JP2000183323A - Contact image capture device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize miniaturization of a contact image reading device and improvement of resolution of the read image, without using expensive lenses or scarificing reliability. SOLUTION: This contact image capture device is provided with plural sensors 12 linearly arranged on a transparent flat substrate 10 for subjecting it to optoelectric conversion and an arithmetic circuit for calculating electric signals from the sensors. Then, an original 16 is directly brought into contact with an opposite plane to the plane on which the sensors are arranged on the flat substrate 10, and light from the original elements are received by the sensors, and the electric signals from the sensors are calculated by an arithmetic circuit so that the original screen can be reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a contact type image reading apparatus which does not use an optical lens.

[0002]

2. Description of the Related Art A conventional general contact type image reading apparatus will be described with reference to FIG. The reflected light from the original 9 illuminated by the light from the light source (the LED array 1 in this figure) provided inside the image reading device passes through a small lens (such as the SLA 2 in this figure) such as a rod array lens and the like. It is adjusted so that the focus is on the sensor (the light receiving element 3 in this figure) facing the sensor. Each sensor sends out an electric quantity corresponding to image information (light quantity) from a document by photoelectric conversion, and this signal enters the reading IC 4.

[0003] Since the lens of the optical system focuses on the light by using the refractive index of the material, the distance between the lens and the document and the distance between the lens and the sensor are required to achieve the focus. Is always required. Therefore, in a contact image reading apparatus using a lens of an optical system, it is necessary to secure an optical path corresponding to the focal length of the lens to be used. Therefore, the conventional general contact-type image reading apparatus, even though it is a contact-type image reading apparatus, has a limit of miniaturization because the distance between the sensor and the lens which is the actual reading part is determined by the focal length. However, it is impossible to make the distance between the original and the read portion equal to or less than a certain value.

In addition, when a color image is taken in, the difference in the refractive index depending on the wavelength also has an effect. Therefore, it is very difficult to design a lens of this kind, for example, a special coating is required on the lens. Resulting in very expensive parts.

As described above, the lens used in the conventional contact-type image reading apparatus has a very special structure in order to promote miniaturization, and is a very expensive component. This is a major issue of cost reduction.

In a perfect contact type image reading apparatus as shown in FIG. 7, a sensor is arranged so as to directly contact a pixel of a document via an extremely thin protective film. The protective film is a transparent thin film for protecting the sensor from abrasion, and has a structure covering the surface of the sensor. For this reason, miniaturization is easier than in the case where a lens is used. However, since the original and the sensor obtain one-to-one image information, the degree of close contact between the sensor and the original is captured and the image becomes clearer. It greatly affects the degree.

In the above-described full-contact type image reading apparatus, it is expected that the sensor and the original are in close contact with each other without any gap. However, in practice, a slight gap is not generated to trace the original surface. In addition, the surface of the actual sensor is covered with the protective film as described above. Therefore,
Since the protective film causes a distance between the original and the sensor, the thickness of the protective film and a gap formed on the original surface greatly deteriorate the resolution of the captured image. In order to ensure the sharpness of the captured image, it is necessary to make the thickness of the protective film as thin as possible compared to the pixel spacing, and to increase the contact pressure to increase the adhesion between the protective film and the document. However, this reduces the protection performance of the sensor, and there is a trade-off between ensuring image clarity and ensuring sensor reliability.

[0008]

As described above, the conventional contact-type image reading apparatus has the following problems. A first problem is that in the case of a contact type image reading apparatus using a lens, the size of the apparatus increases in proportion to the focal length of the lens, and it is difficult to reduce the size. The reason is that when a lens is used, it is necessary to secure an optical distance for forming an image.

The second problem is a problem of the lens itself. Since the lenses of the contact type image reading device are small special parts, there are few manufacturers that can manufacture them, there is always a concern about supply, and it is a major obstacle to cost reduction at present.

A third problem is that, in a completely contact type image reading apparatus, there is a trade-off between the sharpness of a captured image and the reliability of the sensor, and it is difficult to improve the resolution. The reason is that the sensor and the document are in close contact with each other, so that if the distance between the sensor and the document is increased to protect the sensor, the resolution is inevitably reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide a contact-type image reading apparatus without using expensive lenses and without sacrificing reliability. An object of the present invention is to reduce the size and improve the resolution of a read image.

