JP5560945B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including an exposure member in which a plurality of light emitting units are arranged.

  Conventionally, an LED array head and an LED array head as an image forming apparatus that forms an electrostatic latent image by exposing a photosensitive drum by appropriately blinking an exposure member in which a plurality of light emitting units (for example, LEDs) are arranged Is provided with a support frame for supporting the LED array head, and a plate-shaped metal plate member provided between the LED array head and the support frame.

  The LED array head includes a substrate on which a large number of LEDs are arranged, a lens array that collects light emitted from the LEDs on a photosensitive drum, and a head frame that supports the LED array and the lens array. The head frame is a resin casing having an upper opening. Further, leaf springs are fixed to both side walls of the head frame. The leaf spring is arranged between the LED array head and the support frame in a state where the support frame supports the LED array head, and is configured to contact the plate member.

  The support frame is made of resin, and wire springs are fixed to both side walls of the support frame. The wire spring is configured to contact the leaf spring when the support frame supports the LED array head. Further, the wire spring is configured to come into contact with a metal frame provided in the apparatus main body.

  By the way, when the above-described image forming apparatus is operated, static electricity is generated in the image forming apparatus. In order to prevent the static electricity from damaging the electronic components of the board, the static electricity is concentrated on the plate member disposed above the board, the plate member is brought into contact with the leaf spring, and the leaf spring is brought into contact with the wire spring. By adopting a configuration in which the wire spring is in contact with the metal frame, static electricity concentrated on the plate member is released to the ground through the metal frame. (Patent Document 1)

JP 2010-54584 A

  However, in the above-described configuration, if any one of the members of the plate spring, the wire spring, and the metal frame has poor contact, the plate member cannot be electrically grounded, and the electronic component is caused by static electricity. Parts will be damaged.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of preventing an electronic component from being damaged with a simple configuration.

In order to achieve this object, the invention according to claim 1 includes a photosensitive drum and a plurality of light emitting portions arranged on a substrate, and a light emitting member that forms an electrostatic latent image on the photosensitive drum. And an exposure member having a casing formed of resin and holding the light emitting member, a conductive member disposed in the vicinity of the substrate and formed of a conductive material, and a main body frame made of a metal material. In the image forming apparatus, the main body frame is provided with a first engagement portion, and the exposure member is provided with a second engagement portion engageable with the first engagement portion, Both ends of the conducting member have a spring property, and the conducting member extends from one end to the other end in the longitudinal direction of the substrate in a wire shape along the longitudinal direction, and at least One end of the conducting member is the main body Frame is electrically grounded in contact with, in a state in which the conductive member is grounded electrically in contact with the body frame, wherein the first engaging portion based on the biasing force of the conduction member And the second engaging portion engage with each other, whereby the position of the exposure member in the urging direction with respect to the main body frame is determined.

  The invention according to claim 2 is the invention according to claim 1, wherein the conducting member is disposed on the outer side of the outer peripheral edge of the substrate and is disposed so as to surround the substrate. It is characterized by that.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein both ends of the conducting member are in contact with the main body frame and are electrically grounded. Yes.

The invention according to claim 4 is the invention according to any one of claims 1 to 3 , wherein the conducting member is made of stainless steel.

According to the first aspect of the present invention, the conducting member is formed in a wire shape extending along the longitudinal direction from one end to the other end in the longitudinal direction of the substrate, and at least one end of the conducting member is connected to the main body frame. They are in contact and are electrically grounded. With such a configuration, since the conducting member is in contact with only the main body frame and is electrically grounded, the conducting member can be simply configured, and the conducting member can be reliably grounded. In other words, since the conductive member, which is a single component, is electrically grounded by contacting the main body frame, the contact failure is lower than when the conductive member is electrically contacted with the main body frame via a plurality of members. The poor grounding caused by will not occur. As a result, damage to the electronic component can be prevented with a simple configuration.
Further, conduction member, in a state where the conductive member is electrically grounded, by first engaging portion based on the biasing force of the conduction member and the second engaging portion is engaged, the main body frame The position of the exposure member in the biasing direction is determined. With such a configuration, when the conducting member is electrically grounded, the exposure member can be positioned with respect to the main body frame at the same time.

