JPH04109769U - recording head - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to perform high-quality recording with a relatively low-density and inexpensive configuration. [Structure] A cylindrical lens 4 is provided between a rod lens array 3 and a photosensitive drum 11 in parallel to an LED array 1. At this time, the rod lens array 3 and the cylindrical lens 4 are arranged on the optical axis of the light beam emitted from the LED array 1. Further, the cylindrical lens 4 is arranged so as to have a refractive index in a direction along the rotational direction of the photosensitive drum 11.

Description

[Detailed explanation of the idea]

[Purpose of invention]

0001

[Industrial application field]

This invention uses a one-dimensional array of point light sources such as light emitting diodes (LEDs). The recording head exposes the photoreceptor using the light beam emitted from each point light source. related.

0002

[Conventional technology]

Figure 4 is a diagram showing the general configuration of a light emitting diode printer (LED printer). be. In the figure, 11 is a cylindrical photosensitive drum. This photosensitive drum 11 has a Along the surface, a charging device 12, an LED head 13, a developing device 14, and a transfer peeling device 1 are installed. 5, a cleaning device 16, and a static eliminator 17 are provided, respectively. Also, 1 8 is a fixing device.

0003 This LED printer operates as follows. That is, the charging device 12 An image to be recorded on the photosensitive surface of the charged photosensitive drum 11 by the LED head 13 to form an electrostatic latent image. Then, on the photosensitive surface of this photosensitive drum 11, A developing device 14 causes toner to adhere to the formed electrostatic latent image. Next, the feeling The recording paper 19 is placed on the photosensitive surface of the optical drum 11, and the recording paper 19 is transferred from the transfer device 15 to the recording paper 19. By applying charges of the same polarity as the electrostatic latent image, the photosensitive drum 11 is The toner adhering to the light surface is transferred onto recording paper 19. In this way, the toner is transferred The transferred recording paper 19 is peeled off from the photosensitive drum 11, and then the transferred toner is removed. After being fused in the fixing device 18, it is discharged from the device.

0004 On the other hand, after the recording paper is peeled off, the photosensitive surface of the photosensitive drum 11 remains without being transferred. The toner contained therein is removed by a cleaning device 16. Furthermore, the feeling of the photosensitive drum 11 A residual charge is removed from the light surface by a charge removing device 17.

[0005] Here, the LED head 13 includes a large number of LEDs arranged one-dimensionally on a substrate and A rod that forms an image of the luminous flux emitted from each of the LEDs onto the photosensitive drum 11 It is composed of a rod lens array which is an array of lenses. To this LED The shape of the light beam irradiated onto the photosensitive drum 11 by the pad 13 is circular. Therefore, The dots recorded by the above-mentioned LED printer are circular as shown in FIG.

[0006] By the way, the standard recording density for facsimile machines is 8 dots/mm x 3.85 line. s/mm and 8 dots/mm x 7.7 lines/mm, but in recent years, recording heads have a recording density of 8 d. In order to obtain high resolution using ots/mm, we recorded 8dots/mm×15.4lines/mm. A density recording mode is being considered. In other words, the main scanning direction (L (ED arrangement direction) Using dots corresponding to a pixel pitch of 8 dots/mm, as shown in Figure 6. It is possible to change the recording timing in the sub-scanning direction (rotation direction of the photosensitive drum 1). By this, high resolution can be obtained.

[0007] However, when the above recording is performed, as shown in Figure 6, adjacent images in the sub-scanning direction are Some of the dots overlap. For this reason, the recorded image may be distorted, etc. I don't expect much improvement in image quality.

[0008]

[Problem that the idea aims to solve]

As mentioned above, with conventional recording heads, for example, 8 dots/mm x 15.4 lines/mm, When recording at a higher recording density in the sub-scanning direction than in the main-scanning direction, the dot The problem is that the image quality does not improve much because the resolution is poor due to overlapping images. was there.

[0009] This invention was created taking these circumstances into consideration, and its purpose is When recording is performed at a higher recording density in the sub-scanning direction than in the main-scanning direction. It is possible to record with high resolution even in To provide a recording head that is capable of recording at high image quality while It is in. [Structure of the idea]

0010

[Means to solve the problem]

The present invention makes the shape of the luminous flux emitted from a point light source such as an LED into an ellipse. The short axis direction of the resulting elliptical light beam is aligned with the many point lights. A luminous flux emitted from each of the plurality of point light sources so as to intersect with the direction in which the sources are arranged. placed on the optical axis of the

[0011]

[Effect]

By taking such measures, the arrangement direction of many point light sources (main scanning direction) Narrow dots are formed in the direction intersecting with (sub-scanning direction). Therefore, a large number The density of dots in the direction intersecting the arrangement direction of the point light sources can be increased.

