JPS6190458A - Continuous image sensor unit - Google Patents

Abstract

PURPOSE:To unnecessitate the correction circuit by reducing the variability of bit signals by a method wherein the refractive index is continuously changed in the film thickness direction, and the refractive index of a photoconductive layer in the neighborhood of the substrate surface is set at 3.2 or less in the light of 6,328Angstrom wavelength. CONSTITUTION:In this photosensor, the photoconductive layer has the refractive index continuously changing, with respect to the film thickness direction, at least in part in the film thickness direction. Besides, the refractive index of this photoconductive layer in the neighborhood of the substrate surface is 3.2 or less in the light of 6,328Angstrom wavelength. In other words, the photoconductive layer is made of amorphous material, and an a-Si underlay layer 2 have a refractive index of 3.2 or less. An a-Si layer 3 has a refractive index of more than 3.2, preferably approx. 3.4. Such a photoconductive layer can be formed by suitably setting such conditions for glow discharge by reactive sputtering or ion plating as discharge power, substrate temperature, composition of raw material gas, and pressure of raw material gas.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a long image sensor unit used in facsimile machines, digital copying machines, and the like. [Prior Art] It is generally well known that photosensors are used as photoelectric conversion elements in image information processing devices such as facsimiles, digital copying machines, and character reading devices. In particular, in recent years, photosensors have been arranged one-dimensionally to form a long photosensor array, and this has been combined with a light source array for illuminating the original to be read and an imaging array for imaging the original onto the photosensor array. Highly sensitive image reading has also been carried out using a combination of long image sensor units. An example of a photosensor conventionally used in such image reading is a sandwich type photoconductive layer formed with a pair of electrode layers on both sides of a photoconductive layer containing amorphous silicon (hereinafter referred to as a-3i) or the like. An example is what is called. However, since this photosensor uses a method that extracts the primary photocurrent generated in the photoconductive layer by incident light as a signal, the signal output is relatively small.
Further, since this photosensor has a structure in which electrode layers are located on both sides of the photoconductive layer, if there is a pinhole in the photoconductive layer during manufacturing, a short circuit will occur. Therefore, in recent years, a photo sensor called a planar type has been used, in which a pair of electrodes forming at least a part of a light receiving part are formed on the same surface of a photoconductive layer containing a-3i etc. with a gap between them. It has become to. Since this photosensor uses a system in which secondary photocurrent in the photoconductive layer is extracted as a signal, it has the advantage of having a larger signal output than a sandwich-type photosensor. By the way, methods for manufacturing a-5i constituting such a planar type photosensor include plasma CVD method 1 reactive sputtering method, ion blating method, and the like, in which the reaction is promoted by glow discharge. However, in any case, in order to obtain a high quality a-3i film with high photoconductivity, it is necessary to form the film with a relatively low discharge power. However, the photoconductive layer obtained by film formation with such low discharge power does not have sufficient adhesion to the substrate made of glass or ceramic, and it is difficult to adhere to the substrate during the subsequent photolithography process during electrode formation. There was a problem that the film was easily peeled off. Therefore, in order to prevent film peeling, conventionally a method has been adopted in which a-5t is deposited after roughening the surface of the substrate. That is, the surface of the substrate is chemically etched with, for example, hydrofluoric acid, or physically rubbed with, for example, a brush. However, such a method has the following drawbacks. (1) When using chemicals such as hydrofluoric acid, the equipment in the cleaning line becomes complicated and expensive. (2) It is difficult to control the degree of unevenness on the surface of the substrate. (3) Microscopic defects are likely to occur when the substrate surface is roughened, and because the characteristics of the a-5i film deposited on the microscopic defects are different, variations in characteristics are likely to occur. Therefore, when constructing a long image sensor unit using the above-mentioned photosensors, the variation in each bit signal is large, so it is necessary to attach a correction circuit to compensate for the variation, which increases cost. It was the cause.

