JPH07314777A - 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 a pipe 6 in which heating medium flows is provided at the spacer 4.

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 / ℃
Because of the large difference, when used as a light source of an electrophotographic printer, heat such as the fixing device of the electrophotographic printer and heat generated during operation of the light emitting diode element array are generated on both the lens plate and the base plate. When applied, the lens plate undergoes large thermal expansion compared to 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, resulting in a clear image on the photoconductor surface. However, it has a drawback that an accurate latent image cannot be formed.

At the same time, when the temperature of the external environment is low, the lens plate contracts more than the base plate,
As a result, the lens supported by the lens plate and the light emitting diode element array mounted on the base plate are displaced from each other, and a clear and accurate latent image cannot be formed on the surface of the photoconductor. Was there.

[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]

According to the present invention, a lens plate having a plurality of lenses linearly arranged and supported at a predetermined interval, and a base plate having a large number of image element arrays linearly arranged and mounted thereon are provided. 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 have a one-to-one correspondence, wherein a pipe through which a heat medium flows is provided in the spacer. It is a thing.

Further, the image forming apparatus of the present invention includes a lens plate having a plurality of lenses linearly arranged and supported at a predetermined interval, and a base plate having a large number of image element arrays linearly arranged and mounted. Each lens and each image element array are fixed side by side so as to have a one-to-one correspondence with a spacer interposed therebetween, and an electronic device for heating or cooling the base plate and the lens plate is also provided in parallel.

[0011]

According to the image forming apparatus of the present invention, a lens plate having a plurality of lenses linearly arranged and supported at predetermined intervals, and a base plate having a large number of image element arrays linearly arranged and mounted are provided. Since a pipe is provided in the spacer to be fixed, if a cooling medium such as water or alcohol, or a heating medium such as hot water is circulated in the pipe, the base plate and the lens plate will be exposed to the temperature of the external environment and the electrophotographic printer. It is not affected by the heat of the fixing device, etc., and can be set to a predetermined temperature at the time of initial alignment, and as a result, the lenses supported by the lens plate and the image element array mounted on the base plate are The alignment between the two is always accurate, which 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, since the electronic device for heating or cooling the base plate and the lens plate is provided in parallel, the base plate and the lens plate can be heated or cooled by the electronic device. Is not affected by the temperature of the external environment or the heat of the fixing device of the electrophotographic printer, and reaches the predetermined temperature when first aligned, and as a result, it is mounted on the lens supported by the lens plate and the base plate. The position of the image element array arranged is always accurate, and this also makes it possible to form a clear and accurate latent image on the surface of the photoconductor.

[0013]

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 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 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 the upper part of the base plate 1 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 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, for example, glass epoxy resin. Thus, the respective light emitting diode element arrays 2 and the respective lenses 3 are provided side by side in a one-to-one correspondence with a predetermined distance.

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.

The pair of spacers 4 and 4 are made of the same material as the base plate 1 and the lens plate 3 such as glass epoxy resin, and are formed into a predetermined shape by the same method as the base plate 1 and the lens plate 3.

A pipe 6 is formed inside the pair of spacers 4 and 4. If a cooling medium such as water or alcohol, or a heating medium such as hot water is circulated in the pipe 6, the base plate 1 and the lens are provided. The plate 3 is not affected by the temperature of the external environment or the heat of the fixing device of the electrophotographic printer and can be set to a predetermined temperature when it is first aligned. As a result, the plate 3 is supported by the lens plate 3. The lens 3a and the light emitting diode element array 2 mounted on the base plate 1 are always accurately aligned with each other, whereby a clear and accurate latent image can be formed on the surface of the photoconductor 5. .

The pipe 6 is made of, for example, a cylindrical body made of a metal such as copper, and a felt or the like is adhered to the inside of the pipe. When the spacer 4 is formed of glass epoxy resin or the like, Base plate 1 and lens plate 3
Placed near the.

In the embodiment shown in FIGS. 1 and 2, a pipe 6 is provided in the spacer 4, and a cooling medium such as water or alcohol, or a heating medium such as hot water is circulated in the pipe 6 so that the base plate 1 and the lens plate 3 were effectively prevented from being adversely affected by the application of heat.
As shown in, the base plate 1 and the lens plate 3
An electronic device 7 (for example, a Peltier element) that heats or cools the base plate 1 and the lens plate 3 is heated or cooled by the electronic device 7 to cause the same operation as the pipe 6 through which the heat medium flows. May be.

In this case, the electronic device 7 heats or cools the base plate 1 and the lens plate 3 by changing the direction of the current flowing through the electronic device (for example, a Peltier element), and the base plate 1 and the lens plate 3 are heated to the temperature of the external environment. Alternatively, the temperature can be set to a predetermined temperature at the time of initial alignment without being affected by heat of the fixing device of the electrophotographic printer, and as a result, the lens 3a supported by the lens plate 3 and the base plate 1 are Positioning of the mounted light emitting diode element array 2 is always accurate, and thus 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 to cause each light emitting diode element to be 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-mentioned embodiments, the image element array emits light. Although the diode element array is used, it may be replaced with another light emitting element.

[0032]

According to 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 base plate in which a large number of image element arrays are linearly arranged and mounted. Since a pipe is provided on the spacer for fixing the base plate and the lens, the cooling medium such as water or alcohol, or the heating medium such as hot water can be circulated through the pipe to cause the base plate and the lens plate to have a temperature of the external environment, an electrophotographic printer. The temperature of the fixing device is not affected by the heat of the fixing device, and the temperature can be set to a predetermined temperature at the time of initial alignment. As a result, the lens supported by the lens plate and the image element array mounted on the base plate are mounted. The alignment of the two is always accurate, which 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, since the electronic device for heating or cooling the base plate and the lens plate is provided in parallel, the base plate and the lens plate can be heated or cooled by the electronic device. Is not affected by the temperature of the external environment or the heat of the fixing device of the electrophotographic printer, and reaches the predetermined temperature when first aligned, and as a result, it is mounted on the lens supported by the lens plate and the base plate. The position of the image element array arranged is always accurate, and this also makes it possible to form a clear and accurate latent image on the surface of the photoconductor.

[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 ... ..Pipes through which heat medium flows 7 ... Electronic devices

Claims (2)

[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 in which each image element array is fixed side by side so as to have a one-to-one correspondence with each other, and a pipe through which a heat medium flows is provided in the spacer. 2. 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 an electronic device for heating or cooling a base plate and a lens plate is arranged side by side so as to be fixed side by side so as to correspond to each image element array in a one-to-one correspondence.