[0012]

In order to achieve the above object, the present invention provides a contact-type image capturing apparatus shown in the following (1) to (10). (1) A plurality of sensors for performing a photoelectric conversion operation linearly arranged on a transparent flat substrate, and an arithmetic circuit for calculating an electric signal from the sensors are provided, and the sensors of the flat substrate are arranged. The original is brought into direct contact with the plane opposite to the plane, and light from the original pixels is received by the sensor,
A contact type image capturing apparatus, wherein an electric signal from a sensor is calculated by the arithmetic circuit to reproduce a document screen. (2) The contact type image capturing device according to (1), wherein the thickness of the flat substrate is at least twice the distance between adjacent sensors. (3) The contact type image reading device according to (1) or (2), which has a storage circuit that has position information corresponding to each sensor and stores an electric signal from each sensor. (4) The contact-type image reading device according to (3), further comprising a circuit for converting an electric signal from the sensor into an analog signal, and using a digital memory as a storage circuit. (5) The contact type image reading of (3) or (4), wherein the electric signals from the two or more sensors are stored in the storage circuit, and the stored values of the electric signals from the two or more sensors are calculated by the arithmetic circuit. apparatus.

(6) A plurality of sensors for performing a photoelectric conversion operation arranged vertically and horizontally on a transparent flat substrate, and an arithmetic circuit for calculating an electric signal from the sensor are provided. The original is brought into direct contact with the plane opposite to the plane on which the light is received, the light from the original pixels is received by the sensor, and an electric signal from the sensor is calculated by the arithmetic circuit to reproduce the original screen. Contact image capture device. (7) The contact type image capturing device according to (6), wherein the thickness of the flat substrate is at least twice the distance between adjacent sensors. (8) The contact type image reading apparatus according to (6) or (7), which has a storage circuit that has position information corresponding to each sensor and stores an electric signal from each sensor. (9) The contact type image reading apparatus according to (8), further comprising a circuit for converting an electric signal from the sensor into an analog signal, and using a digital memory as a storage circuit. (10) The contact type image reading of (8) or (9), wherein the electrical signals from the two or more sensors are stored in the storage circuit, and the stored values of the electrical signals from the two or more sensors are calculated by the arithmetic circuit. apparatus.

The contact type image reading apparatus of the present invention reproduces a document screen by analyzing data from a sensor by calculation without using an optical lens utilizing a refractive index, thereby reducing the size of the original screen. In addition to the above, it is intended to significantly reduce the cost and eliminate the limitation of the resolution caused by the mechanical processing accuracy.

That is, in a general contact type image reading apparatus, as shown in FIG. 6, light from a document is focused on a light receiving surface of a photoelectric conversion element (hereinafter simply referred to as a sensor) using an optical lens. The sensor receives light from the image as if tied, further performs photoelectric conversion with this sensor, receives an electric signal with a reading IC in the form of voltage or current,
Read the information on the manuscript. In this case, the information from the manuscript
In terms of position, the sensor and the pixel on the document surface have a one-to-one relationship.

In the present invention, as shown in FIG. 1, an image sensor element 14 having a structure in which a plurality of sensors (photoelectric conversion elements) 12 are linearly arranged on a transparent flat substrate (hereinafter simply referred to as a transparent substrate) 10. Is adopted, and the original 16 is brought into direct contact with the plane of the transparent substrate 10 opposite to the plane on which the sensor 12 is arranged, and no lens is used. However, in order to capture the image of the document, a calculation circuit for calculating the electric signal from the sensor is provided as shown in FIGS. 2 and 3, and the process of reproducing the document screen by calculation is performed.

That is, according to the present invention, a plurality of sensors are linearly arranged on a transparent substrate, and the original is brought into direct contact with a plane of the transparent substrate opposite to the plane on which the sensors are arranged. The first problem is the miniaturization of the image sensor element, which is difficult to achieve when using a lens.
It has a structure that can be easily thinned.

Further, as a transparent substrate on which the sensor is arranged,
By using a sensor having a thickness of twice or more the distance between adjacent sensors, light from a unit pixel is incident on a plurality of sensors. Different images can be reproduced. With regard to the weakening of the image information when the adhesion of the document is weakened, the data can be supplemented by the correction operation. Further, the thickness of the transparent substrate also contributes to improving the mechanical strength of the sensor unit (transparent substrate image reading device).