【the purpose】

In view of the above-mentioned prior art, the present invention improves the uniformity of the characteristics of each photosensor in a long photosensor array using Brenner type photosensors, thereby reducing and correcting signal variations between bits. An object of the present invention is to provide a low-cost long image sensor unit that does not require a circuit. [Means for Solving the Problems] According to the present invention, one or more objects are such that the refractive index of the photoconductive layer of each of the seven otosensors changes continuously in the thickness direction in at least a part of the photoconductive layer. This is achieved by a long image sensor unit characterized in that the refractive index of the photoconductive layer near the substrate surface is 3.2 or less for light with a wavelength of 6,328 people. [Example] Hereinafter, specific examples of the present invention will be described. In this specification, the layer of the photoconductive layer that is close to the substrate surface is referred to as the a-3t subbing layer, and one or more layers thereon may also be referred to as the a-3i layer. It is preferable that the photoconductive layer in the a-3i subbing layer and the layer immediately above it have a portion where the refractive index changes continuously in the film thickness direction. Preferably, the layer includes a layer with high photoconductivity. In the photosensor of the present invention, the photoconductive layer has a refractive index that changes continuously in at least a portion of the photoconductive layer in the thickness direction, and the refractive index near the substrate surface of the photoconductive layer has a wavelength of 6328 nm. 3.2 or less under the light of It can be formed by appropriately setting the gas composition, raw material gas pressure, etc. FIG. 1 is a partial plan view of a photosensor in an embodiment of the elongated image sensor unit of the present invention, and FIG. 2 is a sectional view taken along the line 1--2 of the same. 2 is the a-3i subbing layer, 3 is the a-3i layer,
These constitute a photoconductive layer. 4 is an n+ layer which is an ohmic contact layer. 5 is a common electrode, and 6 is an individual electrode. In addition, in FIG. 2, the a-5i subbing layer 2 and the a-Si
Although the boundary with layer 3 is clearly illustrated. In reality, this boundary is a layer whose refractive index changes continuously and has properties intermediate between the two layers. As the substrate 1, glass such as #7059 manufactured by Corning, #7740 manufactured by Corning, SCG manufactured by Tokyo Ohka Co., Ltd., quartz glass, or ceramic such as partially glazed ceramic can be used. The photoconductive layer is made of an amorphous material containing a-3i as a main component, and the a-3i subbing layer 2 has a refractive index of 3.2 or less. Further, a S I P3 has a refractive index greater than 3.2, preferably about 3.4. Photoconductive layer is plasma CVD
method, reactive sputtering method. Methods such as ion blating, especially plasma CVD
Formed by law. In the photoconductive layer thus formed, stress is generated due to hydrogen taken in during layer formation, and if this stress is too large, the adhesion with the substrate deteriorates and the film is likely to peel off. The magnitude of stress in the photoconductive layer can be controlled by appropriately setting the conditions during layer formation, such as glow discharge discharge power, substrate temperature, source gas composition, and source gas pressure. and an a-5i subbing layer 2 adjacent to the substrate l.
For example, by performing glow discharge with a relatively large discharge power to form a layer with low stress, good adhesion to the substrate 1 can be maintained. On the other hand, it is known that the stress in the photoconductive layer has a strong correlation with the refractive index of the layer, and generally, the lower the stress, the lower the refractive index. It has also been found that in order to obtain good photoconductivity of the photoconductive layer, it is necessary to perform glow discharge at a relatively low discharge power. Therefore, after first performing glow discharge at a relatively large discharge power to form an a-Si subbing layer 2 with a relatively small refractive index, for example, a refractive index of 3.2 or less, on the substrate l, the discharge power is gradually reduced. Deposition while reducing the power to a relatively small amount! A portion with a refractive index that continuously changes in the film thickness direction is formed one after another, and then glow discharge is performed with the above-mentioned relatively small discharge power to form a portion with a relatively large refractive index, for example, a refractive index of 3.4. It is preferable to form an a-Si layer 3 having a photoconductivity as high as . The common electrode 5 and the individual electrodes 6 are made of a conductive film such as AI. Hereinafter, the present invention will be explained in detail with reference to Examples. Example 1: Glass substrate of double-sided polishing method (#7059 manufactured by Corning Co., Ltd.)
) was subjected to normal cleaning using a neutral detergent or an organic alkaline detergent. Next, the glass substrate 1 was covered with a mask of a desired pattern and set in a capacitively coupled glow discharge decomposition apparatus, and the apparatus was maintained at 230° C. under an exhaust vacuum of 1×10''6 Torr. 10 epitaxial grade pure SiH4 gas (manufactured by Komatsu Electronics Co., Ltd.)
The flow rate was 300M, and the gas pressure was 0.07 Torr.