  According to the second aspect of the present invention, the conductive member is disposed on the outer side of the outer peripheral edge of the substrate and is disposed so as to surround the substrate. With such a configuration, when an electrostatically charged object approaches from the outside rather than the outer peripheral edge of the substrate, the static electricity is transmitted to the conductive member before reaching the substrate. As a result, damage to the electronic component can be prevented.

  According to the third aspect of the present invention, since both end portions of the conducting member are in contact with the main body frame and are electrically grounded, static electricity can be reliably released from both end portions of the conducting member. Thereby, damage of an electronic component can be prevented.

According to the invention of claim 4 , since the conducting member is made of stainless steel, no whisker is generated in the conducting member. As a result, it is possible to prevent static electricity from flowing through the whisker and flowing to the substrate, thereby further preventing damage to electronic components.

Side sectional view showing schematic configuration of color laser printer Explanatory drawing showing the state when the upper cover is opened 1 is an exploded perspective view when the LED unit in FIG. 1 is viewed from the upper left diagonal direction. Schematic diagram when viewed from the front side after assembling the LED unit in FIG. Explanatory drawing explaining the grounding state of a wire spring when an upper cover is in an open position (A) Enlarged view of the left end when viewed from the diagonally upward direction on the front side of the LED unit in FIG. 1, (b) Left end when viewed from the diagonally downward direction on the rear side of the LED unit in FIG. Enlarged view of Explanatory drawing explaining the relationship between the wire spring and the substrate in the LED head Schematic view of the concave portion of the side frame (left side) in FIG. Explanatory drawing explaining positioning of LED unit and side frame Explanatory drawing explaining the relationship between the wire spring and board | substrate of a modification

  FIG. 1 is a side sectional view showing a schematic configuration of a color laser printer 1 as an example of an image forming apparatus according to the present embodiment.

  In the following description, unless otherwise specified, the vertical direction shown in FIG. 1 is up and down, the right side in FIG. 1 is the back, the left side is the front, the back side of the paper is the left, and the front side of the paper is the right. . The direction here is defined based on the direction seen from the person standing in front of the laser printer 1.

  As shown in FIG. 1, the color laser printer 1 includes a main body housing 10, and in the main body housing 10, a paper feeding unit 20 that supplies paper to the image forming unit 30, and an image on the fed paper. An image forming unit 30 to be formed and a paper discharge unit 90 to discharge the paper on which the image is formed are provided.

An opening 11 is formed in the upper part of the main body casing 10. And the opening part 11 is opened and closed by the upper cover 12 supported by the main body housing | casing 10 so that rotation is possible. (See Figure 2)
The upper cover 12 is rotatably provided up and down at a position covering the opening 11 (closed position) and a position exposing the opening 11 (open position) with the hinge 121 as a fulcrum.

An upper surface of the upper cover 12 serves as a paper discharge tray 13 that accumulates paper discharged from the main body housing 10. Also,
On the lower surface of the upper cover 12, as shown in FIG. 2, a metal metal plate 12a and a plurality of LED attachment members 14 for holding an LED unit 40 described later are provided.

Metal plate 12a is electrically grounded to the side frame 151 to be described later via a conduction cable 12b.

  In addition, a main body frame 15 is provided in the main body housing 10 to detachably accommodate process cartridges 50 described later. The main body frame 15 includes a metal side frame 151 (only one side is shown) as an example of a main body frame provided on the left and right sides, and a pair of cross members 152 that connect the pair of side frames 151. The main body frame 15 is fixed to the main body casing 10.

  The side frames 151 are members that position the photosensitive drum 51 by being disposed on both sides in the arrangement direction (left-right direction or longitudinal direction) of the LED array 412 of the LED head 41 described later. Further, as shown in FIG. 2, the left side frame 151 has a recess 151b that is recessed leftward. The recess 151b accommodates the left end of the LED unit 40 when the upper cover 12 is in the closed position.