Further, a storage circuit (memory) having position information corresponding to each sensor and storing the amount of electric power output from each sensor is provided, and the memory stores information from a plurality of sensors and at least two or more sensors. By calculating the stored value of the electric quantity output from the sensor and reproducing the image data of the original, it is possible to obtain high-quality reproduced image information in a small size.

Further, by providing a circuit for performing analog-to-digital conversion of the output electric quantity by the photoelectric conversion operation of the sensor, it becomes possible to use a digital memory as a memory, whereby image information can be processed by a digital computer. That can be reproduced.

Further, according to the method of the present invention, the same effect can be obtained even if the sensors are arranged two-dimensionally on the transparent substrate.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a contact type image capturing apparatus according to the present invention, as shown in FIG.
The transparent substrate 10 and the document 16 are used in close contact with each other. Here, the electric signal photoelectrically converted by the sensor is extracted in a form in which the arrangement of the sensor is specified. Then, as shown in FIG. 2, the electric signal from each sensor is taken into the memory via an A / D converter connected via a switch. Alternatively, as shown in FIG. 3, a plurality of A / D
After A / D conversion using a converter, the data is switched by a switch and stored in a memory. In any case, the electric signal from the sensor is sent to the arithmetic circuit in a form that can be operated, and the information on the original document surface is reproduced by the operation in the arithmetic circuit.

What is important here is that the resolution of an image to be captured can be determined by setting a calculation formula for performing a calculation from the data in the memory, and thereby the resolution can be changed depending on the setting of the calculation method. It is expected that the performance and application of the image capturing device will be expanded by the correspondence. This situation is very different from the case where the resolution of the captured image is determined by the mechanical processing accuracy of the sensor in the conventional sensor circuit.

Further, in the contact type image capturing apparatus of the present invention, the performance is greatly changed or improved by improving the performance of the hardware itself such as the performance of the sensor itself and the resolution of A / D conversion. In addition to being able to change the processing method, the performance can be greatly changed in terms of the software that determines the calculation method, and the processing capacity of the software that can be handled by the calculation processor according to the development of the calculation processor without changing the hardware. By improving
The configuration is such that the image capturing capability can be improved.

Here, the conceptual structure of the contact type image capturing device of the present invention will be described with reference to FIG. In FIG.
s1 to s8 indicate sensors linearly arranged on the transparent substrate 10, respectively, and p1 to p4 indicate unit pixels on the document. Here, the surface of the transparent substrate that is in contact with the document is subjected to a surface treatment so as to generate scattered light in the direction inside the transparent substrate.
Although not shown, in the contact type image capturing apparatus of the present invention, light for document illumination is emitted from a light source disposed on the sensor surface side, and this light travels through the transparent substrate through the space between the sensors. Illuminate the original surface.

The light is applied to original pixels p1 to p1 existing on the original surface.
When p4 is received, this light becomes reflected light in proportion to the brightness of the pixel, and further becomes scattered light on the surface of the transparent substrate, and then travels straight through the transparent substrate to reach the sensor. here,
It is considered that the outer portions (left side with respect to p1 and right side with respect to p4) of the drawings of p1 and p4 have a light-shielded (light does not enter the transparent substrate) structure. At this time, the light incident on each pixel is applied to each sensor by a light amount in which a coefficient of a1 to a5 is related to the amount of light emitted from each pixel by a straight path in the transparent substrate from the pixel to the sensor. Incident. Since the refractive index of a transparent substrate is usually greater than 1, the area where light from each pixel exits from the surface on which the sensor is disposed is determined by the thickness and the refractive index of the substrate. Light emitted from a certain pixel enters a sensor in this range,
An electric signal corresponding to the intensity of the incident light is generated.

In the above structural diagram, if the range of incidence of light from p1 is limited to s1 to s5, the amount of incidence of light from p1 on each sensor is s1 = a1 * p1. In other words, the incident light at s1 is only the incident light from the pixel p1 due to the relationship of the refractive index, and the amount of light on the document surface p1 can be calculated.

