CN1885897A - Contact image sensor and its photosensitive substrate - Google Patents

Abstract

The present invention provides a contact image sensor and a photosensitive substrate thereof for use in a scanner or a fax machine or other business machine. The image sensor includes a photosensitive substrate, a light source and a lens. During scanning, the light emitted by the light source irradiates the object to be scanned, is reflected or transmitted by the object to be scanned to the lens, and is converged by the lens to the photosensitive substrate. The photosensitive substrate includes at least one long photosensitive chip and a plurality of short photosensitive chips. When scanning a negative film, only the long photosensitive chip needs to be exposed; when scanning a reflective document, all the long and short photosensitive chips on the photosensitive substrate need to be exposed. The present invention reduces the cost of manufacturing a single photosensitive substrate and further reduces the cost of a single image sensor by improving the utilization rate of a single wafer with a fixed cost.

Description

Contact image sensor and its photosensitive substrate

【Technical field】

The invention relates to an image capture device used in business machines such as scanners or fax machines, especially a contact image sensor and its photosensitive substrate.

【Background technique】

A photodiode is a photosensitive element. When its surface is irradiated by light, it will generate a corresponding current output according to the intensity of the light received, and the current will be converted into an analog voltage signal through an appropriate conversion circuit. In practical applications, a photosensitive chip can be formed by integrating a plurality of photodiodes and their corresponding conversion circuits into a semiconductor chip through a semiconductor manufacturing process. A photosensitive array can be formed by arranging and combining multiple photosensitive chips in a certain order. The photosensitive array can be further combined with the peripheral circuit design to form a photosensitive substrate on a circuit board, and then the light source and lenticular lens are precisely combined with the circuit board according to the optical requirements to form a so-called contact image sensor (Contact Image Sensor, CIS ). Today, contact image sensors are widely used in transaction processing machines such as scanners and fax machines.

When using a contact image sensor for document scanning, the light source will project light onto the object to be scanned, and the light reflected or transmitted by the object to be scanned will converge through the lenticular lens, and finally projected on the photosensitive array. After the diode is photosensitive, the optical signal is converted into an analog electrical signal, and then the corresponding conversion circuit (such as: analog-to-digital conversion circuit) on the scanner motherboard converts the analog electrical signal into a digital signal, and finally these digital signals are arranged and combined by software. electronic image files. Since each photodiode corresponds to the corresponding position on the scanning line, according to the strength of the photocurrent collected at these positions, after being processed by the timing control circuit and the amplification circuit, the pattern and pattern of the position on the original can be restored. color.

Taiwan Patent Publication No. 447211 discloses a conventional contact image sensor. Referring to FIG. 1 , the contact image sensor includes a cover 102 , a lenticular lens array 104 , a linear light source 106 , a body 108 and a photosensitive substrate 110 . A plurality of photosensitive chips 1120 are vertically arranged on one side of the photosensitive substrate 110 near its edge. These photosensitive chips 1120 have the same length and are equally spaced to form a photosensitive array 112 . A similar photosensitive array structure can also be found in Taiwan Patent Publication No. 278687, which more clearly reveals that the photosensitive chips are uniformly arranged on the photosensitive substrate with equal lengths. In the photosensitive array formed by connecting multiple photosensitive chips, there is a connection point in the middle, and part of the image at the location of the connection point will be lost. For reflective document scanning, due to the low image resolution required, software calculations can be used to correct the image lost at the position of the splicing point, so as to obtain acceptable image data. However, for negative film scanning, the accuracy and resolution The requirements for high efficiency are relatively high, so the photosensitive chip corresponding to the width of the film must be a whole piece, and there cannot be a connection point. The most common film width in daily life is 35 mm. After calculation, to scan a film with a width of 35 mm, the length of the corresponding photosensitive chip must be at least 27 mm. The length of each photosensitive chip in the image sensor of the scanning function is 27 mm. For the semiconductor manufacturing process, please refer to the known wafer cutting method as shown in FIG. It is used to manufacture the photosensitive chip. However, this wafer cutting method will cause a lot of waste in the peripheral area of the wafer. The blank area marked 206 in FIG. 2 represents a useless area in the wafer. Since the cost of a wafer is fixed, the more effective chips that can be cut from it, the lower the cost of a single chip, so that the cost of manufacturing a photosensitive substrate or an image sensor will be lower. Conversely, if the wafer The larger the useless area in , the higher the cost of manufacturing a photosensitive substrate or an image sensor. Obviously, it is difficult to control the cost of the conventional image sensor and its photosensitive substrate manufactured by cutting chips with the same length from a wafer.