(1) Paper Feed Unit The paper feed unit 20 is provided in the lower part of the main body housing 10 and is detachably attached to the main body housing 10, a paper feed roller 22, a separation roller 23 and a separation roller. A pad 24 is provided.

  In the paper feed unit 20 configured in this way, the paper in the paper feed tray is separated one by one and sent upward and supplied to the image forming unit 30.

(2) Image Forming Unit The image forming unit 30 mainly includes four LED units 40 as an example of an exposure member, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

(2-1) LED unit The LED unit 40 is connected to the LED mounting member 14 so as to be swingable. The configuration of the LED unit 40 will be described in detail later.

(2-2) Process Cartridge The process cartridge 50 is arranged side by side in the front-rear direction between the upper cover 12 and the paper feeding unit 20, and a photosensitive drum 51 on which an electrostatic latent image is formed, a charger 52, A developing roller 53, a toner storage chamber 54 for storing toner, and the like are provided.

  Each process cartridge 50 has the same configuration except for the color of the toner stored in the toner storage chamber.

(2-3) Transfer Unit The transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50, and mainly includes a drive roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel with a space in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyance belt 73 is in contact with each photosensitive drum 51. In addition, four transfer rollers 74 that sandwich the conveyor belt with the respective photosensitive drums 51 are arranged inside the conveyor belt 73 so as to face the respective photosensitive drums 51. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

(2-4) Fixing Unit The fixing unit 80 is disposed on the rear side of each process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller and presses the heating roller. ing.

In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 51 is uniformly charged by a charger and then exposed by each LED unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 51. Thereafter, toner is supplied to the electrostatic latent image from the developing roller, so that the toner image is carried on the photosensitive drum 51.

  The sheet supplied on the conveyance belt 73 passes between each photosensitive drum 51 and each transfer roller 74 disposed inside the conveyance belt 73, so that a toner image formed on each photosensitive drum 51 is obtained. Are transferred onto the paper P in the order of K, Y, M, and C. Then, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

(3) Paper Discharge Unit The paper discharge unit 90 extends upward from the exit of the fixing unit 80 and is formed so as to be reversed forward, and a plurality of pairs of conveyances that convey the paper P. A roller 92 is mainly provided. The sheet on which the toner image has been transferred and heat-fixed is transported along a paper discharge-side transport path 91 by a transport roller 92, discharged outside the main body housing 10, and accumulated in the paper discharge tray 13.

<Detailed configuration of LED unit 40>
Next, a detailed configuration of the LED unit 40 will be described with reference to FIGS.

  FIG. 3 is an exploded perspective view of the LED unit 40 in FIG. 1 as viewed from the upper left diagonal direction. FIG. 4 is a schematic view of the LED unit 40 in FIG. FIG. 5 is an explanatory diagram for explaining the grounding state of the wire spring 43 when the upper cover 12 is in the open position, and FIG. 6A is a right diagonal view of the front side of the LED unit 40 in FIG. FIG. 6B is an enlarged view of the left end when viewed from the upper side, and FIG. 6B is an enlarged view of the left end when viewed from the diagonally lower side of the rear side of the LED unit 40 in FIG. FIG. 7 is an explanatory view for explaining the relationship between the wire spring 43 and the substrate 411 in the LED head 41, and FIG. 8 is a schematic view of the concave portion 151b of the side frame 151 (left side) in FIG. Figure 9 shows the LED unit 0 and is an explanatory view illustrating the positioning of the side frame 151.

  As shown in FIG. 3, the LED unit 40 includes an LED head 41 and a holding frame 42 that holds the LED head 41.

(About LED head 41)
As shown in FIG. 4, the LED head 41 includes a plurality of LED arrays 412 as an example of a light emitting member configured by arranging a large number of LEDs on a substrate 411, and a head frame as an example of a casing that supports the substrate 411. 413 and a lens array 414 that forms an image of light emitted from each LED array 412 on the photosensitive drum 51.

