JPH0367349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image sensor used in an image reading device such as a facsimile and a method for manufacturing the same.

[Technical background of the invention and its problems]

In recent years, close reading image sensors have been actively developed with the aim of downsizing image reading devices used in facsimiles and the like. This is an image sensor in which photoelectric conversion elements are arranged within the width of a document and image information is read in close proximity to the document using a light guiding system such as a rod lens array. Therefore, such an image sensor requires high-density wiring technology on a large-area substrate. For example, for an A4-sized contact image sensor with a resolution of 8 pixels/mm, 1,728 photoelectric conversion elements must be arranged in a line in a 216 mm width, and wiring must be formed to connect to the drive circuit to drive each element. Must be.

When configuring such an image sensor, a matrix drive method is often used as a method of reducing the number of drive circuits, wiring density, and packaging density.

FIG. 1 shows an example of a circuit configuration of a contact type image sensor using a matrix drive method. Here, an example is shown in which a photoconductive element is used as the photoelectric conversion element. That is, R ₁₁ to _{R no} are photoconductive elements whose resistance values change depending on the amount of incident light. Therefore,
Image information can be read by focusing an image on the photoconductive elements _R11 to _Rno and detecting changes in their resistance values. The photoconductive elements R ₁₁ -R _no are divided into m blocks B ₁ -B _n each consisting of n photoconductive elements, and one end of each block is commonly connected by a common electrode C ₁ -C _n . On the other hand, the photoconductive element R ₁₁ ~
The other end of _Rno is connected to the individual electrodes _D1 to _D0 after being commonly connected to each other through the matrix wiring M between the blocks at corresponding positions. V _B
is the drive power supply, P ₁ to _{P n} is the common electrode C ₁ to _{C n} is the power supply V _B
Block selection switches Q ₁ -Q _o are individual selection switches for selectively connecting the individual electrodes D ₁ -D _o to the output current-voltage conversion circuit S.

In this configuration, the common electrode C ₁ is first connected to the power supply V _B via the switch P ₁ , and in that state, the individual electrodes D ₁ to D _o are sequentially subjected to current-voltage conversion via the switches Q ₁ to Q _o . Connect to circuit S. Below common electrode C ₂
By sequentially connecting C _n to the electrode V _B and repeating similar scanning, the resistance values of the photoconductive elements R ₁₁ to R _no can be detected serially. That is, a voltage corresponding to the amount of incident light on the photoconductive elements R ₁₁ to _{R no} is extracted as the image reading output _Vput . At this time, all of the photoconductive elements are connected to the ground side except those selected by the switches _P1 to _Pn and _Q1 to _Qo and connected to the power supply _VB and the current-voltage conversion circuit S.
By doing so, it is possible to prevent current flow, that is, output crosstalk.

As described above, according to the circuit configuration shown in FIG. 1, in order to drive m×n photoconductive elements R ₁₁ to R _no , (m+n)
The number of drive circuits (switches) required can be reduced, and the number of drive circuits and wiring density and packaging density can be reduced, making it possible to obtain a low-cost image sensor. However, since the number of connection points in the matrix wiring M portion is the same as the number m×n of photoconductive elements R ₁₁ to _{R no} , there is a problem in terms of connection reliability and yield improvement.

In addition, in the configuration shown in FIG. 1, the photoconductive elements located at both ends of blocks B ₁ to _{B n}
Destruction of R ₁₁ , R _1o , R ₂₁ , R _2o . . . R _n1 , R _no is often found. The content of the breakdown appears as either a decrease in bright current or an increase in dark current. Although the cause of such destruction is presumed to be static electricity generated during the manufacturing process, the reality is that no simple and effective measures have been considered to prevent this phenomenon.

[Purpose of the invention]

An object of the present invention is to provide an image sensor with excellent connection reliability of matrix wiring sections and high yield.

Another object of the present invention is to provide a method for manufacturing an image sensor that has excellent connection reliability of matrix wiring parts, eliminates specific destruction of photoelectric conversion elements, and can improve yield. be.

[Summary of the invention]

This invention connects a matrix wiring section between a photoelectric conversion element and its individual selection circuit between each other end of the photoelectric conversion element and adjacent blocks, which are located at a line symmetrical position with respect to the boundary line between the blocks. It is characterized in that it is formed of a plurality of U-shaped conductors, and a linear conductor that connects these U-shaped conductors to mutually correspond to each other in the arrangement direction of the photoelectric conversion elements.

In addition, when forming such a matrix wiring part, it is recommended to form a U-shaped conductor and to form a short-circuiting conductor that short-circuits the outermost conductors of the U-shaped conductor, and then to form a linear conductor. It is a feature.