Similarly, in s4, light enters from the pixels p1 to p4, so that s4 = a4 * p1 + a3 * p2 + a2 * p3 + a1 * p
4 can be represented. That is, in s4, the pixels p1 to p4
Is incident, so that the amount of light on the document surface cannot be calculated from the amount of electric signal from a single sensor as in the case of s1.

However, when the relationship between the amount of light from the document and the sensor is completely written out, the relationship between the amount of light incident on each sensor and the amount of light on the document surface is as follows: s1 = a1 * P1 s2 = a2 * p1 + a1 * p2 s3 = a3 * p1 + a2 * p2 + a1 * p1 s4 = a4 * p1 + a3 * p2 + a2 * p3 + a1 * p
4 s5 = a5 * p1 + a4 * p2 + a3 * p3 + a2 * p
4 s6 = a5 * p2 + a4 * p3 + a3 * p4 s7 = a5 * p3 + a4 * p4 s8 = a5 * p5 Here, s1 to s8 become known values by performing measurement, so that light from pixels on the document surface If the coefficients a1 to a5 determined by the positional relationship of the sensor with respect to the pixel are known, p1 to p4 can be theoretically specified by calculation by using the necessary four equations from the above equations. .

Incidentally, the coefficients a1 to a5 can be calculated in the same manner by performing measurement using a known pattern formed on the document surface. In addition, these coefficients a
1 to a5 are structurally determined by the positional relationship between the pixels on the document surface and the sensor, regardless of the location on the document surface. That is,
The coefficient measured once using a known document pattern and calculated from the above equation can be used as a coefficient for reproducing document surface information of an unknown document pattern. Further, if a structure capable of maintaining optical symmetry is adopted, it can be expected that a1 and a5 and a2 and a4, which are symmetrical with respect to each other, have the same value.
Can be determined with relatively high accuracy.

In this case, since the density of the pixels on the document surface can be changed by setting the formula to be set, the reading resolution can be changed by the processing method of the calculation. That is, the pixels p1 and p
If an equation is used with 2 as one pixel, the document information can be reproduced as data with half the resolution. In this case, the operation that must be solved by calculation can be reduced, which leads to an improvement in processing speed.

Conversely, when the assumed number of original pixels is increased, the calculation time increases, but higher-resolution original information can be reproduced while using the same sensor. That is, in the actual manufacturing of the contact type image capturing device, the arrangement density of the sensors is limited due to the limitation of high definition coming from the manufacturing method. In the case of a type image capturing device and a conventional complete contact type image reading device, the reading resolution is limited. On the other hand, in the contact type image capturing apparatus of the present invention, since the resolution changes mainly due to the ability of the arithmetic processing for reproducing the image information, the original having the resolution according to the application is used while using the sensor having the same structure. The information can be reproduced. According to the recent improvement in the performance of computing devices, its performance can be improved over time, and in addition to significant structural cost reductions, future performance improvements will be possible through the development of software. The benefits obtained are huge.

Therefore, according to the contact type image capturing apparatus of the above embodiment, the following advantages can be obtained. Since no lens is used, there is no need for a spatial distance for securing an optical path determined by the focal length of the lens. Therefore, the distance between the sensor and the document is not required in principle, and the size and thickness of the image sensor element can be easily reduced.

By making the thickness of the transparent substrate at least twice as large as the pixel interval, a thickness for securing the strength of the image sensor element can be obtained, and the path of the reflected light from the document surface becomes longer. This makes it possible to ensure incidence on adjacent sensors. That is, when the thickness of the transparent substrate is increased, in the conventional contact method, since the position information of the sensor directly corresponds to the position of the document, there is a disadvantage that the resolution is reduced due to defocus, but in the present invention, There is no problem because the information of the document employs a method of calculating conversion data of a plurality of sensors and calculating the position and the amount of reflected light. In this state, the reflected light from the document is incident on each sensor with a light amount having a constant coefficient corresponding to the distance. This coefficient is uniquely determined based on the structure such as the interval between the sensors and the thickness of the transparent substrate. If this coefficient is used, the intensity of the reflected light from the document surface can be calculated from the amount of incident light of each sensor.
In addition, since this coefficient can be corrected using known image data, it becomes effective for clearer image capture.

