JP2011110761A - Exposure head, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress breakage of a connection portion of an FPC in which a control circuit is mounted and a head substrate on which a light emitting element is disposed in constitution where the FPC is connected to the head substrate. <P>SOLUTION: The exposure head includes: the head substrate on which the light emitting element is disposed; a supporting member which supports the head substrate; a flexible printed circuit board which is connected to the head substrate; a control circuit which is disposed on the flexible printed circuit board and controls light emission of the light emitting element; and a fixing member which fixes the flexible printed circuit board to the supporting member. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure head in which an FPC on which a control circuit is mounted is connected to a head substrate on which a light emitting element is disposed, and an image forming apparatus using the exposure head.

  Patent Document 1 proposes an exposure head in which a plurality of light emitting elements are formed on a glass substrate (a head substrate in the same document), and an optical system is arranged opposite to the plurality of light emitting elements. That is, the exposure head causes each of the plurality of light emitting elements to emit light and forms an image of light from each light emitting element by the optical system. In this way, a light spot can be formed on the exposed surface such as the surface of the photosensitive drum, and the exposed surface can be exposed.

  Further, this exposure head is provided with a driver IC (Integrated Circuit), and this driver IC functions as a control circuit for controlling the light emission of each light emitting element. Moreover, in this exposure head, a flexible printed circuit generally abbreviated as FPC is attached to the end of the head substrate on which the light emitting elements are formed. Film) technology.

JP 2009-160915 A

  That is, in the above-described exposure head, an FPC is pulled out from a head substrate on which a light emitting element is formed, and a driver IC as a control circuit is mounted on the FPC. However, such an exposure head may cause the following problems. In other words, since the FPC has a flexible and flexible structure, the driver IC and the FPC are largely shaken by the weight of the driver IC when the posture of the exposure head is changed, and as a result, the FPC and the head substrate. Excessive stress acts on the connecting portion of the FPC and the connecting portion of the FPC and the head substrate may be damaged.

  The present invention has been made in view of the above problems, and in a configuration in which an FPC on which a control circuit is mounted is connected to a head substrate on which a light emitting element is disposed, the breakage of the connection portion between the FPC and the head substrate is suppressed. The purpose is to provide technology that makes it possible.

  In order to achieve the above object, an exposure head according to the present invention includes a head substrate on which a light emitting element is disposed, a support member that supports the head substrate, a flexible printed circuit connected to the head substrate, and a flexible printed circuit. And a control circuit that controls light emission of the light emitting element and a fixing member that fixes the flexible printed circuit board to the support member.

  In order to achieve the above object, an image forming apparatus according to the present invention generates a latent image by an exposure head having a head substrate on which a light emitting element is disposed and a support member that supports the head substrate, and light emitted from the light emitting element. A latent image carrier to be formed, a flexible printed circuit board connected to the head substrate, a control circuit mounted on the flexible printed circuit board for controlling light emission of the light emitting element, and a fixing member for fixing the flexible printed circuit board to the support member It is characterized by having.

  In the invention thus configured (exposure head, image forming apparatus), the fixing member fixes the flexible printed circuit board to the support member that supports the head substrate. Therefore, since the fixing member restricts the swing of the flexible printed circuit board, it is possible to suppress breakage of the connection portion between the flexible printed circuit board and the head substrate.

  By the way, the control circuit generates heat while repeating the operation. Therefore, it is considered that the heat of the control circuit is conducted to the flexible printed board, and a considerable amount of heat is stored in the flexible printed board. Therefore, the support member may be made of metal, and the fixing member may be configured to bring the flexible printed board into contact with the support member. By comprising in this way, a flexible printed circuit board can be cooled with a metal support member, and the heat storage of a flexible printed circuit board can be suppressed.

  When the flexible printed circuit board is disposed with the surface opposite to the surface on which the control circuit is mounted facing the support member, the fixing member presses the control circuit toward the support member, and the flexible printed circuit board May be configured to be pressed against the support member. In this way, by pressing the flexible printed circuit board against the support member, cooling of the flexible printed circuit board by the support member can be promoted, and as a result, heat storage of the flexible printed circuit board can be more effectively suppressed.

  Further, when an optical member that forms an image of light emitted from the light emitting element is provided, the fixing member may be a cover member that covers from the optical member to the head substrate. As described above, since the fixing member has not only the function of fixing the flexible printed circuit board but also the function of the cover member that covers from the optical member to the head substrate, it is not necessary to provide a member for each function. Therefore, it is possible to reduce the cost of the exposure head and simplify the configuration.

  Further, the number of flexible printed circuit boards is not limited to one. In view of this, a second flexible printed circuit board different from the flexible printed circuit board in which a second control circuit different from the control circuit is disposed may be provided. At this time, the second flexible printed circuit board is provided with a second fixing member that fixes the second flexible printed circuit board to the support member, thereby restricting the swing of the second flexible printed circuit board, and the second flexible printed circuit board and the head substrate. It is possible to suppress the breakage of the connecting portion.

  When the head substrate has a flat plate shape that is long in the first direction and short in the second direction, the flexible printed board is connected to one side of the head substrate in the second direction, and the second flexible printed board is the head You may connect to the other side of the said 2nd direction of a board | substrate. The first fixing member fixes the flexible printed circuit board to one side of the support member in the second direction, and the second fixing member fixes the second flexible printed circuit board to the other side of the support member in the second direction. You may comprise so that it may fix.

  In addition, the data is transferred to the control circuit of the flexible printed circuit board, the first data transfer board having the first component, and the data is transferred to the second control circuit of the second flexible printed circuit board and the second component. And a second data transfer board having At this time, the first data transfer board and the second data transfer board may be arranged to face each other in the second direction. However, from the viewpoint of space saving of the exposure head, it is preferable to reduce the distance between the two data transfer substrates facing each other as much as possible. On the other hand, the contact of each component of the two data transfer boards may be an obstacle to narrowing the distance between the data transfer boards. Therefore, the first component and the second component may be arranged so as to be shifted from each other so as not to overlap when viewed from the second direction. As a result, the space between the two data transfer substrates can be reduced to save the space of the exposure head.

The top view which shows an example of the line head which can apply this invention. The partial step sectional view showing an example of the line head to which the present invention is applicable. Sectional drawing in the AA line of a light shielding member. The disassembled perspective view of a light-shielding member. The partial top view which shows the arrangement | sequence aspect of the light emitting element in a light emitting element group. The block diagram which shows the electric constitution of a line head. The partial expanded view which expanded the structure around the head substrate. The fragmentary perspective view which shows the whole line head structure. The width direction fragmentary sectional view of the whole structure of a line head. The partial exploded perspective view of a line head. The fragmentary perspective view of the structure which supplies video data and a power supply to a data transfer board | substrate. 1 is a diagram illustrating an example of an image forming apparatus to which a line head can be applied. The block diagram which shows the electric constitution of the apparatus of FIG. The partial exploded perspective view of the line head concerning a modification. The partial exploded perspective view of the line head concerning the further modification. The figure which shows the line head using a gradient index rod lens array.

First Embodiment FIG. 1 and FIG. 2 are diagrams showing an example of a line head to which the present invention can be applied. In particular, FIG. 1 is a plan view of the positional relationship between the light emitting elements and the lenses included in the line head 29 as viewed from the thickness direction TKD of the line head 29, and FIG. FIG. 2 is a partial step sectional view of the two-dot chain line of FIG. The line head 29 is long in the longitudinal direction LGD and short in the width direction LTD, and has a predetermined thickness (height) in the thickness direction TKD. In the following drawings including FIG. 1 and FIG. 2, the longitudinal direction LGD, the width direction LTD, and the thickness direction TKD of the line head 29 are shown as necessary. These directions LGD, LTD, and TKD are orthogonal or substantially orthogonal to each other. In the following description, the arrow side in the thickness direction TKD is expressed as “front” or “up”, and the opposite side to the arrow in the thickness direction TKD is expressed as “back” or “down” as necessary.

