JPH0216073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image reading device, and more particularly to a high-speed contact sensor. [Prior Art of the Invention and Problems Therewith] Information processing devices such as computer computers are progressing at an extremely fast pace, and their processing capabilities far exceed those of humans in certain fields. However, the devices for inputting information into this information processing device could not be said to have made sufficient progress. Under these circumstances, in the facsimile field, efforts have been focused on the development of image reading devices due to practical requirements. The technical goal was to achieve high resolution while at the same time miniaturizing the device.
Another purpose was to read color images. Furthermore, in the field of copying machines, different from the conventional electrophotographic method, methods of forming pixels in a dot type, such as a thermal transfer method, are being considered.
At this time, input devices were required to be faster and have higher resolution than normal facsimile devices. A solid-state scanning method is a technology that meets these demands. For example, a combination of a photodiode array for photoelectric conversion and a MOS switch,
Some devices use semiconductor functional elements that have both a pixel resolution function and an optical information storage function. Since such solid-state imaging devices are highly integrated, the size of one chip is much smaller than the original, and a reduction optical system must be used. In particular, the second part of Japanese Patent Application Laid-Open No. 54-79511
At the bottom of the left column of the page is a list of ``commercially available photodiode arrays and
Since the CCD sensor is integrated, a reduction optical system must be used to read the original. For this reason, it is unavoidable that the optical system part becomes larger,
This is extremely inconvenient for manufacturing a small document reading device. This does not mean that the size can be reduced just by adopting a 1:1 original image forming optical system, specifically, a light-receiving element array with a wide original width that can use a self-occurring lens. If you try to make a reading circuit using a commercially available single semiconductor switch, it will be quite large and expensive, judging from the size and number of parts. ” is written. This description clearly represents the situation in this field, and based on this recognition, the contact sensor was developed. The close-contact sensor omits a lens system and has a configuration in which the target object, the document, and the sensor directly correspond on a 1:1 basis. Since this contact sensor does not require the use of a lens system, the device can be miniaturized. However, unless the document and the sensor are in close contact, for example on the order of 10 μm, the quality of the read image will deteriorate significantly. Furthermore, the responsiveness of the sensor material was insufficient, making it impossible to perform high-speed reading. [Object of the Invention] It is an object of the present invention to eliminate the above-mentioned drawbacks, to provide a contact sensor that is capable of reading in a wide range of fields and is inexpensive. [Summary of the Invention] The present invention focuses an image to be read by a contact sensor on an IC image sensor chip as an erect real image of the same size, and transmits this image into multiple images.
It is a device that reads with an IC image sensor chip, and has an integrated structure that includes an optical system, a substrate, and a light source. Preferably, the individual size of the photoelectric conversion elements is set to one-half or less of the pixel size required for this contact sensor. [Effects of the Invention] In the present invention, since one scanning line is covered by two or more photoelectric conversion element rows, it is possible to read a large image. Furthermore, since the read image is formed in the same size and direction over a plurality of photoelectric conversion element rows, a resolution that depends on the size of the photoelectric conversion elements can be realized. For example, if a photoelectric conversion element array made of Si-based material is used, it is possible to easily obtain a highly integrated device using current technology. In addition, since the transfer section is provided corresponding to each of the plurality of photoelectric conversion element rows, the signal transfer is parallel and faster than when electrical signals are transferred using a common transfer section. . At the same time, since the transfer distance is short, the probability of errors occurring is reduced. [Embodiments of the Invention] Next, embodiments of the invention will be described with reference to the drawings. The contact sensor in this embodiment is capable of reading an A4 size color document. This close contact sensor includes a photoelectric conversion element, a transfer section that transfers the charges converted by the photoelectric conversion element, and a focusing robot as an optical system that can form a one-to-one erect real image on the photoelectric conversion element. It consists of a drain lens array and a linear light source. In this example, a CCD (Charge Coupled Device) including a photoelectric conversion element and a charge coupled device as a transfer section is used.