It was set to r. After that, using a 13.56 MHz high frequency power supply, the input voltage 2. OkV, RF (Radio
Glow discharge was performed for 2 minutes at a discharge power of 120 W to form an A-3I subbing layer 2 with a thickness of about 400. Next, the input voltage was gradually lowered and after 5 minutes (1
It was set to 3kV. Thereafter, glow discharge was performed for 4.5 hours at an input voltage of 0.3 kV and a discharge power of 8 W to form an a-5i layer 3 with a thickness of about 0.85 mm. Subsequently, SiH4 diluted to 10% with H2 and lo
Using a gas mixed with PH3 diluted to oppm at a mixing ratio of 1:10 as a raw material, an n-middle layer (thickness approximately 0.15=), which is an ohmic contact layer, was deposited at a discharge power of 30 W. 0.3#L of AI using beam evaporation method
A conductive layer was formed by depositing a thick layer. Next, a positive photoresist (AZ-1 manufactured by Shipley) was applied.
After forming a photoresist pattern in a desired shape using 370), phosphoric acid (85% by volume aqueous solution) and nitric acid (6
0% by volume aqueous solution), glacial acetic acid, and water in a 16:l:2:l
The exposed portions of the conductive layer were removed with a solution mixed in a volume ratio of Then, the exposed portion of the n layer was removed by dry etching using F4 gas at an RF discharge power of 120 W and a gas pressure of 0.07 Torr to form an n layer 4 having a desired pattern.Then, the photoresist was peeled off. On the other hand, for comparison, the surface of the same glass substrate as above was treated for 30 seconds with a mixture of hydrofluoric acid (49% aqueous solution by volume), nitric acid (60% by volume aqueous solution), and acetic acid at a volume ratio of 1:5:40. , a-3i A planar photosensor (hereinafter referred to as "
A photosensor with an acid-treated base and no subbing layer was manufactured. Regarding the above two types of photosensors, λmB from the glass substrate 1 side under the same conditions! When the photocurrent values obtained by incident light of =565 nm were compared, almost the same values were obtained for both. This shows that the presence of the a-5i subbing layer 2 in the photosensor of the present invention does not deteriorate the photocurrent characteristics. Next, we conducted a durability test using a heat cycle under the same conditions for the above two types of photosensors.
Similarly, it was found that the film did not peel off and had sufficient adhesion. Example 2: In the photo sensor manufacturing process of the present invention in Example 1, a
-' When forming the Si subbing calendar 2, the discharge power initially set (hereinafter abbreviated as "discharge power l") and the discharge power l
The same steps as in Example 1 were carried out, except that glow discharge was performed using the following combinations of discharge times. As a result, when the discharge power was 80 W and 50 W, it was possible to obtain a photosensor without film peeling, but when the discharge power was 30 W, 8 W, and 4 W, it was possible to obtain a photo sensor using photoresist AZ-1370. The film peeled off during the process (including cleaning with an ultrasonic cleaner), and the intended good photosensor could not be obtained. Example 3: After forming the a-3i subbing layer 2 in the same manner as in Examples 1 and 2, the substrate 1 was taken out, and the refractive index of the a-3i subbing layer 2 formed on the substrate 1 was measured. . FIG. 3 shows the relationship between the discharge power of glow discharge and the refractive index of the a-3i subbing layer 2. The adhesion between the substrate and the photoconductive layer is related to the discharge power of the glow discharge during film formation, and film peeling is caused by the difference in the coefficient of thermal expansion between the intrinsic stress induced depending on the internal structure of the thin film and the substrate. It is thought that this is due to the total stress due to the combination with the internal stress depending on . Therefore, the total stress of the a-3i subbing layer 2 formed on the substrate 1 was measured. Figure 4 shows the relationship between the discharge power l of glow discharge and the total stress of the a-3i subbing layer 2. The stress appears as compressive stress, and the discharge power 1 has a maximum value near IOW, but the discharge power l The stress decreases as the value increases. The reason why the stress decreases as the discharge power l increases is considered to be mainly because the increasing number of voids in the film generates tensile stress, which cancels out the compressive stress. As mentioned above, the photoconductivity of the photoconductive layer is related to the discharge power during film formation, and in order to obtain the desired photoconductive properties it is necessary to perform the deposition at a relatively low discharge power. The a-5i layer 3 in Nos. 1 and 2 was deposited at a relatively low discharge power. From the above, the a-3i subbing layer 2 of the photosensor in the image sensor unit of the present invention functions as a stress relaxation layer, and can exhibit the effect of improving the adhesion between the substrate and the photoconductive layer. I understand. Furthermore, when using this photosensor by irradiating light from the substrate L side, it is preferable that the thickness of the a-3i subbing layer 2 is not too thick in order to obtain good photoconductive properties. For example 1000
It is desirable that it be less than Å. In addition, when the light is made to enter from the side opposite to the substrate l side, there is no need to consider the effect on the photoconductive properties due to light absorption in the a-3i subbing layer 2, so the a-3i subbing layer 2 may be quite thick. Example 4: In the photo sensor manufacturing process of the present invention in Example 1, a
- After the formation of the 5i layer 3, the discharge power was increased to 80W.