In view of the above reasons, the present invention provides a low-cost contact image sensor and its photosensitive substrate.

【Content of invention】

The main purpose of the present invention is to provide a low-cost contact image sensor and its photosensitive substrate, which mainly considers the utilization rate of the wafer to reduce the cost of a single photosensitive chip, thereby reducing the cost of the photosensitive substrate and image sensor. the goal of.

Another object of the present invention is to provide a wafer dicing solution specially designed for the above-mentioned low-cost contact image sensor, so as to manufacture as many photosensitive chips as possible with one wafer.

Another object of the present invention is to provide a photosensitive substrate with a specific arrangement of photosensitive chips, which can be combined with reflective document scanning and precision scanning of negatives, and the cost of the photosensitive substrate is low.

To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a contact image sensor and its photosensitive substrate that can combine reflective document scanning and film scanning. The image sensor includes a photosensitive substrate, a light source and a lens. The photosensitive substrate includes a longitudinal printed circuit board and a photosensitive array arranged on the printed circuit board, and the photosensitive array includes at least one long photosensitive chip and several short photosensitive chips arranged in a row along the longitudinal direction of the printed circuit board. The length of the long photosensitive chip must at least reach the photosensitive length required for scanning the width of the film, and the length of the photosensitive array formed by the long and short photosensitive chips must at least reach the required photosensitive length for scanning the width of the reflective document. When scanning, the light emitted by the light source shines on the object to be scanned (reflective document or film), is reflected or transmitted to the lens by the object to be scanned, and is converged by the lens to the photosensitive array, and then the photosensitive array senses the intensity of the light, and the Optical signals with different strengths are converted into electrical signals and output to the printed circuit board. When scanning negatives, only the long photosensitive chip is required for photosensitive; when scanning reflective documents, all the long and short photosensitive chips on the photosensitive array need to be photosensitive.

Both the long photosensitive chip and the short photosensitive chip can be cut from the same wafer. A row of long chip groups is cut vertically at the edge or near the center of the wafer, and the rest of the wafer is cut into short chip groups of the same length. Wherein, the long chip group is cut horizontally to form multiple long photosensitive chips, and each short chip group is cut horizontally to form multiple short photosensitive chips.

Compared with the prior art, the contact image sensor and its photosensitive substrate of the present invention can reduce the cost of each photosensitive chip on the photosensitive substrate under the premise that both reflective document scanning and film scanning can be combined to maximize the Wafer utilization is improved, and as many photosensitive chips as possible are cut from a single wafer with fixed cost, thereby reducing the cost of the photosensitive substrate and further reducing the cost of the image sensor.

【Description of drawings】

FIG. 1 is a schematic diagram of the composition of a conventional contact image sensor.

FIG. 2 is a schematic diagram of a conventional arrangement of photosensitive chips on a wafer.

FIG. 3 is a schematic diagram of the composition of the contact image sensor of the present invention.

4 is a schematic structural view of the first embodiment of the photosensitive substrate of the present invention, mainly revealing an arrangement of photosensitive chips on the photosensitive substrate.

FIG. 5 is a schematic structural view of the second embodiment of the photosensitive substrate of the present invention, mainly revealing another arrangement of photosensitive chips on the photosensitive substrate.

FIG. 6 is a schematic diagram mainly revealing the corresponding relationship between the long photosensitive chip and the width of the film in the contact image sensor of the present invention, and the corresponding relationship between the photosensitive array and the width of the reflective document.

FIG. 7 is a schematic diagram of an arrangement of the photosensitive chips disclosed in FIG. 4 and FIG. 5 on a wafer.

FIG. 8 is a schematic diagram of another arrangement of the photosensitive chips disclosed in FIG. 4 and FIG. 5 on the wafer.

