JPS62299980A - Light beam scanning type recording device - Google Patents

Abstract

PURPOSE:To record a uniform image without generating an unscanned part due to a spot by providing the surface of a photosensitive body upon which scanning light beams are made incident with a specific radius of curvature. CONSTITUTION:The photosensitive body 1 is supported and rotated by rollers 9, 10 and the radius of curvature on the point of the photosensitive body upon which laser beams 5 are made incident is set up to <=0.2mm determined by the roller 9. When the radius of the roller 9 is about 0.1mm, the long diameter of a spot, i.e. the spot diameter in the direction parallel with the moving direction 4 of the photosensitive body 1 is 0.116mm. Even if a horizontal scanning line pitch (s) is reduced only a proper value <=10mum from an ideal value and a pitch (v) is increased by a proper value <=10mum from the ideal value, the spots are superposed and there is not unscanned part due to the spots in a solid black image. Consequently, a solid black image with uniform density can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Application of the Invention] The present invention records an image by projecting a light beam modulated according to an image signal, particularly preferably a laser light beam, onto a photoreceptor. The present invention relates to a recording device of a type that uses

[Background of the invention]

2. Description of the Related Art A so-called laser beam printer, which combines a laser beam modulated in accordance with an image signal with an electrophotographic device, is well known as an output device for computers, facsimile machines, etc., or as a copying machine.

FIG. 2 is a schematic diagram showing an example of a conventional laser beam printer. 1 is an endless four-rut-shaped photoreceptor whose outer surface has electrophotographic photosensitive characteristics, and has a width in a direction perpendicular to the plane of the drawing. 2. 2' and 3 are rollers, photoconductor 1
The photoreceptor 1 is moved in the direction of the arrow 4 by being held and rotated multiple times by an appropriate sliding means (not shown). Reference numeral 5 denotes a laser beam modified according to an image signal, which is emitted from a laser oscillator (not shown), and after being reflected by one of the mirror surfaces of a polyhedral mirror 7 rotated by a motor 8, is applied to the surface of a photoreceptor 10. The light enters the surface of the photoreceptor 1 via the lens ie6 provided to focus the light.

The laser beam 5 is repeatedly scanned over the surface of the thin photoreceptor 10 of the polyhedral mirror 7 in a direction perpendicular to the plane of the drawing (width direction of the photoreceptor 1).

Hereinafter, scanning in this direction will be referred to as horizontal scanning. As the photoreceptor 1 rotates in the direction of arrow 4, the laser beam 5 scans the surface of the photoreceptor 1 in the direction from the roller 2' to the roller 2 (the moving direction of the photoreceptor). Hereinafter, scanning in this direction will be referred to as vertical scanning.

Laser light beam 5t - a mechanism for modulating the image signal to be recorded, a mechanism for horizontal scanning, a mechanism for focusing on the photoreceptor 1, a mechanism for forming an electrostatic latent image on the photoreceptor 1, a mechanism for forming an electrostatic latent image on the photoreceptor 1, The specific structure of the mechanism for obtaining a toner image on paper by sequentially developing the image as the photoreceptor 1 moves and transferring it to paper, and the mechanism for fixing the toner image on paper is as follows: Since this is a well-known configuration, its explanation will be omitted.

In the conventional laser beam printer, as shown in FIG. 2, the laser beam 5 is made to enter the photoreceptor 1 in a plane perpendicular to the surface of the photoreceptor 10 and parallel to the width direction. By making the light incident in this way, a well-focused circular spot can be obtained on the surface of the photoreceptor.

Figure 3 (a) shows that in this case,
It shows spots a, b, a, d, . . . of the laser beam formed on the surface of the photoreceptor 10. Arrow, i,
In j, l indicates the direction in which the spot is horizontally scanned. Spora) a, b.

cade・ do not exist at the same time, but according to the vertical scanning of the photoreceptor 1, spora) a appears first on the horizontal scanning line, then b appears on the horizontal scanning line 1, and so on. b ee, d, ・ are sequentially formed,
Scanned horizontally. In the figure, "#tsu'@V" respectively indicates the pitch of the horizontal scanning line. In this example, the soot diameter is the same as the pitch of the horizontal scanning lines.