The same steps as in Example 1 were performed except that glow discharge was performed for 5 minutes and an a-3i layer was further formed. FIG. 5 is a partial sectional view of the planar photosensor thus obtained, showing the same parts as in FIG. 2. In FIG. 5, the same members as in FIG. 3' is the a-3i layer. Is the thickness of the a-3i layer 3'0.3#L? Since the discharge power was increased, the formation speed per unit thickness of this layer was significantly higher than the formation speed per unit thickness j of the a-5i layer 3. In the photosensor obtained in this example, a
-3i subbing layer 2. -a-3i layer 3 and a-5i layer 3'
According to the photosensor of this embodiment, in which the photoconductive layer is constructed as follows, the obtained photocurrent is larger than that of the first embodiment due to the increased thickness of the a-3i layer. Example 5: In the photo sensor manufacturing process of the present invention in Example 1, a
The same steps as in Example 1 were carried out, except that during the formation of the -5t subbing layer 2, the substrate temperature was maintained at 70° C., the discharge power 1 was set to 8 W, and glow discharge was performed for 15 minutes. When the a-3i subbing layer 2 was formed under the same conditions, the substrate 1 was taken out and the refractive index of the a-3i subbing layer H2 was measured and found to be 3.10. The photosensor obtained in this example was as good as the photosensor of the present invention obtained in Example 1. Example 6: In the photo sensor manufacturing process of the present invention in Example 1, a
-5i When forming the subbing layer 2, H2 is used as a raw material gas to form 5i
Using S i H4 diluted to %, discharge power 1 was 30W.
The same steps as in Example 1 were performed except that glow discharge was performed for 10 minutes. When the a-3i subbing layer 2 was formed under the same conditions, the substrate 1 was taken out and the refractive index of the a-5i subbing layer 2 was measured and found to be 3.02. The photosensor obtained in this example was as good as the photosensor of the present invention obtained in Example 1. Example 7: In the photo sensor manufacturing process of the present invention in Example 1, a
- When forming the 3i subbing H2, the gas pressure was set to 0.30 Tor.
The same steps as in Example 1 were carried out, except that glow discharge was performed for 5 minutes at a discharge power of 50 W and a discharge power of 1. When the a-3i subbing layer 2 was formed under the same conditions, the substrate 1 was taken out and the refractive index of the a-Si subbing layer 2 was measured and found to be 3.12. The photosensor obtained in this example was as good as the photosensor of the present invention obtained in Example 1. Example 8: By the same method as in the case of the photosensor of the present invention in Example 1, 864 photosensors were manufactured by arranging them in 7 layers on the same substrate. This can be easily done by appropriately setting a mask in one photolithography step. A schematic partial plan view of the long photosensor array thus obtained is shown in FIG.
are individual electrodes, and 12 is a common electrode. The density of this long photosensor array is 8 bits/mm, and A6
It has the length of the plate width. Uniformity of photocurrent and dark current between bits of the photosensor array obtained in this example was measured. The results are shown in FIG. On the other hand, for comparison, the photocurrent between bits of a long photosensor array manufactured by arranging 864 photosensors on the same substrate by the method described in Example 1 with the base acid treatment and without the subbing layer was shown. The uniformity of dark current was measured. The results are shown in FIG. A comparison between FIG. 7 and FIG. 8 shows that the photosensor of the present invention has no microscopic defects on the substrate and a-St
It can be seen that the uniformity of the photoconductive properties is extremely good because the subbing layer acts as a stress relaxation layer. Example 9: An attempt was made to divide the 864-bit long photosensor array obtained in Example 8 into 27 blocks of 32 bits each and drive them in a matrix manner. That is, after manufacturing a long photosensor array using the same process as in Example 8, polyimide resin (PIQ manufactured by Hitachi Chemical Co., Ltd.) was coated on the entire surface and baked, a negative photoresist (OMR- manufactured by Tokyo Ohka Co., Ltd.) was applied. After forming a pattern in the desired shape using 83), unnecessary portions of PIQ were removed using a polyimide resin etching solution (PIQ etchant manufactured by Hitachi Chemical Co., Ltd.), and OMR-81 was peeled off.
