JP2009018455A - Optical print head and image forming apparatus using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical print head excellent in printing characteristics, by improving heat radiation characteristics. <P>SOLUTION: This LED print head (optical print head) 60 is equipped with an LED array 3 which comprises a plurality of LED elements 3b, a multilayer wiring board 2 which includes a via hole 2d for ground and a via hole 2c for power supply and on the top side of which the LED array 3 is mounted and a heat sink 1 on a mounting surface 1a on which the multilayer wiring board 2 is mounted. The head is so constituted that a conductor layer 24b on the bottom side of the multilayer wiring board 2 and the mounting surface 1a of the heat sink 1 contact directly with each other. Besides, the via hole 2d for ground is so formed as to pierce in the direction of the thickness of the multilayer wiring board 2 so that it extends to the conductor layer 24b on the bottom side, while the via hole 2c for power supply is formed to a middle depth in the direction of the thickness of the board 2 so that it does not extend to the conductor layer 24b on the bottom side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical print head and an image forming apparatus using the same, and more particularly to an optical print head including a substrate on which a light emitting element is mounted and an image forming apparatus using the same.

  Conventionally, an LED array (light emitting element array) in which a plurality of LED (Light Emitted Diode) elements (light emitting elements) are linearly arranged, and a plurality of condensing lenses that collect light from the plurality of LED elements An LED print head (optical print head) having a lens array (imaging element array) in which (imaging elements) are linearly arranged is known, and an electrostatic latent image is formed on a photoreceptor as an image carrier. It is mounted on an electrophotographic printer or the like as an exposure unit for forming an image.

  In such an LED print head, since the LED element (LED array) generates heat due to light emission of the LED element (LED array), the element temperature of the LED element increases when heat generated by the light emission is insufficient. . As a result, a decrease in luminance, a shift in light emission wavelength, and the like occur, and therefore an LED print head used as an exposure unit is strongly required to improve heat dissipation.

  Conventionally, an optical print head (LED print head) with improved heat dissipation characteristics is known in order to meet the above-described demand for improvement in heat dissipation (see, for example, Patent Document 1). Patent Document 1 includes a light emitting element module including an LED array chip and a driver IC chip for driving the LED array chip, a substrate on which the light emitting element module is mounted, and a heat sink mounted on the lower surface side of the substrate. An optical print head in which a through hole for heat dissipation is provided on the substrate is described. Conductive layers are formed on the upper and lower surfaces of the substrate, respectively, and the LED array chip is fixed to the conductive layer on the upper surface of the substrate via a driver IC chip. Further, the through holes for heat dissipation are formed so as to penetrate from the upper surface to the lower surface of the substrate, thereby connecting the conductor layer on the upper surface of the substrate and the conductor layer on the lower surface of the substrate. Further, a heat sink is mounted on the lower surface side of the substrate via an insulating sheet. With such an arrangement, in the optical print head described in Patent Document 1, heat from the LED array chip can be efficiently transmitted to the lower surface side of the substrate through the through holes for heat dissipation. It becomes possible to easily dissipate heat from the chip from the heat sink mounted on the lower surface side of the substrate. Thereby, compared with the structure in which the through hole for heat dissipation is not provided in the board | substrate, a heat dissipation characteristic is improved.

In general, a multilayer wiring substrate is used as a substrate on which the LED array chip (light emitting element module) is mounted. The multilayer wiring board is provided with a power wiring pattern and a ground wiring pattern in addition to a signal wiring pattern. The heat sink is generally made of a metal material.
Japanese Patent Laid-Open No. 10-226107

  However, in the optical print head described in Patent Document 1, since an insulating sheet having a relatively low thermal conductivity is interposed between the substrate and the heat sink, heat from the LED array chip is transferred to the lower surface side of the substrate. Even if it is transmitted efficiently, there is an inconvenience that it is difficult to transmit efficiently to the heat sink due to the thermal resistance of the insulating sheet. On the other hand, when a heat sink is mounted on the lower surface side of the substrate without using an insulating sheet, there is a disadvantage that there is a risk of an electrical short circuit between the power supply wiring pattern and the grant wiring pattern. For this reason, although a heat dissipation characteristic is improved by providing a through-hole for heat dissipation in the substrate, it has not yet been sufficiently improved. As a result, since it is difficult to sufficiently suppress a decrease in luminance, a shift in emission wavelength, and the like, there is a problem that it is difficult to obtain excellent printing characteristics.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide an optical print head and an image forming apparatus having excellent printing characteristics by improving heat dissipation characteristics. It is to be.