  As shown in FIG. 4, the LED array 412 is arranged on the lower surface of the substrate 411 according to a predetermined pixel pitch in the left-right direction. An electronic component 60 (for example, an electrode or a capacitor) for causing the LED to emit light is arranged on the upper surface of the substrate 411.

  As shown in FIG. 3, the head frame 413 has a long shape that is long in the left-right direction, and has an open top surface. The head frame 413 is made of resin and supports the substrate 411, the LED array 412, and the lens array 414.

As illustrated in FIG. 4, the lens array 414 is formed in a long shape that is long in the left-right direction. The lens array 414 is disposed at a predetermined distance from the LED array 412 in the vertical direction, and is fixed to the head frame 413 so as to protrude downward from the lower surface of the head frame 413.

(About the holding frame 42)
As shown in FIG. 4, the holding frame 42 is made of resin and has a base portion 421 extending in the left-right direction and a pair of extending portions 422 extending downward from both ends of the base portion 421.

  As shown in FIG. 3, coil spring accommodating holes 421a that are recessed downward are formed at both ends of the upper surface 420a of the base portion 421. A coil spring 421b for pressing the holding frame 42 toward the photosensitive drum 51 is disposed in the coil spring accommodation hole 421a.

  The upper end of the coil spring 421b is in contact with the metal plate 12a provided on the upper cover 12 in a state where the LED unit 40 is attached to the LED attachment member 14 (see FIG. 4).

  On the lower surface of the base portion 421, a boss 421f protruding downward is formed. The boss 421f is press-fitted into a hole 411a formed in the substrate 411. As a result, the LED head 41 is held by the holding frame 42.

  As shown in FIG. 6A, a groove portion 421c as an example of a second engagement portion is formed at the left end portion of the front side surface 420b of the base portion 421.

  The groove part 421c is formed in a U-shape with the lower part opened. As will be described later, the groove 421c is configured to engage with a protrusion 151a provided on the side frame 151 when the LED unit 40 and the side frame 151 are positioned.

  Further, as shown in FIG. 6B, a protrusion that fixes the wire spring 43 to the holding frame 42 by engaging with the wire spring 43 described later, at the left end of the rear side surface 420c of the base portion 421. 421e is formed. Further, although not shown, the protrusion 421e is also formed on the right end of the rear side surface 420c of the base 421.

  As shown in FIG. 4, the extending portion 422 has a guide roller 422 a at the lower end. The guide roller 422 a is in contact with the circumferential surface of the photosensitive drum 51 and rolls to define the positional relationship between the LED unit 40 and the photosensitive drum 51. More specifically, the distance (interval) between the LED array 412 and the peripheral surface of the photosensitive drum 51 is defined.

(About wire springs)
As shown in FIG. 4, a wire spring 43 as an example of a conductive member is disposed between the head frame 413 and the holding frame 42.

  As shown in FIG. 6B, the wire spring 43 is fixed to the holding frame 42 by engaging with the protrusion 421 e of the holding frame 42. As shown in FIG. 7, the wire spring 43 extends linearly from one end of the substrate 411 to the other end in the left-right direction (longitudinal direction of the substrate 411) above the substrate 411. The wire spring 43 is provided in contact with the lower end portion of the coil spring 421b (see FIG. 4). The wire spring 43 is made of stainless steel.

  At both ends of the wire spring 43, as shown in FIG. 4, a contact portion 431 that is bent so as to protrude from the holding frame 42 and contacts the side frame 151 is provided.

<State of grounding of the wire spring 43>
Next, the grounding state of the wire spring 43 will be described.

  When the upper cover 12 is in the closed position as shown in FIG. 1, the wire spring 43 contacts the side frame 151 with the contact portion 431 of the wire spring 43 as shown in FIG. 4. Thereby, the wire spring 43 is electrically grounded via the side frame 151.

