JPH0396061A - Close-contact reading sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reading sensor for reading originals used in facsimiles and the like.

The conventional reading sensor is JP-A-60-244062.
As described in the publication, a first photoconductor that receives reading light and a second photoconductor that does not receive light are formed, and a voltage is applied in series by connecting them. The potential at the connection point of each photoconductor was taken out as an output voltage.

Another conventional reading sensor is Nikkei Electronics, 434 (1987), pp. 207-22.
As described on page 1, it consisted of a conductivity type element, a storage capacitor, a transfer switch and a reset switch formed of amorphous silicon (hereinafter abbreviated as a-Si) thin film transistors, a signal matrix wiring, and a gate wiring. For reading, the M document is brought into close contact with the transparent substrate on which the photoconductive element is formed, and the document is illuminated through the transparent substrate by a light source placed on the opposite side of the transparent substrate to the side on which the photoconductive element is formed.
The reflected light is captured by a photoconductive element and converted into electricity, performing so-called complete contact reading.

The photoconductive element receives only reflected light from the original, and all generated photocurrent is stored in the storage capacitor for a certain period of time. A-Si
By the switching action of the thin film transistor, the voltage was transferred to the capacitance of 32 signal matrix wirings, and the voltage was sequentially read out by an external circuit. Transfer and reset of signal charges for each block is performed by inputting a signal from the outside to the gate wiring, so that the number of gate wirings is equal to the number of blocks. Further, the number of elements in a block and the number of signal matrix wirings were configured to be the same.

[Problem to be solved by the invention]

The above two conventional technologies do not take into account the illuminance variation of the light source that illuminates the JMH, and the illuminance variation of the light source directly causes
There was a problem with variations in the output signal. In addition, sensitivity changes due to temperature, changes over time, or variations in batting accuracy are also a direct cause of signal fluctuation.

In addition, in the conventional technology discussed later, all of the photocurrent of the photoelectric conversion element is stored in the storage capacitor, so it does not take into account the time it takes to transfer the charge due to thin film transistors with small conductance, which allows for high-speed reading operation. There was a difficult problem.

Furthermore, in the latter conventional technology, the reading matrix is entirely driven by an external circuit, so there is no consideration given to the increase in the number of wiring lines, which is disadvantageous for miniaturization, and there is a problem that the scale of the external circuit is large. there were.

In addition, in the latter conventional technology, since the number of elements in a block and the number of signal matrix wirings are the same, data transfer time and reset time are required when switching blocks, and there is a pause period between signals of each block. No consideration was given to this, and signal readout could become complicated.

An object of the present invention is to reduce variations in read signals due to variations in light sources.

Another object of the present invention is to provide an inexpensive reading sensor that enables high-speed deception using thin film transistors, has a small external circuit, and can be miniaturized. [Means for Solving the Problems] In order to achieve the above object, the present invention includes a reference element that photoelectrically converts direct light from a light source that illuminates a document on a translucent substrate, and a reference element that photoelectrically converts direct light from a light source that illuminates a document, and a reference element that photoelectrically converts direct light from a light source that illuminates a document. It is equipped with a reading element that performs photoelectric conversion.

In this case, it is preferable to connect the read element and the reference element in series to divide the supplied voltage and use it as a read signal, and also to connect a capacitor for reading voltage transfer in parallel with the read element or in parallel with the reference element. It is preferable to provide one.

Note that the reading element and the reference element can be formed in the same process, which is efficient.

Further, it is preferable that the ratio of the photocurrent of the reading element when reading the original document to the photocurrent of the reference element is set to 0.1 to 100, and that the output signal is linearized by a dividing circuit.

In order to achieve the other objects mentioned above, the present invention provides a shift register made of an amorphous silicon thin film transistor, a buffer connected to the output of the shift register,
Reading is performed by sequentially switching readout switches selected by block switches and stabilization switches connected to this buffer and a plurality of divided matrix lines to transfer the charge of the readout element.

In order to achieve the other objects mentioned above, the present invention also provides a shift register made of thin film transistors, a buffer connected to the output of this shift register, a block switch and a stabilization switch connected to this buffer, and a plurality of dividing matrices. This is a reading sensor that performs reading by sequentially switching readout switches selected by lines and has a smaller number of elements in one block than a divided matrix line. The above photoelectric conversion element group is preferably equipped with a transparent laminated member such as a transparent resin film imparted with conductivity, and the side facing the element surface and the position near the element is a scattering surface of incident light and/or a finely uneven surface. (commonly known as a satin matte surface) is preferable.

Incidentally, if this transparent laminated member is mounted without adhesive, there will be no problem regarding capacitance.

The reading assembly of the present invention secures an incident optical path on the back surface of the light-transmitting part of each reading sensor, and also ensures that the platen roller contacts the outside of the film or transparent laminated member and near the photoelectric conversion element group through the paper surface. Preferably, a light source is provided within the base on which the element mounting board is attached to secure the optical path.

Furthermore, the facsimile apparatus of the present invention is characterized in that the reading sensor assembly is housed in a housing together with a recording section consisting of a thermal head and a recording paper roller.

For surface micro-roughness processing, satin matte processing is optimal.

That is, one side of the conductive film is matted to give it a satin finish.
A configuration is achieved by attaching a pear-finished surface to the top of the sensor, or one side of a transparent film is matted in a pear-like pattern, the pear-finished surface is attached to the top of the sensor, and a conductive film is placed on top of the matted film. It is preferable to attach a transparent film.

The conductive film may be attached (adhered) to the upper surface of the sensor substrate either directly or indirectly.

Here, the satin surface refers to a surface that has fine irregularities on its surface, which change and scatter the optical paths of reflected light and transmitted light. Preferably, the average height of the surface roughness is about 0.2 μm to 10 μm, and the transmittance of light including scattered light is 70%.
Refers to the above aspects.