C. for 1 hour under a nitrogen atmosphere to form an insulating layer and through holes for matrix wiring. Next, AI was deposited to a thickness of 2 layers by electron beam evaporation to form a positive photoresist AZ-1370. and etching solution
was used to form the upper electrode of the matrix wiring. A schematic partial plan view of the matrix wiring part of the long photosensor array thus obtained is shown in FIG.
In FIGS. 9 and 10, the cross-sectional view is shown in FIG. 1O, 21 is a base body, 22 is an a-3i subbing layer,
23 is the a-5i layer, 24 is the n-middle layer, 25 is the common electrode, 26 is the individual electrode, 27 is the insulating layer, 28 is the through hole, and 29 is the upper part of the matrix wiring. It is an electrode. FIG. 11 shows a drive circuit diagram for matrix driving the long photosensor array of 8 pixels/mm and A6 size width obtained in this way. In FIG. 11, 31 is the photoconductive layer of the photosensor. , 32 is a block selection switch, 33 is a common switch, and 34 is an amplifier. A partially cutaway perspective view of the image sensor unit used in this example is shown in FIG. 12, and FIG.
In FIG. 0, which is a cross-sectional view, 41 is the base of the photosensor array. A fiber lens array 42 is provided below the base 41, and light emitting diode (LED) arrays 43 are provided on both sides thereof. 44 is a driving IC, and the IC 44 is electrically connected to the matrix wiring section on the base 41 by a flexible conductive material 45. 46 is a document to be read, and 47 is a feeding roller thereof. Further, 48 is a heat radiation fin;
9 is a heat sink. The drive IC is thermally connected to the heat sink 49. Note that the arrangement directions of the photosensor array, fiber lens array 42, and LED array 43 are parallel to each other. The uniformity of the output photocurrent between bits after voltage application toopsec when the image sensor unit was driven in matrix as described above was measured. The results are shown in FIG. 14. As can be seen from FIG. 14, the output photocurrent of each bit shows extremely good uniformity, indicating that signal readout is sufficiently possible with matrix driving. Example 1O: A long image sensor unit was constructed using the photosensor array obtained in Example 9. FIG. 15 is its circuit diagram. In Figure i15, three photosensors E1 to E9 constitute one block, and three blocks constitute a photosensor array. The same applies to the capacitors C1 to C9 and the switching transistors T1 to T9, which respectively correspond to the photosensors El-E9. One electrode (common electrode) of each photosensor El-E9 is connected to a power supply lot, and the other electrode (individual electrode) is grounded via capacitors 01 to C9. Furthermore, individual electrodes having the same order within each block of photosensors E1 to E9 are each connected to one of the common lines 102 to 104 via switching transistors Tl-T9. In detail, the first switching transistors TI, T4, T7 of each block are connected to the common line 102, the second switching transistors T2, T5, T8 of each block are connected to the common line &1103, and the third switching transistors of each block are connected to the common line 102. Transistors T3, T6, and T9 are connected to the common line 104,
each connected. Common lines 102-104 are connected to amplifier 105 via switching transistors T10-T12, respectively. Furthermore, the gate electrodes of the switching transistors TINT9 are connected in common for each block, and are connected to the parallel output terminals of the shift register 106, respectively. Since a high level is sequentially output from the parallel output terminals of the shift register 106 at a predetermined timing, the switching transistors Tl to T9 are sequentially turned on for each block. Further, each gate electrode of the switching transistors Tl0 to T12 is connected to a parallel output terminal of the shift register 107, and a high level is sequentially outputted from this parallel output terminal at a predetermined timing, so that the switching transistors TIO to T12 are sequentially turned on. state. Furthermore, the commonly connected terminals of the switching transistors T10 to T12 are grounded via a discharging switching transistor T13, and the gate electrode of the switching transistor T13 is connected to the terminal 108. The operation of the elongated image sensor unit having such a configuration will be briefly described. When light enters the photosensor El-E9, charges are accumulated in the capacitors C1 to C9 from the power supply 101 according to the intensity of the light, resulting in Δ. Subsequently, high level signals are sequentially output from the shift registers 106 and 107 at respective timings, and it is now assumed that a high level signal is output from the first parallel output terminals of both registers. Then, the switching transistor T of the first block
The switching transistor TIO connected to I-T3 and the common line 102 is turned on, and the charge accumulated in the capacitor Ct is transferred to the switching transistor T1.
