JP2012254539A - Printer head and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer head which can reduce an influence by vibration from the outside without causing the enlargement of a size.SOLUTION: The printer head has a base board 301, a light source, a rod lens array 304, a housing 306, an installation member 310 or the like. The light source has a plurality of LED elements which are aligned along the Y-axial direction and mounted on the base board 301. The rod lens array 304 concentrates a plurality of light fluxes emitted from the light source in the vicinity of the surface of a photosensitive drum. The housing 306 has a ceiling plate with the Y-axial direction set in the longitudinal direction and two side plates which oppose each other with respect to the X-axial direction, and holds the base board 301 and the rod lens array 304. The installation member 310 is partially installed at -Z sides of the two side plates of the housing 306, and raises the rigidity of the printer head. Furthermore, the frequency of the inherent vibration of the housing 306 is adjusted by changing a position of the installation member 310 in the Y-axial direction.

Description

  The present invention relates to a printer head and an image forming apparatus. More specifically, the present invention relates to a printer head disposed close to a photoreceptor surface, and an image forming apparatus including the printer head.

  In recent years, with the development of information equipment, the demand for printers in small offices (small offices) and home offices has increased.

  Since a printer having a printer head having an LED array element (LED array chip) as a light source is relatively easy to downsize and lower in price than a printer having an optical scanning device using a semiconductor laser as a light source. It is suitable for printers for small offices and home offices.

  By the way, in a printer provided with the printer head, it is necessary to dispose the printer head close to the surface of the photoreceptor. In this case, when the frequency of the vibration generated in the printer apparatus is close to the natural frequency of the printer head, the printer head resonates, the amplitude increases rapidly, and the position of the light spot on the photoreceptor varies. There was a fear.

  Therefore, for example, Patent Document 1 includes a substrate table on which a substrate on which a light emitting element array is mounted is provided, and a lens support member that supports a lens array in which lenses are arranged in a row. The lens support member includes a hole protruding through the pin at a predetermined interval, the lens support member includes a hole for penetrating the pin, and the substrate base and the lens support member are formed of the pin inserted into the hole. An optical writing head is disclosed that is secured by an adhesive injected into the periphery.

  However, the optical writing head disclosed in Patent Document 1 has the disadvantage of increasing the size. In the optical writing head, when the environmental temperature changes, the positional relationship between the light emitting element and the lens may change.

  According to a first aspect of the present invention, a light source having a plurality of light emitting units arranged along a first direction and a plurality of light beams emitted from the light source in a second direction orthogonal to the first direction. An optical system that collects each of the light beams, a top plate that holds the optical system, and a third direction orthogonal to both the first direction and the second direction, with the light source interposed therebetween. A housing having two side plates that are fixed to the top plate in the vicinity of one side end portion in the second direction, and a part of the other side end portion in the second direction in the two side plates. And at least one erection member.

  From a second viewpoint, the present invention is an image forming apparatus including an image carrier and the printer head of the present invention that irradiates the image carrier with a light beam.

  According to the printer head of the present invention, the influence of external vibration can be reduced without increasing the size.

  According to the image forming apparatus of the present invention, it is possible to reduce the size without deteriorating the image quality.

1 is a diagram for describing a schematic configuration of a color printer according to an embodiment of the present invention. FIG. FIG. 6 is a perspective view for explaining a positional relationship between a printer head and a photosensitive drum. FIG. 3 is a side view of FIG. 2. FIG. 4 is a first diagram for explaining a printer head; FIG. 6 is a second diagram illustrating the printer head. It is a figure for demonstrating the state which removed the housing and the construction member from the printer head. It is a figure for demonstrating a light source and a light source drive device. It is a figure for demonstrating a rod lens array. FIG. 6 is a first diagram illustrating a printer head housing; FIG. 6 is a second diagram illustrating a printer head housing; It is FIG. (1) for demonstrating a construction member. It is FIG. (2) for demonstrating a construction member. It is a figure for demonstrating attachment of a construction member. It is a figure for demonstrating the relationship between the center position of the construction member regarding a Y-axis direction, and the primary resonance frequency of a printer head. It is a figure for demonstrating the effect of a construction member. It is a figure for demonstrating adjustment of the position of a construction member. It is FIG. (1) for demonstrating the modification 1 of a construction member. It is FIG. (2) for demonstrating the modification 1 of a construction member. FIG. 11 is a diagram for explaining a vibration analysis result of a printer head when there is no installation member of Modification Example 1. FIG. 10 is a diagram for explaining a vibration analysis result of a printer head when there is an erection member according to Modification 1; It is FIG. (1) for demonstrating the modification 2 of a construction member. It is FIG. (2) for demonstrating the modification 2 of a construction member. It is a figure for demonstrating the case where it has a some erection member.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a color printer 2000 according to an embodiment.