  As will be described later, when the line head 29 is applied to the image forming apparatus, the line head 29 is exposed to an exposed surface ES (photosensitive drum) that moves in the sub-scanning direction SD that is orthogonal or substantially orthogonal to the main scanning direction MD. The main scanning direction MD of the exposed surface ES is parallel or substantially parallel to the longitudinal direction LGD of the line head 29, and the sub-scanning direction SD of the exposed surface ES is a line. It is parallel or substantially parallel to the width direction LTD of the head 29. Therefore, as necessary, the main scanning direction MD and the sub-scanning direction SD are also illustrated together with the longitudinal direction LGD and the width direction LTD.

  In the line head 29 of the first embodiment, a plurality of light emitting elements E are grouped to form one light emitting element group EG (the arrangement of the light emitting elements E will be described in detail later with reference to FIG. 5). A plurality of light emitting element groups EG are discretely arranged in a zigzag pattern (3-row zigzag) (FIG. 1). Thus, each of the plurality of light emitting element groups EG is arranged so as to be displaced from each other by the distance Dg in the longitudinal direction LGD and shifted from each other by the distance Dt in the width direction LTD. In other words, it can be said that the light emitting element group rows GR in which the plurality of light emitting element groups EG are linearly arranged in the longitudinal direction are arranged in three rows GRa, GRb, GRc at different positions in the width direction LTD.

  Each light emitting element E is a bottom emission type organic EL (Electro-Luminescence) element having the same emission spectrum. That is, the organic EL elements constituting each light emitting element E are formed on the back surface 293-t of the head substrate 293 which is a glass flat plate that is long in the longitudinal direction LGD and short in the width direction LTD, and sealed by the glass sealing member 294. It has been stopped. The sealing member 294 is fixed to the back surface 293-t of the head substrate 293 with an adhesive.

  One imaging optical system is opposed to each of the plurality of light emitting element groups EG. This imaging optical system includes two lenses LS1 and LS2 that are convex on the light emitting element group EG side. In FIG. 1, the lenses LS1 and LS2 are indicated by alternate long and short dash lines, but these indicate the positional relationship between the light emitting element group EG and the lenses LS1 and LS2 in plan view in the thickness direction TKD. This does not indicate that the lenses LS1 and LS2 are directly formed on the head substrate 293. In FIG. 2, a member 297 is illustrated between the light emitting element group EG and the imaging optical systems LS1 and LS2, which will be described after the description of the imaging optical system.

  In this line head 29, a lens array LA1 in which a plurality of lenses LS1 are arranged in a staggered manner in order to arrange the lenses LS1, LS2 in opposition to a plurality of light emitting element groups EG arranged in a staggered manner in three rows, And a lens array LA2 in which three lenses LS2 are arranged in a staggered manner in three rows. That is, in the lens array LA1 (LA2), each of the plurality of lenses LS1 (LS2) is displaced from the longitudinal direction LGD by a distance Dg and is shifted from the longitudinal direction LTD by a distance Dt.

  Incidentally, the lens array LA1 (LA2) can be configured by forming a resin lens LS1 (LS2) on a light-transmitting glass flat plate. Further, in this embodiment, in view of the fact that it is difficult to produce a lens array LA1 (LA2) that is long in the longitudinal direction LGD with an integral configuration, a resin lens LS1 is formed on a relatively short glass plate. (LS2) is arranged in three rows and staggered to produce one short lens array, and a plurality of short lens arrays are arranged in the longitudinal direction LGD to form a long lens array LA1 (LA2) in the longitudinal direction LGD. Yes.

  More specifically, spacers AS1 are disposed at both ends of the front surface 293-h of the head substrate 293 in the width direction LTD, and each of the plurality of short lens arrays arranged in the longitudinal direction LGD is a spacer AS1, AS1. One lens array LA1 is constructed. In addition, spacers AS2 are arranged on both sides of the surface of the lens array LA1 in the width direction LTD, and each of a plurality of short lens arrays arranged in the longitudinal direction LGD is installed on the spacers AS2 and AS2 to form one lens array. LA2 is configured. Further, a flat support glass 299 is adhered to the surface of the lens array LA2, and each short lens array constituting the lens array LA2 is not only the spacer AS2, but also the support glass 299 from the opposite side of the spacer AS2. It is supported. The support glass 299 also has a function of covering the lens array LA2 so that the lens array LA2 is not exposed to the outside.

  Thus, the lens arrays LA1 and LA2 arranged at a predetermined interval face the head substrate 293 in the thickness direction TKD. As a result, the imaging optical systems LS1 and LS2 having the optical axis OA parallel or substantially parallel to the thickness direction TKD are opposed to the light emitting element group EG, and the light emitted from each light emitting element E of the light emitting element group EG is The head substrate 293, the imaging optical systems LS1 and LS2, and the support glass SS are transmitted in this order and irradiated onto the exposed surface ES (broken line in FIG. 2). As a result, light from each light emitting element E of the light emitting element group EG receives an image forming action from the imaging optical systems LS1 and LS2 and is irradiated to the exposed surface ES as spots, and the exposed surface ES is composed of a plurality of spots. A spot group SG is formed. Here, the imaging optical systems LS1 and LS2 are reduction reversal optical systems in which the absolute value of the imaging magnification is less than 1 and an inverted image is formed (imaging magnification is negative).

  As can be seen from the above description, in the line head 29 of the first embodiment, dedicated imaging optical systems LS1 and LS2 are arranged for each of the plurality of light emitting element groups EG. In such a line head 29, it is desirable that the light from the light emitting element group EG is incident only on the imaging optical system provided in the light emitting element group EG, and not incident on other imaging optical systems. . Therefore, in the first embodiment, a light shielding member 297 is provided between the surface 293-h of the head substrate 293 and the lens array LA1.

  3 is a cross-sectional view taken along line AA of the light shielding member, and FIG. 4 is an exploded perspective view of the light shielding member. In both figures, a light traveling direction Doa is taken in a direction parallel to the optical axis OA and from the light emitting element group EG toward the exposed surface ES (this light traveling direction Doa is parallel or substantially parallel to the thickness direction TKD). Parallel). As shown in both figures, the light shielding member 297 defines the first light shielding flat plate FP, the second light shielding flat plate LSPa, the third light shielding flat plate LSPb, the diaphragm flat plate AP, and the intervals between these flat plates FP, LSPa, LSPb, AP. It consists of a first spacer SSa and a second spacer SSb. Specifically, the flat plate and the spacer are stacked in the thickness direction TKD and fixed with an adhesive.

  Each of the flat plates FP, LSPa, LSPb, AP has a function of allowing a part of the light from the light emitting element group EG to pass and blocking the passage of the other light, and faces the light emitting element group EG. Openings Hf, Ha, Hb, and Hp are provided between the imaging optical systems LS1 and LS2. Each of these openings Hf, Ha, Hb, Hp is positioned so that the geometric center of gravity coincides with or substantially coincides with the optical axis of the imaging optical systems LS1, LS2. That is, as shown in FIGS. 3 and 4, each of the flat plates FP, LSPa, LSPb, AP has a circular opening Hf penetrating in the thickness direction TKD corresponding to the three-row staggered arrangement of the light emitting element groups EG. , Ha, Hb, and Hp are arranged in a three-row zigzag pattern. Of the light emitted from the light emitting element group EG, the light that has passed through the apertures Hf, Ha, Hb, and Hp is incident on the imaging optical systems LS1 and LS2, and most of the other lights are flat plates FP, LSPa, and LSPb. , Blocked by AP. The thicknesses of the flat plates FP, LSPa, LSPb, AP satisfy the following magnitude relationship, FP≈AP≈LSPa <LSPb, and the diameters of the openings satisfy the following magnitude relationship, Hf <Hp <Ha <Hb. ing.

