JPH0716227B2 - Reader - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading device.

[0002]

2. Description of the Related Art Devices such as contact sensors have been developed as input devices for images and the like. One of the advantages of these devices is that the structure is easy and the original is stationary.

For this reason, in many cases, the substrate provided with the photoelectric conversion element is made movable with respect to the document table.
For example, the line type scan is repeated to read the entire screen of the document.

The substrate is required to be lightweight because it can be transported. Therefore, in the conventional reader, only the photoelectric conversion element is provided on the substrate, and the output from this element is supplied to the processing circuit provided outside the substrate by the signal line.

According to such a structure, the substrate itself is made lighter, but the moving distance of the substrate becomes long due to the general demand for widening the reading area, and the signal line becomes long accordingly. In addition, as a matter of course, since the reading device is combined with other electronic devices, it is placed in an environment where noise is likely to occur and a long signal line easily picks up noise.

[0006]

As described above, according to the prior art, since the substrate provided with the photoelectric conversion element is movable, noise is easily picked up by the signal line, and the quality of the read signal is remarkably high. It has fallen.

The present invention provides a reading device that overcomes such conventional problems.

[0008]

According to the present invention, there is provided a reading apparatus having a circuit which makes a substrate provided with a photoelectric conversion element movable, and performs a predetermined process on a signal outputted from the photoelectric conversion element in accordance with the movement. In the circuit that performs the predetermined function, the photoelectric conversion element is provided with a circuit that samples and holds the output signals of the plurality of photoelectric conversion elements and a differential amplifier circuit that amplifies the signal from the sample and hold circuit. It is integrally provided on the substrate, the analog signal from the differential amplifier circuit is converted into a digital signal, and the digital signal is stored in a storage unit provided outside the substrate.

[0009]

According to the present invention, since the output from the photoelectric conversion element is used as it is for the processing performed by the circuit provided on the substrate, more correct processing can be performed.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. The contact sensor in this embodiment is capable of reading a color document of A4 size.

This contact sensor serves as a photoelectric conversion element, a transfer section for transferring charges converted by the photoelectric conversion element, and an optical system capable of forming a one-to-one upright real image on the photoelectric conversion element. It is composed of a converging rod lens array and a linear light source.

In this embodiment, a device including a photoelectric conversion element and a charge-coupled element as a transfer section is a CCD (Charge Couple).
d Device). These are formed on the same chip. Further, in this embodiment, the photoelectric conversion element, that is, the photodiode is formed of C-Si. This C-Si photodiode has a high photoelectric conversion speed and is 1 msec or less. In the following description, the photoelectric conversion element will be called a CCD sensor.

This CCD sensor is provided at a pitch of 14 μm, and 2048 elements are provided on one chip. Eight such CCD chips (11a) to (11h) are provided in a zigzag pattern on the ceramic substrate (12) as shown in FIG. The CCD chips (11a) to (11h) as a whole need to have a length of l = 210 mm which covers at least the width of A4 size. Further, in this embodiment, the CCD chips (11a) to (11h) are overlapped and d = 2.38.
mm, which is equivalent to 170 elements of the CCD sensor.

Such CCD chips (11a) to (11h)
On the other hand, as shown in FIG. 2, two converging rod lens arrays (brand name SELFOC lens, manufactured by Nippon Sheet Glass) (2
Arrange 1a) and (21b) in a V shape. Each of the converging rod lens arrays (21a) and (21b) has a length not less than the width of a document of A4 size and the same as the entire length of the eight CCD chips (11a) to (11h). Further, the height h of the converging rod lens arrays (21a) and (21b) is designed to be 2
0 mm to 50 mm is suitable. This value is for increasing the depth of focus of the focusing rod lens arrays (21a) and (21b). Especially at 50 mm, the depth of focus is deep. The converging rod lens arrays (21a) and (21b) are usually plate-shaped. However, in this embodiment, the ridges of the converging rod lens arrays (21a) and (21b) are cut off so that the two converging rod lens arrays (21a) and (21b) mesh with each other. By adjusting the angle of the slope to be scraped in this way,
The angle formed by the two focusing rod lens arrays (21a) and (21b) can be adjusted. Moreover, the space occupied by these converging rod lens arrays (21a) and (21b) becomes small. However, light is not allowed to enter from the scraped slope.