It is called a coupled device. These are formed on the same chip. Furthermore, in this embodiment, a photoelectric conversion element, that is, a photodiode, is formed of C--Si. This C--Si photodiode has a high photoelectric conversion speed of 1 msec or less. Furthermore, in the following explanation, the photoelectric conversion element will be referred to as a CCD sensor. This CCD sensor is provided with a pitch of 14 μm and 1
The chip has 2048 elements. like this
Eight CCD chips 11a to 11h are provided on a ceramic substrate 12 in a staggered manner as shown in FIG. The CCD chips 11a to 11h as a whole must have a length l=210 mm that covers at least the width of an A4 size sheet. Also, in this embodiment, each CCD chip 1
1a to 11h overlap d=2.38mm, which is CCD
This is equivalent to 170 sensor elements. As shown in FIG. 2, two convergent rod lens arrays (trade name: Self-occurring lens, manufactured by Nippon Sheet Glass) 21a and 21b are arranged in a V-shape for these CCD chips 11a to 11h.
Individual focusing rod lens arrays 21a, 21b
The length should be longer than the width of an A4 size document, and there should be 8 pieces.
The length should be the same as the overall length of the CCD chips 11a to 11h. Also, the height h of the focusing rod lens arrays 21a and 21b is 20 mm in design.
50mm to 50mm is appropriate. This value is for increasing the depth of focus of the convergent rod lens arrays 21a, 21b. Especially the depth of focus at 50mm is deep.
The focusing rod lens arrays 21a and 21b are usually plate-shaped. However, in this embodiment, the two converging rod lens arrays 21a, 21b are arranged so that they mesh with each other.
Cut off the edge of 1b. In this way, by adjusting the angle of the slope to be cut, the angle formed by the two converging rod lens arrays 21a and 21b can be adjusted. Moreover, the space occupied by these convergent rod lens arrays 21a, 21b is reduced. However, the structure is designed to prevent light from entering through the carved slopes. Linear light sources 31a and 31b are required as contact sensors. The linear light sources 31a, 31b are provided with convergent rod lens arrays 21a, 2 as shown in FIG.
It is provided in parallel and close to 1b. The linear light sources 31a and 31b, the focusing rod lens arrays 21a and 21b, and the ceramic substrate 1
2 together constitute a contact sensor. This contact sensor is arranged so as to cross the document 32,
Read each line one by one. Light from the linear light sources 31a and 31b is irradiated onto one line at the original height. The irradiated light is reflected on the original 32 and is reflected by the focusing rod lens arrays 21a and 21b.
The light is received by Focusing rod lens array 21
a and 21b form an image on the original 32 onto a CCD sensor. focusing rod lens array 21a,
21b has a large depth of focus, so even if the distance between the convergent rod lens arrays 21a, 21b and the document 32 is not constant and varies slightly, a clear image is formed on the CCD sensor. Moreover, the converging rod lens arrays 21a and 21b form images on the CCD sensor one-to-one without reducing the image on the original 32. Next, a specific and preferable structure will be explained. As shown in FIG. 4, CCD chips 11a to 11h
A lid 34 provided with windows 33a to 33h is attached to the board 11 on which the windows 33a to 33h are attached. This lid 34 does not allow light to pass through except from the windows 33a to 33h. window 3
3a to 33h are CCD chips 11a to 11h
It is set up correspondingly. For such a substrate 11 and lid 34, the fifth
Attach the support portion 35 as shown in the figure. This support portion 35 has holes 36 provided in the upper wall corresponding to the windows 33a to 33h. At the top of this hole 36,
The focusing rod lens arrays 21a, 2 are arranged so that the focusing rod lens arrays 21a, 21b are positioned.
1b is attached to the support part 35. On the other hand, this support part 35 has one linear light source 31.
Attach a together. As shown in FIG. 5, this linear light source 31a is designed so that light is emitted from only a portion thereof. That is, the window 37 is provided so that light from around a 45° angle to the original 32 is emitted. There is no light irradiation from other parts. Such a contact sensor detects the sixth position on the original 32.
