitted into the LED house,
It is resistant to toner staining and is easy to install.

Cleaning efficiency is improved.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram showing the configuration of a static eliminator 10 according to an embodiment of the present invention.

In the figure, 1] is a printed circuit board on which each component of the static eliminator is arranged and has a linear end surface, 12 is a driver IC 113 for selectively driving a light source, which is attached to the printed circuit board 11, and has a linear end surface. Printed circuit board 11
LED houses 14a to 1.4k are arranged on the printed circuit board 11, and have openings in a plane perpendicular to the LED houses 14a to 1.4k for separating and blocking the light beams from each of the plurality of chip LEDs constituting the light source. Chip LE that emits light in the surface direction
D115 is an LED cover made of a transparent plate attached to the opening of the LED house 13 in order to protect the chip LED from toner staining. This LED cover 15 is
It is fitted between the top plate and side plate of the LED house 13 and the printed circuit board 11.

FIG. 2 is a front view showing the state of the static eliminator of this embodiment when viewed from the opening (front) direction.

FIG. 3 is a sectional view of the photosensitive drum 1 when viewed from the axial direction.

In this case, due to the size of the document and the copying magnification, the image area A in FIG. 1 is the effective image area width of the photoreceptor drum 1, and the areas B and C adjacent to the image area A are It is a non-image area.

Then, the static eliminator 10 includes chip LEDs (chip LEDs in the present invention refer to paired chip LEDs and surface-mounted LED chips) across the entire axial width 2 of the photoreceptor drum 1 so as to face the surface of the photoreceptor drum 1. A large number of electrostatic latent images are arranged, and before the electrostatic latent image is developed, light is irradiated to erase the charges in the non-image areas B and C.

In this example, the chips L E D 1.4 are linearly arranged along the linear end surface of the printed circuit board 11 at regular intervals.

Further, the LED house 13 has an opening on the linear end surface side of the printed circuit board 11 corresponding to the chip LED 14 .

As shown in FIGS. 2 and 3, by irradiating light in a direction parallel to the surface of the printed circuit board 11,
Even considering the distance between the wire of the chip LED 14 and the LED house 13, the height H of the opening (irradiation window) of the LED house
can be kept very small. Therefore, the area occupied by the static eliminator 10 within the image forming apparatus can be considerably reduced. In other words, compared to a conventional static eliminator that is molded and uses an ED to irradiate light horizontally to the printed circuit board, or a paired chip LED that irradiates light perpendicularly to the printed circuit board, this example It can be seen that the static eliminator is quite thin.

Not only is it smaller (thinner), but the broadening of the illumination angle is also suppressed. As shown in FIG. 4, since the irradiation window of the static eliminator 10 has become smaller (the height H of the irradiation window has been suppressed), the angle of incidence on the photoreceptor drum 1 has become smaller, and the outline of the static elimination area is clear. It also has the effect of becoming Therefore, even when removing static electricity from only an arbitrary area of a document, it is possible to eliminate static electricity with a clear outline. In this case, the height H of the window portion is preferably in the range of 0.51II11 to 3.0 mm. This is because if it is larger than 3.0 mm, the irradiation angle becomes too wide, and if it is less than 0.5 mm, the amount of light decreases too much. Further, if it is less than 0.5 mm, the amount of light may become less than the specified value due to toner staining, which is not preferable.

Incidentally, since the printed circuit board 11 also serves as the bottom surface of the lamp house, the amount of material is reduced, which is economical.

In addition, since the transparent LED cover 15 is removed,
Strong against external shocks and resistant to l/ner stains. That is, even if the static eliminator 10 becomes dirty with toner, the LED chip will not get dirty. Furthermore, since the LED cover 15 is flat, cleaning work can be easily performed. In addition, when attaching the LED cover 15, it is only necessary to drop it into the area surrounded by the LED house] 3 and the printed circuit board 11, so troublesome work such as positioning is not necessary.

Therefore, workability in the manufacturing process is significantly improved.

Then, when configured as in 1., the chip LED1
4 can be automatically and easily implemented, throughput can be increased, and costs can be reduced.

If the chip L E Di 4 is a paired chip, it can be mounted in the same process as the paired chip LED mounting process.

In addition, in the case of a surface-mounted LED component, it can be mounted in the same process as a general surface mounting process (chip capacitor, chip resistor, etc.). Therefore, there is no need for a dedicated process like when mounting a molded LED.

FIG. 5 is a block diagram showing the structure of another embodiment of the present invention. The difference from FIG. 3 is that a recess is provided in the top plate portion 13a of the LED house 13 and the printed circuit board 11 in order to fit the LED cover 15 therein. Further, it is also possible to provide the LED cover 15 inside the top plate portion 1.3a as shown in FIG. 6, or to form it into a curved surface as shown in FIG.

