JPH07314778A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus in which aligning of a lens supported to a lens plate and an image element array placed on a base plate is completed, a light irradiated from the array is accurately irradiated to a photosensitive unit surface via the lens, and a latent image having high picture quality can be formed on the unit. CONSTITUTION:An image forming apparatus comprises a lens plate 3 having a plurality of lenses 3a linearly arranged to be supported at a predetermined interval, a base plate 1 having many image element arrays 2 linearly arranged to be placed in such a manner that the plates 3, 1 are fixed together so that a spacer 4 is interposed therebetween and the legs 3a corresponds to the arrays 2 one by one, wherein the outer surfaces of the spacer 4 and the plate 1 are covered with heat insulating members 6.

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 a resin such as polycarbonate in which a plurality of lenses are linearly arranged and supported at a predetermined interval, and a large number of lenses. And a base plate made of glass or the like in which the light-emitting diode element arrays are linearly arranged and mounted so that each lens and each light-emitting diode element array have a one-to-one correspondence. Each light emitting diode element of each light emitting diode element array is caused to individually and selectively emit light in response to an external electric signal, and the light emitted by each light emitting diode element is externally exposed through a lens. It functions as a light source of an electrophotographic printer by irradiating an image on the body surface and forming a latent image on the photoreceptor.

The light emitting diode element array linearly arranged and mounted on the base plate is generally composed of 64 light emitting diode elements linearly arranged therein, and is an electrophotographic type of B4 size. When used as a light source of a printer, the 32 light emitting diode element arrays are mounted on a base plate so that each of the 32 light emitting diode element arrays 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 that supports a lens and an aluminum oxide sintered body or glass on which a light emitting diode element array is mounted are used. The thermal expansion coefficient of the base plate consisting of 1.9 × 10 ^-5 / ℃, 4.0 × 10 ^-6 / ℃ ~ 7.5 × 10 ^-6 / ℃
Therefore, when used as a light source of an electrophotographic printer, when the heat of the fixing device of the electrophotographic printer is applied to both the lens plate and the base plate, the lens plate heats up more than the base plate. It expands, 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, and it is not possible to form a clear and accurate latent image on the photoconductor surface. Had.

At the same time, when heat is generated during operation of the image element array arranged on the base plate and the driving IC for selectively driving the image element array, the heat is applied to the lens plate and the base plate. Then, the lens plate thermally expands much more than the base plate, and as a result, a position shift occurs between the lens supported by the lens plate and the light emitting diode element array mounted on the base plate, resulting in a clear and accurate photoconductor surface. It also has a drawback that it is not possible to form a latent image.

[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]

In the image forming apparatus of the present invention, a lens plate in which a plurality of lenses are linearly arranged and supported at a predetermined interval and a large number of image element arrays are linearly arranged and mounted. A base plate and a lens are fixed side by side so that each lens and each image element array have a one-to-one correspondence with a spacer interposed therebetween, and the outer surfaces of the spacer and the base plate are covered with a heat insulating member. Is.

Further, the image forming apparatus of the present invention is characterized in that a heat storage member is interposed between the heat insulating member and at least the base plate.

Further, the image forming apparatus of the present invention is characterized in that the spacer is provided with a pipe through which a cooling medium flows.

[0012]

According to the image forming apparatus of the present invention, since the outer surfaces of the spacer and the base plate are covered with the heat insulating member, when used as a light source of the electrophotographic printer, both the lens plate and the base plate of the electrophotographic printer are used. Even if the heat of the fixing device or the like is applied, the heat is not blocked by the heat insulating member and applied to the lens plate and the base plate, and as a result, the heat is applied to the lens supported by the lens plate and the base plate. The alignment with the existing image element array is always accurate, and a clear and accurate latent image can be formed on the surface of the photoconductor.

Further, according to the image forming apparatus of the present invention, when the image element array arranged on the base plate or the driving IC for selectively driving the image element array generates heat during operation, the spacer is formed. Also, if a heat storage member is interposed between the base plate and the heat insulating member, or if a pipe is provided in the spacer and a cooling medium such as water is circulated in the pipe, the heat generated by the image element array or the like is generated in the heat storage member or the pipe. It is not absorbed by the cooling medium flowing through and is not applied to the base plate or lens plate as it is, and as a result, the lens plate does not undergo large thermal expansion compared to the base plate, and the lens supported by the lens plate and the base plate The image element array mounted on the can always be accurately aligned, and it is clear and accurate on the photoconductor surface. It is possible to form a latent image.

[0014]

The present invention will now be described in detail with reference to the accompanying drawings. 1 and 2 show an embodiment in which the image forming apparatus of the present invention is adopted in 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 glass epoxy resin, aluminum oxide sintered body, glass, etc., and a plurality of light emitting diode element arrays 2 are linearly arranged and mounted on the upper surface thereof. .

The base plate 1 acts as a supporting member for supporting the light emitting diode element array 2, and is manufactured by, for example, pouring a sol-like epoxy resin into a glass fiber and then thermally curing the epoxy resin. There is.

The light emitting diode element array 2 arranged and mounted on the base plate 1 is composed of a plurality of light emitting diode elements 2a.
Selectively emits light in response to an external electric signal, and forms a latent image for forming an image on the photoconductor 5 by irradiating the surface of the photoconductor 5 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.