In addition, the original purpose can be achieved not only by matte finishing but also by providing a conductive film on the sensor substrate and creating a mechanism for preventing concentrated reflection and concave mirror reflection of light on the surface of the film.

It is desirable that the sensor mounting board be made of an insulating material. 6. The vicinity of the element mounting area refers to the element mounting area and its surroundings. The "surroundings" refers to the area where the sensor element is mounted even if the conductive film and the sensor mounting board are suppressed by the platen roller. This area corresponds to the area that forms the space that is inevitably created due to the thickness of the area.

The significance of translucent/transparent is influenced by the light source used. The light used is in the wavelength range that the sensor element senses, and is a-
In the case of a sensor element made of Si (amorphous silicon), all visible light is used.

Note that the base itself containing the light source may also serve as a sensor mounting support plate.

[Effect]

The reference element that photoelectrically converts the direct light from the light source illuminating the document outputs an output proportional to the brightness of the light source, and the reading element that photoelectrically converts the light reflected from the document outputs an output proportional to the illuminance of the document surface. It also provides a photoelectric detection power proportional to the reflectance of the document surface. Therefore, the photoelectric change detection power of the reading element is an output that corresponds to the reflectance of the document surface that is originally desired to be read, but includes some noise due to variations in illuminance.

The reference element outputs an output proportional to the brightness of the light source, but since the brightness of the light source is proportional to the illuminance of the document surface, by correcting the output of the reading element using the output of this reference element, the reflectance of the document can be adjusted. Only the output corresponding to can be retrieved.

When a read element and a reference element are connected in series and the supply voltage is divided to produce a read signal, the output voltage is divided by the ratio of the resistances of both elements. Since the resistance of the read element and the reference element is inversely proportional to the conductivity, and the conductivity is proportional to the intensity of the light incident on the element, the partial voltage output is inversely proportional to the ratio of the intensity of the light incident on the read element and the reference element. become. Since the output voltage is determined by the ratio of the conductivities of the reading element and the reference element, it is possible to eliminate uneven output due to variations in the light source.

By connecting the reading element and the reference element in series and applying a voltage, and further providing a reading voltage transfer capacitor in parallel with the reading element or in parallel with the reference element, the reading voltage corresponding to the reflectance of the original can be generated as described above. appears at the connection point between the reading element and the reference element. Therefore, the read voltage transfer capacitor can store signal charges proportional to the read voltage. The size of the read voltage transfer capacitance does not depend on the photocurrent size of the read element or reference element and can be set arbitrarily, so the capacitance value can be selected according to the ability of the circuit that reads the signal. Can be done. Although the reading element and the reference element have different light incident directions, they are both semiconductor films that perform photoelectric conversion.By manufacturing them in the same process, variations in the elements can be reduced, and the number of manufacturing steps can be reduced, resulting in inexpensive reading. Enables supply of sensors.

The maximum value of the photocurrent of the reference element and the photocurrent of the reading element,
In other words, the photocurrent value when reading a white (reflectance of about 0.8) M document is significantly different from the S/N ratio when the light source variation is corrected using the reference element as mentioned earlier. Therefore, by setting this photocurrent ratio from 0.1 to 100, the correction error can be reduced. In addition, when a reference element and a reading element are connected in series and the divided signal is used as the reading voltage, if there is a large difference in the current between the two, the voltage change when the photocurrent of the reading element changes The maximum value of the photocurrent of the reading element is set to 0.1 of the photocurrent of the reference element.
By setting the value from 100 to 100, good output can be obtained.

As described above, in reading where a read element and a reference element are connected in series and the divided voltage output is used as the read voltage, the read voltage is divided by the ratio of the resistances of both elements.

When reading JMa, it is preferable to output a read output signal proportional to the light reflectance, that is, the intensity of light incident on the reading element, but the read voltage determined by the ratio of resistance values is proportional to the photoconductivity, that is, the light intensity. The output voltage is inversely proportional to the intensity of the output voltage. Therefore, by taking the reciprocal of the output voltage using a divider circuit, it is possible to obtain an output proportional to the intensity of light.

In an amorphous silicon thin film transistor, the electron mobility in amorphous silicon is 0.2 to 1.0 cd/
Due to the small V-S, it is not possible to create high-speed transistors like crystalline silicon, but by devising circuits, it is possible to form transistor circuits that can drive the read sensor at high speeds. When a block selection start signal is input together with a data transfer clock to a shift register formed of amorphous silicon thin film transistors, the shift register shifts data 1 in synchronization with the transfer clock.

The output of each stage of the shift register is connected to a block switch and a stabilizing switch via a buffer, and the block switch is connected when the output of the shift register is 1 (logic is H).
The stabilizing switch becomes conductive when the output of the shift register is O (when the logic is low). The block switch has the function of connecting the control line of the readout switch and the divided matrix line, and the stabilization switch has the function of connecting the control line of the readout switch to the power supply line on the OFF side. The block switch and stabilization switch are one readout switch for each readout element.
The reading elements are connected one at a time, and a plurality of reading elements form one block.

When the block selection signal is shifted to the shift register,
The block switch becomes conductive via the buffer. Therefore, if you sequentially set multiple divided matrix wirings to High. The readout switches are sequentially turned on one by one, and the signal charges photoelectrically converted by the readout elements are sequentially transferred. When a block is not selected and the block switch is OFF, the stabilizing switch is conductive and the control line of the read switch is connected to the OFF side power supply line. Here, when signals are sequentially added to the divided matrix to read signals of other blocks, the unselected blocks are
Due to the parasitic capacitance of the block switch in the FF state,
The signal from the divided matrix line leaks in, causing the potential of the control line of the read switch to fluctuate.

