JPH0594080A - Light head - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object to provide an optical head that is compatible with both small size and high resolution. [Structure] Line-shaped light emitting element array 23 in which light emitting elements are arranged
And 25, and rod lens arrays 21 and 22 for forming an image of the light on the same writing line 2a of the photoconductor 2 are provided. In the light emitting element array in the linear light emitting element rows 23 and 25 for obtaining a desired resolution, the shortest processing distance is large, and both miniaturization and high resolution can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head having a rod lens array used in an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses using electrophotography have been widely used, but downsizing and higher resolution have been a problem.

Conventionally, optical systems of various systems such as a laser system, an LED system, and a liquid crystal shutter system have been invented as a writing optical system in an image forming apparatus using an electrophotographic technique, and various images using these optical systems have been invented. Forming equipment is utilized.

In particular, the laser type optical system has become the mainstream because of its cost merit, the small variation in the amount of light, the high speed, and the high resolution. However, in recent years, with the demand for downsizing of the apparatus, the LED method, which is much more efficient in space in the apparatus than the laser method, has been in the spotlight, and image forming apparatuses using this LED method are mainly used for low-speed machines. It has been announced by the manufacturer. On the other hand, there is a strong demand not only for downsizing the device, but also for higher image resolution,
The emergence of a writing optical system that can simultaneously realize downsizing, high resolution, and high speed is awaited.

The structure and operation of an image forming apparatus equipped with a conventional LED type writing optical system (hereinafter referred to as an optical head) using a general rod lens array will be described below with reference to the drawings.

FIG. 4 is a side view showing the structure of an image forming apparatus using a conventional optical head, and FIG. 5 is a plan view showing the structure of a line-shaped light emitting element array which is a light emitting member of the conventional optical head. In FIG. 4, 2 is a photoconductor, 3 is a charger, 4 is an optical head, 5 is a developing device, 6 is a transfer device, 7 is a cleaning device,
8 is a static eliminator, and 9 is a sheet.

The mutual relationship and operation of the above components will be described below. The photoconductor 2 is uniformly charged by the charger 3, and is exposed in the main scanning direction by the irradiation of the optical head 4 which emits light according to an image signal from the outside, so that a linear electrostatic latent image is formed on the surface of the photoconductor 2. To be done. Since the photoconductor 2 is rotating in the backward scanning direction, linear electrostatic latent images are sequentially arranged to form a planar electrostatic latent image. The electrostatic latent image is developed as a toner image by the developing device 5, and the toner image is transferred by the transfer device 6 from the paper feeding unit (not shown) to the paper 9 fed one by one. Residual toner, paper dust, etc. on the photoconductor 2 are removed by the cleaning device 7, and the electric potential of the photoconductor 2 is made constant by the static eliminator 8. On the other hand, the sheet 9 on which the toner image is transferred is separated by the curvature of the photoconductor 2 and is fixed by heat and pressure by a fixing device (not shown). The photoconductor 2 and the paper 9 are moved at a substantially constant speed by a gear train and a motor (not shown).

As shown in FIG. 5, the optical head 4 has a line-shaped light emitting element array 10 in which light emitting elements 15 are arranged in the main scanning direction so as to obtain a predetermined resolution, a substrate 13 on which the light emitting elements are mounted, and a line. Rod lens array 11 for erecting the light from the light emitting element array 10 on the photoconductor 2 in an erect image.
It is constituted by the case 12.

The optical head 4 having the above structure emits one line of optical information in the main scanning direction to the writing line 2a on the photosensitive member 2 at a timing corresponding to the moving speed of the photosensitive member 2 and the resolution in the sub scanning direction. To do. By repeating this operation,
A latent electrostatic image having a predetermined resolution is formed on the photoconductor 2 in main scanning and sub scanning.

[0010]

Such a conventional optical head is not suitable for high resolution and has the following problems. That is, the line-shaped light emitting element array of the optical head is shown in FIG.
As shown in FIG. 1, a light emitting element array 1 having a length (D) in the main scanning direction
It is composed of 4 in a row. Therefore, the element array 14
It is necessary to process the distance from the center of the light emitting element 15 at the end to the end of the element row to 1/2 the pitch P of the light emitting element array (P / 2 in FIG. 5). This element array pitch P corresponds to the resolution, and P /
The absolute size of 2 became minute, and there was a limit to high resolution in terms of processing technology. Therefore, it has been difficult to realize an optical head that can achieve both miniaturization and high resolution.