As a contact sensor, linear light sources (31a), (31
b) is required. The linear light sources (31a) and (31b) are provided in parallel with and close to the focusing rod lens arrays (21a) and (21b) as shown in FIG.

The linear light sources (31a), (31b), the converging rod lens arrays (21a), (21b) and the ceramic substrate (12)
Together form a contact sensor. This contact sensor is arranged so as to traverse the original document (32) and reads line by line.

Light from the linear light sources (31a) and (31b) is applied to one line of the document. The emitted light is reflected on the original (32) and is received by the focusing rod lens arrays (21a) and (21b). Focusing rod lens arrays (21a) and (21b) are originals
(32) The image above is formed on the CCD sensor. Since the focusing rod lens arrays (21a) and (21b) have a large depth of focus, the focusing rod lens arrays (21a) and (21b) and the original (3
2) The distance from CC is not constant, and even if there is some fluctuation, CC
A clear image is formed on the D sensor. Moreover, the converging rod lens arrays (21a) and (21b) form an image on the original (32) on the CCD sensor in a one-to-one manner without reducing the image.

Next, a concrete and preferable structure will be described. As shown in FIG. 4, a lid (34) having windows (33a) to (33h) is attached to a substrate (11) on which CCD chips (11a) to (11h) are mounted. This lid (34) has windows (33a) through (33).
Light is not transmitted except from h). Windows (33a) to (33h) are C
It is provided corresponding to the CD chips (11a) to (11h).

For such a substrate (11) and lid (34),
Attach the support (35) as shown in FIG. This support
(35) has holes (36) in the upper wall corresponding to the windows (33a) to (33h). The converging rod lens arrays (21a) and (21b) are attached to the supporting portion (35) so that the converging rod lens arrays (21a) and (21b) are located above the holes (36).

On the other hand, one linear light source is provided on the support portion (35).
Attach (31a) together. This linear light source (31a) is shown in FIG.
As shown in, light is emitted from only a part. That is, the window (37) is provided so that the light is emitted from the vicinity of the angle of 45 ° with respect to the original (32). There is no irradiation of light from other parts.

Such a contact sensor is used for the original (32)
It is arranged as shown in FIG. That is, the converging rod lens arrays (21a) and (21b) are arranged so as to face the document (32), and the window (37) of the linear light source (31a) is positioned at 45 ° with respect to the document (32). Will be arranged.

As shown in FIG. 6, the size of the contact sensor is such that the distance L from the document (32) to the substrate (12) is about 60 mm, and the supporting portion (3) is
The distance w ₁ from the end of 5) to the end of the linear light source (31a) is 60 mm,
The distance w ₂ from the end of the support portion (35) to the end of the lighting circuit (38) of the linear light source (31a) is 100 mm.

Next, the arrangement pitch of the CCD sensors will be described.

The contact sensor has a resolution of 12 in this embodiment.
Book / mm One pixel in this equation is about 84 μm. The size of one pixel is 84 μm on the CCD sensor due to the converging rod lens arrays (21a) and (21b) as shown in FIG. The CCD sensors are provided at a pitch of 14 μm (substantially 72 CCD sensors are provided.
There is a resolution of books / mm. ), A sensor of 6 elements is included in the size of one pixel.

Two filters of white (W), cyan (C), and yellow (Y) are attached in this order to the six elements constituting one pixel as shown in FIG. However, a black filter is attached to the 6 elements at the ends. As will be described later, the attachment of the filter in this embodiment allows a considerable error as compared with the case of attaching one filter.

Next, a circuit for processing such a signal from the CCD will be described. As shown in FIG. 8, this circuit has an input section (51), an integration section (52) for integrating the output from the input section (51) for each color, and an output from the integration section (52). An amplification section (53), an AD conversion section (54) for converting the output from the amplification section (53) into a digital signal, and the AD conversion section
And a storage section (55) for storing the signal from the (54).