, common line 102, and switching transistor TI
Through O. It is input to the amplifier 105 and output as image information. When the charge stored in the capacitor C1 is read out, a high level is applied to the terminal 108. The switching transistor T13 is turned on. Thereby, the residual charge in the capacitor C1 is transferred to the switching transistor T1, the common wA102, the switching transistor TLO1 and the switching transistor TLO1.
completely discharged through 13. Subsequently, while keeping the first parallel output of the shift register 106 at a high level, the shift register 107 is sequentially shifted so that the switching transistors Tl 1. Turn on Tl 2 in turn. As a result, the above reading and discharging operations are performed on the capacitors C2 and C3, and the information stored therein is sequentially read out. When the reading of the information of the first block is completed in this way, the shift register 106 is sequentially shifted, and the reading of the information of the second and third blocks is performed in the same manner as described above. In this way, the information stored in the capacitors 01 to C9 is serially read out and output from the amplifier 105 as image information. Since the elongated photosensor array shown in FIG. 15 has a capacitor for charge storage, it is possible to increase the output signal. Moreover, photosensors E1 to E9. Capacitor C1-C9
When the switching transistors T1 to T9 are formed using thin film semiconductors on the same substrate, there are advantages such as the ability to reduce the number of connection points with external circuits. Example 11: A long image sensor unit was constructed using the photosensor array obtained in Example 9. FIG. 16 is its circuit diagram. However, in this embodiment, the photosensor El-E9, the capacitors 01 to C9, and the switching transistors T1 to T
12, shift registers 106, 107, etc., are the same as those shown in FIG. 15, so their explanation will be omitted. In FIG. 16, the separate electrodes of photosensors E1 to E9 are grounded via switching transistors STI to ST9, respectively. That is, each switching transistor STI~-5T 9 (7) is connected to a capacitor Cl
-09 is connected in parallel. The gate electrodes of the switching transistors STI to ST9 are commonly connected for each block, similarly to the gate electrodes of the switching transistors Tl to T9, and are connected to the parallel output terminals of the shift register 201 for each block. Therefore, depending on the shift timing of the shift register 201, the switching transistors T1 to T9 are turned on for each block. Next, the operation of this embodiment having such a configuration will be described in the first section.
This will be explained using the timing chart of the switching transistors TlNT12 and STI to ST9 shown in FIG. First, when light enters the photosensors E1 to E9, charges are accumulated in the capacitors C1 to C9 from the power supply lO1 according to the intensity of the light. First, a high level is output from the first parallel terminal of the shift register 106, and the switching transistor T
1 to T3 are turned on [FIG. 17(a)]. In the meantime, the shift register 107 shifts and the switching transistors Tl0-T12 are sequentially turned on [FIG. 17(d)-(f)], that is, the amount of data stored in the capacitors 01-C3 of the first block is Optical information is read out sequentially. When the information of the last capacitor C3 of the first block is read out, the shift register 106 is shifted, a level of λ is outputted from the second parallel terminal, and the switching transistors T4 to T6 are turned on [Fig. b)]
. At the same time, a high level is output from the first parallel terminal of the shift register 201, switching transistors STI to ST3 are turned on, and capacitors C1 to C
The residual charge of 3 is completely discharged [FIG. 17(g)]. In parallel with this discharging operation, the switching transistor T
While T4 to T6 are in the on state, the shift register 107
Due to the shift of switching transistor Tl0-T
12 are sequentially turned on, and the optical information stored in the capacitors 04 to C6 of the second block is sequentially read out [FIGS. 17(d) to (f)]. Next, the read operation of the third block [FIG. 17(C)]
] In parallel, the capacitors 04 to C6 of the second block are discharged [FIG. 17(h)], and the above operation is repeated for each block. In this way, the capacitor of the block that has been read can be discharged in parallel with the reading of the next block, and the overall operating time can be shortened. FIG. 18 shows another embodiment of the present invention.
