JPS59109071A - Optical writing head of electronic photographic type printer - Google Patents

Abstract

PURPOSE:To obtain a cheap writing head that can make high speed print by providing a thin film electric field light emission plate using a zinc sulfide film activated by manganese as a light source. CONSTITUTION:The thin film electric field light emission plate used as a light source of the print head consists of a base body 16 made of glass etc., electrodes 17, 18, insulating layers 19, 20 that sandwich manganese-bearing zinc sulfide layer 21 between and stabilizes the light emission plate, and leads 22, 23 to impress alternating voltage to electrodes 17, 18. The base body 16 is made of transparent material, and the electrode 17 is made up of a thin, transparent conductive film of oxide of tin or a thin transparent conductive film of indium oxide and formed by vapor deposition etc. Yttrium oxide, aluminum oxide etc. is used for the insulating layers 19, 20, and the manganese-bearing zinc sulfide layer 21 is formed to the thickness of above 1,500Angstrom by electron beam vapor deposition making manganese-bearing zinc sulfide a source.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical writing head (hereinafter referred to as a print head), which is an important component in an electrophotographic printer.

Conventional Structure and Problems First, the principle of an electrophotographic printer will be briefly explained with reference to FIG. In Figure 1, (1) is the photosensitive drum, (2) is the charger, (3) is the print head, and (4) is the photosensitive drum.
, (5) is the paper, ((1) is the developer for toner development, (7) is the transfer device, (8) is the fixing device, (9) is the stacker, Od is the erasing lamp, αη is a cleaning device, and @ is a plurality of rollers.
) rotates in the direction of the arrow. Image formation in an electrophotographic printer is performed through the following process.

■ A charger (2) uniformly charges the photoreceptor on the surface of the photoreceptor drum (1) (charging process).

(2) A print head (3) selectively irradiates light onto this photoreceptor to form an electrostatic latent image (optical writing process).

(2) This electrostatic latent image is visualized with toner using a developing device (6) (developing process).

■ Transfer the Kono toner image to the paper (7) using the transfer device (7).
5) Transfer to (transcription process).

■ Fusing the paper (5) with the fixing device (8) (fixing process).

There are two types of print heads: one that uses a single light source and photometering means, and the other that uses a plurality of light sources arranged in a row and writes only by blinking each light source.

Laser printers are examples of printers that use print heads that combine a single light source with light deflection means. In this printer, a single, narrowly focused laser beam is deflected by a rotating polygon mirror and scanned over a photosensitive drum. This type of printer is fast and has good print quality, but there is a limit to miniaturization and it is expensive. Therefore, this type of printer is put into practical use as a high-end machine.

On the other hand, a print head in which a plurality of light sources are arranged in a line and writing is performed only by blinking each light source does not require a deflection space and is therefore extremely suitable for miniaturization. Additionally, there are no moving parts like a rotating mirror in a laser system, and everything is electrically controlled, improving reliability. Figure 2 shows a schematic configuration of such a print head in which multiple light sources are arranged in a line and writing is performed only by blinking each light source. is the light source, (
g) is the light emitted from the light source a4. Conventionally, a light emitting diode array has been used as the light source a4. Currently, this light-emitting diode array is produced by connecting one-chip light-emitting diodes ljJ made from a 2-inch wafer to obtain a light-emitting diode array of a desired length.For example, for 84-size printing, requires a light emitting diode array with a length of about 2Bcut. However, this light emitting diode array has the following problems.

■ 1 chip: When connecting light emitting diode arrays, there are assembly problems such as accuracy such as linearity and parallelism with the drum axis.

(2) Currently, the brightness unevenness of each light emitting diode in the L-chip light emitting diode array is approximately twice as large. When used in a print head, it is necessary to suppress the brightness unevenness of each of the four light emitting diodes to within ±ion at most.

■ The higher the brightness of each light emitting diode, the faster printing becomes possible. Currently, an A4 size print is about 8
It takes seconds.

■Currently, 6500A is used as a high-brightness light emitting diode array.
Light emitting diode arrays that emit light at longer wavelengths have been developed. Light emitting diodes with shorter wavelengths have insufficient brightness and there are problems in manufacturing when forming light emitting diode arrays. However, as shown in FIG. 8, current commercially available photosensitive drums have greater sensitivity to light with wavelengths shorter than 6000 A. Note that FIG. 8 shows the sensitivity of a commercially available photosensitive drum to the wavelength of light.