  The color printer 2000 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes four photosensitive drums (1K, 1C, 1M, and 1Y). ) 4 chargers (2K, 2C, 2M, 2Y), 4 printer heads (3K, 3C, 3M, 3Y), 4 developers (4K, 4C, 4M, 4Y), 4 transfer rollers (5K) 5C, 5M, 5Y), four cleaning units (6K, 6C, 6M, 6Y), intermediate transfer belt 201, transport belt 202, secondary transfer roller 203, fixing device 204, paper feed tray 205, paper feed roller 206 , A communication control device 208, and a printer control device 209 that controls the above-described units in an integrated manner.

  The communication control device 208 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  The printer control device 209 includes a CPU, a ROM that stores a program written in code readable by the CPU, various data used when executing the program, a RAM that is a working memory, an analog data An AD conversion circuit for converting the signal into digital data.

  The photosensitive drum 1K, the charging device 2K, the printer head 3K, the developing device 4K, the transfer roller 5K, and the cleaning unit 6K are used as a set and form an image forming station (hereinafter referred to as “K station” for the sake of convenience). (Also called).

  The photosensitive drum 1C, the charging device 2C, the printer head 3C, the developing device 4C, the transfer roller 5C, and the cleaning unit 6C are used as a set, and form an image forming station (hereinafter referred to as “C station” for convenience). (Also called).

  The photosensitive drum 1M, the charger 2M, the printer head 3M, the developing device 4M, the transfer roller 5M, and the cleaning unit 6M are used as a set, and form an image of magenta (hereinafter, “M station” for convenience). (Also called).

  The photosensitive drum 1Y, the charging device 2Y, the printer head 3Y, the developing device 4Y, the transfer roller 5Y, and the cleaning unit 6Y are used as a set, and form an image forming station for forming a yellow image (hereinafter referred to as “Y station” for convenience). (Also called).

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charger uniformly charges the surface of the corresponding photosensitive drum.

  Each printer head irradiates the surface of the corresponding charged photosensitive drum with a light beam based on the image information of the corresponding color in accordance with an instruction from the printer control device 209. As a result, on the surface of each photoconductive drum, the charge disappears only in the portion irradiated with light, and a latent image corresponding to the image information is formed on the surface of each photoconductive drum. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates. Details of each printer head will be described later.

  Each developing device causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum, and visualizes the latent image. Here, the toner-attached image (toner image) moves in the direction of the corresponding transfer roller as the photosensitive drum rotates.

  Each transfer roller transfers the toner image to the intermediate transfer belt 201. The yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 201 to form a color image.

  Recording paper is stored in the paper feed tray 205. A paper feed roller 206 is disposed in the vicinity of the paper feed tray 205. The paper feed roller 206 takes out recording sheets one by one from the paper feed tray 205 and directs them onto the conveyance belt 202 at a predetermined timing. Send it out.

  The recording paper on the conveyance belt 202 moves toward the intermediate transfer belt 201, and the color image on the intermediate transfer belt 201 is transferred by the secondary transfer roller 203. The recording paper on which the color image is transferred is sent to the fixing device 204.

  In the fixing device 204, heat and pressure are applied to the recording paper, whereby the toner is fixed on the recording paper. The recording paper on which the toner is fixed is sent to a paper discharge tray (not shown) via a paper discharge roller (not shown), and is sequentially stacked on the paper discharge tray.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charger again.

  Next, details of each printer head will be described.

  The four printer heads have the same configuration. Therefore, here, as a representative, the printer head 3K of the K station will be described in detail.

  Both ends of the printer head 3K are supported by face plates (see FIG. 2) so that the distance from the photosensitive drum 1K is kept constant. As shown in FIG. 3, each face plate has an abutting portion against which an end of the printer head 3K is abutted. The printer head 3K is fixed to the abutting portion of each face plate by a plate spring and a coil spring. Further, the relative position relationship between the rotation center of the photosensitive drum 1K, the rotation center of the developing roller in the developing device 4K, and the printer head 3K is determined by the face plate.

  As shown in FIG. 4 and FIG. 5 as an example, the printer head 3K includes a substrate 301, a light source 302, a light source driving device 303, a rod lens array 304, a connector 305, a housing 306, a construction member 310, and the like. . FIG. 5 is a cross-sectional view of FIG.

