JPH0522512A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To realize the formation of electric charge transfer capacity without enlarging a sensor part in the contact type image sensor. CONSTITUTION:Earth electrodes 3 are formed on a glass substrate 4, and an insulated layer 2 is formed on it. Further, connection electrodes 1 are provided on it. Thus, an indispensable area for the connection with the external circuit can be used to the formation area of the electric charge transfer capacity and the contact type image sensor can be made small by providing earth electrodes 3 through the insulated layer under the connection electrodes 1 and forming a fixed capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor used in facsimiles, image scanners and the like.

[0002]

2. Description of the Related Art Conventionally, a TFT (thin film transistor) matrix driven image sensor is known as a contact type image sensor used for an image sensor. This is to project image information of an original document or the like onto a light-receiving element array, read the charges generated in each light-receiving element in block units by using a TFT switch, and temporarily store the charges in a charge transfer capacitor for time series. To read.

FIG. 6 shows an example of such an equivalent circuit. In the figure, 21 is a light receiving element, 22 is a TFT, 23 is a common signal line, 24 is an individual signal line, 25 is a gate line, 26
Is a gate pulse generation circuit, 27 is a selection pulse generation circuit,
28 is a matrix wiring part.

The light receiving element 21 is divided into m blocks, and each block is assigned n light receiving elements. The light receiving elements P ₁₁ to P _1n is the first block, the light receiving elements P ₂₁ to P _2n is the second block, below, in that order, the light receiving elements P _m1 to P _mn is in the m-th block. The output of each light receiving element is T _{11 to} T _1n , T _{21 to} T _2n , ... T _{m1 to} T
_{The mn} TFT 22 is connected to each drain as a switching element, the source of each TFT is connected to the individual signal line 24, and each individual signal line has the same common signal line 23 of the same rank in each block. , S _n are connected to the common signal lines S ₁ , S ₂ , ..., S _n . TFT of _{T 11 ~T 1n, T 21 ~T} 2n, ·····
The gates T _{m1 to} T _mn are connected to the gate pulse generation circuit 26 by gate lines G ₁ , G ₂ , ..., G _m commonly for each block. Common signal lines S ₁ , S
_2, ..., the S _n, the charge transfer capacitance C _1, C _2, ·
· ·, C _n are connected, select constituted by FET each switch _{SW 1, SW 2, ···,} SW n
Connected to the drain of. Selection switch SW ₁ , S
The sources of W ₂ , ..., SW _n are collectively output line C
Each gate is connected to the OM and has a selection pulse generating circuit 27.
It is connected to the.

The gate pulse generation circuit 26 turns on the TFT 22 which is a switching element for each block.
The output signal of the common signal line 23 is sequentially selected by the read signal from the selection pulse generation circuit 27 in synchronization with the gate pulse. First, it is assumed that the gate pulse generation circuit 26 outputs a gate pulse to the signal line G ₁ . As a result, the switching elements T _{11 to} T _{1n of} the first block are turned on, and the outputs of the light receiving elements P _{11 to} P _1n are supplied to the common signal line S ₁ ,
S _2, ···, connected to S _n, the charge transfer capacitance C _1, C
_2, ..., it accumulates in C _n. Charge transfer capacitors C ₁ , C
₂ , ..., The output signals accumulated in C _n are selected by the read signal from the selection pulse generation circuit 27 to select switch S.
W ₁ , SW ₂ , ..., SW _n are sequentially turned on, and the output of the first block is output to the output line COM as a time series signal. Next, from the gate pulse generation circuit 26 to the signal line G
₂ gate pulse is output to the switching elements T ₂₁ through T _2n of the second block is turned on, connecting the output of the light receiving element P ₂₁ to P _2n common signal lines S _1, S _2, · · ·, to S _n Similarly, the selection switches SW ₁ , SW ₂ , ..., SW _n are sequentially turned on by the read signal from the selection pulse generation circuit 27, and the output of the second block is output to the output line COM as a time series signal. Output. Hereinafter, similarly, the output up to the m-th block is output to the output line COM as a time series signal, the image information of one line in the original is read, the sub-scan is performed, and the next line is read in the same manner.
By repeating this, the image information of the entire document can be read out as a time series signal. 28 circuits surrounded by dotted lines
It is a matrix wiring part.

In such a contact-type image sensor, the charge transfer capacitor is formed by using a lead pattern from the matrix wiring portion, as described in JP-A-63-9358.