  To achieve the above object, an optical print head according to a first aspect of the present invention includes a light emitting element array including a plurality of light emitting elements, and a plurality of light beams emitted from the light emitting element arrays on an image carrier. An imaging element array including imaging elements, an insulating layer and a conductor layer are alternately stacked, and includes a first via hole for ground and a second via hole for power supply, In addition, a multilayer substrate on which the light emitting element array is mounted on the upper surface and a heat radiating member that includes a flat mounting surface and on which the multilayer substrate is mounted are provided. The conductor layer on the lower surface of the multilayer substrate and the mounting surface of the heat dissipating member are configured to contact directly or indirectly through a conductive member, and the first via hole for ground is formed on the lower surface. It is formed so as to penetrate the multilayer substrate in the thickness direction so as to reach the conductor layer, while the second via hole for the power supply does not reach the conductor layer on the lower surface. It is formed.

  In the optical print head according to the first aspect, as described above, the first via hole for the ground reaching the conductor layer on the lower surface is formed on the multilayer substrate on which the light emitting element array is mounted, thereby emitting light along with light emission. Even if the element array generates heat, the heat from the light emitting element array can be efficiently transmitted to the lower surface side (lower conductive layer) of the multilayer substrate through the first via hole for ground. The multilayer substrate on which the light emitting element array is mounted is configured such that the conductor layer on the lower surface thereof and the mounting surface of the heat dissipation member are in direct contact or indirect contact with each other through a conductive member. The heat transmitted to the lower surface side (the conductor layer on the lower surface) can be efficiently transmitted to the heat radiating member. Thereby, since the heat from the light emitting element array can be effectively radiated from the heat radiating member, the heat radiation characteristics of the optical print head can be sufficiently improved. As a result, it is possible to suppress inconveniences such as a decrease in luminance and a shift in emission wavelength due to an increase in the temperature of the light emitting element array, and thus excellent printing characteristics can be obtained. In the optical print head according to the first aspect, excellent printing characteristics can also be obtained.

  Further, in the first aspect, as described above, the first via hole for ground is formed so as to penetrate the multilayer substrate in the thickness direction so as to reach the conductor layer on the lower surface, whereby the heat dissipation member is made of a metal material. Since the heat dissipation member and the ground can be electrically connected, the electrical impedance of the ground line can be reduced. Thereby, electrical characteristics can be improved. Specifically, the operation of a circuit formed on the multilayer substrate can be stabilized. Therefore, it is possible to obtain excellent printing (printing) characteristics.

  Further, in the above configuration, since the second via hole for power supply is formed to an intermediate depth so as not to reach the conductor layer on the lower surface of the multilayer substrate, in the case where the heat dissipation member is made of a metal material Even if the multilayer substrate is placed on the placement surface of the heat dissipation member without using an insulating layer (insulating sheet) or the like, the first via hole for ground and the second via hole for power supply are electrically connected to each other. It is possible to suppress connection. That is, an electrical short circuit can be suppressed. Therefore, the multilayer substrate can be placed on the placement surface of the heat dissipation member so that the conductor layer on the lower surface of the multilayer substrate is in direct contact with the placement surface of the heat dissipation member or indirectly through the conductive member. it can.

  In the optical print head according to the first aspect, preferably, a plurality of ground first via holes are formed in the multilayer substrate at a predetermined interval. With this configuration, the heat from the light emitting element array can be easily transmitted to the heat radiating member via the first via hole for ground and the conductor layer on the lower surface, and efficiently radiated from the heat radiating member. Can be made.