  Here, in the XYZ three-dimensional orthogonal coordinate system, the axial direction (longitudinal direction) of the photosensitive drum 1K will be described as the Y-axis direction, and the light emission direction from the printer head 3K will be described as the Z-axis direction.

  FIG. 6 shows a state where the housing 306 and the installation member 310 are removed from the printer head 3K.

  The substrate 301 is a rectangular plate member whose longitudinal direction is the Y-axis direction.

  The light source 302 includes a plurality of LED arrays as shown in FIG. 7 as an example. The plurality of LED arrays are arranged along the Y-axis direction and are mounted on the surface of the substrate 301 on the + Z side. Each LED array has a plurality of LED elements arranged along the Y-axis direction. Each LED element emits a light flux in the + Z direction.

  For example, when the A4 width (210 mm) can be accommodated and the writing density is 600 dpi, 4960 LED elements are required at intervals of about 42.3 μm. At this time, when an LED array having 100 LED elements is used, 50 LED arrays are mounted on the substrate 301.

  For example, when the A3 width (297 mm) can be accommodated and the writing density is 1200 dpi, 14009 LED elements are required at intervals of about 21.2 μm. At this time, if an LED array having 100 LED elements is used, 141 LED arrays are mounted on the substrate 301.

  As shown in FIG. 7 as an example, the light source driving device 303 has a plurality of driving IC chips corresponding to a plurality of LED arrays. The plurality of driving IC chips are arranged along the Y-axis direction and are mounted on the + Z side surface of the substrate 301. Each driving IC chip has a plurality of driving transistors integrated therein, and one driving transistor corresponds to one LED element.

  The connector 305 is attached to the −Z side surface of the substrate 301. A transmission cable from the printer control device 209 is connected to the connector 305.

  The rod lens array 304 is disposed on the + Z side of the light source 302. The rod lens array 304 condenses a plurality of light beams emitted from the light source 302 in the vicinity of the surface of the photosensitive drum. Here, the rod lens array 304 is a so-called equal magnification imaging optical system.

  As shown in FIG. 8 as an example, the rod lens array 304 is a bundle of a plurality of rod lenses 304_1. The plurality of rod lenses 304_1 is so-called staggered along the Y-axis direction.

  Each rod lens is a so-called refractive index distribution type rod lens having a columnar shape with the Z-axis direction as the height direction and a quadratic refractive index distribution in the radial direction. Opaque resin 304_2 is filled and cured in the gaps between the plurality of rod lenses 304_1 to suppress flare light leaking between the rod lenses.

  The plurality of rod lenses 304_1 are held by resin members 304_3 in which glass powder having a linear expansion coefficient equivalent to that of the rod lenses is dispersed from both sides in the X-axis direction.

  Instead of the rod lens array 304, a micro lens array may be used.

  As an example, the housing 306 includes a top plate and two side plates, as shown in FIGS. 9 and 10. The top plate has a rectangular shape whose longitudinal direction is the Y-axis direction, and has an opening whose longitudinal direction is the Y-axis direction at the center. A rod lens array 304 is inserted into the opening. That is, the top plate holds the rod lens array 304.

  The two side plates face each other in the X axis direction. The end faces on the + Z side of the two side plates are fixed to the top plate. Moreover, the groove | channel extended in the Y-axis direction is formed in the surface where two side plates oppose. A substrate 301 is inserted into each groove. Here, each groove is formed so that the light source 302 has a desired position and posture with respect to the rod lens array 304.

  The outer dimension of the housing 306 in the X-axis direction is W, the outer dimension of the housing 306 in the Y-axis direction is L, and the distance between the two side plates is D.

  The top plate and the two side plates are made of a material having conductivity and a small coefficient of thermal expansion. In this case, it is possible to suppress a change in the positional relationship between the light source 302 and the rod lens array 304 due to heat generated by the driving IC chip.

  By the way, around the printer head 3K, many members such as a charger 2K, a developing device 4K, a transfer roller 5K, and a cleaning unit 6K are arranged. Therefore, the printer head 3K needs to have a thin dimension in the X-axis direction in order to avoid interference with other members. For this reason, the dimension W in the X-axis direction of the top plate is made as small as possible.

  As shown in FIG. 11 and FIG. 12 as an example, the erection member 310 has an erection part and two guide parts.