It is arranged so that it can be transported as shown in the figure. That is, the converging rod lens arrays 21a and 21b are arranged to face the original 32, and the window 37 of the linear light source 31a is arranged at an angle of 45 degrees with respect to the original 32. As shown in FIG. 6, the size of the contact sensor is such that the distance L from the original 32 to the substrate 12 is approximately 60 mm, and the distance W ₁ from the end of the support section 35 to the end of the linear light source 31a is approximately 60 mm.
60 mm, and the distance W ₂ from the end of the support part 35 to the end of the lighting circuit part 38 of the linear light source 31a is 100 mm. Next, the arrangement pitch of the CCD sensor will be explained. The resolution of the contact sensor in this example is 12 lines/mm
shall be. One pixel at this time is approximately 84 μm. The size of this one pixel is determined by the CCD by focusing rod lens arrays 21a and 21b as shown in FIG.
It is also 84 μm on the sensor. This CCD sensor is provided with a pitch of 14 μm (in effect,
The CCD sensor has a resolution of 72 lines/mm. ), so
Six element sensors are included in the size of one pixel. Two white (W), cyan (C), and yellow (Y) filters are attached in this order to each of the six elements constituting one pixel, as shown in FIG. However, a black filter is pasted on the 6 elements at the end. As will be described later, when attaching the filter in this embodiment, a considerable error is allowed compared to when attaching a single filter. Next, a circuit for processing signals from such a CCD will be explained. As shown in FIG. 5, this circuit includes an input section 51 , an integration section 52 that integrates the output from this input section 51 for each color, an amplification section 53 that amplifies the output from this integration section 52 , and an amplification section 53 that amplifies the output from this integration section 52. Part 5
A-D converts the output from 3 into a digital signal
It consists of a converting section 54 and a storage section 55 that stores the signal from the A-D converting section 54 . The input section 51 includes first to eighth CCD chips 11a to 11h that output serial signals, sampling and hold circuits 56a to 56h as zero level clamp circuits, and differential amplifiers 57a to 57h. 1 CCD chip 1
Each of the output signals 1a to 11h is input to each of sampling and hold circuits 56a to 56h and differential amplifiers 57a to 57h. Further, the outputs of the sampling and holding circuits 56a to 56h serve as another input to the differential amplifier. The integrating section 52 includes multiplexers 58a to 58h that separate the outputs of the differential amplifiers 57a to 57h for each color, and multiplexers 58a to 58h.
an integrator 591 that integrates the output signal for each color from
a, 591b, 591c (first CCD chip 11
corresponding to the output signal of a), 592a, 592b, 5
92c (corresponding to the output signal of the second CCD chip 11b), 593a, 593b, 593c (corresponding to the output signal of the third CCD chip 11b),
(corresponds to the output signal of CCD chip 11c), 594
a, 594b, 594c (4th CCD chip 11
c), 595a, 595b, 5
95c (corresponding to the output signal of the fifth CCD chip 11d), 596a, 596b, 596c (corresponding to the output signal of the sixth CCD chip 11d)
(corresponds to the output signal of CCD chip 11e), 597
a, 597, 597c (7th CCD chip 11f
), 598a, 598b, 59
8c (corresponding to the output signal of the eighth CCD chip 11g). The amplifying section 53 includes amplifiers 531a and 531a, which amplify the output signals for each color from the integrators 591a to 598c.
531b, 531c, 532a, 532b, 53
2c, 533a, 533b, 533c, 534
a, 534b, 534c, 535a, 535b,
535c, 536a, 536b, 536c, 53
7a, 537b, 537c, 538a, 538
b, 538c. The A-D converter 54 includes a selector 541a that switches and outputs signals amplified for each of the three colors in a time-division manner.
541h to 541h and the selectors 541a to 541
It consists of A/D converters 542a to 542h that convert analog signals from h to digital signals. The storage unit 55 has memories for white, cyan, and yellow, and is provided with two lines for each color.
