JPS60162375A - Reading device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of reading performance of a device which reads originals optically by using SiOxNy (x>0, y>0) to form a protecting layer. CONSTITUTION:The 1st electrode 2 is formed on a substrate 1, and a photoelectric conductor 3 is formed on the electrode 2. Then a 2nd electrode 4 is formed on the conductor 3 with a light transmitting material, and a protecting layer 8 is formed on the electrode 4. The layer 8 is formed with SiOxNy (x>0, y>0) and therefore excels in the wear resistance with high hardness and reduced flaws. Furthermore the transparency is kept satisfactory for a long period of time with a small refractive index for the layer 8. Thus the incident angle at which the total reflection is caused in increased at the interface of air between the layer 8 and the original 9. This reduces the generation of noises.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, for example, a facsimile transmitter, etc.
The present invention relates to a reading device for optically reading a document image.

Conventionally, a reading device is formed by forming a photoconductor in a sandwich on a transparent substrate using, for example, a first electrode and a photosensitive second electrode, and transmitting light from nine light sources disposed on the substrate side. The light passes through a light passing hole formed in the first electrode, the photoconductor, and the second electrode, and the reflected light from the document placed on the opposite side of the light source is received by the photoconductor near the light passing hole. configured to do so. In a reading device having such a configuration, it is necessary to form a protective layer on the second electrode to prevent wear and damage during traveling of the document.

An object of the present invention is to provide a reading device having a protective layer with excellent wear resistance.

FIG. 1 is a sectional view of an embodiment of the present invention. A first *pole 2, which is a common electrode, is formed on a substrate 1 made of a light-transmitting transparent material, such as glass. This first electrode 2
is formed by vapor-depositing chromium, aluminum, etc. A photoconductor 3, such as an amorphous silicon semiconductor, is formed on the first electrode 2 to form a photodiode.

On this photoconductor 3, a second photoconductor made of a light-transmitting transparent material is provided.
The electrode 4 is formed by sputtering, vapor deposition, or the like. An extraction electrode 5 is formed on the second electrode 4 by vapor deposition of chromium or the like.

FIG. 2 is a plan view of such a configuration. A light passage hole 6 is formed in the first electrode 2, the photoconductor 3, and the second electrode 4. A light source 7 is arranged on the substrate 1 side. The light from the light source 7 passes through the light passage hole 6. A protective layer 8 is formed on the second electrode 4 and the like. A document 9 to be read is placed and run on the protection shaft 8 side. The light from the light source 7 is irradiated onto the original 9 through the light passage hole 6, and the reflected light from the original 9 is received by the photoconductor 3 near the light passage hole 6.

In this way, a photodiode is formed near the optical di hole 6. A plurality of these 7 Otogiodes are arranged along the width direction perpendicular to the running direction of the thread @ 9, and as the document 9 runs, a trimming operation is performed sequentially.

Protective layer 8h consists of SiO, N, (x>O, y>O). The protective layer having such a composition has high hardness and excellent wear resistance. In addition, the protective layer 8 maintains good transparency over a long period of time even though it is scratched. Furthermore, the protective layer 8 has excellent crack resistance and is chemically stable. Further 1, protective layer 8f''i first electrode 2,
The second electrode 4, photoconductor 3, exposed electrode 5, and substrate 1 have excellent tightness.

Moreover, the protective layer 8 has a relatively small refractive index of, for example, 1.6 to 1.7°. Since the protective layer 8 has a small refractive index, light is irradiated from the light source 7 to the original 9 through the light passing hole 6, and the light is reflected by the W and 9 and received by the photoconductor 3. The amount of light incident on the conductor 3 increases. The reason for this situation is
If the refractive index of the protective layer 8 is small, the amount of light incident on the protective layer 8 at the boundary between the substrate 1 and the protective layer 8 in the light passing hole 6 increases, and the amount of light incident on the protective layer 8 at the boundary between the protective layer 8 and the atmosphere on the document 9 side increases. The amount of light irradiated to the seed 9 side is large, and the amount of light entering the protective layer 8 from the atmosphere on the seed 9 side becomes large. Furthermore, at the boundary between the protective layer 8 and the second electrode 4, the amount of light that enters the second electrode 4 from the protective layer 8 increases. Due to the small refractive index of the protective layer 8, the amount of light reflected at the boundary between the protective layer 8 and the atmosphere on the document 9 side becomes small.