Further, as shown in FIG. 8, it is also possible to configure the printed circuit board 11 separately for a portion where the LED house 13 is provided and a portion where the driver IC 12 is provided. in this case,
Printed circuit board 11A and driver I on the LED house 13 side
C12 side printed circuit board] and IB are connected by a flexible printed circuit board 11C. In this way, the static eliminator 10 can be freely arranged in a small space inside the image forming apparatus.

FIGS. 9 and 10 are configuration diagrams showing the configuration of still another embodiment of the present invention. In the configuration shown in this figure, parts corresponding to the conventional LED cover and LED house are formed integrally with a transparent material.
Opaque paint is applied to the parts that will become the house (other than the windows). That is, a coating film 21A, 2], B made of an opaque paint is formed on at least one of the inner or outer surface of the portion other than the window portion 21. The paint to be applied should be selected to have the desired reflectance and gloss.

In this case, the number of parts is reduced, which reduces costs and improves reliability. Also, transparent LED
The manufacturing process can be simplified by forming the coating films 21A and 21B on the house 20 in advance and then attaching the transparent LED house 20 to the printed circuit board 11.

Here, the inner surface of the LED house 13 and the coating film 21A, 2]
, B will be explained.

FIG. 11 is a characteristic diagram showing the relationship between the position from the optical axis on the drum surface and the amount of irradiated light when the reflectance is 40% and 10%. Further, FIG. 12 is a characteristic diagram showing the relationship between the position from the optical axis on the drum surface and the copy optical density [OD]. In these figures, 0D = 0 means that the toner does not adhere to the drum surface due to static electricity removal and becomes white, and 0D = 1 means that the toner adheres to the drum surface without static electricity removal and becomes black. . At a reflectance of 10%, the edges of the light amount distribution are sharp and the spread is small. On the other hand, when the reflectance is 40%, the tail of the light amount distribution is widening.

Further, it can be seen that at a reflectance of 40%, the halftone region from 0D=0 to 0D=1 (the part where incomplete charge removal is performed) is wide, and so-called blurring is likely to occur. For these reasons, it has been confirmed through experiments that the reflectance is desirably 30% or less.

Further, in the conventional static eliminator that irradiates in the direction perpendicular to the substrate, it is impossible to arrange the static eliminator at an accurate distance of 1 L from the photoreceptor drum 1 due to the deflection of the printed circuit board. That is, due to the deflection of the printed circuit board, the distances from the photosensitive drum 1 differ between the LEDs at the center and the LEDs at the ends of the static eliminator.

On the other hand, in this embodiment, since the irradiation is performed horizontally to the printed circuit board, no error occurs due to the deflection of the printed circuit board. Further, by positioning the chip LED with reference to the linear end surface of the substrate, the distance from the photosensitive drum 1- can be determined extremely accurately. For this reason,
The amount of light irradiated will also be accurate.

In addition, in order to eliminate static electricity by reducing the illumination angle as explained above, size of paired chip LED: 0.4 mm square adjacent L
Distance from ED: Bmm.

LED position: 3mm from the edge of the second board.

LED house wall thickness: 1mm (uniform).

LED cover thickness: 0.5mm.

The reflectance of the inner surface of the LED house is 30% or less.Height of the window:
Best results were obtained between 0.5 and 8.0 mm.

Note that it is important to make the wall thickness of the LED house uniform in order to improve accuracy. That is, when manufacturing an LED house by injection molding, a molten polymer is put into a mold and taken out after cooling. At this time, since the wall thickness is uniform, cooling and solidification proceed uniformly, there is less distortion and warping, and dimensional accuracy is achieved accurately.

In addition, as the material of the LED house 13, modified PPE (
PPE (polyphenylene ether))/PS (polystyrene) based resin, PPE/PBT (polybutylene tephthalate 1-), PPE/PET (polyethylene terephthalate), PPE/PCT (poly]-4-cyclohexane dimethylene tephthalate)) , Chemical resistant PPE (PPE/PA (polyamide) resin), Glass-filled (0-40%) modified PPE.

Polycarbonate (PC), Polyamide (PA), Polybutylene terephthalate (PBT), Polyethylene terephthalate (PET), Glass reinforced PET (GF-P
ET), poly 1-4-cyclohexane dimethylene tephthalate (PCT), polyacecool (POM), polymethylene pentene (PMP), glass fiber reinforced PMP (FR-PMP), ethylene vinyl alcohol copolymer (EVOH), polyphenylene sulfide (PPS), polyarylate (PAR), polysulfone (PSF), polyarylsulfone (PASF), polyethersulfone (PES), polyetherimide (PEI), ketone polymers (polyetheretherketone (PE
EK), polyketone, etc.), imide polymers (polyimide (PI), polyamideimide (FAI), etc.), fluororesins (polytetrafluoroethylene (PTFE), etc.)
etc.), acrylic acid resins, liquid crystal polymers (LCP), etc., and composites thereof can be used.