Since the stabilization switch is in a conductive state, this potential fluctuation is turned off.
Since it works to set the potential on the FE side, it prevents the read switch from malfunctioning and reading out the signal charges of the non-selected block.

Furthermore, with the structure of the read sensor formed of the shift register, buffer, block switch, stabilization switch, divided matrix wiring, and photoelectric conversion element formed using amorphous silicon thin film transistors, as explained above, the photoelectric conversion of each block is performed. If the number of conversion elements is smaller than that of divided matrix wiring, from the stage with the output of the shift register,
Moving to the next stage, it is now permissible for there to be a period in which the selected block and the next block are selected at the same time.6 In other words, the number of photoelectric conversion elements in each block is divided by N. Let the number of matrix wirings be N+n. Even if a certain block is selected, signals are sequentially input to the divided matrix wiring, the elements are sequentially read out, the Nth element is read out, the next block is simultaneously selected, and the N+nth element is read out, the two selected blocks are Since there is only one element on the same divided matrix line, two elements are never read out at the same time. Therefore, the time required to read out n elements allows two blocks to be overlapped, and becomes a margin time when switching blocks. Therefore, the read signal can be read without a particular pause period when switching blocks.

In addition, by attaching a matte transparent conductive film to the reading sensor and performing complete contact reading, the electric field due to static electricity generated when the document is running is shielded, so induced noise due to electric field fluctuations is not induced in the wiring.
This prevents thin film transistors from malfunctioning and prevents minute read signal fluctuations.

Here, the matte transparent conductive film is a transparent film that can be elastically deformed, has conductivity with a sheet resistance of 100 kΩ/hole or less, and has an uneven surface on the side that comes into contact with the sensor surface, allowing light to pass through. This refers to the film that is the surface that is scattered.

Also, the film is attached so that the matte surface is on the reading sensor board side, but this is because the light from the light source that illuminates the document from the back of the board is scattered by the matte surface of the film surface, so it is difficult to press the document against it. When the film is deformed into a concave mirror shape when the film is in close contact with the film, it is possible to prevent the reading output from becoming abnormal due to light condensation due to reflection.

That is, by mounting a conductive transparent film on a substrate, a fully contact sensor with stable reading performance and easy to manufacture can be obtained. Conductive transparent film easily deforms elastically when a load is applied, so it is difficult to break. Further, since the conductive transparent film acts as a shield against radio waves and electrostatic induction, it has the effect of preventing noise in the output signal of the complete contact type continuity sensor. It also acts as a spacer between the document surface and the sensor element, so it also functions as a transparent spacer for illumination and as a wear-resistant protective film. Because of these effects, a complete contact type continuation sensor using this film is easy to assemble and can stably obtain reading performance comparable to conventional sensors.

If a polymer film is used as the conductive film, the mirror surface area will be reduced and the scattering effect will be improved, which will help the reading sensor function.

When one side of the conductive film is matted to have a satin finish and the satin finish is attached to the top side of the optical/electrical conversion element, the illumination light from the back side is scattered by the satin finish and is transmitted and reflected. When an original is pressed against a matte finish, the conductive film is deformed and the direction of reflection changes, but on a smooth surface without a matte finish, the specular reflection of the illumination light enters the photoelectric conversion element and is added to the light from the original. There is a drawback that the white output becomes abnormally large, but on the other hand, the satin surface can prevent such reflected light until it is also scattered. Therefore, in addition to the above effects,
Abnormal white output due to film surface warping can be eliminated, and stable reading performance can be ensured.

If you separate the conductive film and the satin-finished film and separate their functions, you can scatter reflected light by attaching a film with a satin finish on one side to the photoelectric conversion element with the satin-finished surface on the top side of the photoelectric conversion element. This prevents output abnormalities caused by specular reflection of illumination light from the back side of the sensor substrate and incident on the sensor element. Furthermore, by adhering a conductive transparent film to the sensor substrate, the deformation of the film when a document is read and pressed against the sensor is suppressed, which suppresses the reflection of illumination on the sensor substrate side surface of the film from entering the sensor element. Output abnormalities are less likely to occur. In addition, when the sensor substrate and the conductive transparent film are bonded together, there is no air layer with a low refractive index between the sensor substrate and the conductive transparent film, so the reflectance on the surface of the conductive film on the sensor substrate side decreases. Similarly, it works to prevent output abnormalities from occurring.

Further, by mounting a conductive transparent film on the sensor substrate to prevent reflection on the surface of the conductive transparent film, reflected light other than the reflected light from the original is prevented from entering the sensor element. This allows stable sensor output to be obtained.

Note that it is of course within the scope of the present invention to use a glass plate instead of the transparent film.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a complete contact type continuity sensor according to an embodiment of the present invention. In the overall configuration, a matte conductive film 13 is mounted on a reading sensor board 100, and a document 1l is pressed against the reading sensor board 100 by a platen roller 10. Original 11 on reading sensor board 100
A light 114 is placed on the opposite side. The illumination light from the light source 14 illuminates the surface of the document 11 to be read through the transparent part of the reading sensor board 100 and the matte conductive film 13, and the diffusely reflected light increases the reflection density (characters) of the surface of the document 11. The light enters the reading element 2 formed on the reading sensor substrate 100 with an intensity corresponding to the presence, absence, etc., and is photoelectrically converted.

In facsimile 63 standard document reading, the reading elements 2 are arranged in a line at a rate of 8 per lun, and for an A4 size document, the number of elements is approximately 1728, 8.
Approximately 2048 elements are lined up in a sensor for reading 4-size originals. The reading width is 216lIII each.
In a so-called contact type reading sensor that reads a document at its original size, the size of the sensor itself must be the same as the size of the document, and the light source 14 must also illuminate the entire size of the document. However, fluorescent lights used as light sources have different illuminance between the center and the edges, and light sources with a large number of light emitting diodes lined up have uneven illuminance due to variations in the individual light emitting diodes.