The present invention solves the above problems, and an object of the present invention is to provide an optical head capable of achieving both miniaturization and high resolution.

[0012]

In order to achieve the above object, the present invention provides a line in which a plurality of light emitting elements are arranged in a straight line in an optical head for writing data by irradiating a writing line on a surface of a photoreceptor. A plurality of linear light emitting element rows, and a rod lens array for focusing the light of the linear light emitting element rows on the same writing line on the photoconductor surface, corresponding to each of the linear light emitting element rows. It is an optical head.

[0013]

According to the present invention, in the above-mentioned structure, the light of the plurality of line light emitting element rows is imaged on the same writing line on the photoconductor surface by the rod lens array corresponding to each row.

[0014]

【Example】

(Embodiment 1) An optical head according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the configuration of an image forming apparatus using the optical head of the first embodiment of the present invention, and FIG. 2 is a plan view showing the configuration of the linear light emitting elements of the optical head of the present embodiment. is there. The same components as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

This embodiment is different from the prior art in that the rod lens arrays 21 and 22 are connected to the same writing line 2 of the photoconductor.
The light emitting element rows 26 having two rows corresponding to a are arranged in a staggered manner at the object plane positions of the respective rod lens arrays so as to form two linear light emitting element rows 23 and 25. The point is that the and are configured.

In FIG. 1, 2 is a photoconductor and 20 is an optical head of this embodiment. Reference numerals 21 and 22 denote rod lens arrays that form the light beams of the linear light emitting element arrays 23 and 25 on the same writing line 2a on the photoconductor 2 in an erect image, and 23 and 25 denote rod lens arrays 21 and 2, respectively.
It is arranged at the object plane position of 2.

In FIG. 2, each of the line-shaped light emitting element rows 23 and 25 is a line-shaped light emitting element row in which light emitting element rows 26 of length D in which light emitting elements 27 are arranged at a pitch P are arranged at intervals. The light emitting element rows 26 are arranged on the substrate 24 in a zigzag pattern in the main scanning direction to form two line light emitting element rows. The array pitch P of the light emitting elements 10a corresponds to a predetermined resolution.

The operation of the above configuration will be described below.
The light emitting element arrays 23 and 25 of the optical head 20 emit light at the timings when the photoconductor 2 corresponds to the moving speed and the resolution in the sub-scanning direction, and the rod lens arrays 21 and 2 respectively.
2, the optical information for one line is emitted to the same writing line 2a on the photoconductor 2. Hereinafter, the process of forming an electrostatic latent image on the photoconductor and transferring and fixing the toner image on the sheet is the same as in the conventional image forming apparatus, and the description thereof will be omitted.

The resolution in the main scanning direction of the image obtained by the above optical head is determined by the arrangement pitch P of the light emitting elements. On the other hand, as shown in FIG. 2, the distance P1 from the center of the light emitting element 27 at the end of the light emitting element array 26 having the length D to the end of the element array may be longer than the pitch P. Therefore, it is not necessary to process the pitch of the light emitting elements 27 to half as in the conventional case,
High resolution can be easily achieved.

As described above, according to the optical head of the first embodiment of the present invention, the light emitting element rows of a predetermined length are arranged in a zigzag manner to form two linear light emitting element rows, which correspond to each other. By forming the image on the same writing line on the surface of the photoconductor with the rod lens array, the process for forming the line-shaped light emitting element array is simplified, and a compact and high resolution optical head can be realized.

In the embodiment, two rod lens arrays are used.
Although the case of using columns has been described, the configuration may be two or more columns.

Further, although the above-mentioned line-shaped light emitting element array can be constructed by disposing light emitting elements alone, it may be constructed by disposing a light emitting element array block in which a plurality of light emitting elements are formed on one semiconductor substrate. ..