The output signals of A/D converters 542a to 542h are stored. Now, regarding the operation of such a circuit, let's use the case of reading a white original as an example.
The explanation will focus on the output signal 1a. First to eighth CCD chips 11a to 11h
A pulse signal is supplied from a CCD scanning pulse generator (not shown). In synchronization with this pulse signal, signals photoelectrically converted by the CCD sensor are output from the CCD chips 11a to 11h. The signals serially output from the first CCD chip 11a are as shown in FIG.
For the dots, a black filter is pasted on the CCD sensor, so the voltage of the output signal is _V1 .
This voltage is the voltage associated with the dark current of the CCD sensor. Often 2 to 8 volts. On the other hand, W, Y, and C filters were pasted.
The voltage of the output signal of the CCD sensor is V ₁ ,
The amount of change is only on the order of 100mV. In the following, the voltage V ₁ will be referred to as a reference voltage. Among these signal groups, the signal from the CCD sensor to which the black filter is attached is held by the sampling hold circuit 56a. This sampling hold circuit 56a sends a signal having the reference voltage _V1 to the differential amplifier 57a until all output signals from the 2048 CCD sensors are sent to the differential amplifier 57a. Therefore, the differential amplifier 57a takes the difference between the voltage of the output signal from the CCD sensor to which the W, C, and Y filters are attached and the reference voltage, and appropriately amplifies this difference voltage at the same time. At this time, the output of the differential amplifier 57a is the output of the CCD with a W filter attached, as shown in FIG.
The signal 71W from the sensor, the signal 71Y from the CCD sensor to which the Y filter is attached, and the signal 71C from the CCD sensor to which the C filter is attached are successive in this order. However, these signals 71W, 71Y, and 71C are outputs from two CCD sensors. Therefore, the size of the small image reading pixel of the CCD sensor (resolution if color is not considered) at this time is 28 μm (36 lines/mm). These continuous analog signals are separated for each color in a multiplexer 58a. Figure 8a
A W filter as shown in is pasted.
The signal 71W from the CCD sensor is integrator 591a
Enter. Signal 7 from a CCD sensor with a Y filter attached as shown in Figure 8b
1Y is input to the integrator 591b. A signal 71C from the CCD sensor as shown in FIG. 8c is input to an integrator 591c. Charge is accumulated in capacitors (not shown) included in the integrators 591a, 591b, and 591c. Integrator 591 as shown in FIG.
Time when signals are input to a, 591b, 591c
Integral operation is performed during t ₀ . When the integration is finished,
The voltage value at this time as shown by the solid line in FIG. 9 is held and sent to amplifiers 531a, 531b, and 531c. Integrators 591a, 591b, and 591c have the following effects. For example, consider a case where the nozzle rides on the signal before inputting it to the integrators 591a, 591b, and 591c, as shown in FIG. Such signals are transmitted to integrators 591a and 59
1b and 591c, as shown by the dotted line in FIG. 9, there is only a slight fluctuation in the integral value, and the influence of noise is almost eliminated. In this way, signals free from the influence of noise are supplied to amplifiers 531a, 531b, and 531c. The individual amplification factors of the amplifiers 531a, 531b, and 531c are adjusted so that the output voltages for each color are the same. Therefore, amplifiers 531a, 53
When the outputs of 1b and 531c are all white images, signals of the same voltage _V2 are output. Such a signal is supplied to the selector 541a. The selector 541a is a kind of switch. This selector 541a performs a switch operation, that is, a switching operation, at a cycle twice as long as the cycle of the pulse signal from the CCD scanning pulse generator. Therefore, the selector 541a multiplexes and outputs time-divided signals as shown in FIGS. 14a, b, and c. The signals thus time-divided are supplied to the A/D converter 542a. three amplifiers 531a,
One A/D converter 542a is used in a time-division manner corresponding to 531b and 531c. The A/D converter 542a is expensive, and it is preferable to have fewer A/D converters. The output of the A/D converter 542a is stored in the storage section 55 . As described above, this storage unit 55 includes memories 121W for white, yellow, and cyan,
121Y and 121C are available. Furthermore, this storage section 55 is provided with a gate. This gate corresponds to signal switching by selectors 541a to 541h. That is, A/D converter 542
The digital signals from a to 542h are CCD
Depending on the color of the filter attached to the sensor,
The gate is opened and the data is stored in the memories 121W, 121Y, and 121C for white, yellow, and cyan. The memories 121W, 121Y, and 121C do not store 2048×8 signals. As mentioned above, since filters of the same color are attached to the two CCD sensors, the number of signals is reduced to 1/2.