  In the optical print head according to the first aspect, preferably, the light emitting element array is mounted on a conductor layer on an upper surface of the multilayer substrate, and the multilayer substrate connects the conductor layer on the upper surface and the conductor layer on the lower surface. A plurality of through holes for heat dissipation are further included. With this configuration, heat from the light-emitting element array can be transferred to the conductor layer on the lower surface of the multilayer board by the through-hole for heat dissipation in addition to the first via hole for ground. The heat from the light emitting element array can be transferred to the conductor layer on the lower surface of the multilayer substrate. Thereby, since the heat from the light emitting element array can be more efficiently transmitted to the heat radiating member, the heat from the light emitting element array can be radiated from the heat radiating member more efficiently.

  In the optical print head according to the first aspect, the conductive paste is preferably embedded in at least a part of the plurality of first via holes and the plurality of through holes. If comprised in this way, the thermal conductivity of the 1st via hole and the through-hole for heat radiation can be improved easily.

  In the optical print head according to the first aspect, preferably, the heat dissipating member is made of a metal material containing aluminum as a main component. If comprised in this way, since the thermal radiation efficiency of a thermal radiation member can be improved easily, the thermal radiation characteristic of an optical print head can be improved easily.

  In the optical print head according to the first aspect, the light emitting element array may be formed of a light emitting diode array (LED array) including a plurality of light emitting diode elements (LED elements).

  An image forming apparatus according to a second aspect of the present invention is an image forming apparatus including an image carrier and the optical print head according to the first aspect. If comprised in this way, the image forming apparatus excellent in the printing characteristic can be obtained easily. In the image forming apparatus according to the second aspect, excellent printing characteristics can also be obtained.

  As described above, according to the present invention, it is possible to easily obtain an optical print head and an image forming apparatus having excellent printing characteristics by improving heat dissipation characteristics.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an LED print head which is an example of an optical print head will be described.

  FIG. 1 is an overall perspective view of an LED print head according to an embodiment of the present invention, and FIG. 2 is a plan view of the LED print head according to an embodiment of the present invention. 3 is a cross-sectional view taken along line 100-100 in FIG. 2, and FIG. 4 is a cross-sectional view showing a part of a multilayer wiring board of an LED print head according to an embodiment of the present invention. 5 to 11 are views for explaining the structure of an LED print head according to an embodiment of the present invention. With reference to FIGS. 1-11, the structure of the LED print head 60 by one Embodiment of this invention is demonstrated.

  As shown in FIGS. 1 to 3, an LED print head 60 according to an embodiment includes a heat sink 1 having a flat mounting surface 1a and a multilayer wiring board 2 mounted on the mounting surface 1a of the heat sink 1 (see FIG. 3), a light-emitting diode array (LED array) 3 (see FIG. 3) mounted on the multilayer wiring board 2, a housing member 4 covering the LED array 3 and the like, and the light emitted from the LED array 3 is collected. A lens array (rod lens array) 5 and a holding member 6 that holds the periphery of the lens array 5. The multilayer wiring board 2 is an example of the “multilayer board” in the present invention, and the heat sink 1 is an example of the “heat radiating member” in the present invention.

  As shown in FIGS. 1 and 3, the heat sink 1 is made of a metal material such as an aluminum extruded material having excellent thermal conductivity, and has a function of radiating heat generated by light emission of the LED array 3. Yes. A mounting surface 1 a is formed on the upper side of the heat sink 1. The mounting surface 1a is finished to be a smooth surface by cutting or the like, and is formed so as not to warp in the longitudinal direction (A direction). A plurality of fin portions 1 b for improving heat dissipation are formed on the lower side of the heat sink 1. Further, as shown in FIGS. 1 and 2, the LED print heads 60 are respectively disposed on both sides of the heat sink 1 in the longitudinal direction (A direction) as well as the predetermined area of the mounting surface 1a. A screw hole 1c is provided which is screwed when attached to a casing portion (not shown) of the case.