Therefore, it is desirable to have a light source that emits light with a much shorter wavelength than the current commercially available photoreceptor drums.

Further, when using a conventional light source based on an array of light emitting diodes, new photoreceptor drums have been developed, but are still insufficient.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and provides an optical condensation head for an electrophotographic printer that is inexpensive and capable of high-speed printing, is compact, has excellent durability, and has a good yield during production. The purpose is to provide

Structure of the Invention In order to achieve the above object, the optical writing head of the electrophotographic printer of the present invention is configured to include a thin film electroluminescent plate using a zinc sulfide thin film activated with manganese as a light source.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows a thin film electroluminescent plate C and a thin film EL as a light source used in a print head in an embodiment of the present invention.
), QQ is a substrate made of glass etc., and a
'; h- is an electrode, (19) (201 is a zinc sulfide layer containing manganese (an insulating layer to stabilize the thin film HL by sandwiching 2υ, @ (2) is an electrode Q?) (181 is an alternating voltage Normally, light is extracted from the substrate (6) side, which is the lead for applying the voltage, so the substrate 0 is made of a transparent material, and the electrode (b) is made of a conductive transparent oxide thin film or a conductive transparent material. It is composed of an indium oxide thin film.Also, light may be extracted from the electrode side, and in this case, the electrode must be formed of a conductive transparent indium oxide thin film, etc.These thin films are usually vapor-deposited. It is formed by a sputtering method or a sputtering method.

Each of the insulating layers θ has a thickness of 15,004 mm or more. This insulating layer 09)6!1 is made of yttrium oxide (Y
, O,), aluminum oxide (AI, O8), silicon nitride, etc. are used, and the formation of this insulating layer (31(5) is
By vapor deposition or sputtering method. The manganese-containing zinc sulfide layer +21) has a thickness of 1500 A or more and is usually formed by electron beam evaporation using manganese-containing zinc sulfide as a source. The thin film FiL formed in this way
is then heat-treated, usually at a high temperature of 800°C or higher. Thereafter, depending on the case, it is immersed in silicone oil, and an alternating voltage is applied for 50 hours or more to age it. In this way, a thin film BL with no luminance deterioration for a long time is completed.

The print head requires a resolution of about 10 to 16 lines per hour. In the light emitting part of the optical writing head according to the present invention, as schematically shown in FIG. 5 or 6, one electrode is an electrode on one side, and the other 'fI! , the poles are divided into patterns corresponding to the resolution.

6 and 6, α・ is a substrate made of a transparent insulator such as glass, α′I) (181 is an electrode, 09
)6!0) is an insulating layer, H is a zinc sulfide layer containing manganese, FIG. 5 shows electrodes (1 to 1), and FIG. 6 shows an example in which the electrode α force is subdivided. By doing this, since the insulating layer (19)■ and the zinc sulfide layer C2υ have high resistance, only the part directly under the electrode to which voltage is applied among the subdivided electrodes Qη or the electrodes lights up. , insulating layer (19) fi,!: The combined thickness with zinc sulfide comb 1 is a little less than 1/7 m, and electrode Q1~ is 1000^~60
It is rank 00^. The width (l,) of the electrode divided by a is about 50 μrn when the resolution is 10 lines/mm. Note that FIG. 6 is a diagram of the principle, and in the case of an actual print head, the number of subdivided electrodes reaches several hundred. For example, when producing 84-size printed matter, approximately 2,500 pieces are required. This subdivided electrode is made to blink independently by a group of electronic switches. Also, this subdivided light source image is created by a rod lens play (2
) is used to form an image on the photoreceptor drum (1).

Next, a more specific embodiment will be explained.

[Specific Example 1] A print head using a light source having a structure as shown in FIG. 6 was manufactured. l1li (11,) of electric W1a'h is 50
pm, and the distance (l,) between adjacent electrodes O1η was also 50 μm. The procedure is described below. First, Corning standard #7059 was coated with a commercially available conductive transparent tin oxide thin film.
I got the glass. Considering A-4 size printing, the length of the glass was set to 2oC1rL. Next, an organic resist pattern is formed on this conductive transparent tin oxide thin film using a commercially available organic resist, which is further reduced in hydrogen plasma, and further immersed in hydrochloric acid to form an electrode pattern α.
η was formed. Next, yttrium oxide (Y20 g), zinc sulfide containing manganese, and further yttrium oxide (Y2O3) were sequentially deposited by electron beam at a vacuum level of 5 x 10' Torr or lower and a temperature of 280°C.

