JPH081993A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To form a latent image having high image quality on a photosensitive member by completely aligning lenses supported to a lens plate with an image element array mounted on the plate, and accurately emitting the lights emitted from the array to the member surface via the lens. CONSTITUTION:An image forming apparatus comprises a lens plate 3 for supporting a plurality of lenses 3a and a base plate 1 loaded with many light emitting diode element arrays 2 and a driving IC for driving the light emitting diode element arrays 2, a spacer 4 interposed between the plate 3 and the plate 1 so that the lenses 3 and the arrays 2 are so fixed as to correspond one by one, wherein the lower surface of the plate 1 is sequentially covered with a heat conductive layer 1a and a heat storage layer 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used as a light source of an electrophotographic printer.

[0002]

2. Description of the Related Art Recently, with the progress of information processing apparatus and communication technology, a compact and inexpensive electrophotographic printer capable of outputting a large amount of arbitrary kanji and figures on plain paper at high speed and high quality. Is required. Therefore, in order to meet this demand, an electrophotographic printer using an image forming apparatus in which a plurality of light emitting diode elements as image elements are linearly mounted on one main surface of an electrically insulating substrate is used as a light source of the printer. It is proposed as a small size and high resolution type.

An image forming apparatus used in this conventional electrophotographic printer usually has a spacer, a lens plate made of resin such as polycarbonate in which a plurality of lenses are linearly arranged and supported at predetermined intervals, and an upper surface. A plurality of light emitting diode element arrays and a base plate made of aluminum oxide sintered material, glass or the like on which a driving IC for driving the light emitting diode element arrays is mounted, each lens and each light emitting diode element array forming a pair. 1 has a structure provided side by side so that each light emitting diode element of each light emitting diode element array selectively emits light in response to an external electrical signal, and each light emitting diode element emits light. The formed light is projected onto the external photoconductor surface through a lens to form an image, and a latent image is formed on the photoconductor to form an electronic image. Functions as a light source of the formula printer.

The light emitting diode element array mounted on the base plate is generally composed of 64 light emitting diode elements linearly arranged therein, and serves as a light source of a B4 size electrophotographic printer. When used, the light emitting diode element array is
The individual pieces are mounted on the base plate so that each lens has a one-to-one correspondence with each lens.

Further, when each lens supported by the lens plate and each light-emitting diode element array mounted on the base plate are displaced from each other, the image formed on the surface of the photoconductor is bleeded, white stripes, or black. Since it is impossible to form a sharp and accurate latent image by generating streaks or the like, it is necessary to align each lens and each light emitting diode element array with extremely high accuracy.

[0006]

However, in this conventional image forming apparatus, a lens plate made of resin such as polycarbonate for supporting the lens and an aluminum oxide sintered body or glass on which the light emitting diode element array is mounted. The thermal expansion coefficient of the base plate consisting of 1.9 × 10 ^-5 / ℃, 4.0 × 10 ^-6 / ℃ ~ 7.5 × 10 ^-6 / ℃
However, when used as a light source of an electrophotographic printer, when the light emitting diode element array or a driving IC for selectively driving the light emitting diode element array generates heat, the heat is generated by the lens. When applied to the plate or the base plate, the lens plate thermally expands more than the base plate, and as a result, a positional deviation occurs between the lens supported by the lens plate and the light emitting diode element array mounted on the base plate.
It has a drawback that a clear and accurate latent image cannot be formed on the surface of the photoconductor.

At the same time, when used as a light source of an electrophotographic printer, when heat of the fixing device of the electrophotographic printer is applied to both the lens plate and the base plate, the lens plate thermally expands more than the base plate. As a result, there is also a drawback that a positional deviation occurs between the lens supported by the lens plate and the light emitting diode element array mounted on the base plate, and a clear and accurate latent image cannot be formed on the surface of the photoconductor. Was.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object of the present invention is to complete alignment between a lens supported by a lens plate and an image element array mounted on a base plate, and to provide an image element array. It is an object of the present invention to provide an image forming apparatus capable of accurately irradiating the surface of a photoconductor with light emitted from the photoconductor to form a latent image with high image quality on the photoconductor.

[0009]

The present invention comprises a lens plate for supporting a plurality of lenses, and a base plate on which a large number of image element arrays and driving ICs for driving the image element arrays are mounted. An image forming apparatus in which a spacer is sandwiched between and each lens and each image element array are fixed side by side so as to correspond to each other in a one-to-one correspondence, wherein a heat conduction layer and a heat storage layer are sequentially deposited on the lower surface of the base plate. It is characterized by.

The present invention is also characterized in that the region of the heat storage layer facing the image element array and the region of the driving IC element facing each other are divided by grooves.

Furthermore, the present invention is characterized in that a heat storage layer is interposed between the lens plate and the spacer.