Only part A in Figure 6 is different. That is, amplifiers 202 to 104 are connected to common lines 102 to 104, respectively.
204 is connected, and each output of the amplifiers 202 to 204 is connected to a parallel input terminal of a shift register 205. Image information is then serially output from the serial output terminal of the shift register 205. Therefore, in this configuration, one block of information is input to the shift registers 20.5 at the same time, and then serial image information is output by shifting in the shift register 205. In this embodiment as well, when information for one block is output from the shift register 205, the capacitor of that block can be discharged and the next block can be read out in parallel. Note that the switching transistors STI to ST9 may be thin film transistors similarly to the switching transistors T1 to T9, and in that case, they can be formed on the same substrate as other elements. Even if thin film transistors are used as the switching transistors 5TI-5T9, it is possible to discharge the capacitors of one block and read out the next block in parallel, so the overall readout time is shorter than in Example 1O. is shortened. In the above embodiments, a-5 with a constant refractive index is used.
An example has been shown in which a layer whose refractive index changes continuously in the film thickness direction is formed between the i subbing layer 2 and the a-5i layer 3 having a constant refractive index. In the photo sensor of the long image sensor unit of the present invention, the a-3i subbing layer 2 having a constant refractive index at a predetermined thickness in the film thickness direction is not formed, but is gradually and continuously formed from the surface of the substrate 1. A layer having a refractive index that continuously changes in the film thickness direction may be formed. [Effects of the Invention] According to the elongated image sensor unit of the present invention as described above, the characteristics of the photosensor can be made uniform, so that costs can be reduced without using a correction circuit. Furthermore, in the long image sensor unit of the present invention,
Since the refractive index of the photoconductive layer of the photosensor changes continuously in the film thickness direction, stress relaxation at the layer interface is achieved, resulting in good adhesion. Further, during use, reflection at the layer interface becomes extremely small, thereby preventing loss of light quantity.

[Brief explanation of drawings]

FIG. 1 is a partial plan view of a photosensor of an image sensor unit of the present invention, and FIG. 2 is a cross-sectional view taken along line 1--2. FIGS. 3 and 4 are graphs showing the characteristics of the a-3i subbing layer. FIG. 5 is a partial sectional view of the photosensor of the image sensor unit of the present invention. FIG. 6 is a partial plan view of the photosensor array, and FIGS. 7 and 8 are graphs showing the characteristics of the photocurrent and dark current. FIG. 9 is a partial plan view of the matrix wiring section, and FIG. 10 is a sectional view taken along the line xx. FIG. ti is a matrix drive circuit diagram. FIG. 12 is a partially cutaway perspective view of the elongated image sensor unit, and FIG. 13 is a sectional view of the long image sensor unit. FIG. 14 is a graph of output photocurrent. 15th
16 and 16 are circuit diagrams of the long image sensor unit, FIG. 17 is a timing chart, and FIG.
The figure shows a partial modification of FIG. 16. l2 substrate 2: a-Si subbing layer 3Ha-Si
Layer 4: n+ layer 5: Common electrode 6: Individual electrode 41: Photo sensor array base 42: Fiber lens array 43: LED array 44: Drive IC 46: Reading original Figure 1 Figure 2 Figure 3 rC force (W ) Figure 5 Figure 6 Bit S statement Figure 10 Figure 11 Figure 12 Figure 13

Claims (2)

[Claims] (1) A photoconductive layer containing amorphous silicon as a main component is formed on the substrate, and a pair of electrodes are arranged on the same surface of the photoconductive layer with an interval that forms at least a part of the light receiving section. a photosensor array in which a plurality of photosensors are arranged in an array; a light source array for illuminating the read original that is arranged substantially parallel to the photosensor array; In a long image sensor unit including an imaging array arranged substantially parallel to the photosensor array to form an image, the photoconductive layer of each photosensor has a refractive index in at least a portion thereof in the film thickness direction. changes continuously in the film thickness direction, and the refractive index near the substrate surface of the photoconductive layer is 6.
1. A long image sensor unit, characterized in that the wavelength of light of 328 Å is 3.2 or less. (2) The refractive index of a portion of the photoconductive layer near the substrate surface with a thickness of 1000 Å or less is 3.2 or less, Claim 1
Image reading device.