  The spacers SSa and SSb are frame bodies in which substantially rectangular long holes Hsa and Hsb penetrating in the thickness direction TKD are formed. The long holes Hsa and Hsb are formed to have a size sufficient to completely include the openings Hf, Ha, Hb, and Hp when the light shielding member 297 is seen in a plan view from the thickness direction TKD. . Therefore, the light emitted from each light emitting element group EG travels through the long holes Hsa and Hsb toward the exposed surface ES (FIG. 2).

  Next, a more specific arrangement mode of the light shielding members 297 will be described in detail. The first light shielding flat plate FP is placed and fixed on the surface 293-h (FIG. 2) of the head substrate 293, and the second light shielding flat plate LSPa is disposed on the light traveling direction Doa side of the first light shielding flat plate FP. Has been. Two spacers SSa and SSb are interposed between the first light shielding plate FP and the second light shielding plate LSPa. On the light traveling direction Doa side of the second light shielding flat plate LSPa, a stray light absorbing layer AL is composed of two types of flat plates, and a first spacer SSa is provided between the second light shielding flat plate LSPa and the stray light absorbing layer AL. It is inserted. The stray light absorbing layer AL is obtained by alternately stacking two types of light shielding plates LSPa and LSPb having different opening diameters and thicknesses in the light traveling direction Doa. Specifically, the four first light shielding plates LSPa and 3 The second light-shielding flat plate LSPb is used. On the light traveling direction Doa side of the stray light absorbing layer AL, the first light shielding flat plate LSPa and the diaphragm flat plate AP are arranged in this order in the light traveling direction Doa. A spacer SSa is interposed between the stray light absorbing layer AL and the first light shielding plate LSPa, and two spacers SSa and SSb are interposed between the first light shielding plate LSPa and the aperture plate AP. It is inserted.

  Thus, by providing the light shielding member 297, a plurality of openings Hf, Ha, Hb, and Hp are provided in the light traveling direction between each light emitting element group EG and the imaging optical systems LS1 and LS2 facing the light emitting element group EG. It will be lined up in Doa. As a result, of the light emitted from the light emitting element group EG, the light passing through the openings Hf, Ha, Hb, Hp facing the light emitting element group EG reaches the imaging optical systems LS1, LS2, and the other Most of the light is shielded by the light shielding flat plates FP, LSPa, LSPb, and AP and does not reach the imaging optical systems LS1 and LS2. In this way, it is possible to realize good exposure with little influence of ghost.

  Subsequently, an arrangement mode of the light emitting elements E in the light emitting element group EG will be described. FIG. 5 is a partial plan view showing the arrangement of the light emitting elements in the light emitting element group. The one-dot chain line circle at the left end of the figure is an excerpt of the range surrounded by the one-dot chain circle in the approximate center of the figure. This figure shows the configuration of the back surface 293-t of the head substrate 293, and all the configurations shown in the figure are formed on the back surface 293-t of the head substrate 293. As shown in the figure, 17 light emitting elements E are linearly arranged at a pitch Pe1 in the longitudinal direction LGD to form one light emitting element row ER, and one light emitting element group EG includes: It is composed of four light emitting element rows ER1 to ER4 arranged at different positions in the width direction LTD. More specifically, the light emitting element group EG has the following arrangement of the light emitting elements E.

  The light emitting element row ER1 and the light emitting element row ER2 are shifted from each other by a pitch Pe2 (= Pe1 / 2) in the longitudinal direction LGD. As a result, the light emitting element row ER1 and the light emitting element row ER2 belong to the light emitting element row ER1. The light emitting elements E are alternately arranged in a staggered pattern with a pitch Pe2 in the longitudinal direction LGD. Similarly, the light emitting element row ER3 and the light emitting element row ER4 are shifted from each other by the pitch Pe2 in the longitudinal direction LGD, and as a result, the light emitting elements E belonging to the light emitting element row ER3 and the light emitting belonging to the light emitting element row ER4. The elements E are alternately arranged in a staggered pattern with a pitch Pe2 in the longitudinal direction LGD. The staggered arrangement ZA12 composed of the light emitting elements E of the light emitting element rows ER1 and ER2 and the staggered arrangement ZA34 composed of the light emitting elements E of the light emitting element rows ER3 and ER4 are mutually spaced by a pitch Pe3 (= Pe2 / 2) in the longitudinal direction LGD. There is a shift. As a result, the four light emitting elements E belonging to the light emitting element rows ER2, ER4, ER1, and ER2 are periodically arranged in this order at a pitch Pe3 in the longitudinal direction LGD.

  Here, for example, the pitch of the light emitting elements E in the longitudinal direction LGD can be obtained as the distance in the longitudinal direction LGD between the geometric centers of gravity of the two light emitting elements E arranged in the pitch.

  In the light emitting element group EG, distances Dr12, Dr23, and Dr34 in the width direction LTD between the four light emitting element rows ER1 to ER4 are as follows. That is, the distance Dr12 between the light emitting element row ER1 and the light emitting element row ER2, the distance Dr23 between the light emitting element row ER2 and the light emitting element row ER3, and the distance Dr34 between the light emitting element row ER3 and the light emitting element row ER4 have an integer ratio. Fulfill. That is, the following equation, Dr12: Dr23: Dr34 = 1: m: n (l, m, n are positive natural numbers) is satisfied. In particular, in the first embodiment, Dr12: Dr23: Dr34 = 1: m: n = 2: 3: 2.

  Here, for example, the distance Dr12 is a virtual straight line passing through the geometric center of gravity of the light emitting element E of the light emitting element row ER1 and parallel to the longitudinal direction LGD, and the longitudinal direction LGD passing through the geometric center of gravity of the light emitting element E of the light emitting element row ER2. It is calculated | required as a distance to the width direction LTD between the virtual straight lines parallel to. The distances Dr23 and Dr34 can be obtained in the same manner.

  Also, on one side of the light emitting element group EG in the width direction LTD, driving circuits DC1 and DC2 for driving a plurality of light emitting elements E belonging to the light emitting element rows ER1 and ER2 and constituting the staggered arrangement ZA12 are arranged. Yes. Specifically, the drive circuit DC1 for driving the light emitting element E in the light emitting element row ER1 and the drive circuit DC2 for driving the light emitting element E in the light emitting element row ER2 are alternately arranged in the longitudinal direction LGD. These drive circuits DC1, DC2,... Are linearly arranged in the longitudinal direction LGD with a pitch Pdc (> Pe2). Each of the drive circuits DC1 and DC2 is composed of a thin film transistor (TFT), and temporarily holds a signal value written by a driver IC 295 described later (specifically, a voltage value as a signal value is stored). And a drive current corresponding to the signal value is supplied to the light emitting element E.

  Further, in the width direction LTD, a plurality of contacts CT are formed between the light emitting elements E constituting the staggered arrangement ZA12 and the drive circuits DC1, DC2,. The plurality of contacts CT are provided adjacent to each other in a one-to-one correspondence with the plurality of light emitting elements E constituting the staggered arrangement ZA12, and in the longitudinal direction LGD at the same pitch Pe2 as the plurality of light emitting elements E. They are arranged in a straight line. Each light emitting element E constituting the staggered arrangement ZA12 and the contact CT adjacent to the light emitting element E are connected by a wiring WLa (broken line in FIG. 5). As shown in FIG. 5, the wiring Wla connecting the light emitting element E and the contact CT in the light emitting element row ER1 has a substantially constant width. On the other hand, the width of the wiring Wla connecting the light emitting element E and the contact CT in the light emitting element row ER2 is not constant, and the tip portion on the light emitting element E side is narrow. This is because the wiring WLa passes through the light emitting elements E of the light emitting element row ER1 to the light emitting elements E of the light emitting element row ER2.

  Then, the contact CT connected to the light emitting element E in the light emitting element row ER1 and the drive circuit DC1 are connected by the wiring WLb. Further, the contact CT connected to the light emitting element E in the light emitting element row ER2 and the drive circuit DC2 are connected by the wiring WLb. The drive circuits DC1 and DC2 supply drive currents to the corresponding light emitting elements E through these wiring paths. As shown in FIG. 5, among the plurality of light emitting elements E constituting the staggered arrangement ZA12, drive circuits DC1 and DC2 are connected to two light emitting elements E formed at both ends in the longitudinal direction LGD. Absent. That is, these light emitting elements E are dummy elements that are not supplied with a drive current and do not actually emit light.