  As shown in FIG. 4, the multilayer wiring board 2 has a laminated structure in which insulating layers 2a made of glass epoxy resin or the like and conductor layers 2b made of Cu (copper) or the like are alternately laminated. Have. Further, the inner conductor layer 2b (21b) of the multilayer wiring board 2 is configured to function as a power supply plane layer, and the inner conductor layer 2b (22b) facing the conductor layer 2b (21b). Is configured to function as a plane layer for ground (GND). The conductor layer 2b (21b) for power supply and the conductor layer 2b (22b) for ground (GND) are connected to another conductor layer by a via hole 2c for power supply and a via hole 2d for ground (GND), respectively. 2b. Specifically, metal plating layers 21c and 21d are formed on the inner side surfaces of the power supply via hole 2c and the ground via hole 2d, respectively. The conductor layers 2b are electrically and thermally connected to each other. The ground via hole 2d and the power supply via hole 2c are examples of the “first via hole” and the “second via hole” in the present invention, respectively.

  In addition, a conductor layer 2b for wiring is formed on the upper surface of the multilayer wiring board 2 with a predetermined wiring pattern. A predetermined region of the wiring conductor layer 2 b is covered with a resist layer 7. The resist layer 7 has a function of suppressing an electrical short circuit between the wiring conductor layer 2 b provided on the upper surface and another member such as the housing member 4.

  Here, in the present embodiment, the ground via hole 2 d is formed so as to penetrate in the thickness direction of the multilayer wiring board 2, while the power supply via hole 2 c has a thickness from the upper surface of the multilayer wiring board 2. It is formed to a depth in the middle of the direction. That is, the via hole 2d for ground is formed in the through hole so as to connect the conductor layer 2b (23b) on the upper surface of the multilayer wiring board 2 and the conductor layer 2b (24b) on the lower surface. On the other hand, the power supply via hole 2 c is formed so as not to reach the conductor layer 2 b (24 b) on the lower surface of the multilayer wiring board 2. The conductor layer 2b (24b) on the lower surface of the multilayer wiring board 2 is configured to function as a heat radiation plane layer. Therefore, the conductor layer 2b (24b) on the lower surface of the multilayer wiring board 2 is configured not to be electrically connected to another conductor layer 2b used for wiring by a through hole (not shown). Further, the conductor layer 2b (24b) on the lower surface of the multilayer wiring board 2 is exposed without being covered with the resist layer.

  Further, in the present embodiment, as shown in FIG. 5, a plurality of ground via holes 2d are formed in a predetermined region of the multilayer wiring board 2 at a predetermined interval. Further, a plurality of through holes 2e for heat dissipation are formed in the vicinity of the mounting area of the LED array chip 3a on the multilayer wiring board 2. As shown in FIG. 6, the heat radiating through hole 2e is formed so as to penetrate in the thickness direction of the multilayer wiring board 2, whereby the upper surface conductor layer 2b (23b) and the lower surface heat radiating conductor layer are formed. 2b is connected. A metal plating layer 21e for electrically and thermally connecting the upper conductor layer 2b (23b) and the lower heat conductor layer 2b is formed on the inner side surface of the heat radiating through hole 2e. Has been.

  Furthermore, in this embodiment, as shown in FIGS. 4 and 6, conductive pastes 22c, 22d, and 22e are embedded inside the via holes 2c and 2d and the through holes 2e for heat dissipation, respectively. Yes. The multilayer wiring board 2 is placed on the placement surface 1a of the heat sink 1 so that the lower conductor layer 2b (24b) and the placement surface 1a of the heat sink 1 are in direct contact.