Figure 3 (b) shows a part of the recorded image when the laser is on for the entire horizontal scanning period shown in Figure 3 (a), and shows a so-called solid black image. . In FIG. 3(a), ideal vertical scanning is performed, so that there is no part of the solid black image shown in FIG. 3(a) that cannot be scanned by the spot. Therefore, a solid black image with uniform density can be obtained.

However, an ordinary laser beam printer that can be constructed at a reasonable cost cannot perform the ideal vertical scanning as described above, but the pitch of the horizontal scanning lines varies as shown in FIG. 4(a). For example, in FIG. 4(a), the pitch of the horizontal scanning lines is smaller than the ideal value, and the pitch ma is larger than the ideal value. When there is such a pitch variation, as is clear from FIG. 4(b), there will be parts in the solid black image that are not scanned by the spot.
This d (appears as white streaks).

A solid black image in which such white streaks appear here and there can be said to be an image with uneven density and significantly degraded quality.

Such variations in the pitch of horizontal scanning lines are caused by uneven rotation of the photoreceptor 1 or variations in the inclination of each mirror surface of the polyhedral mirror 7, and in actual equipment, the pitch is different from the ideal pitch. It is difficult to keep the pitch variation within ±10 μm.

[Purpose of the invention]

The present invention was made in order to eliminate the drawbacks of the above-mentioned conventional example, and it is possible to record a uniform image without generating unscanned parts due to spots even if there is scanning unevenness that cannot be eliminated with ordinary efforts. The object of the present invention is to provide a light beam scanning type recording device that can perform the following steps.

[Summary of the invention]

The present invention is a light beam that records an image by making a scanning light beam modulated according to an image signal enter a moving photoreceptor surface within a plane that intersects the photoreceptor surface in a line perpendicular to the moving direction of the photoreceptor surface. The scanning recording apparatus is characterized in that the surface of the photoreceptor on which the scanning light beam is incident is a cylindrical surface having a generatrix in the direction of the above-mentioned intersection line and having a radius of curvature of 0.2- or less.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention.

The difference from the conventional example shown in FIG. 2 is that the photoreceptor 1 is supported and rotated by rollers 9 and 10, and that specific conditions are added to the shape and dimensions of the roller 9 facing the incident beam 5, so that the laser beam The point is that the curvature of the photoreceptor 1 at the point where the light beam 5 is incident is set to a specific value determined by the roller 9, which will be described later.

FIG. 5 is an enlarged view of the vicinity of p-ra 9 in FIG. 1. In FIG. 5, reference numeral 11 indicates the direction in which the laser beam 5 is incident on the photoconductor 1, a line segment 12 indicates the beam diameter of the radar beam 5, and an arc 14 indicates the direction in which the laser beam 5 is incident on the photoconductor 1. 2 shows the diameter of the sudette in the direction parallel to the moving direction 4 of the photoreceptor 1 when the photoreceptor 1 is irradiated with light.

The shapes of the spots formed on the photoreceptor 1 in FIG. 5 are a, b, e, and d as shown in FIG. 6(a).

·become that way.

Hereinafter, the curvature conditions of the photoreceptor 10, which are requirements for the embodiments of the present invention, will be explained with reference to FIGS. 1, 5, and 6.

Normally, the beam diameter 12 of the laser beam 5 in this type of recording device is 480 lines/inch at a horizontal scanning line density of 480 lines/inch.
00 lines/inch, 300V inch.

or 0, 05 corresponding to 240 lines/inch, etc.
3 wm, 0.064■, 0.085 kaku, or 0,
106- etc. are selected. In this way, the beam diameter is often selected to be the same as the pitch of the horizontal scanning lines.

However, the beam diameter may be selected to be slightly larger than the pitch of the horizontal scanning lines. It will be clear from the following description that the present invention can be applied to either method of selecting the beam diameter. Here, we will take as an example a case where the horizontal scanning line density is 240 lines/inch and the beam diameter is 0.106.

The radius of the roller 9 in FIGS. 1 and 5 is approximately 0.1
−. (To be more precise, it is 0.08 m. However, if the beam diameter of 12 is chosen to be slightly larger than the pitch of the horizontal scanning line), the object of the present invention can be achieved even with 0.1 m. ) At this time, it can be calculated geometrically that the length of the circular arc 14 is 0.116■. If the radius of the roller 9 is smaller, the length of the arc 14 will be larger;
It will be clear from the following description that the present invention can be applied even to cases where the radius of the radius is very small.