When arranging the light emitting elements alone, it is easy to secure the arrangement accuracy by mounting them on one substrate, but the light emitting element rows are grouped on the substrate and mounted on a separate substrate to form a line. It goes without saying that the light emitting element array may be configured.

(Embodiment 2) An optical head according to a second embodiment of the present invention will be described below with reference to the drawings. The second embodiment is different from the first embodiment only in the arrangement of the light emitting elements, and the other configurations are the same as those in the first embodiment, and the description thereof will be omitted.

FIG. 3 is a plan view showing the arrangement of the light emitting elements in the optical head according to the second embodiment of the present invention. In FIG.
The line-shaped light emitting element rows 23 and 25 in which the light emitting elements 27 are connected are provided on the substrate 24, and the arrangement pitch of the light emitting elements 27 is 2 ×.
Let P. Further, the light emitting element 27 is the line-shaped light emitting element row 2
3 and 25 are displaced by a distance P.

Each of the line-shaped light emitting element arrays having the above-described structure is formed by a rod lens array, and the same writing line 2 is formed on the photosensitive member.
When the image is formed on a, the image is formed at the interval P, and the resolution of the obtained image is determined by P instead of 2 × P. Therefore, it is only necessary to arrange the light emitting elements at an arrangement interval twice as large as the desired resolution, and the light emitting element array can be created more easily than before. on the other hand,
The distance from the center of the light emitting element 10a at the end of the element array to the end of the element array may be processed to be P, and it is not necessary to process to P / 2 as in the conventional example.

As described above, according to the optical head of the second embodiment of the present invention, two line-shaped light emitting element rows in which the light emitting elements are arranged at equal intervals are provided, and the corresponding rod lens array is provided on the photosensitive member surface. By forming an image on the same writing line, it is possible to easily arrange the linear light-emitting element arrays and to easily increase the resolution.

Although the line-shaped light emitting element row is divided into the light emitting element rows having the length D, it goes without saying that the whole light emitting element row may be formed without division.

It goes without saying that two or more sets of the line-shaped light emitting element array and the rod lens array may be provided.

[0030]

As is apparent from the above-described embodiments, the present invention is an optical head for writing data by irradiating a writing line on the surface of a photoconductor to write data, in which a plurality of light emitting elements are arranged in a straight line. An optical head provided with a plurality of element rows and a rod lens array for forming the light of the linear light emitting element rows on the same writing line on the surface of the photoconductor in association with each of the linear light emitting element rows. By doing so, the processing when forming the line-shaped light emitting element array becomes simple, and a compact and high-resolution optical head can be realized.
It can contribute to the realization of a compact and high-quality image forming apparatus.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of an image forming apparatus using an optical head according to a first or second embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a line-shaped light emitting element array in the optical head according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a configuration of a line-shaped light emitting element array in an optical head according to a second embodiment of the present invention.

FIG. 4 is a side view showing a configuration of an image forming apparatus using a conventional optical head.

FIG. 5 is a plan view showing a configuration of a line-shaped light emitting element array in a conventional optical head.

[Explanation of symbols]

 2 Photoreceptor 20 Optical Head 21, 22 Rod Lens Array 23, 25 Line-shaped Light Emitting Element Array 27 Light Emitting Element

Claims (3)

[Claims] 1. An optical head for writing data by irradiating light to a writing line on a surface of a photoconductor, comprising a plurality of linear light emitting element rows in which a plurality of light emitting elements are arranged in a straight line.
An optical head provided with a rod lens array for forming an image of the light of the linear light emitting element array on the same writing line on the photoconductor surface for each of the linear light emitting element arrays. 2. The optical head according to claim 1, wherein the light emitting element rows of a predetermined length in which the light emitting elements are arranged at a predetermined interval are arranged in a staggered manner at a predetermined interval to form two linear light emitting element rows. .. 3. The light emitting elements are arranged at a predetermined interval to form a line light emitting element row, and when a plurality of line light emitting element rows are imaged on the same writing line on the surface of the photoconductor, the respective light emitting elements are mutually arranged. The optical head according to claim 1, wherein the line-shaped light emitting element arrays are arranged so as to form images at equal intervals.