  Similarly, on the other side of the light emitting element group EG in the width direction LTD, a plurality of drive circuits are arranged at a pitch Pdc (> Pe2) in the longitudinal direction LGD. These drive circuits DC3 and DC4 are provided for driving a plurality of light emitting elements E belonging to the light emitting element rows ER3 and ER4 and constituting the staggered arrangement ZA34. The drive circuits DC3 and DC4 and the light emitting element rows ER3 are provided. The relationship with ER4 (staggered arrangement ZA34) is the same as the relationship between the drive circuits DC1 and DC2 and the light emitting element rows ER1 and ER2 (staggered arrangement ZA12) described above, and a description thereof will be omitted.

  As described above, the drive circuits DC1 to DC4 are connected to the light emitting elements E of the light emitting element group EG, and each light emitting element E emits light in response to the drive current supplied from the drive circuits DC1 to DC4. . The current supply by the drive circuits DC1 to DC4 is controlled by the electrical configuration of the line head 29.

  FIG. 6 is a block diagram showing an electrical configuration of the line head. As shown in FIG. 6, the electrical configuration of the line head 29 includes a data transfer board TB and a plurality of driver ICs 295 in addition to the drive circuits DC1 to DC4 described above. The data transfer board TB transfers the video data VD received from the outside to each driver IC 295. Each driver IC 295 writes video data VD (specifically, video data VD converted into a voltage value) into the drive circuits DC1 to DC4, and performs light emission control of the light emitting element E. At this time, the driver IC 295 may write the video data VD corrected according to the deterioration of the light emitting element E, temperature characteristics, or the like into the drive circuits DC1 to DC4. Further, this writing operation may be executed by so-called time-division driving.

  The data transfer board TB also has a function of supplying power Vdd supplied from the outside to the head board 293 (drive circuits DC1 to DC4 thereof). The line head 29 according to the first embodiment has a configuration as shown in FIG. 7 around the head substrate 293 in order to realize transfer of video data VD to the head substrate 293 and power supply of the power source Vdd.

  FIG. 7 is a partial development view in which the configuration around the head substrate is expanded, and shows a state in which the configuration around the head substrate 293 is expanded as viewed from the front surface 293-t side of the head substrate 293. In addition, the broken line part of the figure has shown the part hidden in the head board | substrate 293 and the data transfer board | substrate TB in planar view. As shown in the figure, data transfer boards TB and TB are provided on both sides of the head board 293 in the width direction LTD. The data transfer board TB receives the video data VD from the outside via the flexible printed board Ftb and receives the supply of the power supply Vdd from the outside via the power harness Vtb. The data transfer board TB transfers and supplies the video data VD and the power supply Vdd received in this way to the head board 293 via the flexible printed boards 2961 and 2962. Specifically, the data transfer board TB transfers the video data VD to the respective drive circuits DC1 to DC4 of the head board 293 through the flexible printed board 2961, and supplies the power supply Vdd through the flexible printed board 2962 to the head board 293. Power to That is, the flexible printed circuit board 2961 is used for transferring video data VD, and the flexible printed circuit board 2962 is used for supplying power to the power source Vdd.

  In order to realize such an operation, specifically, each end portion in the width direction LTD of the head substrate 293 and the data transfer substrate TB are connected by flexible printed circuit boards 2961 and 2962. More specifically, the terminals of the flexible printed boards 2961 and 2962 are connected to terminals (not shown) formed on the connector Ctb of the data transfer board TB or the head board back surface 293-t. That is, in FIG. 7, terminals (not shown) are formed at both ends of the surfaces of the flexible printed boards 2961 and 2962 (surfaces seen in the plan view), and one of the flexible printed boards 2961 and 2962 (the other is the other). ) Terminal is connected to the terminal on the back surface 293-t of the head substrate, and the other (one) terminal of the flexible printed circuit boards 2961 and 2962 is connected to the connector Ctb of the data transfer board TB.

  Further, as described above, the writing to the video data VD with respect to the drive circuits DC1 to DC4 of the head substrate 293 is executed under the control of the driver IC 295. Therefore, in FIG. 7, a terminal (not shown) is formed at the center of the surface of the flexible printed circuit board 2961 (the surface seen in plan view), and a driver IC 295 is mounted on the terminal by the COF technique. . Accordingly, the video data VD output from the data transfer board TB is once delivered to the driver IC 295, and then the driver IC 295 writes the video data VD into the drive circuits DC1 to DC4 of the head board 293.

  As described above, in the first embodiment, since the driver IC is mounted on the flexible printed board 2961 instead of the head board 293, the head board 293 can be narrowed in the width direction LTD. Space saving of the head 29 can be realized.

  In the first embodiment, a plurality of flexible printed boards 2961 and 2962 are provided on each of one side and the other side of the head substrate 293 in the width direction LTD. That is, four flexible printed boards 2962 are provided on one side of the width direction LTD of the head substrate 293 with a space in the longitudinal direction LGD, and two sheets are provided between the adjacent flexible printed boards 2962 and 2962. Flexible printed circuit boards 2961 and 2961 are provided. Thus, on one side of the head substrate 293 in the width direction LTD, two flexible printed boards 2961 and 2961 and one flexible printed board 2962 are periodically provided in this order in the longitudinal direction LGD. Similarly, on the other side of the head substrate 293 in the width direction LTD, two flexible printed boards 2961 and 2961 and one flexible printed board 2962 are periodically provided in this order in the longitudinal direction LGD.

  Incidentally, for the flexible printed circuit board 2961 provided on one side in the width direction LTD of the head substrate 293, each light emitting element E of the light emitting element group row GRa and each of the light emitting element rows ER1 and ER2 of the light emitting element group row GRb. A drive circuit for driving the light emitting element E is connected. On the other hand, for the flexible printed circuit board 2961 provided on the other side in the width direction LTD of the head substrate 293, each light emitting element E of the light emitting element group row GRc and light emitting element row ER3 of the light emitting element group row GRb, A drive circuit for driving each light emitting element E of ER4 is connected. As described above, in the first embodiment, by providing the flexible printed circuit boards 2961 on both sides in the width direction LTD of the head substrate 293, the wiring for connecting the drive circuits DC1 to DC4 and the flexible printed circuit board 2961 can be easily routed. Yes. In particular, when the line head 29 is configured so that exposure can be performed at a resolution of 2400 dpi (dot per inch) or more, the flexible printed circuit board 2961 is drawn from both sides in the width direction LTD, and wiring is performed on the head board 293. It is preferable to simplify.

  Further, as described above, the two flexible printed boards 2961 and 2961 and the one flexible printed board 2962 are periodically provided in this order in the longitudinal direction LGD. In other words, the flexible printed boards for a plurality of data are provided. While the printed circuit board 2961 is disposed, the flexible printed circuit boards 2962 for each power source are disposed in a distributed manner. In this way, by distributing the power supply flexible printed circuit board 2962 in the longitudinal direction LGD and supplying power to the head substrate 293, the length of the power supply line on the head substrate 293 can be shortened and the voltage drop can be suppressed. it can.

  As described above, the line head 29 has an electrical configuration in which the head substrate 293 and the data transfer substrate TB are connected by the flexible printed boards 2961 and 2962, and the driver IC is mounted on the flexible printed board 2961. The line head 29 has an overall configuration as described below in order to integrally support these electrical configurations and the optical configuration shown in FIG. FIG. 8 is a partial perspective view showing the overall configuration of the line head. FIG. 9 is a partial cross-sectional view in the width direction of the overall configuration of the line head. FIG. 10 is a partially exploded perspective view of the line head, and particularly shows a state where a cover member 291 described later is removed.