  The installation part is a part parallel to the XY plane, and the two guide parts are parts extending in the + Z direction from the end face in the X-axis direction of the installation part. The distance between the two guide portions in the X-axis direction is substantially the same as the dimension W in the X-axis direction of the top plate. The external dimension of the erection member 310 in the Y-axis direction is 0.1L.

  As an example, as shown in FIG. 13, the erection member 310 is attached so that part of the −Z side end surfaces of the two side plates in the housing 306 abuts the erection part. That is, here, the erection member 310 has a shape that sandwiches part of the two side plates from the outside.

  By the way, conventionally, as a method of fixing the printer head to the printer housing, a method of holding both ends in the longitudinal direction of the printer head using a leaf spring or the like on a positioning member provided in the printer housing, a bracket A method of fixing with bolts or a method of fixing by soldering is employed.

  At this time, when the printer head is fixed only at both ends, there is a risk of fluctuations in the position of the light spot on the surface of the photosensitive drum and unevenness in the amount of light due to vibration generated inside the printer. These reduce the quality of the output image.

  In the present embodiment, the rigidity of the printer head is enhanced by partially constructing the −Z side end portions of the two side plates of the housing 306 with the construction member 310.

  FIG. 14 shows the relationship between the center position of the installation member 310 in the Y-axis direction and the primary resonance frequency of the printer head. In FIG. 14, f0 is the primary resonance frequency of the printer head when the installation member 310 is not attached. L is the dimension of the printer head in the Y-axis direction.

  According to FIG. 14, when the installation member 310 is attached, the primary resonance frequency of the printer head becomes higher than f0, and when the center position of the installation member 310 is L / 2, the primary resonance frequency of the printer head becomes maximum. Note that the maximum value of the primary resonance frequency is f1.

  In this case, as shown in FIG. 15 as an example, when the frequency of vibration generated in the printer apparatus is f0 [Hz], the printer head is subjected to vibration with a large displacement a before the installation member 310 is attached. However, when the installation member 310 is attached, the primary resonance frequency of the printer head is shifted to f1 [Hz], and the displacement can be reduced to a ′.

  Therefore, as shown in FIG. 16, the natural frequency of the housing 306 can be adjusted by sliding the installation member 310 along the Y-axis direction and changing the position of the installation member 310 in the Y-axis direction. . As a result, it is possible to adjust the variation of the natural frequency due to the individual difference of the printer head.

  By the way, the frequency of vibration that causes deterioration of the output image may differ depending on the model of the printer on which the printer head is mounted and the installation environment of the printer. Even in such a case, the deterioration of the output image can be suppressed by sliding the construction member 310 along the Y-axis direction and adjusting the natural frequency of the printer head.

  The fixing method of the erection member 310 whose position is adjusted in the Y-axis direction can be appropriately selected from holding by pressing from the side plate, bonding by UV adhesive, screwing, holding by a leaf spring, and the like.

  Here, the material of the erection member 310 is the same as the material of the housing 306. In this case, the deformation of the housing 306 can be suppressed even when the environmental temperature changes. In addition, when it is not necessary to consider the change in environmental temperature, the material of the erection member 310 and the material of the housing 306 may be different.

  As described above, each printer head according to the present embodiment includes the substrate 301, the light source 302, the light source driving device 303, the rod lens array 304, the housing 306, the erection member 310, and the like.

  The light source 302 has a plurality of LED elements arranged along the Y-axis direction, and is mounted on the substrate 301. The rod lens array 304 collects a plurality of light beams emitted from the light source 302 in the vicinity of the surface of the photosensitive drum.

  The housing 306 includes a top plate whose longitudinal direction is the Y-axis direction and two side plates that face each other in the X-axis direction, and holds the substrate 301 and the rod lens array 304.

  The erection member 310 partially erections the −Z side ends of the two side plates of the housing 306 to enhance the rigidity of the printer head.

  In addition, the natural frequency of the printer head can be adjusted by changing the position of the erection member 310 in the Y-axis direction.

  Therefore, each printer head can reduce the influence of external vibration without increasing the size.

  The color printer 2000 according to the present embodiment includes four printer heads (3K, 3C, 3M, and 3Y). As a result, the size can be reduced without degrading the image quality. Can do.

  Here, a modified example of the erection member 310 will be described.

<< Modification 1 >>
As an example, as illustrated in FIG. 17, the erection member 311 of the first modification is inserted between two side plates. Also in this case, as shown in FIG. 18, the natural frequency of the printer head can be adjusted by moving the erection member 311 in the Y-axis direction. In this case, since the installation member does not come out of the housing 306, it is advantageous for downsizing the printer.