Since the intensity of the reflected light from the document 12 is proportional to the illuminance of the document surface, the illuminance unevenness with which the light source 14 illuminates the document 11 directly becomes the output unevenness of the reading sensor, and is called shading. If the output of the reading sensor with this shading is converted into black and white based on a certain standard, it is not preferable because the output deviates from the actual reflection density of the document, causing image deterioration.

Generally, the shading when a uniformly white document is read is stored in memory in advance, and when the document is actually read, the stored shading value is referred to and correction is made as if there were no shading. However, in practice, it is difficult to make a large shading correction industrially due to the accuracy of A/D conversion of the correction circuit and limitations on the input voltage amplitude. The present invention attempts to eliminate such shading by devising a structure of the reading sensor.

The reading sensor board 100 has a transparent substrate 101 and
Electrode 102, light shielding film 102a, insulating film 103, photoelectric conversion film 104, ohmic contact layer 105, electrode 106
, the protective film 107 and the light shielding film 108 are formed. A predetermined shape is formed into a predetermined pattern using photolithography technology similar to that used in pattern formation of ICs and the like. In this way, the reading element 2, the storage capacitor 2a, the reference element 1
, readout switch 3 is made. The satin-finished conductive film 13 is obtained by laminating a conductive transparent film 13a and a satin-finished film 13c with a lamination layer 13b interposed therebetween.

FIG. 2 is a combined drawing of a plan view formed in the example of FIG. 1 and a corresponding circuit diagram. The read element 2 and the reference element 1 use photoconductive photoelectric conversion elements, and the read switch 3 is a field effect thin film transistor. Note that in this figure, the light shielding film 108 and the like are omitted to make the shape easier to understand.

The reading element 2 is configured so as not to directly receive the light from the light source 14 by the light shielding film 102a, and photoelectrically converts the reflected light from the light source 14 onto the original 11. On the other hand, the reference element 1 formed near the reading element has a light shielding film 102.
There is no a, and the light from the light source 14 is directly photoelectrically converted. Further, at this time, a light shielding film 108 is formed on the reference element 1, so that reflected light from the original 11 does not enter. Reading element 2
The photoelectric conversion output is proportional to the illuminance and reflectance of the original 11.

Furthermore, since the photoelectric conversion output of the reference element 1 is proportional to the directional intensity of the light source 14, if the photoelectric conversion output of the reading element 2 is corrected using this, uneven illuminance of the document, that is, unevenness of the directional intensity of the light source can be corrected. does not depend on

Output that depends on reflectance can be extracted.

In this embodiment, the reference element 1 is connected to the reading element 2 in series, and the constant applied voltages Vss and Vou are divided, and the read output signal is output as a voltage at the connection point A between the reading element 2 and the reference element 1. The configuration is as follows. Furthermore, the read capacitor 2a is arranged in parallel with the read element 2, and a signal charge Q = C (Vs+a
- Vss).

The readout switch 3 is turned on at regular readout intervals to transfer charge to the signal line SIG, and readout is performed.

The main part of this embodiment is shown in FIG.

The voltage Vs+a at the connection point is R t + R, where the resistances of the reading element 2 and reference element 1 are R2 and Rz, respectively.
2. The conductivity σ2 of the picking element is proportional to the radiation intensity ■ of the light source 14 and the reflectance γ of the original, and the conductivity σ1 of the reference element 1 is proportional to the radiation intensity of the light source 14. Therefore, the signal voltage V
sra is expressed as 1+-γ1, and an output that does not depend on variations in the light source and changes only depending on the reflectance of the original is obtained.

Here, B is the ratio of conductivity between the reading element and the reference element when the reflectance γ=■, and can be designed depending on the layout of the element and the arrangement of the light source and the element.

The output voltage is inversely proportional to this ratio. Therefore, whether B is large or small, the output voltage change will be small, so it is necessary to set it to an appropriate value.

Since the signal charge Q is an output that depends on the signal voltage Vsxa and the read capacitance C, the magnitude of the signal charge Q can be selected by changing the capacitance C of the read capacitor. Therefore, when transferring charges to the signal line SIG using a readout switch made of field-effect thin film transistors as in this embodiment, readout depends on the speed required for reading and the drive current capacity of the readout switch 3. Charge Q can be changed. This is a big difference from conventional reading sensors, which store all the photocurrent of the reading element that photoelectrically converts the light reflected from the document in a storage capacitor. Such a reading element configuration consisting of the reading element 2, the reference element 1, and the reading capacitor 2a greatly improves the performance of the reading sensor and the degree of freedom in the configuration of the circuit.

Further, in this embodiment, the reading element and the reference element are made of the same photoelectric conversion film and are made in the same process.

Therefore, even if a reading element, a reference element, and two photoelectric conversion elements are provided, the number of steps does not increase. Since the films and processes are the same, they are subject to material variations and pattern accuracy variations in common, so this embodiment, which performs readout based on the ratio of conductivity between the reference element and the reading element, has the effect of reducing element variations. .

This embodiment includes a plurality of inventions, and these will be described separately as follows.

By providing a reading element formed on a translucent substrate that photoelectrically converts the light reflected from the original and a reading element that photoelectrically converts the direct light from the light source, shading caused by variations in the light source can be corrected and the reflectance of the original can be corrected. This has the effect of making it possible to obtain a signal containing only In this embodiment, a photoconductive type photoelectric conversion element is used as the reading element and the reference element, but a laminated type photoelectric conversion element that operates as a photodiode may also be used. Furthermore, in this embodiment, the reading element 1
However, if the shading is gentle, one reference element may be provided for a plurality of reading elements. In order to correct light source variations, it is necessary to calculate the ratio of the outputs of the reading element and the reference element as in the embodiment. Therefore, if the number of reading elements and reference elements is not 1=1, it is sufficient to take out the photoelectric conversion outputs of the reading element and the reference element separately and perform the division externally. The photoelectric conversion output includes voltage, current, and charge, but any output may be used as long as it is proportional to the amount of light incident on the element.