Further, the base plate 1 on which the light emitting diode element array 2 is mounted is provided with a lens plate 3 on its upper part at a constant distance, and a plurality of holes are linearly arranged in the lens plate 3. The lens 3a is formed so as to cover the hole while being formed.

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 onto the photosensitive member 5 to form an image, and a transparent resin such as acrylic resin or polycarbonate resin, or 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, respectively. The light emitting diode element array 2 and each lens 3 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.

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, a heat insulating member 6 is disposed with a heat storage member 7 interposed therebetween, and further the outer surfaces thereof. A cover member 8 made of a metal material such as iron or aluminum is disposed on the.

The heat insulating member 6 is made of paper, wood, plastic such as styrofoam, and when used as a light source of an electrophotographic printer, heat of an external fixing device or the like is applied to both the base plate 1 and the lens plate 3. Effectively prevents the base plate 1 and
Also, the lens plate 3 does not greatly expand thermally,
The light emitting diode element array 2 mounted on the base plate 1 and the lens 3 supported by the lens plate 3
It is possible to form a clear and accurate latent image on the surface of the photoconductor 5 by always aligning the position with a.

The heat storage member 7 is made of calcium chloride, glass or the like, and has a light emitting diode element array 2 arranged on the base plate 1 and a driving IC (not shown) for selectively driving the light emitting diode element array 2. ), Etc. generate heat during operation, they effectively prevent the heat from being applied to the base plate 1 and the lens plate 3 as they are, so that the lens plate 3 has a larger thermal expansion than the base plate 1. Never do
The light emitting diode element array 2a mounted on the base plate 1 and the lens 3a supported by the lens plate 3 can always be accurately aligned, and a clear and accurate latent image is formed on the surface of the photoconductor 5. It becomes possible.

The heat insulating member 6 and the heat storage member 7 are attached by a cover member 8 so as to be in close contact with the outer surfaces of the pair of spacers 4 and 4 and the outer surface of the base plate 1.

In the embodiment shown in FIGS. 1 and 2, the heat storage member 7 is arranged between the heat insulating member 6 and the spacer 4 and the base plate 1, and the light emitting diode element array 2 and the like are operated by the heat storage member 7. The heat generated at times is absorbed so that unnecessary heat is not applied to the base plate 1 and the lens plate 3. However, as shown in FIG. 3, a pipe 9 is provided on the pair of spacers 4 and 4, and the pipe 9 is provided. A cooling medium such as water or alcohol may be circulated in the container 9. In this case, even if the light emitting diode element array 2 and the like arranged and mounted on the base plate 1 generate heat during operation, the heat is absorbed by the cooling medium flowing in the pipe 9 and the base plate 1 and the lens plate 3 are kept as they are. As a result, the lens plate 3 does not thermally expand more than the base plate 1, and the light emitting diode element array 2a mounted on the base plate 1 and the lens supported by the lens plate 3 are not applied. 3a can always be accurately aligned with each other, and a clear and accurate latent image can be formed on the surface of the photoconductor 5.

Thus, according to the image forming apparatus of the present invention, a predetermined electric power is applied to each light emitting diode element 2a of the light emitting diode element array 2 linearly mounted on the base plate 1, and each light emitting diode element is applied. 2a individually and selectively emit light, and the light emitted by each light emitting diode element 2a is irradiated and image-formed on the photoconductor 5 through the lens 3a to function as a light source of an electrophotographic printer.

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

[0033]

According to the image forming apparatus of the present invention, since the outer surfaces of the spacer and the base plate are covered with a heat insulating member, when used as a light source of an electrophotographic printer, both the lens plate and the base plate are electrophotographic type. Even if heat from the fixing device of the printer is applied, the heat is not blocked by the heat insulating member and applied to the lens plate and the base plate, and as a result, the heat is applied to the lens supported by the lens plate and the base plate. The alignment with the existing image element array is always accurate, and a clear and accurate latent image can be formed on the surface of the photoconductor.

According to the image forming apparatus of the present invention, when the image element array arranged on the base plate or the driving IC for selectively driving the image element array generates heat during operation, the spacer Also, if a heat storage member is interposed between the base plate and the heat insulating member, or if a pipe is provided in the spacer and a cooling medium such as water or alcohol is circulated in the pipe, the heat generated by the image element array or the like is stored in the heat storage member or It is not absorbed by the cooling medium flowing through the pipe and applied to the base plate or lens plate as it is, and as a result, the lens plate does not undergo a large thermal expansion compared to the base plate, and is supported by the lens plate. The lens and the image element array mounted on the base plate can always be accurately aligned with each other. It is possible to form a clear and precise latent image.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 1 ... Base plate 2 ... Light emitting diode element array 2a ... Light emitting diode element 3 ... Lens plate 3a ... Lens 4 ... Spacer 5 ... Photoconductor 6 ... ..Heat insulation member 7 ... Heat storage member 9 ... Pipe

Claims (3)

[Claims] 1. A lens plate in which a plurality of lenses are linearly arranged and supported at a predetermined interval, and a base plate on which a large number of image element arrays are linearly arranged and mounted, and a spacer is interposed between each lens. An image forming apparatus characterized in that each image element array is fixed side by side so as to have a one-to-one correspondence, and the outer surfaces of the spacer and the base plate are covered with a heat insulating member. 2. The image forming apparatus according to claim 1, wherein a heat storage member is interposed between the heat insulating member and at least the base plate. 3. The image forming apparatus according to claim 1, wherein the spacer is provided with a pipe through which a cooling medium flows.