Therefore, the current due to stray light in the photodiode is reduced. Further, when *@9 is black and absorbs light, noise generation is suppressed due to the small amount of reflected light described above.

Since the refractive index of the protective layer 8 is small, the angle of incidence at which total reflection occurs at the boundary between the protective layer 8 and the atmosphere on the document 9 side becomes large. Therefore, as described above, a photodiode with small current and noise components due to stray light can be advantageously realized.

The protective layer 8 having the composition as described above also has good light transmittance.

Protective layer 8tfi, as shown in FIG.
/y m is configured to be small. According to the inventor's actual application, 0.15 > x > 1.90 -=il10.15
>y>1.3...f2) is preferred.

By increasing the x/y distance on the substrate 1 side, the Si
A part of the O2 molecules acts as Si20 and closely contacts the boundary of the photoconductor 3 with great intensity. In addition, kneading with a large X/y value has a small refractive index and good transparency, which is advantageous. The larger the x/y value, the smaller the internal residual stress and the smaller the strain. What is the smallest value for the thickness of the second electrode 4?

Therefore, the second electrode 4 will not be destroyed due to the distortion of the protective layer 8, and the second electrode 4 will be sufficiently protected by the protective layer 8.

Protective layer 8 is 11? , the x/y ratio is smaller on the 9th side, so the wear resistance is better. As the X/y value decreases, the internal afterglow stress increases and distortion increases, and the refractive index and light transmittance deteriorate, resulting in coloring. It can be reduced as much as possible by changing along the thickness direction.

The protective layer 8 is formed by conventional dry processes, such as sputtering, plasma CVD (chemical vapor deposition) and vapor deposition. When forming the protective layer 8 by sputtering, pure phosphoric nitride is used, and the distance between the target and the sample h is set at 15 to 30 mm.
The sample was rotated in a gas of argon and oxygen, the image frequency power was 1.5 to 3.8 kW, and the pressure during sputtering was 5. After press sputtering is performed at OX 10'' Torr, sputtering is performed. The substrate 1 etc. may be heated before press sputtering.

When forming the protective layer 8 by plasma CVD method,
Using a mixed gas of 5sH4 and N2, the Si substrate 1 was
The temperature was kept at 00°C and the pressure during the reaction was I Torr.

This forms an amorphous protective layer 8.

FIG. 4 shows the internal residual stress of the protective layer 8 depending on the oxygen partial pressure according to experiments conducted by the inventor of the present invention. It can be seen that internal residual stress is reduced by increasing the oxygen partial pressure.

The fifth problem is a graph showing the experimental results of the present inventor showing the relationship between the light transmittance and the oxygen partial pressure.

In Figure 5+1), the wavelength of light is 540 nm, and
In case (2), the wavelength of light is 570 nm. The light transmittance is based on air being 100%. According to the experimental results, it can be seen that the light transmittance is improved by increasing the oxygen partial pressure.

In the above embodiment, the x/y value of the protective layer 8 was changed to y in the thickness direction, but in another embodiment of the present invention, the x/y value
The y value may be set to a constant value in the thickness direction. The present invention can be implemented in general hospital storage devices in which a light receiving element is formed on a substrate and a protective shaft facing a document is formed on the light receiving element.

As described above, according to the present invention, a protective layer with high hardness and excellent wear resistance is formed, thereby preventing damage caused by originals. The protective layer has Shima hardness, which prevents scratches.
<Transparency is maintained well over a long period of time, thus preventing deterioration in reading performance.

[Brief explanation of drawings]

1 is a sectional view of an embodiment of the present invention, FIG. 2 is a simplified plan view of the embodiment shown in FIG. 1, and FIG. 3 is a protective layer 8.
Figure 4 is a graph showing the internal residual stress depending on oxygen partial pressure, which shows the experimental results of the inventor, and Figure 5 shows the experimental results of the inventor. 2 is a graph showing light transmittance dependent on oxygen partial pressure. DESCRIPTION OF SYMBOLS 1... Substrate, 2... First electrode, 3... Photoconductor,
4...Second electrode, 5...Extraction electrode, 6...Light passage hole, 7...Light source, 8...Protective layer, 9...Matsumoto Hara, patent attorney, Kei Shikyo - Immediately! A1 diagram

Claims (1)

[Claims] A light receiving element is formed on the substrate, and a protective layer facing the original is formed on the light receiving element, and this protective layer is made of SiOx N y
(x > O, y > 0).