Each film thickness is sequentially 2500λ, aoooλ, 25o
oAtoLJ,=.

That'-! Well, it was kept in a vacuum at 800'C for 80 minutes, and then an electric gradient was formed by vapor deposition of aluminum. Next, the insulating layer θlI)(ig) and the zinc sulfide layer were appropriately covered and filled with commercially available silicone oil.

The thin film EL obtained in this way is mounted on a drive circuit, and
I installed the rod and lens row and completed the print head.

Furthermore, electrophotographic printing was performed using a commercially available selenium (8e) drum as a photoreceptor drum. As a result, first of all, A4 size printing is possible with this thin film EL x book, there are no problems with conventional connections, and implementation is easy. In addition, when the brightness unevenness of this thin film EL was measured using an optical fiber and Photomaru, it was within ±5%. Furthermore, in an alternating electric field of 5kHz peak value 220V, 40
A luminance of 0St-L (Foot-Lambert) was obtained. Moreover, the emission wavelength of this thin film BL showed a wide spectrum centered around 5800A.

Furthermore, conventionally, when using a light emitting diode array, it took about 8 seconds to print an A4 size, but when using this thin film EL, it was possible to print an A4 size in about 1 second.

[Specific Example 2] A print head using a light source having a structure as shown in FIG. 5 was manufactured. The width of the electrode 0 barrel (l!, > was 5 eμm, and the interval (12) between adjacent electrodes fIS u was also 50 μm. The procedure is described below. First, a corning coated with a commercially available conductive transparent tin oxide thin film was used. I got the $7059 glass from Shakiji. Considering the A4 size print, I changed the length of the glass to 2.
I set it to 0. Next, silicon nitride was formed by sputtering at 200 OA. Furthermore, zinc sulfide containing manganese was deposited with an electron beam at a base temperature of 200°C, and aooo
Next, silicon nitride was made into a layer with a thickness of 200O
It was formed using A sputtering and heat-treated in vacuum at 400°C for 180 minutes. Next, an electrode was formed by vapor deposition of aluminum, and an electrode was obtained by etching using a commercially available organic resist. This was assembled and evaluated as in Example 1. In this case as well, it was superior to the conventional example, similar to the first example.

As described in detail, the present invention provides the following effects.

■ Glass, etc. can be used for the substrate, and since the manufacturing method is based on the evaporation method, long ones can be manufactured, and there is no need to connect chips as in the case of conventional light emitting diode arrays. There are no problems associated with this.

(2) Since the thin film EL is mainly manufactured by the vapor deposition method, the surface of each layer has a flatness of about 5000 A or less, and microfabrication of the electrodes to the order of several micrometers is possible.

- Since thin film EL is used, brightness unevenness can be suppressed to within ±10 inches.

■ The brightness of conventional light emitting diodes is difficult to measure. Comparisons are therefore difficult.

In the case of a thin film EL, it is easy to produce a luminance of 8008t-L (foot/belt) with a 5kHz alternating electric field with a peak value of 220V.

■ Zinc sulfide thin film EL activated with manganese is 6800λ
It has a wide emission spectrum centered around
Unlike the conventional example, it is possible to use a photosensitive drum that is currently available on the market and has excellent reliability.

■ From the above, it is possible to realize an optical writing head for an electrophotographic printer that is inexpensive and capable of high-speed printing, is compact, has excellent durability, and has a good yield rate during production.

[Brief explanation of the drawing]

Figure 1 is an illustration of the principle of an electrophotographic printer, Figure 2 is an illustration of the method of forming a light source image using a Rondo lens array, and Figure 8 is an explanation of the light wavelength dependence of the sensitivity of a commercially available photoreceptor drum. Figure 4 shows the thin film E used in the optical writing head of the present invention.
A schematic configuration diagram of L, FIG. 5 (Al is a vertical cross-sectional front view of a thin film EL used in an optical writing head in one embodiment of the present invention, FIG. Figure (B) is a plan view of the thin film EL.
・Insulating layer, sheet... Zinc sulfide layer agent Yoshihiro Morimoto Figure 1 Figure 2 Figure 3 500θ 6am
7otpo CA length Fig. 4 2 5 □- Fig. 5

Claims (1)

[Claims] 1. An optical writing head of an electrophotographic printer with a thin film electroluminescent plate using a zinc sulfide thin film activated with manganese as a light source.