Further, the wire spring 43 is in contact with the coil spring 421b, the coil spring 421b is in contact with the metal plate 12a, in contact with the side frame 151 through the metal plate 12a Gashirube communication cable 12b. Thereby, the wire spring 43 is electrically grounded via the coil spring 421b, the metal plate 12a, the conductive cable 12b, and the side frame 151.

  On the other hand, when the upper cover 12 is in the open position as shown in FIG. 2, the wire spring 43 is not in contact with the side frame 151 as shown in FIG. 5, but the coil spring 421b, the metal plate 12a, It is electrically grounded through the conductive cable 12b and the side frame 151.

  As described above, the wire spring 43 is electrically grounded via the side frame 151 regardless of whether the upper cover 12 is in the open position or the closed position. Can prevent damage.

<Positioning method of LED unit 40 and side frame 151>
Next, positioning of the LED unit 40 and the side frame 151 will be described.

  As shown in FIG. 8, the side frame 151 is provided with a protruding portion 151 c that extends rightward from the side frame 151.

  As shown in FIG. 9, the protrusion 151c is formed to extend upward, and is provided with a protrusion 151a as an example of a first engagement portion that engages with the groove 421c.

  As shown in FIG. 9A, when the upper cover 12 is in the open position (see FIG. 2), the contact portion 431 of the wire spring 43 is not in contact with the side frame 151. Moreover, the groove part 421c is a state which has not moved to the position engaged with the projection part 151a.

  Then, as shown in FIG. 9B, the contact portion 431 of the wire spring 43 contacts the side frame 151 while the user moves the upper cover 12 from the open position to the closed position. At the same time, the groove 421c moves to a position where it engages with the protrusion 151a of the side frame 151.

  When the user further brings the upper cover 12 closer to the closed position, the wire spring 43 urges the LED unit 40 to the right as shown in FIG. 9C. At this time, since the left side surface 421d of the groove portion 421c and the left side surface 151d of the protrusion portion 151a are in contact with each other, the LED unit 40 is restricted from moving in the left-right direction. Thereby, the positioning of the LED unit 40 in the left-right direction is completed.

  As described above, the wire spring 43 positions the LED unit 40 in the left-right direction with respect to the side frame 151 by bringing the protrusion 151a and the groove 421c into contact with each other based on the biasing force of the wire spring 43.

<Action and effect>
The operation and effect of the color laser printer 1 configured as described above will be described.

  The wire spring 43 is formed to extend in a wire shape along the left-right direction from one end to the other end of the substrate 411 in the left-right direction, and the contact portion 431 of the wire spring 43 contacts the side frame 151 and is electrically grounded. Therefore, the grounding failure caused by the contact failure is suppressed rather than the plurality of members brought into contact with the wire spring 43 and brought into contact with the side frame 151 to be electrically grounded.

  That is, the wire spring 43 can be simply configured and the grounding of the wire spring 43 can be reliably realized.

  As a result, the wire spring 43 can prevent the electronic component 60 from being damaged due to static electricity.

  Further, since the contact portions 431 at both ends of the wire spring 43 are in contact with the side frame 151 and are electrically grounded, the wire spring 43 can reliably release static electricity from both contact portions 431. Thereby, damage to the electronic component 60 can be prevented.

  The wire spring 43 is a protrusion provided on the side frame 151 by moving the LED unit 40 to the center side of the holding frame 42 based on the urging force of the wire spring 43 in a state where the contact portion 431 is in contact with the side frame 151. By positioning the left side surface 151d of the portion 151a and the left side surface 421d of the groove portion 421c provided in the base portion 421, the LED unit 40 is positioned in the left-right direction with respect to the side frame 151.

  With such a configuration, when the wire spring 43 is electrically grounded via the side frame 151, the LED unit 40 can be positioned with respect to the side frame 151 at the same time.

  Since the wire spring 43 is made of stainless steel, no whisker is generated in the wire spring 43. As a result, static electricity can be prevented from flowing through the whiskers to the substrate 411, and damage to the electronic component 60 can be further prevented.