0012

【Example】

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of the recording head according to this embodiment, and here the LED head This example shows the case where it is applied to a code. In the figure, 1 is a one-dimensional array of many LEDs. This LED array is attached to the board 2. And this LED thing A 1 is arranged to face the photosensitive drum 11 in order to irradiate the photosensitive drum 11 with emitted light. Ru. 3 is a rod lens array, which has the same number of LEDs as the LED array 1. It consists of a one-dimensional array of rod lenses. This rod lens array 3 is It is installed between the LED array 1 and the photosensitive drum 11 in parallel to the LED array 1. I get kicked. The above configuration is the same as that of a conventional LED head.

[0013] 4 is a cylindrical lens having a refractive index in only one direction. This cylinder The linear lens 4 has an LED array between the rod lens array 3 and the photosensitive drum 11. It is provided in parallel to A1.

[0014] By the way, the rod lens array 3 and the cylindrical lens 4 are shown in FIG. The LED array 1 is arranged on the optical axis of the light beam emitted from the LED array 1. Also The cylindrical lens 4 has a refractive index in a direction along the rotation direction of the photosensitive drum 11. It is arranged so that it has.

[0015] Thus, for the above LED heads, each LED constituting the LED array 1 The luminous flux (circular shape) emitted from each rod lens composing the rod lens array 3 An image is formed on the photosensitive drum 11 by each of them. However, at this time, the above luminous flux is The rotational direction of the photosensitive drum 11, that is, the sub-scanning direction, is controlled by the cylindrical lens 4. It is refracted only in the direction, with the long axis in the main scanning direction and the short axis in the sub-scanning direction. It has an elliptical shape. Therefore, the refractive index of the cylindrical lens 4 should be optimized. For example, by setting the pixel pitch to 8 dots/mm, The sub-scanning direction is faster than the main scanning direction, such as recording at a recording density of 8dots/mm x 15.4lines/mm. Even when recording at a high recording density in the scanning direction, the drive There will be no overlap between the pieces. Therefore, the resolution is good and the image quality is sufficiently improved. can be done.

[0016] Note that the present invention is not limited to the above embodiments. For example, in the above example, Although the recording head according to the present invention is applied to an LED head in the explanation, for example, fluorescent It may be a light source other than LED such as the body or EL (electroluminescence). Alternatively, a device using a liquid crystal shutter or the like may be used.

[0017] Further, in the above embodiment, the cylindrical lens 4 is connected to the rod lens array 3 and the photosensitive It is installed between the drum 11, the LED array 1 and the rod lens array 3. It may be installed in between. In addition, various modifications may be made without departing from the gist of the present invention. It is possible to implement.

[0018]

[Effect of the idea]

According to the present invention, the shape of the luminous flux emitted from a point light source such as an LED can be shaped into an ellipse. The short axis direction of the obtained elliptical light beam is the same as above. emitted from each of the plurality of point light sources so as to intersect with the direction in which the point light sources are arranged. Because it is placed on the optical axis of the light beam, it can record at a higher density in the sub-scanning direction than in the main scanning direction. Even when recording in degrees, it is possible to record with good resolution, which makes it Although it has a relatively low-density and inexpensive configuration, it is possible to record with high image quality. It becomes the recording head.

[Brief explanation of drawings]

[Fig. 1] A recording head (LED
FIG. 2 is a perspective view showing the configuration of a head.

[Fig. 2] A recording head (LED
FIG. 3 is a side view showing the configuration of the head.

FIG. 3 is a diagram showing an example of a recorded image.

FIG. 4 is a diagram illustrating the prior art.

FIG. 5 is a diagram illustrating the prior art.

FIG. 6 is a diagram illustrating the prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... LED array, 2... Substrate, 3... Rod lens array, 4... Cylindrical lens, 11... Photosensitive drum.

Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H04N 1/036 A 9070-5C

Claims (1)

[Scope of utility model registration request] 1. A recording head having a one-dimensional array of a large number of point light sources, in which a cylindrical lens that makes the shape of the light beam emitted from the point light source elliptical is arranged in the short axis direction of the resulting elliptical light beam. The recording head is arranged on the optical axis of the light beam emitted from each of the plurality of point light sources so as to intersect with the arrangement direction of the plurality of point light sources.