  Further, as shown in FIG. 5, the LED array 3 has a conductor layer 2b (23b) on the upper surface of the multilayer wiring board 2 so as to be parallel to the longitudinal direction (A direction) of the multilayer wiring board 2 (see FIG. 6). Implemented above. The LED array 3 is composed of a plurality of LED array chips 3a, and each LED array chip 3a is linearly arranged so as to be parallel to the longitudinal direction (A direction) of the multilayer wiring board 2. Further, as shown in FIG. 7, the LED array chip 3a is provided with a plurality of LED elements 3b arranged in a straight line with a density of, for example, 600 dpi (dot per inch) on each upper surface. A driver IC chip 8 for driving the LED array chip 3a is mounted on the upper surface of the multilayer wiring board 2 along the LED array chip 3a. The LED array 3 is an example of the “light emitting element array” in the present invention, and the LED element 3b is an example of the “light emitting element” in the present invention.

  Further, as shown in FIGS. 1 and 3, the housing member 4 is composed of a rectangular frame portion 4a that covers the LED array 3 (see FIG. 3) and the like. A rectangular opening 4b is formed. As shown in FIGS. 1 to 3, a plurality of screw holes 4 c are provided in a predetermined region of the frame body portion 4 a of the housing member 4. Further, as shown in FIG. 3, the housing member 4 is arranged above the multilayer wiring board 2 and is screwed through a screw hole 4c on the mounting surface 1a of the heat sink 1 so as to cover the LED array 3 and the like. 9 is fixed. At this time, the housing member 4 is fixed to the heat sink 1 so that the opening 4b is positioned directly above the LED array 3.

  Further, as shown in FIGS. 8 and 9, the lens array 5 has a structure in which a plurality of fiber-like condensing lenses 5a are linearly arranged so that their optical axes are parallel to each other. Adhesive members 5b are filled in the gaps between the condenser lenses 5a. As shown in FIG. 10, the condensing lens 5a is composed of a refractive index distribution type collecting optical fiber lens that can form an equal magnification image, condenses the diffused light 30 emitted from the LED element 3b, It has a function of emitting as convergent light 40. That is, in order to form an electrostatic latent image on the photoreceptor 50 (see FIGS. 10 and 11) as an image carrier, the diffused light 30 emitted from the LED element 3b is condensed into a minute spot light. Therefore, the LED print head 60 according to the present embodiment is configured such that a good spot light is formed by providing the lens array 5 composed of the condenser lens 5a. The lens array 5 is an example of the “imaging element array” in the present invention, and the condenser lens 5a is an example of the “imaging element” in the present invention.

  As shown in FIGS. 1 and 2, the holding member 6 has a long shape, and an opening for holding the periphery of the lens array 5 is provided at the center thereof. The lens array 5 is fixed to the opening of the holding member 6 with an adhesive or the like.

  As shown in FIG. 3, the holding member 6 to which the lens array 5 is fixed is disposed so as to be inserted between the openings 4 b of the housing member 4. As a result, the lens array 5 is disposed directly above the LED array 3, and the condenser lens 5 a of the corresponding lens array 5 is positioned directly above the plurality of LED elements 3 b constituting the LED array 3. It is configured.

  In the present embodiment, as described above, the ground via hole 2d reaching the conductor layer 2b (24b) on the lower surface is formed in the multilayer wiring board 2 on which the LED array 3 is mounted. 3 (LED element 3b) generates heat, the heat from the LED array 3 (LED element 3b) is transferred to the lower surface side of the multilayer wiring board 2 via the ground via hole 2d (lower conductive layer 2b (24b)). Can be transmitted efficiently. The multilayer wiring board 2 on which the LED array 3 is mounted is configured such that the conductor layer 2b (24b) on the lower surface thereof and the mounting surface 1a of the heat sink 1 are in direct contact with each other. The heat transmitted to the side (the lower conductor layer 2b (24b)) can be efficiently transmitted to the heat sink 1. Thereby, since the heat from the LED array 3 (LED element 3b) can be effectively radiated from the heat sink 1, the heat radiation characteristics of the LED print head 60 can be sufficiently improved. As a result, it is possible to suppress inconveniences such as a decrease in luminance and a shift in emission wavelength due to an increase in the temperature of the LED array 3 (LED element 3b), and thus excellent printing (printing). Characteristics can be obtained.