<Modification>
The wire spring 43 is configured to extend linearly in the left-right direction from one end to the other end of the substrate 411 in the left-right direction above the substrate 411. However, the wire spring 43 is an electron on the substrate 411. Even if it is arranged so as to surround the part 60, the same effect as in the present embodiment can be obtained.

  Further, the contact portions 431 at both ends of the wire spring 43 are configured to be in contact with the side frame 151 and electrically grounded, but at least the contact portion at one end of the wire spring 43 is connected to the side frame 151. Even in a configuration in which the contact is electrically grounded, the grounding of the wire spring 43 can be reliably realized.

  Further, the wire spring 43 is configured to extend linearly in the left-right direction from one end to the other end of the substrate 411 in the left-right direction above the substrate 411, but as shown in FIG. The spring 43 may be disposed on the outer side of the outer peripheral edge 411 b of the substrate 411 and may be disposed so as to surround the substrate 411.

  More specifically, the wire spring 43 is located on the outer side of the substrate 411 with respect to the outer peripheral edge 411 b of the substrate 411 and linearly extends in the left-right direction, and between the substrate 411 and the edge of the substrate 411. A second wire spring 43b that is outside and is bent in a U-shape so as to surround the edge of the substrate 411, and the first wire spring 43a and the second wire spring 43b are soldered. The first wire spring and the second wire spring are fixed on the outer peripheral edge of the head frame 413.

  With such a configuration, when an electrostatically charged object approaches from the outside rather than the outer peripheral edge of the substrate 411, the static electricity is transmitted to the wire spring 43 before reaching the substrate 411 and is grounded via the side frame 151. This can prevent the electronic component 60 on the substrate 411 from being damaged.

  Further, although the groove portion 421c is provided in the base portion 421 of the holding frame 42, even if it is provided in the end portion of the head frame 413, the same effect as in this embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Color laser printer, 10 ... Main body housing, 30 ... Image forming part, 11 ... Opening part, 12 ... Upper cover, 14 ... LED attachment member, 15 ... Main body frame, 151... Side frame, 151a... Projection, 151b... Recess, 151c... Projection, 40... LED unit, 41. 411 ... Substrate, 412 ... LED array, 413 ... Head frame, 414 ... Lens array, 421 ... Base part, 421a ... Coil spring accommodation hole, 421b ... Coil spring, 421c ... Groove part, 421e ... Projection part, 422 ... Extension part, 422a ... Guide roller, 43 ... Line spring, 431 ... Contact part, 51 ... Photoconductor drum, 60・And electronic parts

Claims (4)

A photosensitive drum;
An exposure member having a plurality of light emitting portions arranged on a substrate, and having a light emitting member that forms an electrostatic latent image on the photosensitive drum, and a casing that is made of resin and holds the light emitting member;
A conducting member disposed in the vicinity of the substrate and formed of a conductive material;
An image forming apparatus including a main body frame made of a metal material,
The main body frame is provided with a first engagement portion, the exposure member is provided with a second engagement portion engageable with the first engagement portion, and both end portions of the conducting member are Has springiness,
The conducting member is
The substrate is formed to extend from one end to the other end in the longitudinal direction in a wire shape along the longitudinal direction, and at least one end of the conductive member is in contact with the main body frame and is electrically grounded. ,
In a state where the conductive member is grounded to the electrical contact with the body frame, that said second engagement portion and the first engagement portion is engaged on the basis of the urging force of the conduction member In the image forming apparatus, the exposure member is positioned in the biasing direction with respect to the main body frame. The conducting member is
The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed on an outer side of an outer peripheral edge of the substrate and is disposed so as to surround the substrate.   The image forming apparatus according to claim 1, wherein both ends of the conductive member are in contact with the main body frame and are electrically grounded. The conducting member is
The image forming apparatus according to claim 1, wherein the image forming apparatus is made of stainless steel.