JPS6142664A - Information recording device - Google Patents

Abstract

PURPOSE:To prevent an interference fringe caused by the uneven film thickness of a photosensitive layer, and to prevent a moire generated by scanning exposure, by using a photosensitive body which has roughened a conductive body by a roughness pitch l for satisfying 0.7<d/l<70, when a recording dot pitch is denoted as (d). CONSTITUTION:A photosensitive body 16 is electrified uniformly as to its surface by a corona electrifying device 17, and thereafter, subjected to scanning exposure in the direction roughly parallel to a revolving shaft of the photosensitive body by a laser beam 13, and forms an electrostatic charge latent image. A modulation pitch of a laser beam is (d), therefore, a recording dot pitch on the photosensitive body, namely, a picture element pitch is (d). Also, the photosensitive body 16 receives an action of a developing device 18, and a toner image is formed on the surface. The toner image is transferred by a transfer electrifying device 22 onto a transfer paper fed by a feed paper roller 20 and a pair of resist rollers 21 from a transfer paper casstte 19, and thereafter, the transfer paper is separated from the photosensitive body 16 by a separating electrifying device 23. Also, the transfer paper is carried to a fixing device 25 by a carrying belt 24 and the toner image is fixed, and said paper is discharged to a discharge paper tray 26.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an information recording apparatus that scans an electrophotographic photoreceptor with a laser beam modulated in accordance with a recorded information signal.

(Technical Background) Information recording devices that use lasers as light exposure light sources for electrophotography are already well known.

By using laser light, which is coherent light, as a light source, it has become possible to irradiate light with an extremely small spot diameter onto the photoreceptor, making it possible to record clear images with high resolution.

On the other hand, photoreceptors used in electrophotography include CDS, Se, and a-3i (amorphous silicon) on a conductor.
A stack of photosensitive layers of optical semiconductors such as . There are two types of photosensitive layers: one that consists of only one layer, and one that consists of multiple layers that have separate complex semiconductor functions.

There are also photoreceptors that further have a protective layer, an insulating layer, etc. on the surface, if necessary.

Since the above photoreceptor is used repeatedly, it is used in the form of a drum or a belt, and the photoreceptor layer has a uniform thickness in either shape. However, in reality, the film thickness differs from place to place to the extent that unevenness in potential does not pose a problem within a practical range.

Even if a photoconductor has uneven film thickness, if it is exposed to non-coherent light from a light source 1 used in a normal copying machine, such as a fluorescent lamp or a halogen lamp, the interference pattern due to uneven film thickness will appear as an electrostatic image. No such problem will occur.

However, when laser light, which is coherent light, is used as a light source, the laser light causes interference within the photosensitive layer, resulting in a striped light intensity pattern due to uneven thickness of the photosensitive layer.

(Hereinafter, the interference pattern caused by uneven film thickness will be referred to as interference fringes.) Therefore, a high level of technology is required to manufacture photoreceptors for laser recording in order to prevent interference fringes from occurring. .

The reason why interference fringes occur in conventional laser recording will be described using FIG.

The electrophotographic photoreceptor 2 is irradiated with a laser beam 1 indicated by a solid arrow in FIG.

The photoreceptor 2 described here has an organic optical semiconductor (hereinafter referred to as a C0 layer) 4 as a charge generation layer and an organic optical semiconductor (hereinafter referred to as a CT layer) 5 as a charge transfer layer on a conductive substrate 3.
This is a type of photoreceptor in which layers are laminated in order.

The laser beam l incident on the photoreceptor 2 is CT15,
CG? 0 travels through the photoreceptor layer while being absorbed by 4, but reaches the conductor substrate surface 3 with some portion not being absorbed).
Usually, the surface of the conductive substrate is finished to a mirror finish. Therefore, the laser beam reaching the conductive substrate 3 is reflected.

Furthermore, if the refractive index between the CT layer 4 and the 00 layer 5 is different,
A portion of the laser beam is reflected by the boundary surface. The straight light and the reflected light of these laser lights will interfere with each other.

When the laser beam is used as recording light, the photoreceptor is scanned in both x-7 directions. Therefore, if there is any unevenness in film thickness on the photoreceptor 2, fringes of light intensity similar to the contour lines of the film thickness, so-called interference fringes, will occur.

If the beam absorption within the semiconductor layer (photosensitive layer) of the photoreceptor 2 is sufficient, interference fringes will not occur, that is, thick seed interference fringes will tend to be less likely to occur.

Considering the economic efficiency of film formation, there is a limit to increasing the thickness of the photosensitive layer. In particular, in the case of an amorphous semiconductor photoreceptor whose main component is silicon, the so-called amorphous silicon photoreceptor, there is a film thickness limit due to the cost because it takes time to form a film, and the film thickness is about 20 μm. It is normal to

However, if the surface of the conductor, that is, the side on which the photosensitive layer is laminated, is roughened and the surface is roughened to scatter the laser light that reaches it, the interference fringes can be prevented even if the film is thin. It was found to be effective. However, depending on the degree of surface roughness, the interference fringes disappear, while the laser beam scanning and the pitch of the surface roughness interfere with each other, creating a new periodic moiré pattern (hereinafter referred to as moiré fringes). It turns out that it does.

(Purpose and Overview of Structure) The present invention solves the above-mentioned drawbacks, namely, prevents interference fringes caused by uneven thickness of the photosensitive layer in a recording device that scans and exposes a photoreceptor to a laser beam to obtain a recorded image, and also prevents moiré caused by scanning exposure. The purpose is to prevent

That is, by using a photoreceptor whose conductor is roughened with a roughness pitch that satisfies 0.7<d/fL<70, where the recording dot pitch is d, the interference fringes and moire pattern can be suppressed. .