FIG. 5 is an example thereof, and is a plan view showing an outline of a contact image sensor. In the figure, 11 is a light receiving element, 12 is a TFT, 13 is a matrix wiring portion, 14 is a charge transfer capacitance portion, and 15 is an I / O terminal portion. In addition,
To make the figure easier to see, the number of bits in one block is 16
And Further, the light receiving element 11 and the TFT 12 are schematically illustrated, and the gate wiring and the like are omitted. Matrix wiring part 1
In FIG. 3, the lines shown in the vertical direction are the individual signal lines, and the lines shown in the horizontal direction are the common signal lines. The charge transfer capacitance section 14 is one in which the individual signal lines of the matrix wiring section are drawn out of the matrix wiring section and faced to a ground electrode (not shown) via an insulating layer.

By the way, such a matrix drive type sensor is not suitable from the viewpoint of miniaturization, because the charge transfer capacitance is formed outside by using the lead pattern from the matrix wiring. Moreover, it is required to increase the number of individual arrays to read an image with higher density, and the density of the light receiving elements is increasing. When the light receiving elements are arranged at a high density, the wiring in the matrix wiring portion also becomes dense and the line width becomes narrow. Therefore, the fixed capacitance per unit length of the wiring in the charge transfer capacitance section becomes small, the width of the charge transfer capacitance section 14 needs to be increased, and miniaturization is difficult.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and the formation of a charge transfer capacitor is as follows.
The object is to realize the sensor unit without increasing the size thereof.

[0010]

According to the present invention, in a contact image sensor, the invention of claim 1 is characterized in that a charge transfer capacitor is formed in a connection portion with an external circuit. The invention of item 2 is characterized in that the charge transfer capacitors are formed in a triangular shape in the end blocks of the matrix wiring portion.

[0011]

According to the present invention, since the charge transfer capacitance is formed in the connection portion with the external circuit, the charge transfer capacitance can be formed in the connection electrode, the connection wiring, etc., and the connection portion is charged. It can be used as a space for forming a capacity for use. Of course, a charge transfer capacitor may be formed by a pattern drawn from the matrix wiring portion, but in this case as well, the capacitance portion formed outside the matrix wiring portion can be small, and the sensor can be downsized.

Further, since the charge transfer capacitance is formed in a triangular shape in the end block of the matrix wiring portion, a space which has not been conventionally used can be used as a charge transfer capacitance formation region. In this case, the individual signal line can be used as the capacitance forming electrode, but when the common signal line is used as the capacitance forming electrode, the electrode width can be made larger, so that a larger charge transfer capacitance can be formed. In this case also, the charge transfer capacitance may be formed outside the matrix wiring portion by the extraction pattern, but since the shortage can be compensated for, the external capacitance portion can be small and the sensor can be downsized.

A charge transfer capacitor according to claim 1 and claim 2
Both of the charge transfer capacitors may be formed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a contact type image sensor according to a first embodiment of the present invention, in which a portion near a connecting portion is broken away. In the figure, 1 is a connection electrode, 2 is an insulating layer, 3 is a ground electrode, and 4 is a glass substrate. The conventional connection electrode is provided on the glass substrate, but in this embodiment, the ground electrode 3 is formed in the region on the glass substrate 4 where the connection electrode 1 is provided. The insulating layer 2 was coated thereon, and the connection electrode 1 was further provided thereon. Insulation layer 2
Serves as a dielectric layer.

When the OLB connection is performed, the size of the connection electrode is 10 mm × 0.7 because of the contact resistance and strength.
A relatively large area of about mm is required. Therefore, as in this embodiment, by forming an electrostatic capacitance between the connection electrode 1 and the ground electrode 3, a charge transfer capacitance can be secured, or the line width of the routing pattern can be reduced, It is also possible to compensate for the shortage of the charge transfer capacitance when the array size is reduced.

As described above, the ground electrode is provided below the connection electrode via the insulating layer to form the fixed capacitance,
An area indispensable for connection with an external circuit can be used as an area for forming a charge transfer capacitor. Therefore, it is not necessary to separately provide an area for forming the charge transfer capacitance on the sensor, or even if an area for forming the charge transfer capacitance is provided on the sensor, a small area will suffice and the contact image sensor can be made compact. it can.