According to this embodiment, since a reference element that receives illumination light and a reading element that receives reflected light from the original are provided, a reading signal without shading can be obtained by taking the ratio of these two elements and the photoelectric conversion output. There is.

Next, when the reading element and the reference element are connected in series and the supplied voltage is divided to produce a reading signal, the shading due to light source variation can be corrected using an N-only configuration, and the shading can be adjusted to correspond to the reflectance of the original. This has the effect of increasing the output voltage.

In this embodiment, the reading element and the reference element are photoconductive type photoelectric conversion elements, but the same effect can be obtained even if a stacked photodiode is used as the photoelectric conversion element. Either the reference element or the reading element may be on the ground side.

Next, by arranging the reading element and the reference element in series, and further providing a reading charge transfer capacitor in parallel with the reading element or in parallel with the reference element, the photocurrent of the reading element and the reference element is not dependent. Since the readout signal charge can be set without any problem, the signal charge can be set in accordance with the drive capability of the readout circuit. Therefore, there is an effect that the degree of freedom in design is improved.

Next, if the reading element and the reference element are manufactured in the same process, it is possible to make the variation in element slam and physical properties the same for the reading element and the reference element, which has the effect of reducing variations.

Further, these elements can also be formed in the same process as the thin film transistor. By forming the reading element and the reference element in the same process, there is an effect that high-performance reading can be performed without increasing the number of processes.

Next, the conductivity ratio of the reading element and the reference element will be explained with reference to FIGS. 4 and 5. Figures 1 and 2
As mentioned in the description of the example in the figure, the reading voltage is determined by the formula (
It depends on the ratio B between the conductivity of the reading element and the conductivity of the reference element expressed in 1), and whether B is large or small, the output voltage will be saturated and the error will become large. Practically about B
If it is set to = LO, the voltage change can be made large, but the linearity is best when B = 1, and it may be set in the range of 0.1 to 100 depending on the purpose. The setting of B is determined by the size and layout of the reading element and reference element, the positional relationship with the light source, etc., and is a value with a large degree of freedom in design. In this way, by setting the ratio of the photoconductivity of the reading element when the reflectance is 1 to the photoconductivity of the reference element to 0.1 to 100, the change in the read voltage due to the change in the read voltage original reflectance can be greatly reduced. This has the effect of improving reading accuracy.

In addition, in a small range of B, the reflectance and the output voltage change have a nearly linear relationship, so there is an effect that a high quality signal can be obtained.

Note that the minimum reading resolution requires the reading gap resolution, that is, the voltage change in the upper gradation to be larger than the noise level, and depends on the noise level of the reading sensor system.

Next, the readout circuit of the readout sensor explained in FIGS. 2 to 5 will be explained using FIGS. 6 and 7. In the embodiments described in FIGS. 2 to 5, the read voltage is expressed by the ratio B between the read element conductivity and the reference element conductivity as shown in equation (1). Here, when the reflectance γ changes, the read voltage Vs is approximately inversely proportional to the reflectance.
Ia comes out. Although the form of the signal differs depending on the readout method, the intensity of the output is inversely proportional to the reflectance γ in any of the voltage, current, and charge readouts. This nonlinearity is a characteristic that is not very desirable for reading and distinguishing many gradations (intermediate color depth), and as shown in Figure 6, when a constant voltage Y is divided by the output By doing so, a linear output Z can be obtained. The output X of the reading sensor is not allowed to become O, so care must be taken. In the embodiment described in FIGS. 1 and 2, the output signal is read out as a charge, and the current amplification circuit 201, integration circuit 202, and division circuit 203 shown as an example in FIG.
A circuit using this is advantageous for high-speed reading. In a small range of B, the linearity of the signal is good, so the division circuit 203 can be omitted.

In this way, as shown in the embodiments shown in Figs. It is effective for high-quality reading such as gradation reading because it provides an output proportional to the reflectance, that is, the intensity of the reflected light. An embodiment of the present invention will be described using the circuit diagram of FIG. 8 and the signal timing diagram of FIG. 9. The read sensor of the present invention includes a shift register section 7 made of amorphous silicon thin film transistors, a buffer section 6, a division matrix@B, a block switch 5, a stabilizing switch 44, a read transfer switch 3 which is a photoelectric conversion element, a reference element 1, and a read element. Consists of 2.

All of the circuits shown in FIG. 8 are fabricated on a transparent substrate. There are reading elements from S1 to 82048, and G3
This is an example of a standard facsimile.

In addition. Some of the elements 31 to 82048 have been omitted or abbreviated with numbers. After the shift register sets data on the input line IB, the data is sequentially transferred from shift register stage SRO to SR64 by clocks φ and T. The signal is transmitted from the shift register unit 7 via the buffer 6 to drive the block switch 5 for selecting l block (32 elements in this case) and the stabilization switch 4. The buffer drives a push-pull circuit 6a via a NOR gate 6c and an inverter 6b for logic adjustment. During this time, the drive current is amplified by adjusting the signal logic and increasing the switch size. There are two sets of push-pull circuits in one block; one operates the gate electrodes of the 32 block switches, and the other operates in reverse logic to the push-pull circuit for driving the block switches, driving the gate line of the stabilizing switch. ing.