Furthermore, since the signals are completely separated and stored for each of the three colors, the memories 121W, 121Y, 121 for each color are
The number of signals stored in C is further reduced to one-third.
Therefore, as a whole, the memory for each color is 121W, 121.
Y, 121C only needs to have the ability to accommodate one-sixth the number of signals of all CCD sensors. Such memories 121W, 121Y for each color,
The signal stored in 121C is transmitted to read memories 122W, 122Y, 12 having the same storage capacity.
2C in parallel. When reading from the read memories 122W, 122Y, and 122C, the following precautions should be taken. As shown in FIG. 1, the first to eighth CCD chips 11a to 11h are spectroscopically overlapped on the scanning line for image reading, with a total of 170 CCD sensors. Therefore, it is necessary to read while removing this portion. In this embodiment, when the first and eighth CCD chips 11a to 11h are provided by the hybrid technology, the overlapping portion can be found, so that the pixels corresponding to this overlapping can be removed. However, when referring to pixels on the CCD chips 11a to 11h,
6 pieces with W, C, and Y filters attached.
Refers to a group of CCD sensors. For example, as shown in FIG. 13, the n-th pixel from the left end of the first CCD chip 11a is
A case will be explained in which the pixel does not overlap with the CCD chip 11b, but overlaps with the second CCD chip 11b from the (n+1)th pixel onward. In this embodiment, C filters are attached to all pixels after the (n+1)th pixel. Each of the memories 121W, 121Y, 121C and the readout memories 122W, 122Y, 122C stores one signal for one pixel. Therefore, from the (n+1)th CCD chip 11
It is sufficient to remove signals up to the end pixel on a (assumed to be the _n0th pixel). This can be done by skipping it when reading. This skip is used when reading from the readout memories 122W, 122Y, and 122C for each color. Identification of overlapping parts is
For example, regarding the W signal, after hybridization, a CCD color sensor reads an original with thin vertical lines of about 80 μm, and the digital signal from the W memory is D/A converted and output as an analog value. Since the signal is obtained as two signals, this can be easily done by removing the memory address at the rear end of the CCD sensor so that it becomes one signal. Next, a description will be given of where the above circuits are placed. In this embodiment, the input section 51 is provided on the ceramic substrate 12. However, in FIG. 1, only the first to eighth CCD chips 11a to 11h are shown. The integrating section 52 , the amplifying section 53 , the A-D converting section, and the storage section 55 are connected to the substrate 1 constituting the contact sensor.
It is not provided on the substrate 12, but is provided outside the substrate 12. Then, these circuits and the input section 51 are electrically connected with a cord. This advantage is as follows: (i) CCD chips 11a to 11h, sampling and hold circuits 56a to 56h, differential amplifiers 57a to 57h, and linear light sources 31a, 3;
1b, focusing rod lens array 21a, 21
b is provided integrally with the substrate 12, so it is lightweight. (ii) Even if noise is picked up by the code, the noise is substantially canceled by the integrating section 52 . There are two points. Furthermore, since filters of the same color are attached to the two CCD sensors, even if one CCD sensor has a defect, the signal from the other CCD sensor can be used. In fact, when 2048 CCD elements are formed on one chip, two or three defective elements often occur. In this case, it was discarded as a defective product, but if it is used in this way, even if there is a defective element, it is essentially equivalent to having no defective element. This is more effective when reading black and white originals. If there are no defects, using signals from two CCD sensors will increase the S/N. However, 1
A pixel may be read by three CCD sensors.