Now, when the radius of the p-ra 9 is about 0.1 m, the shape of the spot formed on the photoreceptor 1 is a in FIG. 6(c).
b, a, d, etc., and the length of the slit 4 in the direction parallel to the moving direction 4 of the photoreceptor l is 0.1.
It becomes 16■. FIG. 6(b) shows a black image recorded using such a suit. Here, as in FIG. 4, the pitch of the horizontal scanning line is smaller than the ideal value by an additional value of 10 μm or less, and the pitch V is 10 μm or less than the ideal value.
This shows a case where the additional tooth value has increased by a value of μm or less. In this case, the spots overlap as shown in FIG. 6(a), and there is no portion in the peta black image of FIG. 6(b) that is not moved by the spots. Therefore, a solid black image with uniform density can be obtained.

As a supplementary explanation, electrophotographic recording has a characteristic that when a certain amount of light or more is irradiated, there is no change in the black density of the image obtained, so the image obtained in this example has There is virtually no difference in density between the areas where the spots overlap and the areas where the spots do not overlap.

In the embodiments shown in FIGS. 1 and 5, a roller 9 is used to give the photoreceptor 1 an appropriate curve. However, it is also possible to configure the photoreceptor 1 to be driven only by the roller 10 shown in FIG. 1, and to have the photoreceptor 1 slide on the roller 9 without rotating it.

Further, as shown in FIG. 7, the present invention may also be implemented by providing a platen 15 in place of the roller 9 and configuring the curvature of the irradiated part of the laser beam 5 to correspond to a cylinder with a diameter of 0.2 mm or less. can be implemented.

All of the above conventional examples and detailed description of the present invention are based on the photoreceptor 1.
We have described the case of a type of recording method in which toner adheres only to the areas irradiated with the laser beam 5 above, resulting in black color.

Such a method is usually called an image exposure method.

On the other hand, there is also a well-known recording method that uses an electrophotographic method with different characteristics so that toner adheres only to the portions of the photoreceptor 1 that are not irradiated with the laser beam 5, resulting in black color. Such a method is usually called a background exposure method. The present invention can also be applied to the background exposure method, and in the conventional example and the detailed explanation of the present invention, the "solid black image" is replaced with "solid self-portrait", and the "white stripe" is replaced with "black stripe". It is clear that by replacing the word `` with '', a similar effect can be brought about for peta self-portraits using the pack-ground exposure method.

〔Effect of the invention〕

As described above, according to the present invention, even with a light beam-using recording apparatus having normal scanning unevenness, it is possible to record a flat black or solid self-portrait with a uniform density with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the implementation example of the present invention, Fig. 2 is a block diagram of the conventional example, and Figs. 3 (a) and (b) are explanatory diagrams showing the ideal state of the conventional example and the resulting Diagram showing a peta black image, Figure 4 (a)
, (b) is an explanatory diagram showing the actual state of the conventional example and a diagram showing the obtained nine-peta black image, FIG. 5 is an explanatory diagram for explaining FIG. 1 in detail, and FIG. 6 (a) , ←) is an explanatory diagram showing a practical state in an embodiment of the present invention and a diagram showing an obtained peta black image. FIG. 7 is a diagram showing another embodiment of the present invention. 1... Endless belt-shaped photoreceptor 5... Laser light beam 6... Imaging lens 7...
・Polyhedral mirror 8...Motor 9.10...
Roller 12...Beam diameter 14...Diameter of the spot in the direction of movement of the photoreceptor 15...Platen Fig. 2 Fig. 3 (a) (b) Fig. 6 Fig. 7

Claims (1)

[Claims] A light beam scanning type recording device that records an image by making a scanning light beam modulated according to an image signal enter a moving photoreceptor surface within a plane that intersects the photoreceptor surface at a line perpendicular to the direction of movement of the photoreceptor surface. In , the photoreceptor surface on which the scanning light beam is incident has a generatrix in the direction of the above-mentioned intersection line and has a width of 0.2 mm.
A light beam scanning type recording device characterized by exhibiting a cylindrical surface having the following radius of curvature.