  In the present embodiment, as described above, the ground via hole 2d is formed so as to penetrate the multilayer wiring board 2 in the thickness direction so as to reach the conductor layer 2b (24b) on the lower surface. 1 and the ground (GND) can be electrically connected, so that the electrical impedance of the ground line can be reduced. Thereby, electrical characteristics can be improved. Specifically, the operation of a circuit (not shown) formed on the multilayer wiring board 2 can be stabilized. Therefore, it is possible to obtain excellent printing (printing) characteristics.

  Further, in the configuration of the present embodiment described above, the power supply via hole 2c is formed to an intermediate depth so as not to reach the conductor layer 2b (24b) on the lower surface of the multilayer wiring board 2, so that the insulating layer ( Even if the multilayer wiring board 2 is placed on the placement surface 1a of the heat sink 1 without using an insulating sheet), the ground via hole 2d and the power via hole 2c are electrically connected to each other. Can be suppressed. That is, an electrical short circuit can be suppressed.

  Further, in the present embodiment, by forming a plurality of ground via holes 2d at a predetermined interval, heat from the LED array 3 can be easily transferred to the ground via holes 2d and the conductor layer on the lower surface. The heat can be transmitted to the heat sink 1 through 2b (24b) and can be efficiently radiated from the heat sink 1.

  In the present embodiment, the multi-layer wiring board 2 is formed with a plurality of heat-dissipating through holes 2e connecting the upper conductor layer 2b (23b) and the lower conductor layer 2b (24b). The heat from the LED array 3 can be transferred to the conductor layer 2b (24b) on the lower surface of the multilayer wiring board 2 by the heat radiating through hole 2e in addition to the via hole 2d. Can be transferred to the conductor layer 2 b (24 b) on the lower surface of the multilayer wiring board 2. Thereby, since the heat from the LED array 3 can be transmitted to the heat sink 1 more efficiently, the heat from the LED array 3 can be radiated from the heat sink 1 more efficiently.

  In this embodiment, the conductive vias 22d and 22e are embedded in the inner surfaces of the plurality of via holes 2d and the plurality of through holes 2e, so that the via hole 2d for ground and the through hole for heat dissipation can be easily obtained. The thermal conductivity of 2e can be improved.

  Further, as shown in FIG. 11, the LED print head 60 according to the present embodiment is disposed so as to face the photoconductor 50 as an image carrier, thereby forming an electrostatic latent image on the photoconductor 50. It can be used in an electrophotographic printer (image forming apparatus) 70 as an exposure unit. Thereby, an electrophotographic printer (image forming apparatus) 70 having excellent printing (printing) characteristics can be easily obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which the present invention is applied to an LED print head that is an example of an optical print head has been described. However, the present invention is not limited thereto, and the present invention is applied to an optical print head other than an LED print head. May be. As an optical print head other than the LED print head, for example, an organic EL print head can be considered.

  In the above embodiment, the multilayer wiring board is placed on the placement surface of the heat sink so that the conductor layer on the lower surface and the placement surface of the heat sink are in direct contact, but the present invention is not limited thereto, The multilayer wiring board may be mounted on the mounting surface of the heat sink so that the lower conductive layer and the mounting surface of the heat sink are in indirect contact with each other via a conductive member such as a conductive sheet.

  Moreover, although the example which provided the through-hole for heat dissipation in the multilayer wiring board was shown in the said embodiment, this invention is not restricted to this, You may make it the structure which does not provide the through-hole for heat dissipation.

  In the above embodiment, the conductive paste is embedded inside each of the ground via hole and the heat radiating through hole. However, the present invention is not limited thereto, and the ground via hole and A conductive paste may be embedded in a part of the heat dissipation through hole. Alternatively, the conductive paste may not be embedded in each of the ground via hole and the heat radiating through hole.