(Example) FIG. 2 is a diagram illustrating the entire apparatus of a laser beam printer embodying the present invention. In FIG. 2, a semiconductor laser 11 is modulated and outputted by a recorded information signal from a document reading device or a computer (modulation pitch d), and is swept by a one-rotation polygon mirror 12. The laser beam 13 is imaged by an imaging lens 14 having f-〇 characteristics on an electrophotographic photoreceptor 16 rotating in the direction of the arrow. Note that 15 is a mirror for bending the beam optical path. After the surface of the photoreceptor 16 is uniformly charged by a corona charger 17, it is scanned and exposed by a laser beam 13 in a direction substantially parallel to the rotation axis of the photoreceptor to form an electrostatic latent image. As mentioned above, since the modulation pitch of the laser beam is d, the recording dot pitch, ie, the pixel pitch, on the photoreceptor is d. Further, the photoreceptor 16 is operated by a developing device 18 to form a toner image on its surface. Paper feed roller 20 from transfer paper cassette 19
After the toner image is transferred by a transfer charger 22 onto a transfer paper fed by a pair of registration rollers 21, a separation charger 2
At step 3, the transfer paper is separated from the photoreceptor 16. The transfer paper is further transported to a fixing device 25 by a transport belt 24, the toner image is fixed thereon, and the paper is ejected to a paper ejection tray 26. The remaining toner on the -1 photoreceptor 16 is cleaned by a cleaner 27 and used repeatedly.

xmt*Figure 2 is an explanatory diagram of a photoreceptor used in the apparatus. 13-1 is a laser beam corresponding to the recorded information signal for one recording dot, and 13-2 is a laser beam corresponding to the recorded information signal for one recording dot following the above signal.

The pitch between the beams 13-1 and 13-2, that is, the recording dot pitch is d.

In FIG. 1, a photoreceptor 16 has a photoconductive photosensitive layer 7 laminated on a conductive (for example, aluminum) substrate 6. As shown in FIG.

Amorphous silicon can be used as the photosensitive layer 7.

In this case, the layer structure of the amorphous silicon photoreceptor is such that a high-resistance blocking layer is provided on the aluminum substrate as necessary, and a high-resistance blocking layer is formed on the aluminum substrate by glow discharge method, sputtering method, etc. in the presence of active hydrogen such as silane gas. -St layer can be provided. Also, the blocking layer is a-5i
Of course, it may be provided above.

Furthermore, the a-5i layer may be a P-type a-St layer doped with an element of group m of the periodic table such as aluminum, indium, gallium, arsenic, etc. N-type a- doped with m-group elements
It may include a 5t' layer, and a retainer 15 can be provided on the upper layer of the a-5t layer to improve durability.

The photosensitive layer 7 may be a photoreceptor formed by coating dye-sensitized zinc oxide, selenium powder, polyvinyl carbazole, phthalocyanine pigment, oxysadiazole pigment, etc. together with a binder resin if necessary. In addition, an undercoat layer may be provided between the conductive layer and the photosensitive layer as necessary to improve adhesion, improve coatability, protect the substrate, cover defects on the substrate, and the like.

The surface 6' of the substrate 6 on which the photosensitive material N7 is to be laminated has been roughened in advance before lamination. As this roughening method, any method normally used for roughening metal surfaces, such as cutting or etching, can be employed.

If the average roughness pitch of the rough surface formed in this way is taken as a statement, if dll is smaller than 0.3, the roughness pitch will be too large and the unevenness in the thickness of the S photosensitive layer will remain almost the same as the interference fringes. This will occur as follows. Furthermore, as d/l>70, the conductive substrate becomes almost a mirror surface to the laser beam, so that the scattering effect disappears, and the contrast of interference fringes due to unevenness in film thickness increases.

On the other hand, when dll is smaller than 0.7, the contrast of the moire fringes increases.

Therefore, by roughening the surface of the conductive substrate so as to satisfy the condition of 0.7<d/u<70, it is possible to obtain a high-quality recorded image in which the interference fringes and moiré fringes are sufficiently suppressed.

Note that the roughening direction of the conductive substrate may be in the direction of the rotational axis of the photoreceptor, in the rotational circumferential direction, or in the oblique direction.

Further, the roughening pattern may be a unidirectional spiral, a mesh, or a lattice.

Further, even if the conductor is formed as an a-layer on another substrate, it does not matter as long as the surface of the conductor is substantially rough so as to satisfy 0.7<dll<70.

(Effects) By carrying out the present invention as described above, it has become possible to obtain a recording device that not only can prevent interference fringes but also can prevent moiré fringes. In particular, the yield was dramatically improved due to the uniformity of the thin film, which was difficult in the production of photoreceptors. Cause? As a result, the resulting photoreceptor is also low-cost, and running costs can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the main part of an embodiment of the present invention, FIG. 2 is an embodiment of the present invention, and FIG. 3 is a conventional example.
1 is a laser, 16 is an electrophotographic photoreceptor, 22 is a conductor,
23 is a photosensitive layer.

Claims (1)

[Scope of Claims] In an information recording device that scans an electrophotographic photoreceptor having a photosensitive layer on a conductor with a laser beam modulated in accordance with a recorded information signal, The information recording is characterized in that the surface is roughened so that it has an average roughness pitch l that satisfies 0.7<d/l<70, where d is the recording dot pitch. Device.