Further, the present invention is characterized in that a heat insulating member is arranged on the outer surface side of the spacer and the base plate.

[0013]

According to the image forming apparatus of the present invention, the heat conduction layer and the heat storage layer are sequentially deposited on the lower surface of the base plate on which a large number of image element arrays and the driving ICs for driving the image element arrays are mounted on the upper surface. As a result, even if the image element array and the driving IC that selectively drives the image element array generate heat during operation, the heat is favorably absorbed by the heat storage layer via the heat conduction layer, and as a result, , The base plate does not expand abnormally, and the lens supported by the lens plate and the image element array mounted on the base plate can be aligned accurately at all times. An accurate latent image can be formed.

Further, according to the image forming apparatus of the present invention, if the heat storage layer deposited on the lower surface of the base plate is divided by the groove into a region facing the image element array and a region facing the driving IC element. Even if the driving IC element generates a large amount of heat during operation as compared with the image element array, the heat is preferentially and efficiently absorbed by the heat storage layer existing in the area facing the driving IC element, and the base plate becomes abnormal. There is no thermal expansion to, and as a result, the lens supported by the lens plate and the image element array mounted on the base plate can always be accurately aligned,
This makes it possible to form a clear and accurate latent image on the surface of the photoconductor.

Further, according to the image forming apparatus of the present invention, if the heat storage layer is interposed between the lens plate and the spacer, the image element array and the driving IC for selectively driving the image element array are emitted. Even if the heat or the heat generated by the fixing device of the electrophotographic printer is applied to the lens plate, the heat is well absorbed by the heat storage layer, and the lens plate does not expand abnormally. The lens supported by the lens plate and the image element array mounted on the base plate can always be accurately aligned, which also makes it possible to form a clear and accurate latent image on the photoconductor surface. Become.

Furthermore, according to the image forming apparatus of the present invention,
If a heat insulating member is arranged on the outer surface side of the spacer and the base plate, the heat generated by the fixing device of the electrophotographic printer may be applied to both the lens plate and the base plate when used as the light source of the electrophotographic printer. However, the heat is not blocked by the heat insulating member and is not applied to the lens plate and the base plate.
Positioning of the lens supported by the lens plate and the image element array mounted on the base plate is always accurate, and a clear and accurate latent image can be formed on the surface of the photoconductor.

[0017]

The present invention will now be described in detail with reference to the accompanying drawings. 1 to 3 show an embodiment in which the image forming apparatus of the present invention is applied to an optical printer head using a light emitting diode element, 1 is a base plate, 2 is a light emitting diode element array as an image element array, 3 Is a lens plate, and 4 is a spacer.

The base plate 1 is made of an electrically insulating material such as a glass epoxy resin, an aluminum oxide sintered body and glass, and has a plurality of light emitting diode element arrays 2 on its upper surface and a driving element for driving the light emitting diode element arrays 2. IC5 is mounted.

The base plate 1 acts as a supporting member for supporting the light emitting diode element array 2 and the driving IC 5, and for example, a sol-like epoxy resin is poured into glass fiber, and then the epoxy resin is thermally cured. Is produced by.

The light emitting diode element array 2 mounted on the base plate 1 is composed of a plurality of light emitting diode elements 2a, and the light emitting diode elements 2a are individually driven by driving a driving IC 5 corresponding to an external electric signal. A latent image for forming an image is formed on the photoconductor P by selectively emitting light and irradiating the surface of the photoconductor P with the emitted light.

The light emitting diode element 2a is a GaAsP type,
GaP-based light-emitting diodes are used.For example, in the case of GaAsP-based light-emitting diodes, the GaAs substrate is first heated to a high temperature in a furnace and AsH ₃ (arsine), PH ₃ (phosphine), Ga (gallium) are used. ) Is contacted with a gas containing an appropriate amount of) and n-type semiconductor GaAsP (gallium-arsenic-phosphorus)
Is grown on the GaAsP single crystal surface, and then a window film of Si ₃ N ₄ (silicon nitride) is deposited on the surface of the GaAsP single crystal and Zn is deposited on the window portion.
It is formed by exposing a (zinc) gas to diffuse Zn into a part of an n-type semiconductor GaAsP single crystal to form a p-type semiconductor, and providing a pn junction.

In the case of a B4 size optical printer head, the number of the light emitting diode elements 2a is 2048 (8 per 1 mm).
Are arranged in a straight line. Specifically, 32 light emitting diode element arrays 2 each having 64 light emitting diode elements 2a as one unit are arranged in a straight line to obtain 2048 light emitting diode elements 2a. Are arranged on the base plate 1.