  As shown in these drawings, the line head 29 includes a base 290 having a substantially rectangular parallelepiped shape elongated in the longitudinal direction LGD. The base 290 is a rigid member using a metal such as iron as a base material. The base 290 supports the optical configuration shown in FIG. Specifically, the bottom surface of the sealing member 294 bonded to the back surface 293-t of the head substrate 293 is bonded and fixed to the top surface of the base 290.

  Further, below the base 290, the two data transfer boards TB and TB described above are arranged in a state of facing each other in the width direction TKD. As described above, the reason why the data transfer boards TB and TB are arranged at positions deviating downward from the base 290 is that a sufficient space for mounting components on the data transfer board TB is secured without being interfered with the base 290. It is to do. Further, a substrate support plate 2901 for supporting these data transfer substrates TB and TB is provided on the bottom surface of the base 290. The substrate support plate 2901 is positioned substantially in the middle of the data transfer substrates TB and TB in the thickness direction TKD, and the upper end thereof is fixed to the bottom surface of the base 290. The substrate support plate 2901 is provided at three locations in the longitudinal direction LGD. Then, the data transfer board TB is fixed to the spacer 2902 provided on each board support plate 2901 by screws 2903. Thus, the data transfer boards TB and TB are fixed to the base 290.

  As described above, since the data transfer boards TB and TB are provided below the base 290, the flexible printed boards 2961 and 2962 connected to the head board back surface 293-t are curved to the outside in the width direction LTD, It is pulled out to the data transfer board TB through the side of 290 (in the width direction LTD). When passing through the side of the base 290, the flexible printed circuit board 2961 directs the surface on which the driver IC is not mounted to the side surface in the width direction LTD of the base 290, while the surface on which the driver IC is mounted is the width direction. Point to the outside of the LTD. Further, as described above, since the driver IC 295 is mounted on each of the plurality of flexible printed boards 2961, the plurality of driver ICs 295 are arranged in a substantially straight line in the longitudinal direction LGD on the side of the base 290 in the width direction LTD. (FIG. 10).

  Further, as shown in FIGS. 8 to 10, metal cover members (sheet metal covers) 291 and 291 are provided on both sides in the width direction LTD. A cover frame 2911 that is curved outward in the width direction LTD is formed on the cover member 291. The cover frame 2911 covers the space between the head substrate 293 and the lens array LA2 from the width direction LTD side, and functions to suppress light leakage from the inside of the line head 29 and electromagnetic waves from the outside of the line head 29. In this embodiment, a light shielding sheet 298 is attached from the support glass 299 to the cover frame 2911 in order to more reliably suppress such light leakage and electromagnetic wave intrusion. The light shielding sheet 298 is an opaque insulating resin sheet.

  Further, the upper surface of the cover frame 2911 is greatly cut out in the longitudinal direction LGD to form a cutout portion 2912. Therefore, the light emitted from the light emitting element group EG and transmitted through the imaging optical systems LS1 and LS2 can go to the exposed surface ES through the notch 2912.

  On the other hand, a plurality of pressing pieces 2913 and a plurality of screw fixing pieces 2915 are formed below the cover member 291. As can be seen from FIGS. 8 and 10, the pressing pieces 2913 and the screw fixing pieces 2915 are alternately formed in the longitudinal direction LGD. A screw insertion hole for inserting a screw 2916 is formed through the screw fixing piece 2915. The cover member 291 can be attached to the base 290 by attaching the screw 2916 to the screw hole of the base 290 with the screw 2916 inserted into the screw insertion hole.

  When the cover member 291 is mounted, the pressing piece 2913 pushes the flexible printed circuit board 2962 (FPC on which no driver IC is mounted) toward the base 290 side, and the flexible printed circuit board 2962 is moved to the side surface of the base 290 in the width direction LTD. Along. Similarly, when the cover member 291 is attached, the pressing piece 2913 contacts the driver IC 295. Therefore, when the screw 2916 is tightened into the screw hole of the base 290, the pressing piece 2913 presses the driver IC toward the base 290 and presses the flexible printed board 2961 against the base 290. Thus, the flexible printed circuit board 2961 is fixed to the base 290 by the pressing force from the pressing piece 2913 and the frictional force on the contact surface with the base 290.

  Incidentally, at this time, an insulating film (film) may be inserted between the surface of the driver IC 295 and the pressing piece 2913 so that the pressing piece 2913 presses the driver IC 295 through the insulating film. In such a case, since the driver IC 295 is electrically insulated from the cover member 291 by the insulating film, inductive noise or the like that jumps into the cover member 291 from the outside can suppress the influence on the potential of the silicon substrate of the driver IC. it can. As a result, the malfunction of the driver IC 295 due to the induction noise jumping into the cover member 291 can be suppressed.

  In the first embodiment, by providing such cover members 291 on both sides in the width direction LTD, the flexible printed circuit board 2961 on one side in the width direction LTD is fixed to one side in the width direction LTD on the base 290, The flexible printed board 2961 on the other side in the width direction LTD is fixed to the other side of the base 290 in the width direction LTD.

  As described above, in the line head 29 according to the first embodiment, the cover member 291 fixes the flexible printed board 2961 to the base 290 that supports the head board 293. Therefore, the swing of the flexible printed circuit board 2961 is restricted, and breakage of the connection portion between the flexible printed circuit board 2961 and the head substrate 293 can be suppressed.

  In particular, when the line head 29 is used inside an image forming apparatus (details will be described later), the flexible printed circuit board 2961 vibrates due to the influence of a vibration source inside the image forming apparatus, whereby the flexible printed circuit board 2961 and the head substrate are vibrated. The connection state with 293 may be deteriorated. On the other hand, according to the line head 29 of the first embodiment, since the flexible printed board 2961 is fixed to the base 290 with the cover member 291, vibration of the flexible printed board 2961 can be suppressed. It can be expected that the connection portion between the flexible printed board 2961 and the head board 293 is prevented from being deteriorated.

  Incidentally, the driver IC 295 as described above generates heat while repeating its operation. Therefore, it is considered that the heat of the driver IC 295 is conducted to the flexible printed circuit board 2961 and a considerable amount of heat is stored in the flexible printed circuit board 2961. On the other hand, in the line head 29 of the first embodiment, a metal base 290 is used, and the cover member 291 makes the flexible printed board 2961 contact the metal base 290. Therefore, the flexible printed circuit board 2961 can be cooled by the metal base 290, and the heat storage of the flexible printed circuit board 2961 can be suppressed.

  In particular, in the first embodiment, since the flexible printed circuit board 2961 is pressed against the base 290, cooling of the flexible printed circuit board 2961 by the base 290 can be promoted, and as a result, the heat storage of the flexible printed circuit board 2961 is more effective. Can be suppressed. In the first embodiment, a metal cover member 291 is disposed near the flexible printed board 2961, and heat radiation of the flexible printed board 2961 by the cover member 291 can be expected.

  In the line head 29 according to the first embodiment, the cover member 291 covers the lens array LA2 to the head substrate 293, and functions to suppress light leakage from the inside of the line head 29 and electromagnetic waves from the outside of the line head 29. Also fulfills. As described above, the cover member 291 has not only a function of fixing the flexible printed board 2961 but also a function of suppressing light leakage and electromagnetic wave intrusion. Accordingly, since it is not necessary to provide a member for each function, it is possible to reduce the number of parts of the line head 29 and to reduce the cost of the line head 29 and simplify the configuration.

Second Embodiment In the first embodiment, as shown in FIG. 7, the two data transfer boards TB and TB are arranged to face each other in the width direction LTD. Each of the data transfer boards TB and TB receives the video data VD from the outside via the flexible printed board Ftb and receives the supply of the power Vdd from the outside via the power harness Vtb. Therefore, in the second embodiment, a configuration for supplying the video data VD and the power supply Vdd to the data transfer boards TB and TB will be described.

  FIG. 11 is a partial perspective view of a configuration for supplying video data and power to the data transfer board. In the second embodiment, out of the two data transfer boards TB and TB facing the width direction LTD, the reference numeral TB1 is given to the board TB on one side in the width direction LTD, and the board TB on the other side in the width direction LTD is attached. A description will be given with reference to TB2. In the following description, unless otherwise specified, it is assumed that electronic components are mounted on surfaces (component mounting surfaces) of the data transfer boards TB1 and TB2 that face each other.