At that time, use W, Y, and C filters one by one.
Paste it on the CCD sensor. When reading a black and white original, one pixel may be read by one CCD sensor. Furthermore, if filters of the same color are attached to one pixel, color separation can be ensured even if there is some error in attaching the filters. The circuit features of this embodiment are summarized as follows. (i) Strong against noise. (ii) Fewer A/D converters are required. (iii) It is possible to adjust the signal for each color. (iv) The number of components provided on the moving board is small and does not interfere with the movement of the board. The advantages of (i) and (iv) are related; the input section 5 extracts only the signal corresponding to the color and at the same time appropriately amplifies it.
Since only 1 is provided on the board, the weight of the board is light. The signal obtained here is sent to the integrating section 52 via a signal line.
Therefore, even if noise is picked up by the signal line, the noise is eliminated by the integrating section 52. After the noise is eliminated, the amplification section 53 amplifies the signal, so that the influence of the noise does not appear. The advantage of (ii) is that it is used in time division. The advantage of (iii) is that an amplifier is provided for each color. Further, in this embodiment, signals are transferred using a CCD, and the CCD has a high transfer speed. Furthermore, when reading an A4-sized document, for example, it is better to use eight CCDs as in this embodiment than to use one CCD of this size because signal transfer is performed in parallel, so the transfer time is shorter. is short. The extra read signal is stored in the read memory 12 as described above.
All you have to do is select and read the signals from 2W, 122Y, and 122C, and it is a big task.
The time required for reading is the same as when one CCD is used. The embodiments of this invention have been described above, but
No promises are made in the examples. In the embodiment, the photoelectric conversion element array and the transfer section are realized by a CCD, but a CTD (Charge Transfer Device) may also be used. For example, BBD
(Bucket Brigade Device), CID (Charge
Injection Device), LCD (Light Coupled
device), PCD (Plasma Coupled Device), and scanter. Furthermore, the photoelectric conversion element arrays do not need to be arranged in a staggered manner, but may be arranged in three rows so as to cover the reading area, or may be arranged in any plurality. The optical system is not limited to a focusing rod lens array. The number of light sources is not limited, and may be one instead of two. Also, as a light source, a fluorescent lamp,
It may also be an LED (Light Emitting Diode). In short, any modification is included in this invention as long as it does not depart from the spirit of this invention.

[Brief explanation of drawings]

1 to 16 show the contact sensor according to the embodiment, FIG. 1 shows the arrangement of eight CCD chips, and FIG. 2 shows the positional relationship between the CCD chips and the focusing rod lens array. A schematic perspective view showing the third
The figure is a schematic sectional view of a contact sensor to explain image formation on a CCD chip, Figure 4 is an assembly diagram when configuring a substrate with a CCD chip as a contact sensor, and Figure 5 is a close contact sensor. Perspective view of sensor, 6th
The figures are a side view of the contact sensor shown in Fig. 5, Fig. 7 is a diagram showing how to attach a filter onto the CCD sensor, Fig. 8 is an electrical circuit diagram of this contact sensor, and Figs. FIG. 14 is a diagram showing the signals of each part in this electric circuit diagram, FIG. 15 is a diagram showing the storage section, and FIG. 16 is a diagram showing the overlapping of CCD chips. 11a, 11b, 11c, 11d, 11e, 1
1f, 11g, 11h...CCD chip, 21a,
21b...Focusing rod lens array, 31a,
31b... Linear light source.

Claims (1)

[Scope of Claims] 1. A light source, a substrate provided opposite to the original onto which the light from the light source is irradiated, and a plurality of light sources arranged on the substrate in a staggered manner so as to completely cover the width of the original. a plurality of IC image sensor chips, and an optical system for forming a one-to-one erect real image of reflected light from the irradiated scanning line portion on the document on the plurality of IC image sensor chips, A contact sensor characterized in that the optical system, the substrate, and the light source have an integrated structure.