FIG. 2 is for explaining a second embodiment of the contact type image sensor of the present invention, in which a part of the vicinity of the connecting portion is broken and a connecting electrode of the flexible printed board and the I / O terminal portion is formed. It is the perspective view which separated and illustrated. Illustration of the protective layer and the like of the flexible printed board is omitted. In the figure, 1 is a connection electrode, 4 is a glass substrate, 5 is a flexible printed board, 6 is a base film, 7 is its conductor portion, and 8 is a ground electrode. In this example, the charge transfer capacitance portion was formed at the connection portion of the flexible printed board connected to the I / O terminal portion of the sensor portion. The flexible printed board 5 is provided with the conductor portion 7 on the lower surface of the base film 6, and
Of the ground electrode 8 on the surface opposite to the portion of the tip of the sensor connected to the I / O terminal of the sensor, that is, the upper surface.
Is provided. Therefore, the conductor portion 7 and the ground electrode 8
A capacitance is formed between and. When the connection electrode 1 and the conductor portion 7 are connected, the capacitance formed between the conductor portion 7 of the flexible printed board 6 and the ground electrode 8 is applied to the connection portion of the I / O terminal portion. Will be formed. It goes without saying that the ground electrode 8 is connected to an appropriate circuit such as the ground potential of the sensor section. The ground electrode 8 is
It is not necessary to be provided so as to face all of the conductor portions 7, and I /
The O terminal portion may be provided so as to face only the conductor portion corresponding to the connection electrode of the circuit in which the charge transfer capacitance needs to be formed. In this embodiment, no special structure for forming the charge transfer capacitor is required in the terminal portion on the sensor side, so that the structure of the sensor portion may be the same as the conventional one. In addition, a shield effect can be expected at the connection portion.

FIG. 3 is a plan view showing the outline of a contact type image sensor for explaining the third embodiment of the present invention. In the figure, the same parts as those in FIG. As in FIG. 5, in order to make the diagram easier to see, the number of bits in one block is 16, and the light receiving element 1
1, the TFT 12 is schematically illustrated, and the gate wiring and the like are omitted. Reference numeral 16 is a charge transfer capacitance section. In this embodiment, the charge transfer capacitance section 16 is formed in the matrix wiring section 13 in a triangular shape from the connection points at both ends of the individual signal lines shown by vertical lines and the common signal lines shown by horizontal lines to the outer end blocks. The charge transfer capacitor section 16 was formed. As can be seen from FIG. 5, this end block is conventionally a region of the matrix wiring portion 13 and is a region where individual signal lines and common signal lines are extended. Also, there are some which do not extend the signal line to this portion. In this embodiment, this end block is provided with a ground electrode in a triangular shape on the substrate,
Only the common signal line was extended on the insulating layer. Therefore, a charge transfer capacitance can be added to the common signal line. Both ends of the matrix wiring part 13 are
Since they are formed in an inverted triangular shape, by using both ends of the common signal line as the charge transfer capacitance sections 16, the additional capacitance of each common signal line becomes equal and there is no variation between bits.

The individual signal lines may be extended instead of the common signal line. However, the individual signal line is regulated by the distance between the light receiving elements 11. Therefore, if the density is increased, the individual signal line becomes thin and a large value of the additional capacitance in the end block cannot be expected. Since the common signal line can have a width regardless of the density of the array, it is possible to form a certain capacitance value even if the array has a high density.

In this embodiment, the charge transfer capacitance portion 14 is provided outside the matrix wiring portion 13 as in the conventional example. However, by providing the charge transfer capacitance section 16, a desired capacitance value can be obtained even if the width of the charge transfer capacitance section 14 is reduced.

If the value of the additional capacitance is sufficient due to the charge transfer capacitance section 16, it is not necessary to provide the charge transfer capacitance section 14 formed outside the matrix wiring section 13, and the sensor can be made smaller.

In the end block of the matrix wiring portion 13 in the third embodiment, as shown in FIG. 4, a lead-out portion from the matrix wiring portion 13 to the I / O terminal portion is provided in the central portion. 4 of 17 shown with diagonal lines
In some cases, it may be formed at a part of the place or more. In such a case, a charge transfer capacitance part may be formed in each end block.

[0023]

As is apparent from the above description, according to the present invention, the charge transfer capacitance can be formed in the connection portion to the external circuit and the end block of the matrix wiring portion, so that the space can be utilized effectively. Therefore, the sensor can be downsized. Moreover, since the formed additional capacitance has a structure close to that of a parallel plate, there is an effect that the capacitance can be easily estimated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a matrix wiring section.

FIG. 5 is a plan view showing an outline of a conventional contact image sensor.

FIG. 6 is an equivalent circuit diagram of an example of a conventional contact image sensor.

[Explanation of symbols]

1 connection electrode, 2 insulating layer, 3 ground electrode, 4 glass substrate, 5 flexible printed board, 11 light receiving element, 1
2 TFT, 13 matrix wiring part, 14 charge transfer capacitor part, 15 I / O terminal part, 16 charge transfer capacitor part.

Claims (2)

[Claims] 1. A contact image sensor, wherein a charge transfer capacitor is formed in a connection portion with an external circuit in the contact image sensor. 2. A contact type image sensor, wherein the charge transfer capacitor is formed in a triangular shape in an end block of a matrix wiring portion in the contact type image sensor.