【Detailed ways】

The contact image sensor of the present invention is an image capture device, which is mainly used in office machines such as scanners or facsimile machines combined with reflective document scanning functions and negative film scanning functions. Please refer to FIG. 3, the contact image sensor 3 of the present invention mainly includes: a body 31 with a certain longitudinal dimension, a lens 32 and a light source 33 installed in the upper storage space of the body 31, and a cover that can seal the upper opening of the body 31. body 34, and a photosensitive substrate 35 mounted on the bottom of the body 31. Wherein, the lens 32 may adopt a cylindrical lens array, or may adopt an optical lens with a high depth of field. The light source 33 includes a light emitting diode 332 and a light guide plate 334 extending longitudinally. During scanning, the light emitted by the light source 33 is irradiated on the document to be scanned (reflective document or film) and is reflected or transmitted by the document to be scanned. In a specific embodiment, the light source 33 can be a white light source composed of cold cathode tubes (Cold Cathode Flourcent Lamp), and the photosensitive array matched with it is a color photosensitive array. Since the structures of the body 31 , the lens 32 , the light source 33 and the cover 34 are all known technologies, they will not be repeated here. In the following, the photosensitive substrate 35 will be introduced in combination with preferred embodiments of the present invention.

4 and 5 respectively disclose the first and second embodiments of the photosensitive substrate of the present invention. The photosensitive substrate 35 (35') includes a printed circuit board 352 (352') with a certain longitudinal dimension and a photosensitive array 354 (354') and a control circuit 355 (355') disposed on the printed circuit board 352 (352'). Photosensitive array 354 (354') is formed by a long photosensitive chip (abbreviated as long chip) 356 (356') near the longitudinal edge and a plurality of short photosensitive chips (abbreviated as short chip) 358 (358') with the same length. All photosensitive chips are arranged in a row, and the long chip 356 (356') is located at the beginning (as shown in Figure 4) or the end (as shown in Figure 5) of the row. Of course, in other embodiments, the long chip is not limited to be located at one end of the photosensitive array. The "long chip" referred to here refers to the chip whose length is long enough to sense the reflected light or transmitted light from the width of the film in film scanning. For the common 35 mm wide film, the length of the long chip should be greater than 27 mm; and the so-called "short chip" refers to a chip whose length is less than the length of a long chip. In the first and second embodiments, only the arrangement positions of the long chip 356 (356') and the short chip 358 (358') on the printed circuit board 352 (352') are different, while the long chip 356 (356') is different from the short chip 358 (358'). The lengths and working principles of the short chips 358 ( 358 ′) are the same, so only the first embodiment will be described below with reference to FIG. 4 and FIG. 6 . The long chip 356 and the short chip 358 require different control signals when they work, and the control circuit 355 sends different control signals (such as clock signals) respectively for the long chip 356 and the short chip 358 to ensure that both the long and short chips 356 and 358 works fine. The contact image sensor 3 of the present invention can be applied to the scanning of the reflective document 62 or the negative film 61 . Because the precision required for scanning the negative 61 is relatively high, so in the photosensitive array 354, the long chip 356 corresponding to the width of the negative 61 must be a chip that can satisfy the photosensitive length of the negative 61, and cannot be spliced by several short chips. Otherwise it will cause the image loss of chip splicing position; and the scanning accuracy requirement of reflective document 62 is relatively low, plus the consideration of chip cost, so the way of chip splicing is used to obtain a long row of photosensitive array, the length of the photosensitive array must be It is sufficient to meet the photosensitive length of the reflective file 62, and the image lost at the splicing can be supplemented by software calculation. When scanning the negative 61, only the long chip 356 needs to be photosensitive; when scanning the reflective document 62, all the chips on the photosensitive array 354 need to be photosensitive. In a preferred embodiment of the present invention, the light emitted by the light source 33 is irradiated on the object to be scanned 61 or 62, transmitted through the object to be scanned 61 or 62 to the lens 32, and converged by the lens 32 to the photosensitive array 354, and the control circuit 355 According to the type of document to be scanned, different clock signals are sent to drive the corresponding photosensitive chip to work. The driven photosensitive chip senses the change of optical brightness, converts the optical signal with different intensity into an electrical signal and outputs it to the printed circuit board 352 Corresponding processing circuit (not shown), so as to obtain a line of image data on the width of the object to be scanned. Then the contact image sensor 3 moves along the length direction of the object 61 or 62 to be scanned under the drive of the transmission mechanism (not shown), and then obtains multiple lines of image data on the width of the object 61 or 62 to be scanned until the last line is scanned. complete. Finally, the processing circuit on the above-mentioned printed circuit board 352 integrates the electrical signals of all the image data it collects into an electronic image file. When scanning the film 61, the image sensor 3 can either use a color photosensitive array with a white light source as a penetrating light source during scanning, or use a black and white photosensitive array with a color light source to switch red, green and blue light as a penetrating light source during scanning. . Specifically, the light source can be a color light source composed of a group of light-emitting diodes and a light guide plate, and the corresponding photosensitive array is a black and white photosensitive array; or the light source is a white light source composed of a group of light-emitting diodes and a light guide plate. The corresponding photosensitive array is a color photosensitive array; or the light source is a white light source composed of a cold cathode tube (Cold Cathode Flourcent Lamp), and the corresponding photosensitive array is a color photosensitive array.