  Moreover, although the example using the LED array in which a plurality of LED elements are arranged is shown in the above embodiment, the present invention is not limited to this, and a light emitting element array other than the LED array may be used. As a light emitting element array other than the LED array, for example, an organic EL array in which organic EL elements are arranged can be considered. Further, a halogen light source and a liquid crystal optical shutter array in which a plurality of liquid crystal cells are arranged for each pixel in front of the halogen light source can be considered.

  In the above-described embodiment, an example using a lens array in which a gradient index optical fiber collecting lens is arranged is shown. However, the present invention is not limited to this, and a roof prism lens array in which a roof prism lens is arranged or the like. Other lens arrays may be used.

1 is an overall perspective view of an LED print head according to an embodiment of the present invention. 1 is a plan view of an LED print head according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line 100-100 in FIG. 2. It is sectional drawing which showed a part of multilayer wiring board of the LED print head by one Embodiment of this invention. It is the top view which showed a part of multilayer wiring board of the LED print head by one Embodiment of this invention. It is sectional drawing which showed another part of the multilayer wiring board of the LED print head by one Embodiment of this invention. 1 is a plan view schematically showing an LED array of an LED print head according to an embodiment of the present invention. 1 is a perspective view illustrating a lens array of an LED print head according to an embodiment of the present invention. It is the top view which showed a part of lens array of the LED print head by one Embodiment of this invention. It is sectional drawing for demonstrating the structure of the lens array of the LED print head by one Embodiment of this invention. 1 is a diagram schematically illustrating the inside of an electrophotographic printer using an LED print head according to an embodiment of the present invention.

Explanation of symbols

1 Heat sink (heat dissipation member)
1a Mounting surface 2 Multilayer wiring board (multilayer board)
2a Insulating layer 2b Conductor layer 2c Via hole for power supply (second via hole)
2d Ground via hole (first via hole)
2e Through hole for heat dissipation 3 LED array (light emitting element array)
3a LED array chip 3b LED element (light emitting element)
4 Housing member 5 Lens array (imaging element array)
5a Condensing lens (imaging element)
22d, 22e conductive paste 50 photoconductor (image carrier)
60 LED print head (optical print head)
70 Electrophotographic printer (image forming device)

Claims (7)

A light emitting element array including a plurality of light emitting elements;
An imaging element array including a plurality of imaging elements for imaging light emitted from the light emitting element array on an image carrier;
Insulating layers and conductor layers are alternately stacked, and includes a first via hole for ground and a second via hole for power supply, and the light emitting element array is mounted on the upper surface. A multi-layer substrate,
Including a flat placement surface, and a heat dissipation member on which the multilayer substrate is placed on the placement surface,
The conductor layer on the lower surface of the multilayer substrate and the mounting surface of the heat dissipation member are configured to be in direct contact or indirectly in contact via a conductive member,
The first via hole for ground is formed so as to penetrate in the thickness direction of the multilayer substrate so as to reach the conductor layer on the lower surface, while the second via hole for power supply is formed on the conductor on the lower surface. An optical print head characterized by being formed up to a depth in the middle of the thickness direction of the multilayer substrate so as not to reach a layer.   2. The optical print head according to claim 1, wherein a plurality of the first via holes for the ground are formed in the multilayer substrate at a predetermined interval. The light emitting element array is mounted on a conductor layer on an upper surface of the multilayer substrate,
3. The optical print head according to claim 1, wherein the multilayer substrate further includes a plurality of heat radiating through-holes connecting the upper conductive layer and the lower conductive layer. 4.   The optical print according to claim 1, wherein a conductive paste is embedded in at least a part of the plurality of first via holes and the plurality of through holes. head.   The optical print head according to claim 1, wherein the heat radiating member is made of a metal material mainly composed of aluminum.   The optical print head according to claim 1, wherein the light emitting element array is a light emitting diode array including a plurality of light emitting diode elements.   An image forming apparatus comprising: an image carrier; and the optical print head according to claim 1.

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