A heat conducting layer 1a and a heat accumulating layer 1b are sequentially deposited on the lower surface of the base plate 1, and the heat conducting layer 1a is used for driving the light emitting diode element array 2 mounted on the base plate 1 and for driving. The IC 5 has a function of transmitting heat generated during operation to the heat storage layer 1b, and the heat storage layer 1b has a function of absorbing and storing heat of the light emitting diode element array 2 and the driving IC 5 transmitted through the heat conduction layer 1a. Do

Since the heat conduction layer 1a and the heat storage layer 1b are sequentially deposited on the lower surface of the base plate 1, the light emitting diode element array 2 and the driving IC 5 mounted on the base plate 1 generate heat. However, the heat is well absorbed in the heat storage layer 1b through the heat conduction layer 1a,
As a result, unnecessary heat is not applied to the base plate 1 to cause abnormal thermal expansion in the base plate 1. As a result, the light emitting diode element array 2 mounted on the base plate 1 is supported by the lens plate 3 described later. It is possible to always accurately align the lens 3a with the lens 3a, and it is possible to form a clear and accurate latent image on the surface of the photoconductor P.

The heat conducting layer 1a is made of aluminum,
It is made of a metal such as copper or iron or a ceramic having high thermal conductivity and is adhered or pressed onto the lower surface of the base plate 1, and the heat storage layer 1b is made of calcium chloride, glass, or the like, and by adopting a sputtering method or the like, or The thin plate is attached to the lower surface of the heat conduction layer 1a by adhering it with an adhesive.

As shown in FIG. 3, the heat storage layer 1b deposited on the lower surface of the base plate 1 divides the facing area B of the light emitting diode element array 2 and the facing area A of the driving IC 5 by the groove 6. I for driving when operating
Even if the C element 5 generates more heat than the light emitting diode element array 2, the heat is generated by the IC for driving the heat storage layer 1b.
The elements 5 are preferentially and efficiently absorbed in the opposing region B, and as a result, the base plate 1 does not undergo abnormal thermal expansion, and the light emitting diode element array 2 and the lens plate mounted on the base plate 1 are prevented. The lens 3a supported by 3 can be more accurately aligned, and a clear and accurate latent image can be formed on the surface of the photoconductor P.

Further, the base plate 1 on which the light emitting diode element array 2 and the driving IC 5 are mounted is provided with a lens plate 3 above the base plate 1 at a predetermined distance.
A plurality of holes are linearly formed in the lens plate 3 and a lens 3a is fitted so as to close the holes.

The lens plate 3 includes a plurality of lenses 3
The holes act as a supporting member for supporting a at a predetermined interval, and the holes serve to transmit the light emitted by each light emitting diode element 2a of the light emitting diode element array 2 to the lens 3a.

The lens plate 3 is made of the same material as the base plate 1 on which the light emitting diode element array 2 such as glass epoxy resin is mounted.

Further, each lens 3a supported by the lens plate 3 has a function of irradiating the light emitted from each light emitting diode element 2a on the photoconductor P to form an image, and a transparent resin such as an acrylic resin or a polycarbonate resin, or a glass. A lens formed of a transparent inorganic material such as is preferably used.

Further, the base plate 1 on which the light emitting diode element array 2 is mounted and the lens plate 3 on which the lens 3a is supported are bonded to a pair of spacers 4 and 4 made of glass epoxy resin or the like, respectively. The light emitting diode element array 2 and each lens 3a are provided side by side with a predetermined distance so as to correspond one to one.

The pair of spacers 4, 4 has a first reference surface 4a on the upper surface thereof and a second reference surface 4b on the lower portion thereof,
By fixing the outer peripheral portion of the lower surface of the lens plate 3 to the first reference surface 4a of the spacers 4 and 4 and the outer peripheral portion of the upper surface of the base plate 1 to the second reference surface 4b of the spacers 4 and 4, respectively, each light emitting diode element array 2 The lenses 3a and the lenses 3a are accurately corresponded to each other with a predetermined distance therebetween.

If a heat storage layer 3b made of glass, calcium chloride or the like is interposed between the pair of spacers 4 and 4 and the lens plate 3, the light emitting diode element array 2 and the light emitting diode element array 2 are formed. Even if the heat generated by the driving IC 5 for selectively driving or the heat generated by the fixing device of the electrophotographic printer is applied to the lens plate 2, the heat is favorably absorbed by the heat storage layer 3b and the lens plate 3 Can be prevented from abnormally thermally expanding, and as a result, the lens 3a supported by the lens plate 3 and the light emitting diode element array 2 mounted on the base plate 1 can always be accurately aligned. Therefore, a clear and accurate latent image can be formed on the surface of the photoconductor P.