In the present invention, the structural form of the photosensitive array 354 composed of at least one long chip 356 and multiple short chips 358 is mainly considered from the aspect of chip cost. For the semiconductor manufacturing process, the cost of a wafer is fixed. If they are all cut into short chips, it is obviously not enough to meet the photosensitive length required by the film, and if they are all cut into long chips, it will cause a large area of wafer waste (as shown in the figure) 2). Considering that the photoelectric characteristics of different wafers will vary greatly, it is not suitable to cut chips from different wafers to manufacture an image sensor. Therefore, the present invention proposes a design scheme of designing two types of chips with different lengths on one wafer.

Please refer to FIG. 7 , a row of long rectangular chip groups 72 is designed on the edge of the wafer 7 , and the remaining part is designed as long and rectangular short chip groups 74 as much as possible. The long chip group 72 is then cut laterally into a plurality of long chips 356 (356') with the same length, and each short chip group 74 is then cut into a plurality of short chips 358 (358') with the same length. The short chips 356 ( 356 ′), 358 ( 358 ′) can be arranged into a plurality of photosensitive arrays 354 ( 354 ′) in the manner disclosed in FIG. 4 and FIG. 5 , and then a plurality of image sensors 3 can be manufactured. The blank part in the figure represents the useless area 76. Obviously, in this design scheme, the useless area is much less than the useless area 206 in FIG. The cost of , 358 (358') is relatively reduced, and the cost of the contact image sensor 3 is further reduced.

Referring again to Fig. 8, a column of vertically long rectangular chip groups 72' is designed in the center of the wafer 7', and the remaining parts are designed as vertically long rectangular chip groups 74' as much as possible. Same as the first design scheme, the long chip group 72' and the short chip group can be cut into a plurality of long chips 356 (356') and a plurality of short chips 358 (358') in the lateral direction respectively to form a plurality of photosensitive arrays 354 ( 354'), and then manufacture a plurality of image sensors 3. Obviously, the useless area 76' in this design is much less than the useless area 206 in Fig. 2 . It can be seen that this design can also improve the utilization rate of the wafer, thereby reducing the manufacturing cost of the image sensor 3 .

Of course, the present invention also has other design methods. According to the needs, a plurality of long chip groups can be designed on a wafer, and the arrangement position of the long chips on the photosensitive substrate can be adjusted according to the position of the negative film on the scanning platform, and The number of long chips in the photosensitive array can be changed according to the number of negatives scanned at the same time.

Through the above analysis, it can be seen that compared with the conventional technology, the contact image sensor 3 and its photosensitive substrate 35 of the present invention have a better chip cost advantage, compared with image sensors or photosensitive substrates made of long chips The cost can be reduced by about 20%. In addition, the long and short chips are arranged and manufactured in the same wafer, which can make the photoelectric characteristics of the long and short chips tend to be consistent, and avoid the large difference in uniformity between the two, which will cause poor image scanning.