When the block switch 4 selects the data in the shift register section 7 via the buffer and then sets one of the divided matrix lines 8 to 1 (positive logic), when the data is selected by the block switch 5 and the matrix of the divided matrix 1lA8, it becomes 1. The readout switch 3 becomes conductive. This results in 1
The read charges of the read elements are transferred to the signal line. Here, the reading element is the one in which the reading element 2 and the reference element 1 are arranged in series, as already explained in FIGS. 1 and 2. Although omitted here, it is shown in the circuit diagram in FIG. It has a read capacity of 2a.

V out in FIG. 9 shows an example in which the signal on the signal line Sea is amplified, integrated, and divided using the circuit described in FIG. 7. Only the signal strength is shown here.

Such signal timing depends on the block division method of the reading elements.In this embodiment, the number of constituent elements in one block is 32, and it takes 6 to drive 2048 elements.
Four blocks are required. There are 65 shift registers from SRO to SR64 since the logic of block selection is repeated, and there are 64 dividing matrix lines from A1 to A64. In general divided matrix driving, the number of matrix lines and the number of elements in one block are the same, and in this case it would probably be 32, but if you try to select from one block to the next block, the block will be blocked due to the operation delay. Requires a rest period in between. According to the configuration of this embodiment, the number N of divided matrix lines 8 is larger than the number N of elements belonging to one block. By increasing the block switching period and readout time per element to 1.11, tu(
can be increased by N*Na). In the embodiment shown in FIG. 8, N=2NB, and a continuous output can be obtained without any pause period with M simple logic.

All the switches used in FIG. 8 can be made of so-called inverted staggered amorphous silicon thin film transistors as shown in FIG. A gate electrode 102, an insulating film 103, an i-type amorphous silicon 104, an n-type amorphous silicon 105, and so on are formed on a transparent substrate 101. Source electrode 106a, drain electrode 106b, protective layer 107
are sequentially laminated and patterned into a predetermined shape using photolithography technology.

This structured thin film transistor switch is an n-channel MIS field effect transistor, and the gate electrode 1
When a voltage of Vc is applied to 02, an operation similar to the basic formula of an L MOS type transistor is performed, which is expressed by the conductor Wcance gm=-CIμ(vG-vt). Here, W is the channel width, L is the channel length, and CI
is the capacitance per unit area of the gate, μ is the electron mobility, v
D represents the threshold voltage.

However, such amorphous silicon thin film transistors generally have an electron mobility μ of 0.1 to 1a.
Since #/VS is about three orders of magnitude smaller than crystalline silicon, it is difficult to drive a large current.

By increasing the operating speed by matrix driving, reducing the driving capacity, and selecting the read element capacity, in the embodiment shown in Fig. 8, the shift register has a 20 KHz, the number of matrices in one block is 32, and the overall operating speed is 600 KHz.
degree is obtained. This speed is a reading speed sufficient for practical use according to the G3 standard. Furthermore, since the reading element and the thin film transistor can be shared, it is possible to simplify the process, reduce the amount of wiring, and downsize the substrate, making it possible to provide a high-performance and inexpensive reading sensor.

Note that an E/R inverter or an inverter with an E/E inverter CMOS structure can be used as the basic inverter.

The 11th shift register circuit using an E/R inverter
As shown in the figure. The inverter with this configuration is about 6 times faster than the E/E inverter, which is advantageous, but the E/R, E
/E Either inverter may be used.

According to this embodiment, the amount of wiring can be reduced by using the low capacitance reading element shown in FIGS. 1 and 2, a shift register section formed of amorphous silicon thin film transistor switches, a buffer section, a block switch, a stabilizing switch, and a separation matrix line. This has the effect of making it possible to downsize the substrate and supplying an inexpensive and high-performance reading sensor.

Furthermore, in the present invention, by making the number of divided matrix lines larger than the number of elements constituting the ↓ block, it is possible to have a margin in block switching time, so that continuous read output can be obtained.

A cross-sectional structure of an embodiment of a reading sensor constructed according to the present invention is already shown in FIG. The operation of the circuit and elements has already been described.

Here, an example of a matte transparent conductive film will be described. As described above, the original 11 is pressed against the reading element by the platen roller 1o via the matte transparent conductive film, and predetermined reading is performed. At this time, the surface of the satin-finished transparent conductive film is electrostatically charged by the pressing movement of the document 1l. When the charged state changes (as the document runs), the surrounding electric field changes, and without the matte transparent conductive film 11, noise would be induced in the wiring of the reading sensor.
This may cause the thin film transistor to malfunction or the reading sensor output to become abnormal. The matte transparent conductive film consists of a transparent film base made of polyester, acrylic, etc., a transparent conductive layer 13b made of ITO (indium tin oxide) or tin oxide for shielding, and a matte finish surface 13c.

IT○ has the role of shielding noise due to static electricity generated on the base film surface on which the original 1l runs due to the running of the JM manuscript, and also has a matte surface 13c. This prevents abnormal output from the element that would otherwise occur. That is, if there is no matte surface, the film may be moved by the pressing of the platen roller 10 and may take on a concave mirror shape near the reading element 2. As a result, if the sensor surface side of the film is not satin-finished, the light from the light source on the sensor surface side of the film may be condensed with an effect similar to a concave mirror, resulting in an abnormally high output. The pear surface 13c has an uneven shape, and is a surface that scatters transmitted light and reflected light.This scatters the light from the light source, allowing stable reading even if the film is deformed into a concave shape. It has a great effect.

Note that the satin-finished transparent conductive film can also be obtained by adhering a film coated with ITO on one side and a satin-finished film with the ITO surface and the non-matin finish.

FIG. 12 is a perspective view of a sensor portion according to the present invention, and as shown in the figure, upper and lower electrodes 102, 1 constituting a photoelectric conversion element are shown.
A large number of duplicates of 06 will be provided.