  Vibration analysis by simulation was performed for the case where there was no erection member and the case where the erection member 311 was present. The analysis result when there is no installation member is shown in FIG. 19, and the analysis result when there is an installation member 311 is shown in FIG. In the simulation, the length of the installation member 311 in the Y-axis direction is 1/10 of the length L of the side plate of the housing 306 in the Y-axis direction. Further, with respect to the Y-axis direction, the center of the erection member 311 and the center of each side plate are made to coincide.

  The natural frequency of the printer head without the erection member was 95 [Hz], and the natural frequency of the printer head with the erection member 311 was 114 [Hz]. That is, by attaching the erection member 311, the rigidity of the printer head is improved, and the natural frequency of the printer head is about 1.2 times.

<< Modification 2 >>
As an example, as illustrated in FIG. 21, the erection member 313 according to the second modification has a shape in which a part is inserted between two side plates. Also in this case, as shown in FIG. 22, the primary resonance frequency of the printer head can be adjusted by moving the erection member 313 in the Y-axis direction. In particular, in this case, the installation member 313 can be easily attached to and detached from the housing 306. In addition, it can be made hard to interfere with an external member by making the dimension regarding the X-axis direction of the part located in the -Z side of the housing 306 in the construction member 313 into W or less. Further, the erection member 313 according to the second modification is easier to slide than the erection member 311 according to the first modification, when slid along the Y-axis direction. Furthermore, when recycling the printer head, the erection member can be easily removed and reused easily.

  In the above embodiment, the case where the center position of the erection member 313 is L / 2 in the Y-axis direction has been described, but the present invention is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the external dimension of the construction member 310 regarding a Y-axis direction was 0.1L, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the one construction member 313 was attached, it is not limited to this. For example, as shown in FIG. 23, three erection members 313 may be attached. In this case, a secondary resonance frequency can be dealt with. That is, when it is necessary to correspond to an n-th order (n is an integer of 2 or more) resonance frequency, a plurality of erection members 313 may be attached accordingly.

  In the above embodiment, the case where the image forming apparatus is a tandem multi-color printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow) has been described. However, the present invention is not limited to this. Is not to be done. For example, it may be a multicolor printer that further uses auxiliary colors, or a printer that forms a monochrome image.

  In the above-described embodiment, the case of a printer is described as the image forming apparatus. However, an image forming apparatus other than the printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated may be used.

  DESCRIPTION OF SYMBOLS 201 ... Intermediate transfer belt, 202 ... Conveyor belt, 203 ... Secondary transfer roller, 204 ... Fixing device, 209 ... Printer control device, 301 ... Substrate, 302 ... Light source, 303 ... Light source driving device, 304 ... Rod lens array (optical) System), 306 ... housing, 310 ... installation member, 311 ... installation member, 313 ... installation member, 2000 ... color printer (image forming apparatus), 1K, 1C, 1M, 1Y ... photosensitive drum (image carrier), 2K , 2C, 2M, 2Y ... charger, 3K, 3C, 3M, 3Y ... printer head, 4K, 4C, 4M, 4Y ... developer, 5K, 5C, 5M, 5Y ... transfer roller, 6K, 6C, 6M, 6Y ... cleaning unit.

JP 2004-17382 A

Claims (7)

A light source having a plurality of light emitting units arranged along a first direction;
An optical system that collects a plurality of light beams emitted from the light source in a second direction orthogonal to the first direction;
The top plate that holds the optical system is opposed to the third direction perpendicular to both the first direction and the second direction with the light source interposed therebetween, and one side end of the second direction A housing having two side plates, the vicinity of which is fixed to the top plate;
A printer head comprising: at least one erection member for erection of a part of the other side end of the two side plates in the second direction.   2. The printer head according to claim 1, wherein the position of the at least one erection member in the first direction is adjusted so that the natural frequency becomes a desired value.   The printer head according to claim 1, wherein a material of the at least one erection member is the same as a material of the housing.   The printer head according to claim 1, wherein the at least one erection member is inserted between the two side plates.   The printer head according to claim 1, wherein a part of the at least one erection member is inserted between the two side plates. The at least one erection member is a plurality of erection members,
The position of the plurality of installation members in the first direction is adjusted so as to suppress n-order vibration (n is an integer of 2 or more) of the housing. The printer head according to any one of the above. An image carrier;
An image forming apparatus comprising: the printer head according to claim 1, wherein the image bearing member is irradiated with a light beam.