Claims (18)

1. A contact image sensor, comprising a photosensitive substrate, a light source and an optical assembly, wherein the photosensitive substrate includes a printed circuit board and a photosensitive array arranged on the printed circuit board; the light emitted by the light source is irradiated onto the object to be scanned, and then Reflection or transmission of the scanned object; the optical component is used to converge the light reflected or transmitted by the object to be scanned to the photosensitive array; it is characterized in that: the photosensitive array includes a plurality of photosensitive chips arranged continuously along a certain direction of the printed circuit board, and these photosensitive chips It includes at least one long photosensitive chip and at least one short photosensitive chip with different lengths. 2. The contact image sensor according to claim 1, wherein the long photosensitive chip is located at a longitudinal end of the photosensitive substrate. 3. The contact image sensor according to claim 1, wherein the photosensitive array includes a long photosensitive chip and a plurality of short photosensitive chips, the long photosensitive chips and the short photosensitive chips are arranged in a row, and the long photosensitive chips are located in the The beginning or end of a row chip. 4. The contact image sensor according to claim 2 or 3, wherein the light source is a color light source composed of a group of light emitting diodes and a light guide plate; the photosensitive array is a black and white photosensitive array. 5. The contact image sensor according to claim 2 or 3, characterized in that: the light source is a white light source composed of a group of light emitting diodes and a light guide plate; the photosensitive array is a color photosensitive array. 6. The contact image sensor according to claim 2 or 3, wherein the light source is a white light source composed of a cold cathode tube; the photosensitive array is a color photosensitive array. 7. The contact image sensor according to claim 1, 2 or 3, characterized in that: the length of the long photosensitive chip must at least meet the photosensitive length required for scanning negatives. 8. The contact image sensor according to claim 7, wherein the length of the long photosensitive chip is not less than 27 mm. 9. The contact image sensor according to claim 7, wherein the long photosensitive chip and the short photosensitive chip are cut from the same wafer. 10. The contact image sensor according to claim 1, wherein the photosensitive substrate further comprises a control circuit for providing different control signals to the long photosensitive chip and the short photosensitive chip respectively. 11. An image sensor that combines the functions of film scanning and reflective document scanning, including a light source, the light emitted by it can be irradiated on the film or reflective document; a photosensitive array; and a lens, which transmits the light emitted by the light source through the film or reflection The light reflected or transmitted by the type document converges on the photosensitive array; it is characterized in that: the photosensitive array includes at least one long photosensitive chip and at least one short photosensitive chip, the length of the long photosensitive chip reaches at least the photosensitive length required by the film, and the The photosensitive array is at least as long as the photosensitive length required for reflective documents. 12. The image sensor according to claim 11, wherein the length of the long photosensitive chip is not less than 27 mm. 13. The image sensor according to claim 12, wherein the photosensitive array comprises a long photosensitive chip and a plurality of short photosensitive chips. 14 . The image sensor according to claim 13 , wherein the long photosensitive chip and all the short photosensitive chips are successively arranged in a row, and the long photosensitive chip is located at the beginning or the end of the row. 15. The image sensor according to claim 14, wherein the long photosensitive chip and the short photosensitive chip are cut from the same wafer. 16. The image sensor according to claim 13 or 15, wherein the photosensitive substrate further comprises a control circuit for providing different control signals to the long photosensitive chip and the short photosensitive chip respectively. 17. A photosensitive substrate, characterized in that: the photosensitive substrate includes a vertically long printed circuit board; several short photosensitive chips mounted on the printed circuit board, the lengths of these short photosensitive chips are the same, and along the length of the printed circuit board Arranged in a row vertically; a long photosensitive chip mounted on a printed circuit board is longer than any short photosensitive chip, and the long photosensitive chip is arranged in the same row as all short photosensitive chips, and is located at the beginning or end of the row terminal; and a control circuit on the printed circuit board, which is used to provide different control signals to the long photosensitive chip and the short photosensitive chip to respectively drive the long photosensitive chip and the short photosensitive chip to work. 18. The photosensitive substrate according to claim 17, wherein the long photosensitive chip and the short photosensitive chip are cut from the same wafer.

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