If a heat insulating member 7 is arranged on the outer surfaces of the pair of spacers 4 and 4 and the outer surface of the base plate 1 fixed to the spacers 4 and 4, the lens plate 3 is used when it is used as a light source of an electrophotographic printer. Even if the heat generated by the fixing device of the electrophotographic printer is applied to both the base plate 1 and the base plate 1, the heat is not blocked by the heat insulating member 7 and applied to the lens plate 3 and the base plate 1. As a result, The lens 3a supported by the lens plate 3 and the light emitting diode element array 2 mounted on the base plate 1 are always aligned accurately, and a clear and accurate latent image can be formed on the surface of the photoconductor P. Becomes

Thus, according to the image forming apparatus of the present invention, each of the light emitting diode elements 2a of the light emitting diode element array 2 mounted on the base plate 1 has a driving I.
A predetermined electric power is applied in accordance with the driving of C5 to individually and selectively emit light from each light emitting diode element 2a, and the light emitted from each light emitting diode element 2a is irradiated and imaged on the photoconductor P via the lens 3a. By doing so, it functions as a light source of the electrophotographic printer.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-mentioned embodiments, the image element array emits light. Although the diode element array is used, it may be replaced with another light emitting element.

[0037]

According to the image forming apparatus of the present invention, the heat conduction layer and the heat storage layer are sequentially formed on the lower surface of the base plate on which a large number of image element arrays and the driving ICs for driving the image element arrays are mounted. Since it is deposited, the image element array and the driving I for selectively driving the image element array
Even if C generates heat during operation, the heat is favorably absorbed by the heat storage layer via the heat conduction layer, and as a result, the base plate does not undergo abnormal thermal expansion and the lens supported by the lens plate It is possible to always accurately align the image element array mounted on the base plate, and it is possible to form a clear and accurate latent image on the surface of the photoconductor.

According to the image forming apparatus of the present invention, if the heat storage layer deposited on the lower surface of the base plate is divided by the groove into a region facing the image element array and a region facing the driving IC element. Even if the driving IC element generates a large amount of heat during operation as compared with the image element array, the heat is preferentially and efficiently absorbed by the heat storage layer existing in the area facing the driving IC element, and the base plate becomes abnormal. There is no thermal expansion to, and as a result, the lens supported by the lens plate and the image element array mounted on the base plate can always be accurately aligned,
This makes it possible to form a clear and accurate latent image on the surface of the photoconductor.

Further, according to the image forming apparatus of the present invention, if the heat storage layer is interposed between the lens plate and the spacer, the image element array and the driving IC for selectively driving the image element array are emitted. Even if the heat or the heat generated by the fixing device of the electrophotographic printer is applied to the lens plate, the heat is well absorbed by the heat storage layer, and the lens plate does not expand abnormally. The lens supported by the lens plate and the image element array mounted on the base plate can always be accurately aligned, which also makes it possible to form a clear and accurate latent image on the photoconductor surface. Become.

Furthermore, according to the image forming apparatus of the present invention,
If a heat insulating member is arranged on the outer surface side of the spacer and the base plate, the heat generated by the fixing device of the electrophotographic printer may be applied to both the lens plate and the base plate when used as a light source of the electrophotographic printer. However, the heat is not blocked by the heat insulating member and is not applied to the lens plate and the base plate.
Positioning of the lens supported by the lens plate and the image element array mounted on the base plate is always accurate, and a clear and accurate latent image can be formed on the surface of the photoconductor.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an image forming apparatus of the present invention.

2 is a cross-sectional view of FIG.

FIG. 3 is a partially enlarged sectional view of FIG.

[Explanation of symbols]

 1 ... Base plate 1a ... Heat conduction layer 1b ... Heat storage layer 2 ... Light emitting diode element array 2a ... Light emitting diode element 3 ... Lens plate 3a ... Lens 4.・ ・ Spacer 5 ・ ・ ・ ・ Driving IC 6 ・ ・ ・ ・ Groove 7 ・ ・ ・ ・ Heat insulation member

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04N 1/036 A

Claims (4)

[Claims] 1. A lens plate for supporting a plurality of lenses, and a base plate on which a large number of image element arrays and driving ICs for driving the image element arrays are mounted on an upper surface of each lens with a spacer interposed therebetween. An image forming apparatus in which the image forming device and each image element array are fixed side by side so as to correspond to each other in a one-to-one correspondence, wherein a heat conductive layer and a heat storage layer are sequentially deposited on the lower surface of the base plate. . 2. The image forming apparatus according to claim 1, wherein in the heat storage layer, a region where the image element array faces and a region where the driving IC element faces is divided by a groove. 3. The image forming apparatus according to claim 1, wherein a heat storage layer is interposed between the lens plate and the spacer. 4. A heat insulating member is arranged on the outer surface side of the spacer and the base plate.
The image forming apparatus according to item 1.