A sectional view of an example of the reading sensor shown in FIGS. 1 and 8 installed in a facsimile will be explained with reference to FIG. 12. In this cross-sectional view, a read sensor assembly 300 of the present invention, a platen roller 10. A thermal recording head 301 and thermal paper 302 are shown, and other circuits, power supplies, etc. are omitted. The read sensor assembly 300 includes:
It has a structure as shown in the sectional view of FIG. 1, and also includes a matte transparent conductive film 13 and a light source 14.

As shown in this figure, when a document is placed with the document surface facing downward in the direction of the arrow 303, the document is pressed against the reading sensor assembly by the platen roller 10a and is read as described above. In addition, the thermal head 301
The thermal paper 302 is pressed against the heating element by the platen roller 10b to obtain a predetermined recording surface. As shown in this figure, the implementation of a facsimile consists of a reading system formed by a reading sensor assembly 300 and a platen roller 10a, a thermal head 301, a platen roller 10b, and a thermal paper 3.
The design is constrained by the arrangement of the recording system comprised of 02. By using the reading sensor of the present invention, a compact design as shown in FIG. 12 is possible, which has the effect of increasing the degree of design freedom.

This requires a reduction optical system, which was often used in the past.
This is difficult with a CD sensor reading system.

That is, the CCD sensor requires an optical path length of about 25 cm because it is necessary to image the surface of the document on a small sensor surface using a reduction optical system. In addition, post-assembly adjustments were required, and the design was largely restricted by the reading system. On the other hand, in the so-called full-contact type continuation sensor, which reads the document in close contact with the reading sensor assembly, the optical path length is around 100 μm, which has the effect of significantly reducing the size and increasing the degree of design freedom. .

According to the embodiments described above, the reading element formed on the transparent substrate and the reference element respectively detect the reflected light of the document and the
Since the surface light of the light source can be photoelectrically converted, the shading caused by variations in the light source of the reading element can be corrected with the output of the reference element, so it is possible to provide a high-performance, fully contact type continuation sensor that can correct shading. be.

Furthermore, since the read element and the reference element are connected in series and the supplied voltage is divided to produce a read signal, it is possible to correct shading due to light source variations with a simple structure.

Furthermore, according to the embodiment, since the reference element is connected in series with the reading element and the reading capacitor is provided in parallel with the reading element or in parallel with the reference element, the separation is possible regardless of the magnitude of the photocurrent of the reading element. This has the effect of setting the signal charge determined by the product of the pressure signal and the read capacitance. This has the effect of greatly increasing the degree of freedom in designing the readout circuit.

According to this embodiment, since the reading element and the reference element are manufactured in the same process, there is an effect that high-performance reading is possible without increasing the number of processes.

In addition, since they are manufactured in the same process, there is little variation in the materials and batting accuracy of the reference element and the reading element, and as a result, it is possible to read with less variation.

The conductivity of the reference element and the read element are set to 0.1 to 1.
If it is set to 00, the change in the output voltage is large, which has the effect of improving reading accuracy.

In addition, since the output signal can be linearized by the division circuit,
This has the effect of enabling high-quality reading including halftones.

Furthermore, since the shift register, buffer, block switch, and stabilization switch made of amorphous silicon thin film transistors can be switched by dividing matrix lines to switch the readout switch and take out the signal of the readout element, it is possible to provide a compact sensor with less wiring.

In addition, according to this embodiment, rather than the number of dividing matrix lines,
Since the number of elements in one block is small, there is no pause period when switching blocks, and there are few external circuits, and continuous read output that is easy to use for facsimile can be obtained.

Static electricity is generated due to friction between the original and the conductive transparent film. If there is no conductive transparent film, static electricity may occur.
Surrounding radio waves induce noise in photoelectric conversion elements and circuit wiring, making the output signal unstable, but this conductive transparent film has the effect of shielding the induction and providing stable output. be. Conductive transparent films are easily deformed by external forces, so they do not break and are easy to assemble.
Highly reliable. This conductive transparent film can be made of polyester, nylon, acrylic, etc. that transmits light, and for conductivity, transparent conductive materials such as ITo (indium tin oxide), tin oxide, or coating with a metal thin film can be used. It is easy to get. Preferably, the sheet resistance is smaller than IOOKΩ/mouth.

Matting one side of the conductive transparent film prevents abnormal output caused by light reflected from the film surface and provides a stable output signal. In other words, if the surface of the conductive transparent film on the sensor substrate side is smooth, the film will deform when an original is pressed to bring it into close contact with the sensor, and the illumination light will be reflected on this surface and more likely to enter the sensor element. be. In this case, light other than the light reflected from the surface of the document enters the sensor element, resulting in an abnormal output signal. By making this surface a matte surface as in this embodiment, the illumination light reflected on the matte surface is scattered, so that a stable output signal can be obtained.

In addition, since the satin-finished conductive transparent film can be easily replaced if the surface becomes soiled, it also has the advantage of being easy to maintain.

By mounting a matte transparent conductive film on the reading sensor substrate, there is no malfunction of the thin film transistor, and no electrical or chemical noise is generated in the read signal, resulting in high quality reading. In addition, complete close reading has the effect of making the facsimile more compact and increasing the degree of freedom in design.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce read signal variations due to light source variations.

In addition, high-speed drive using thin film transistors becomes possible.
This has the effect that the scale of the external circuit can be reduced.