〔Effect of the invention〕

According to this invention, the number of connection points in the matrix wiring section is n·m/2, where m is the number of blocks of photoelectric conversion elements and n is the number of elements in one block.
Reduce by half. Furthermore, the area of the connection point can also be increased. Therefore, short-circuit accidents and the like are reduced, connection reliability is increased, and yield is also improved.

Furthermore, in the present invention, since the blocks of the photoelectric conversion element are electrically short-circuited via the short-circuit conductor, even if static electricity is generated during the manufacturing process, the static electricity is quickly discharged. Therefore, the peculiar phenomenon of destruction of the photoelectric conversion elements at the end of the block due to static electricity is eliminated, and from this point of view as well, the yield can be improved.

[Embodiments of the invention]

FIG. 2 is a circuit diagram of an image sensor according to an embodiment of the present invention. In the figure, 1 is a photoelectric conversion element array, in this example photoconductive elements R ₁₁ , R ₁₂
...R _no is arranged in a line. Note that a junction type photoelectric conversion element having a photovoltaic effect such as a photodiode may be used instead of the photoconductive element. Photoconductive element R ₁₁ , R ₁₂ …R _no is R ₁₁
~ R _1o , R ₂₁ , R _2o ... R _n1 ~ R _no It is divided into m blocks B ₁ , B ₂ , ... B _n each consisting of n blocks, and one end of each block is common to each block. Electrode C ₁ ,
Commonly connected by C ₂ ,...C _n . These common electrodes C ₁ , C ₂ , . . . , _{C n are} selectively connected to the drive power source V _B through switches P ₁ , P ₂ , . .

On the other hand, each other end of the photoconductive elements R ₁₁ , R ₁₂ ...R _no .
Between adjacent blocks, that is, between B ₁ - B ₂ , B ₃ - _{B 4}
U _{- shaped} conductor l ₁ ,
connected by l ₂ ,... _lo . That is, if the blocks B ₁ -B ₂ are arranged in a row, each other end of the photoconductive element is a U-shaped conductor l ₁ with the combinations R ₁₁ -R _2o , R ₁₂ -R _2o-1 , and R _1o -R ₂₁ . , l ₂ , ... _lo .
These U-shaped conductors l ₁ , l ₂ , ... _lo are photoconductive elements R ₁₁ ,
R ₁₂ ...R _no's that correspond to each other in the arrangement direction (horizontal direction in the figure), that is, l ₁ corresponds to l ₁ , l ₂ corresponds to l ₂
linear _{conductors L 1 ,}
Connected by L ₂ ,...L _o .

These linear conductors L ₁ , L ₂ , ...L _o constitute switches Q ₁ , Q ₂ , ...Q _o that constitute the individual selection circuit 3.
are selectively connected to the current-voltage conversion circuit S through the respective terminals.

When reading an image with such a configuration, the image on the surface of the document to be read is formed on the photoconductive elements R ₁₁ , R ₁₂ , ...R _no , and the switches P ₁ , P ₂ , ... P _o are sequentially turned on. Selectively turn the power supply V to _{the B} side, and block B ₁ , B ₂ ,...
B Select _n in sequence. Each time each block is selected, the switches Q ₁ , Q _{2 ,} . However, switch Q ₁ ,
Q ₂ ,...Q _o operate in the order of Q ₁ →Q ₂ →...Q _o-1 →Q _o when the odd numbered blocks B ₁ , B ₃ ,...B _o are selected, and when the even numbered blocks When B ₂ , B ₄ , ... are selected, the operations are performed in the order of Q _o →Q _o-1 →...Q ₂ →Q ₁ .

Due to this operation, the photoconductive elements R ₁₁ , R ₁₂
...R _no is selected one by one from the left in the figure and energized from the power supply V _B. The current flowing at this time corresponds to the amount of incident light. Therefore, these photoconductive elements R ₁₁ ,
The image reading output V _put can be obtained by converting the current sequentially flowing through R ₁₂ . . . R _no into a voltage using the current-voltage conversion circuit S.

FIG. 3 is a plan view showing the structure of the matrix wiring section of this image sensor, in which parts corresponding to those in FIG. 2 are designated by the same reference numerals. In the figure, 11 is an insulating substrate on which the photoconductive elements R ₁₁ , R ₁₂ . . . R _no are arranged, and the common electrodes C ₁ , C _{2 ,} .
U-shaped conductors l ₁ , l ₂ , . . . _lo and short-circuit conductors l _s are formed on this substrate 11. And U-shaped conductors l ₁ , l ₂ ,...
l _o , a linear conductor L ₁ coated on the insulator 12,
L ₂ ,...L _o are openings 1 formed in the insulator 12
Connected through 3. In this case, the U-shaped conductor l ₁ ,
The number of _connection points between l ₂ , . . . L _o and the linear conductors L ₁ , L ₂ , .