  Although omitted in the description of FIG. 7, as shown in FIG. 11, two data connectors Cf1, Cf1 (Cf2, Cf2) are spaced apart in the longitudinal direction LGD on the data transfer board TB1 (TB2). As well as being mounted, the power connector Cv1 (Cv2) is mounted between the data connectors Cf1, Cf1 (Cf2, Cf2) in the longitudinal direction LGD. A head controller HC (head control board HC) is disposed below the data transfer boards TB1 and TB2. On one side of the width direction LTD of the head controller HC, connectors J1-A, J1-v, J1-B are arranged in this order in the longitudinal direction LGD, and on the other side, connectors J2-A, J2-v and J1-B are arranged in this order in the longitudinal direction LGD. Incidentally, the number of pins of the connectors J1-A and J2-A is different from the number of pins of the connectors J1-B and J2-B. In this way, by making the number of pins of the connector different, it is configured so that an incorrect flexible printed circuit board Ftb is not connected to the connectors J1-A, J2-A, J1-B, J2-B. Yes.

  The connectors J1-A, J1-B (J2-A, J2-B) are connected to the data connectors Cf1, Cf1 (Cf2, Cf2) via the flexible printed circuit board Ftb. The video data VD is transmitted from the head controller HC to the data transfer board TB1 (TB2). On the other hand, the connector J1-v (J2-v) is connected to the power connector Cv1 (Cv2) via the power harness Vtb, and the power is supplied from the head controller HC to the data transfer board TB1 (TB2) via this path. Vdd is supplied.

  As described above, the line head 29 is arranged with the data transfer boards TB1 and TB2 facing the width direction LTD. However, from the viewpoint of space saving of the line head 29, it is preferable to reduce the distance between the two data transfer boards TB1 and TB2 as much as possible. On the other hand, the contact of each component of the data transfer boards TB1 and TB2 may be an obstacle to narrowing the board interval. In particular, the power connectors Cv1 and Cv2 tend to increase in size in order to ensure sufficient power supply capability, and thus tend to hinder the narrowing of the board interval. Therefore, in the second embodiment, when viewed from the width direction LTD, the power connector Cv1 and the power connector Cv2 are disposed so as not to overlap each other. Therefore, it is possible to reduce the space between the line heads 29 by narrowing the distance between the two data transfer boards TB1 and TB2.

  In the second embodiment, data connectors Cf1 and Cf2 and a power connector Cv1 (Cv2) are provided on the data transfer boards TB1 and TB2, and the flexible printed board Ftb and the power harness Vtb are provided for the data transfer boards TB1 and TB2. Is configured to be detachable. Therefore, when a defective product is found at the time of assembly or the like, the defective product can be replaced with a non-defective product, and assemblability is improved.

Third Embodiment FIG. 12 is a diagram showing an example of an image forming apparatus to which the above-described line head can be applied. FIG. 13 is a block diagram showing the electrical configuration of the apparatus of FIG. In the third embodiment, an example of an image forming apparatus including the above-described line head 29 will be described with reference to these drawings. The image forming apparatus 1 includes four image forming stations 2Y (for yellow), 2M (for magenta), 2C (for cyan), and 2K (for black) that form images of different colors. The image forming apparatus 1 includes a color mode in which four color toners of yellow (Y), magenta (M), cyan (C), and black (K) are overlapped to form a color image, and black (K). A monochrome mode in which a monochrome image is formed using only toner can be selectively executed.

  In this image forming apparatus, when an image forming command is given from an external device such as a host computer to a main controller MC having a CPU, a memory, etc., the main controller MC provides a control signal to the engine controller EC and also supports the image forming command. The video data VD to be transmitted is supplied to the head controller HC. At this time, every time the main controller MC receives the horizontal request signal HREQ from the head controller HC, the main controller MC supplies video data VD for one line to the head controller HC in the main scanning direction MD. The head controller HC also sets the line heads 29 of the image forming stations 2Y, 2M, 2C, and 2K for each color based on the video data VD from the main controller MC, the vertical synchronization signal Vsync from the engine controller EC, and the parameter values. Control. Accordingly, the engine unit ENG executes a predetermined image forming operation, and forms an image corresponding to the image forming command on a sheet-like recording medium RM such as copy paper, transfer paper, paper, and an OHP transparent sheet.

  Each of the image forming stations 2Y, 2M, 2C, and 2K has the same structure and function except for the toner color. Therefore, in FIG. 12, in order to make the drawing easier to see, reference numerals are given only to the components constituting the image forming station 2 </ b> C, and description of the reference numerals to be attached to the other image forming stations 2 </ b> Y, 2 </ b> M and 2 </ b> K is omitted. In the following description, the structure and operation of the image forming station 2C will be described with reference to the reference numerals in FIG. 12, but the structure and operation of the other image forming stations 2Y, 2M, and 2K also differ in toner color. It is the same except that.

  The image forming station 2C is provided with a photosensitive drum 21 on which a cyan toner image is formed. The photosensitive drum 21 is arranged so that the rotation axis thereof is parallel or substantially parallel to the main scanning direction MD (direction perpendicular to the paper surface of FIG. 12), and is at a predetermined speed in the direction of arrow D21 in FIG. Is driven to rotate. As a result, the surface of the photosensitive drum 21 moves in the sub-scanning direction SD that is orthogonal or substantially orthogonal to the main scanning direction MD.

  Around the photosensitive drum 21, a charger 22 that is a corona charger that charges the surface of the photosensitive drum 21 to a predetermined potential, and an electrostatic latent image is formed by exposing the surface of the photosensitive drum 21 according to an image signal. A line head 29 for forming the electrostatic latent image, a developing device 24 for visualizing the electrostatic latent image as a toner image, a first squeeze unit 25, a second squeeze unit 26, and the surface of the photosensitive drum 21 after transfer. Cleaning units for cleaning are arranged along the rotation direction D21 (clockwise in FIG. 12) of the photosensitive drum 21 in this order.

  In this embodiment, the charger 22 includes two corona chargers 221 and 222, and the corona charger 221 is disposed upstream of the corona charger 222 in the rotation direction D 21 of the photosensitive drum 21. In addition, the two corona chargers 221 and 222 are configured to be charged in two stages. Each of the corona chargers 221 and 222 has the same configuration and does not contact the surface of the photosensitive drum 21 and is a scorotron charger.

  The line head 29 forms an electrostatic latent image on the surface of the photosensitive drum 21 charged by the corona chargers 221 and 222 based on the video data VD. That is, when the head controller HC transmits the video data VD to the data transfer board TB (FIG. 6) of the line head 29, the data transfer board TB transfers the video data VD to each driver IC 295, and the driver IC receives the video data VD. Based on this, each light emitting element E is caused to emit light. As a result, the surface of the photosensitive drum 21 is exposed to form an electrostatic latent image corresponding to the image signal. The specific configuration of the line head 29 is as already described.

  Toner is applied from the developing device 24 to the electrostatic latent image formed in this manner, and the electrostatic latent image is developed with the toner. The developing device 24 of the image forming apparatus 1 has a developing roller 241. The developing roller 241 is a cylindrical member, and is provided with an elastic layer such as polyurethane rubber, silicon rubber, NBR, or PFA tube on the outer periphery of an inner core made of metal such as iron. The developing roller 241 is connected to a developing motor, and is rotated counterclockwise on the paper surface of FIG. 12 to rotate with respect to the photosensitive drum 21. Further, the developing roller 241 is electrically connected to a developing bias generator (constant voltage power source) (not shown) so that the developing bias is applied at an appropriate timing.