[Brief explanation of drawings]

Fig. 1 is a sectional view of essential parts of a complete contact type continuation sensor according to an embodiment of the present invention, Fig. 2 is a combination diagram of a plan view and a circuit diagram of the embodiment sensor of Fig. FIG. 2 is a partially enlarged view of the embodiment circuit of the present invention; FIG. 4 is a characteristic diagram showing the relationship between the reading output voltage ratio and the ratio of the reading element conductivity to the reference element conductivity in the embodiment sensor of the present invention; FIG. 5 is a characteristic diagram showing the relationship between output voltage ratio and reflectance, FIG. 6 is a block diagram showing an example of the output circuit of the reading sensor according to the embodiment of the present invention, and FIG. A circuit diagram showing an example of an output circuit, FIG. 8 is an overall circuit diagram of a reading sensor according to an embodiment of the present invention, FIG. 9 is a signal timing diagram of the circuit in FIG. 8, and FIG. 10 is applied to the present invention. FIG. 11 is a sectional view of an embodiment of a shift register, FIG. 12 is a perspective view of a main part showing an electrode group of a fully contact type sensor, and FIG. 13 is a sectional view of an embodiment of a thin film transistor according to the present invention. 1 is a schematic cross-sectional view of a device showing an example of facsimile implementation to which the method is applied. 1...Reference element. 2...Reading element, 2a...
Read capacity, 3... Transfer switch, 4... Stabilization switch, 5... Block switch, 6... Buffer section, 7... Shift register section, 8... Divided matrix wiring, 10. ...Platen roller, 11... Original, 12... Satin transparent conductive film. Leather 1 Figure 2 2 reflections Ra Chi 6 Figure 3 Figure 4 Figure 13 Figure 36Z To the mouth, > ``1 ``1

Claims (1)

[Scope of Claims] 1. Comprising a light-transmitting substrate and a plurality of photoelectric conversion elements arranged on the light-transmitting substrate, and each photoelectric conversion element is connected to a light source with the light-transmitting substrate in between. In the complete contact type continuation sensor located on the opposite side, each of the photoelectric conversion elements includes a reference element section that photoelectrically converts direct light from the light source, and a reading element section that photoelectrically converts light reflected from the original. A complete contact type continuation sensor characterized by comprising: 2. The complete contact type continuation sensor according to claim 1, wherein the reading element and the reference element are connected in series, and a supply voltage is divided to obtain a reading signal. 3. The complete contact type continuation sensor according to claim 2, further comprising a read charge transfer capacitor provided in parallel with the read element. 4. The complete contact type continuation sensor according to claim 2, further comprising a read charge transfer capacitor provided in parallel with the reference element. 5. The complete contact type continuation sensor according to claim 1, 2 or 3, wherein the reading element and the reference element are formed in the same process. 6. Complete contact according to claim 1, 2, 3, or 4, wherein the ratio of the photocurrent of the reference element to the maximum value of the photocurrent of the reading element is 0.1 to 100. Mold continuation sensor. 7. The complete contact type continuation sensor according to claim 2, 3 or 4, further comprising a dividing circuit to linearize the output signal. 8. Sequentially switching readout switches selected by a shift register made of an amorphous silicon thin film transistor, a buffer connected to the shift register output, a block switch and a stabilization switch connected to the buffer, and a plurality of dividing matrix lines; , a reading sensor that performs reading by transferring electric charge of a reading element. 9. Read by sequentially switching readout switches selected by a shift register made of a thin film transistor, a buffer connected to the output of the shift register, a block switch and a stabilization switch connected to the buffer, and a plurality of divided matrix lines. A read sensor that performs reading by transferring charges of elements, characterized in that the number of elements in one block is smaller than the number of dividing matrix lines. 10. The reading sensor according to any one of claims 1 to 9, wherein the upper surface of the light-transmitting substrate is provided with a transparent resin film laminated to cover the photoelectric conversion element group, and the transparent resin film has conductivity. A completely contact type continuation sensor characterized by being attached. 11. The reading sensor according to any one of claims 1 to 9, wherein the upper surface of the transparent substrate is provided with a conductive transparent resin film laminated to cover the photoelectric conversion element group, and one side of the film is A completely contact type continuation sensor, characterized in that at least a side facing the surface and a position near the element is a finely uneven surface. 12. The reading sensor according to any one of claims 1 to 9, wherein the upper surface of the transparent substrate is provided with a transparent laminated member laminated to cover the photoelectric conversion element group, and one side of the transparent laminated member is A complete contact type continuation sensor, characterized in that at least a side facing the element surface and a position near the element is a finely uneven surface. 13. The reading sensor according to any one of claims 1 to 9, wherein the upper surface of the transparent substrate is provided with a conductive transparent resin film laminated to cover the photoelectric conversion element group, and one side of the film is A completely contact type continuation sensor, characterized in that at least a side facing the element surface and a position near the element serves as a diffusing surface for incident light. 14. The reading sensor according to any one of claims 1 to 9, wherein the upper surface of the transparent substrate is provided with a transparent laminated member laminated to cover the photoelectric conversion element group, and one side of the transparent laminated member has at least A completely contact type continuation sensor, characterized in that a side facing the sensor surface and a position near the sensor serves as a scattering surface for incident light. 15. A plurality of the photoelectric conversion elements are mounted on a substrate having a light-transmitting region near the light-transmitting region, and a transparent laminated member is further mounted without adhesive so as to cover the group of elements. The complete contact type continuation sensor according to any one of claims 10 to 14. 16. In the reading sensor according to any one of claims 10 to 15, an incident optical path is secured on the back surface of the light-transmitting part, and a platen roller is provided outside the film or the transparent laminated member and in the vicinity of the photoelectric conversion element group through the paper surface. A read sensor assembly comprising: a reading sensor assembly configured to abut; 17. A reading sensor assembly according to claim 16, characterized in that a light source is provided within a base to which the element mounting substrate is attached in order to secure an optical path. 18. A facsimile device comprising the reading sensor assembly according to claim 16 or 17 housed in a housing together with a recording section comprising a thermal head and a recording paper roller.