An example of the manufacturing process of this image sensor will be explained. First, as a photoconductive material on a glass substrate,
CdSe is formed by vapor deposition to a thickness of approximately 1 μm. This CdSe film is activated by heat treatment and patterned by photoetching to form photoconductive elements R ₁₁ , R ₁₂ ...R _no
form. As the CdSe etching solution, for example, a mixed solution of nitric acid and phosphoric acid may be used. Next, 2000 Å of Ti and 3000 Å of Au were sequentially deposited on the entire surface of the substrate, and common electrodes C ₁ , C ₂ , ... C _o and U-shaped conductors l ₁ , l ₂ , ... L _o were formed by photoetching, and at the same time, the outermost U-shaped A short-circuit conductor L _s is formed to short-circuit the conductors L ₁ to each other. Furthermore, Au plating 3 is applied to the matrix connection part.
~5 μm, and then the linear conductors L ₁ , L ₂ , . . . _Lo formed on the flexible lead tape are bonded at predetermined positions. Linear conductors L ₁ , L ₂ ,...
L _o is a copper wire plated with tin, and the bonding is made of gold-tin eutectic.

In the above process, the short circuit l _s is caused by the U-shaped conductors l ₁ , l ₂ ,
...It can be easily formed by preparing a single mask pattern that combines a pattern corresponding to L _o and a pattern corresponding to short-circuit conductor L _S and performing etching. In this case, the U-shaped conductor l ₁ is a linear conductor L ₁
Since the U-shaped conductors l ₁ , l ₂ ,
...There is no problem even if they are short-circuited to each other by the short-circuit conductor l _s at the stage of forming the l _o .

By using this manufacturing process, photoconductive elements
R ₁₁ , R ₁₂ , . . . R _no are all connected to each other from the stage of forming the U-shaped conductor. Therefore, destruction of the element due to static electricity can be prevented. Note that the method for preventing damage caused by static electricity shown here cannot be applied to the normal matrix configuration shown in FIG. 1, and can only be achieved by employing matrix wiring using U-shaped conductors.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an image sensor using conventional matrix wiring, Fig. 2 is a circuit diagram of an image sensor according to an embodiment of the present invention, and Fig. 3 is a plan view of the matrix wiring section of the same embodiment. It is a diagram. 1...Photoelectric conversion element row, R11 _{- Rno} ...Photoconductive element, _B1 - _Bn ...Block, C1 _{- Cn} ...Common electrode, P1 _{- Pn} ...Switch, 2... Block selection circuit, V _B ... Drive power supply, l ₁ ~ _{l o} ... U-shaped conductor, l _s
... Short circuit conductor, L ₁ to L _o ... Linear conductor, 3 ... Individual selection circuit, S ... Current-voltage conversion circuit, 11 ...
...Insulating substrate, 12...Insulator, 13...Opening.

Claims (1)

[Scope of Claims] 1 A plurality of photoelectric conversion elements arranged on an insulating substrate are divided into a plurality of blocks each having the same number of elements, each block is sequentially selected, and the photoelectric conversion elements in each block are selected. In an image sensor that sequentially and individually selects and reads images formed on photoelectric conversion elements, one end of each photoelectric conversion element is commonly connected for each block and connected to the block selection circuit of the photoelectric conversion element, and each other The ends of adjacent blocks are connected to each other by a plurality of U-shaped conductors, which are located symmetrically to each other with respect to the boundary line between the blocks.
The outermost conductors of the U-shaped conductors are connected to each other with short-circuit conductors, and all U-shaped conductors that correspond to each other in the arrangement direction of the photoelectric conversion elements are connected with linear conductors. An image sensor characterized by being connected to an individual selection circuit of photoelectric conversion elements. 2 Divide a plurality of photoelectric conversion elements arranged on an insulating substrate into a plurality of blocks each having the same number of elements, and sequentially select each of the blocks, and sequentially and individually select the photoelectric conversion elements in each block. When manufacturing an image sensor that reads an image formed on a photoelectric conversion element, one end of each photoelectric conversion element is commonly connected for each block and connected to the block selection circuit of the photoelectric conversion element, while the other end of each block is connected to the block selection circuit of the photoelectric conversion element. A plurality of U-shaped conductors are formed between matching blocks to connect elements that are line-symmetrically located with respect to the boundary line between the blocks, and a short-circuiting conductor is formed to mutually short-circuit the outermost conductors of these U-shaped conductors. After that, linear conductors are formed to connect all the U-shaped conductors to correspond to each other in the arrangement direction of the photoelectric conversion elements, and these linear conductors are connected to individual selection circuits of the photoelectric conversion elements. A method for manufacturing an image sensor. 3. The method for manufacturing an image sensor according to claim 2, wherein the linear conductor is formed on an insulator and connected to the U-shaped conductor through an opening formed in the insulator. .