By storing data corresponding to the amount of electricity from each sensor, it is possible to secure information for reproducing document information by calculating image data.
Further, by performing the analog-digital conversion, a digital memory can be used for the storage circuit, so that the device can be configured at low cost.

By using the information in the storage circuit and solving the determinant using the coefficients as described above, the amount of reflected light can be calculated for each position of the document, and the information on the document surface can be reproduced. become able to. This operation can be performed if there is at least two or more pieces of storage information, and a necessary resolution can be obtained by changing the size of a matrix to be used and the number of pieces of storage information used.

In the above description, the contact type image capturing device in which the sensors are arranged one-dimensionally has been described.
In this method, the same effect can be obtained even if the arrangement is performed two-dimensionally. Therefore, an embodiment having a configuration as shown in FIG. 5 is also possible. In this case, it is necessary to dramatically improve the performance of the arithmetic circuit. However, in view of the recent increase in the processing speed of the arithmetic unit (CPU), a sufficiently practical arithmetic speed will be achieved in the near future. It can be realized. In this case, depending on the configuration of the processing circuit, it is possible to capture a three-dimensional image that reproduces a certain degree of perspective. However, the configuration of the sensor, the basic A / D conversion circuit, the memory, and the arithmetic circuit are the same, and processing based on the same concept as the invention of the embodiment in which the sensors are arranged one-dimensionally becomes possible.

[0038]

As described above, the contact-type image reading apparatus of the present invention can be downsized and the resolution of the read image can be improved without using an expensive lens and without sacrificing reliability. Has been realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an image sensor element of a contact type image reading apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a contact image reading apparatus according to the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a contact image reading apparatus according to the present invention.

FIG. 4 is an explanatory view showing a conceptual structure of a contact type image capturing device according to the present invention.

FIG. 5 is an explanatory view showing an example of a contact type image reading apparatus according to the present invention.

FIG. 6 is a schematic view showing an example of a conventional contact image reading apparatus.

FIG. 7 is a schematic diagram illustrating an example of a conventional contact image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transparent board 12 Sensor 14 Image sensor element 16 Original

Claims (10)

[Claims] 1. A sensor comprising: a plurality of sensors for performing a photoelectric conversion operation linearly arranged on a transparent flat substrate; and an arithmetic circuit for calculating an electric signal from the sensor, wherein the sensors on the flat substrate are arranged. The original is brought into direct contact with the plane opposite to the plane on which the light is received, the light from the original pixels is received by the sensor, and an electric signal from the sensor is calculated by the arithmetic circuit to reproduce the original screen. Contact image capture device. 2. The contact type image capturing device according to claim 1, wherein the thickness of the planar substrate is at least twice the distance between adjacent sensors. 3. The contact-type image reading device according to claim 1, further comprising a storage circuit having position information corresponding to each sensor and storing an electric signal from each sensor. 4. The contact type image reading apparatus according to claim 3, further comprising a circuit for converting an electric signal from the sensor into an analog signal and a digital signal, and using a digital memory as a storage circuit. 5. The close contact type according to claim 3, wherein electric signals from two or more sensors are stored in a storage circuit, and a storage value of the electric signals from the two or more sensors is calculated by an arithmetic circuit. Image reading device. 6. A sensor comprising a plurality of sensors for performing a photoelectric conversion operation, which are arranged vertically and horizontally on a transparent flat substrate, and an arithmetic circuit for calculating an electric signal from the sensors, wherein the sensors of the flat substrate are arranged. The original is brought into direct contact with a flat surface opposite to the flat surface, light from the original pixels is received by the sensor, and an electric signal from the sensor is calculated by the arithmetic circuit to reproduce the original screen. Contact type image capture device. 7. The contact type image capturing device according to claim 6, wherein the thickness of the flat substrate is at least twice the distance between adjacent sensors. 8. The contact type image reading device according to claim 6, further comprising a storage circuit having position information corresponding to each sensor and storing an electric signal from each sensor. 9. The contact type image reading apparatus according to claim 8, further comprising a circuit for converting an electric signal from the sensor into an analog signal, and using a digital memory as a storage circuit. 10. The close contact type according to claim 8, wherein electric signals from two or more sensors are stored in a storage circuit, and a storage value of the electric signals from the two or more sensors is calculated by an arithmetic circuit. Image reading device.