  An anilox roller is provided to supply the liquid developer to the developing roller 241, and the liquid developer is supplied from the developer storage unit to the developing roller 241 via the anilox roller. As described above, the anilox roller has a function of supplying the liquid developer to the developing roller 241. This anilox roller is a roller in which a concave pattern is formed by spiral grooves or the like engraved finely and uniformly on the surface so as to easily carry the liquid developer. Similar to the developing roller 241, a metal cored bar wrapped with a rubber layer such as urethane or NBR, or a PFA tube is used. The anilox roller is connected to a developing motor and rotates.

  The liquid developer stored in the developer storage section is volatile at room temperature at a low concentration (1-2 wt%) and low viscosity using Isopar (trademark: Exon) as a liquid carrier, which is generally used conventionally. Not a volatile liquid developer having a solid particle having a mean particle size of 1 μm, in which a colorant such as a pigment is dispersed in a non-volatile resin having a high concentration and high viscosity at room temperature, an organic solvent, silicon oil, mineral oil or A liquid developer having a high viscosity (about 30 to 10,000 mPa · s) added to a liquid solvent such as edible oil together with a dispersant and having a toner solid content concentration of about 20% is used.

  As described above, the developing roller 241 supplied with the liquid developer rotates simultaneously with the anilox roller and rotates so as to move in the same direction as the surface of the photosensitive drum 21 and is carried on the surface of the developing roller 241. The liquid developer thus conveyed is conveyed to the development position. In order to form a toner image, the rotation direction of the developing roller 241 needs to be rotated so that the surface thereof moves in the same direction as the surface of the photosensitive drum 21, but is opposite to the anilox roller. It may be configured to move in either the direction or the same direction.

  In the developing device 24, a toner compression corona generator 242 is disposed opposite to the developing roller 241 immediately before the developing position in the rotation direction of the developing roller 241. The toner compression corona generator 242 is an electric field applying means for increasing the charging bias on the surface of the developing roller 241 and is electrically connected to a toner charge generator (not shown) configured with a constant current power source. When a toner charge bias is applied to the toner compression corona generator 242, an electric field is applied to the liquid developer toner conveyed by the developing roller 241 at a position close to the toner compression corona generator 242. Then, charging and compression are performed. For the toner charging and compression, a compaction roller that is charged by contact may be used instead of corona discharge by applying electrolysis.

  Further, the developing device 24 configured as described above can reciprocate between a developing position for developing the latent image on the photosensitive drum 21 and a retracted position away from the photosensitive drum 21. Therefore, when the developing device 24 is moved to the retracted position and positioned, supply of new liquid developer to the photosensitive drum 21 is stopped in the cyan image forming station 2C.

  A first squeeze portion 25 is disposed on the downstream side of the developing position in the rotation direction D <b> 21 of the photosensitive drum 21, and a second squeeze portion 26 is disposed on the downstream side of the first squeeze portion 25. These squeeze portions 25 and 26 are provided with squeeze rollers 251 and 261, respectively. Then, the squeeze roller 251 rotates in response to the rotational driving force from the main motor while contacting the surface of the photosensitive drum 21 at the first squeeze position to remove excess developer in the toner image. Further, in the rotation direction D21 of the photosensitive drum 21, the squeeze roller 261 rotates in response to the rotational driving force from the main motor while contacting the surface of the photosensitive drum 21 at the second squeeze position downstream of the first squeeze position. Then, excess liquid carrier and fog toner in the toner image are removed. In this embodiment, a squeeze bias generator (constant voltage power supply) (not shown) is electrically connected to the squeeze rollers 251 and 261 in order to increase the squeeze efficiency, and the squeeze bias is applied at an appropriate timing. It is configured to be. In this embodiment, the two squeeze portions 25 and 26 are provided. However, the number and arrangement of the squeeze portions are not limited to this, and for example, one squeeze portion may be disposed.

  The toner image that has passed through these squeeze positions is primarily transferred to the intermediate transfer member 31 of the transfer unit 3. The intermediate transfer member 31 is an endless belt as an image carrier that can temporarily carry a toner image on its surface, more specifically, on its outer peripheral surface. The intermediate transfer member 31 includes a plurality of rollers 32, 33, 34, 35, and 36. It is being handed over. Among these, the roller 32 is connected to the main motor, and functions as a belt driving roller that drives the intermediate transfer member 31 in the direction of the arrow D31 in FIG. In the present embodiment, an elastic layer is provided on the surface of the intermediate transfer body 31 in order to improve the adhesion with the recording paper RM and improve the transferability of the toner image onto the recording paper RM. A toner image is supported.

  Here, of the rollers 32 to 36 over which the intermediate transfer body 31 is stretched, only the belt driving roller 32 is driven by the main motor, and the other rollers 33 to 36 are driven without a driving source. It is a roller. Further, the belt driving roller 32 winds the intermediate transfer member 31 on the downstream side of the primary transfer position TR1 and the upstream side of the secondary transfer position TR2 described later in the belt moving direction D31.

  The transfer unit 3 includes a primary transfer backup roller 37, and the primary transfer backup roller 37 is disposed to face the photosensitive drum 21 with the intermediate transfer member 31 interposed therebetween. At the primary transfer position TR1 where the photosensitive drum 21 and the intermediate transfer member 31 are in contact, the outer peripheral surface of the photosensitive drum 21 is in contact with the intermediate transfer member 31 to form the primary transfer nip portion NP1c. Then, the toner image on the photosensitive drum 21 is transferred to the outer peripheral surface of the intermediate transfer member 31 (the lower surface at the primary transfer position TR1). Thus, the cyan toner image formed by the image forming station 2C is transferred to the intermediate transfer member 31. Similarly, the toner images are transferred at the other image forming stations 2Y, 2M, and 2K, so that the toner images of the respective colors are sequentially superimposed on the intermediate transfer member 31 to form a full-color toner image. On the other hand, when a monochrome toner image is formed, the toner image is transferred to the intermediate transfer member 31 only in the image forming station 2K corresponding to the black color.

  The toner image transferred to the intermediate transfer member 31 in this way is conveyed to the secondary transfer position TR2 via the winding position around the belt driving roller 32. At the secondary transfer position TR2, the secondary transfer roller 42 of the secondary transfer unit 4 is disposed opposite to the roller 34 around which the intermediate transfer body 31 is wound, with the intermediate transfer body 31 interposed therebetween. The surface 31 and the surface of the transfer roller 42 are in contact with each other to form the secondary transfer nip portion NP2. That is, the roller 34 functions as a secondary transfer backup roller. The rotation shaft of the backup roller 34 is supported elastically by a pressing portion 345 which is an elastic member such as a spring and can be moved toward and away from the intermediate transfer member 31.

  At the secondary transfer position TR2, the single-color or multi-color toner images formed on the intermediate transfer member 31 are transferred from the pair of gate rollers 51 to the recording medium RM conveyed along the conveyance path PT. Further, the recording medium RM on which the toner image is secondarily transferred is sent from the secondary transfer roller 42 to the fixing unit 7 provided on the transport path PT. In the fixing unit 7, heat or pressure is applied to the toner image transferred to the recording medium RM to fix the toner image on the recording medium RM. In this way, a desired image can be formed on the recording medium RM.

Others As described above, in the above embodiment, the line head 29 corresponds to the “exposure head” of the present invention, and the photosensitive drum 21 corresponds to the “latent image carrier” of the present invention. The light emitting element E corresponds to the “light emitting element” of the present invention, the head substrate 293 corresponds to the “head substrate” of the present invention, the flexible printed circuit board 2961 corresponds to the “flexible printed circuit board”, The driver IC 295 corresponds to the “control circuit” and “second control circuit” of the present invention, the base 290 corresponds to the “support member” of the present invention, and the cover member 291 corresponds to the present invention. Corresponds to “fixing member” and “second fixing member”. Further, the lens array LA1 and the lens array LA2 cooperate to function as the “optical member” of the present invention. Further, the data transfer board TB corresponds to the “first data transfer board” and “second data transfer board” of the present invention, and the power connectors Cv1 and Cv2 are the “first component”, “first” of the present invention. Corresponds to “part 2”. The longitudinal direction LGD corresponds to the “first direction” of the present invention, and the width direction LTD corresponds to the “second direction” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. For example, in the above embodiment, the cover member 291 presses the driver IC 295 to fix the flexible printed board 2961 to the base 290. However, the flexible printed circuit board 2961 may be fixed by a member other than the cover member 291.