In addition, the materials used for the LED cover 15 include polycarbonate (PC), acrylic acid resin, polyarylate (PAR), liquid crystal polymer (LCP), polybutylene phthalate (PBT), polybutylene ethylene phthalate (PET), etc. can do.

In addition, the integrated transparent LED/Us 2 shown in Figure 9
0, the above-mentioned material of the LED cover may be used.

FIG. 13 is a cross-sectional view showing the structure of another embodiment of the present invention as viewed in the direction of the printed circuit board. Further, FIG. 14 shows a cross section (13th
FIG. 2 is a cross-sectional configuration diagram showing a section taken along line AA' in the figure.

In this embodiment, instead of the chip LED 14 of the paired chip of the static eliminator of the embodiment shown in FIG.
6 is used. In other words, even if a surface mount component LED1.6 is used instead of the bare chip LED14,
Effects similar to those of the aforementioned embodiments can be obtained.

In addition, in the above-mentioned embodiment, an LE is set for each adjacent chip LED.
Although the partition wall of the D house is provided, the partition wall may be provided in accordance with the paper size of the transfer paper or the division of the static elimination area, but it is also possible to provide no partition wall in other parts.

(Effects of the Invention) As described in detail above, in the present invention, the photoreceptor drum is arranged so as to face the surface of the photoreceptor drum, and the unnecessary charge on the photoreceptor drum is erased by illuminating the photoreceptor drum. A static eliminator for a copying machine includes: a printed circuit board on which an LED driving IC and an LED are arranged and whose linear end face faces the photoreceptor drum; 90 LEDs, an opening on the linear end surface side of the printed circuit board, and a partition wall at a predetermined position.
The device includes an ED house and an LED cover made of a transparent plate fitted into an opening in the light irradiation direction of the LED house. As a result, it is possible to reduce the height of the LED house, making it possible to configure the static eliminator with a thin structure, and also to suppress the spread of the amount of irradiation light in the direction of rotation of the photoreceptor drum, making it possible to reduce the irradiation. There will also be no difference in the distribution of light amount. In addition, the LED cover made of a transparent plate is
Since it is fitted between the ED house and the printed circuit board, it is resistant to toner staining and is easy to install and clean. Therefore, it is a compact static eliminator suitable for small-diameter photoreceptor drums, has a clear outline of the static neutralization area, is resistant to toner staining, is easy to install with an LED cover, and is easy to clean. I was able to make it happen.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the configuration of a static eliminator according to a first embodiment of the present invention, FIG. 2 is a front view showing the front of the static eliminator according to the embodiment shown in FIG. 1, and FIG. 4 is an explanatory diagram showing the irradiation angle of the static eliminator of the embodiment shown in FIG. 1; FIG. 5 is another embodiment of the present invention. 6 is a cross-sectional diagram showing the configuration of still another embodiment of the present invention. FIG. 7 is a cross-sectional diagram showing the configuration of still another embodiment of the present invention. FIG. 9 is a cross-sectional configuration diagram showing the configuration of still another embodiment of the present invention. FIG. 10 is a cross-sectional configuration diagram showing the configuration of still another embodiment of the present invention. 11 is a characteristic diagram showing the characteristics of the drum position and irradiation light amount. FIG. 12 is a characteristic diagram showing the characteristics of the drum position and copy density. FIG. 13 is another embodiment of the present invention. FIG. 14 is a cross-sectional view showing the AA' cross section of the embodiment shown in FIG. 12; FIG. 15 is a side view showing the conventional static eliminator together with a photoreceptor drum. Figure 16 is a configuration diagram showing the external configuration of a conventional static eliminator, Figure 17 is a configuration diagram showing the configuration of a conventional static eliminator in detail, and Figure 18 is an irradiation angle in the drum rotation direction of a conventional static eliminator. FIG. 19 is an explanatory diagram showing how static electricity is removed on transfer paper, FIG. 20 is an enlarged perspective view showing the main parts of a conventional static eliminator, and FIG. 21 is a conventional static eliminator. FIG. 2 is a cross-sectional view showing the cross-sectional configuration of the static eliminator of FIG. 1... Photoreceptor drum ] 0... Static eliminator 11...
・Printed circuit board 13...LED house 15...LED cover

Claims (1)

[Scope of Claims] A static eliminator for a copying machine that is arranged to face the surface of a photoreceptor drum and illuminates the photoreceptor drum to erase unnecessary charges on the photoreceptor drum, comprising: a light-emitting element; A printed circuit board (11) on which a driving IC and a light emitting element are arranged and whose linear end face faces the photoreceptor drum; A light emitting element (14), a light emitting element house (13) having an opening on the linear end surface side of the printed circuit board (11) and having a partition wall at a predetermined position, and an opening in the light irradiation direction of the light emitting element house (13). A static eliminator for a copying machine, comprising a light emitting element cover (15) made of an fitted transparent plate.