  FIG. 14 is a partially exploded perspective view of a line head according to a modification. In the line head shown in the drawing, a metal driver IC holder 2917 having a flat plate shape elongated in the longitudinal direction LGD is provided. In the driver IC holder, screw insertion holes are formed through a plurality of locations in the longitudinal direction LGD. Then, with the screw 2916 inserted in the screw insertion hole, the screw 2916 is attached to the screw hole of the base 290, so that the driver IC holder 2917 is mounted on the base 290.

  In this mounted state, the driver IC holder 2917 pushes the flexible printed circuit board 2962 (FPC on which no driver IC is mounted) toward the base 290 side so that the flexible printed circuit board 2962 is aligned with the side surface of the base 290 in the width direction LTD. Similarly, the driver IC holder 2917 contacts the driver IC 295 in the mounted state. Accordingly, when the screw 2916 is tightened into the base 290, the driver IC holder 2917 presses the driver IC toward the base 290 side, and presses the flexible printed board 2961 against the base 290. Thus, the flexible printed circuit board 2961 is fixed to the base 290 by the pressing force from the pressing piece 2913 and the frictional force on the contact surface with the base 290. Therefore, the swing of the flexible printed circuit board 2961 is restricted, and breakage of the connection portion between the flexible printed circuit board 2961 and the head substrate 293 can be suppressed. Also in the example of the figure, since the flexible printed circuit board 2961 is in contact with the metal base 290, the flexible printed circuit board 2961 is cooled by the metal base 290 to suppress heat storage of the flexible printed circuit board 2961. It is possible. In this embodiment, a metal driver IC holder 2917 is disposed near the flexible printed board 2961, and heat radiation of the flexible printed board 2961 by the driver IC holder 2917 can be expected.

  FIG. 15 is a partially exploded perspective view of a line head according to a further modification. In the line head 29 shown in the drawing, two screw insertion holes 2918 and 2918 are formed through the flexible printed circuit board 2961 so as to sandwich the driver IC from the longitudinal direction LGD. The flexible printed circuit board 2961 can be fixed to the base 290 by screwing the screws 2919 and 2919 into the screw holes of the base 290 with the screws 2919 and 2919 inserted into the screw insertion holes 2918 and 2918. In this way, the swing of the flexible printed circuit board 2961 is restricted, and breakage of the connection portion between the flexible printed circuit board 2961 and the head substrate 293 can be suppressed. Also in the example of the figure, since the flexible printed circuit board 2961 is in contact with the metal base 290, the flexible printed circuit board 2961 is cooled by the metal base 290 to suppress heat storage of the flexible printed circuit board 2961. It is possible.

  Further, in the line head 29 of FIG. 15, the ground pattern of the flexible printed board 2961 may be electrically set on the base 290. At this time, not only the flexible printed circuit board 2961 for data but also the ground pattern of the flexible printed circuit board 2962 for power supply may be electrically set on the base 290. With this configuration, the ground potential of the flexible printed boards 2961 and 2962 can be stabilized.

  In the line head 29 of the above-described embodiment, the light emitting elements E are grouped for each predetermined number to form the light emitting element group EG, and the plurality of light emitting element groups EG are arranged discretely and two-dimensionally. It was. However, the line head 29 to which the present invention can be applied is not limited to this. In other words, a line head can be configured by using a rod lens array in which a plurality of gradient index rod lenses having erecting equal magnification imaging characteristics are stacked, but when this rod lens array is used, The plurality of light emitting elements E are formed on the glass substrate without being grouped.

  FIG. 16 is a diagram showing a configuration of a line head using a gradient index rod lens array, and particularly shows a case where a member formed on the back surface 293-t of the head substrate is viewed in plan view. As shown in the figure, on the head substrate 293, a plurality of light-emitting elements E are formed in a four-row staggered arrangement in the longitudinal direction LGD. Further, on one side of the light-emitting elements E in the width direction LTD, A plurality of drive circuits DC are linearly arranged in the longitudinal direction LGD. This driving circuit DC is provided for each light emitting element E, and supplies a driving current to the light emitting element E via the wiring WL. Further, wiring (selection line Ws, data line Wd) is drawn out to one side of the drive circuit DC in the width direction LTD. These wirings Ws and Wd are connected to a flexible printed circuit board provided on one side in the width direction LTD of the head substrate 293, and transmit signals from a driver IC mounted on the flexible printed circuit board to the drive circuit DC. In the line head of FIG. 16, it is sufficient to provide the flexible printed board only on one side in the width direction LTD. And the effect similar to the above can be show | played by fixing the pulled-out flexible printed circuit board to the base 290 in the way mentioned above.

  In the above embodiment, a bottom emission type organic EL element is used as the light emitting element E. However, a top emission type organic EL element may be used as the light emitting element E, or an LED (Light Emitting Diode) other than the organic EL element may be used as the light emitting element E.

  DESCRIPTION OF SYMBOLS 21 ... Photosensitive drum, 29 ... Line head, E ... Light emitting element, EG ... Light emitting element group, 290 ... Base, 291 ... Cover member, 293 ... Head substrate, 295 ... Driver IC, 2961 ... Flexible printed circuit board (for data) 2962 ... Flexible printed circuit board (for power supply), LA1, LA2 ... Lens array, TB, TB1, TB2 ... Data transfer board, Cv1, Cv2 ... Power supply connector, HC ... Head controller, LGD ... Longitudinal direction, LTD ... Width direction , TKD: Thickness direction

Claims (8)

A head substrate provided with a light emitting element;
A support member for supporting the head substrate;
A flexible printed circuit board connected to the head substrate;
A control circuit disposed on the flexible printed circuit board for controlling light emission of the light emitting element;
A fixing member for fixing the flexible printed circuit board to the support member;
An exposure head comprising:   The exposure head according to claim 1, wherein the support member is made of metal, and the fixing member brings the flexible printed board into contact with the support member.   The flexible printed circuit board has a surface opposite to the surface on which the control circuit is mounted facing the support member, the fixing member presses the control circuit toward the support member, and the flexible printed circuit board is supported by the support member. The exposure head according to claim 2, wherein the exposure head is in pressure contact with the exposure head.   The exposure head according to claim 3, further comprising an optical member that forms an image of light emitted from the light emitting element, wherein the fixing member is a cover member that covers from the optical member to the head substrate.   A second flexible printed circuit board different from the flexible printed circuit board on which the second control circuit different from the control circuit is disposed, and a second fixing for fixing the second flexible printed circuit board to the support member The exposure head according to claim 1, further comprising a member.   The head substrate has a flat plate shape that is long in the first direction and short in the second direction, the flexible printed circuit board is connected to one side of the head substrate in the second direction, and the second flexible printed circuit board Is connected to the other side of the head substrate in the second direction, and the first fixing member fixes the flexible printed circuit board to the one side of the support member in the second direction, 6. The exposure head according to claim 5, wherein the fixing member fixes the second flexible printed circuit board to the other side of the support member in the second direction.   Transferring data to the control circuit of the flexible printed circuit board and transferring data to the first data transfer board having a first component and the second control circuit of the second flexible printed circuit board and second A second data transfer board having the above components, wherein the first data transfer board and the second data transfer board are opposed to each other in the second direction, and the second data transfer board is viewed from the second direction. The exposure head according to claim 6, wherein the first part and the second part are arranged so as not to overlap each other. An exposure head having a head substrate on which a light emitting element is disposed and a support member for supporting the head substrate;
A latent image carrier on which a latent image is formed by light emitted from the light emitting element;
A flexible printed circuit board connected to the head substrate;
A control circuit mounted on the flexible printed circuit board for controlling light emission of the light emitting element;
A fixing member for fixing the flexible printed circuit board to the support member;
An image forming apparatus comprising:

Images