The input section (51) includes first to eighth CCD chips (11a) to (11h) for outputting a serial signal, and a sampling hold circuit (56 as a zero level clamp circuit.
a) to (56h) and differential amplifiers (57a) to (57h). The output signals of one CCD chip (11a) to (11h) are supplied to the sampling and holding circuit (56a) to
Input to each of (56h) and each of the differential amplifiers (57a) to (57h). The sampling and holding circuits (56a) to (56a)
The output of h) becomes another input of the differential amplifier.

The integrating section (52) includes differential amplifiers (57a) through (57).
multiplexer (58a) for separating the output of h) for each color
(58h) and output signals for each color from the multiplexers (58a) to (58h) are output to integrators (591a), (591b), (591c) (first
(Corresponding to the output signal of CCD chip (11a)), (592a), (5
92b), (592c) (corresponding to the output signal of the second CCD chip (11b)), (593a), (593b), (593c), (corresponding to the output signal of the third CCD chip (11c)), (594a), (594b), (594c)
(Corresponding to the output signal of the fourth CCD chip (11c)), (595
a), (595b), (595c) (corresponding to the output signal of the fifth CCD chip (11d)), (596a), (596b), (596c) (sixth CCD
Corresponding to the output signal of chip (11e)), (597a), (597b), (5
97c) (corresponding to the output signal of the seventh CCD chip (11f)),
(598a), (598b), (598c) (corresponding to the output signal of the eighth CCD chip (11g)).

The amplification section (53) is an amplifier (531a), (531b), which amplifies the output signal for each color from the integrators (591a) to (598c),
(531c), (532a), (532b), (532c), (533a), (533b), (5
33c), (534a), (534b), (535c), (536a), (536b), (536
c), (537a), (537b), (537c), (538a), (538b), (538c)
It consists of and.

The A-D converter (54) is a selector (541a) through which the signals amplified for each of the three colors are switched by time division and output.
(541h) and A / D converters (542a) to (542h) for converting analog signals from the selectors (541a) to (541h) into digital signals.

The storage section (55) has a memory for each of white, cyan and yellow, and is provided for two lines for each color.
The output signals of the / D converters (542a) to (542h) are stored.

Regarding the operation of such a circuit, taking the case of reading a white original as an example, the first CCD chip (11
The output signal of a) will be mainly described.

The first to eighth CCD chips (11a) to (1
1h) is supplied with a pulse signal from a CCD scanning pulse generator (not shown). CC synchronized with this pulse signal
The signals photoelectrically converted by the D sensor are output from the CCD chips (11a) to (11h).

The signal output serially from the first CCD chip (11a) has a black filter attached to the CCD sensor for the first 6 dots as shown in FIG. The voltage is V ₁ . This voltage is CCD
It is the voltage associated with the dark current of the sensor. Often 6-8 volts. On the other hand, the voltage of the output signal of the CCD sensor to which the W, Y, and C filters are attached has a change amount of only 100 mV with respect to V ₁ . Hereinafter, the voltage V ₁ will be referred to as the reference voltage.

Of such a signal group, the signal from the CCD sensor to which the black filter is attached is held by the sampling hold circuit (56a). The sampling and holding circuit (56a) sends a signal having the reference voltage V ₁ to the differential amplifier (57a) until all the output signals from the 2048 CCD sensors are sent to the differential amplifier (57a). To do.

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 at the same time amplifies the voltage of this difference appropriately. To do.

The output of the differential amplifier (57a) at this time is shown in FIG.
As shown in 0, the signal from the CCD sensor with the W filter attached (71W), the signal from the CCD sensor with the Y filter attached (71Y), from the CCD sensor with the C filter attached Signals (71C) are consecutive in this order. However, these signals (71W), (71Y), (71C) are 2
This is the output from each CCD sensor. Therefore, at this time, the size of the image reading pixels of the CCD sensor (resolution without considering color is 28 μm (36 lines / m)
m).

Such a continuous analog signal is separated for each color in the multiplexer (58a). Figure 11 (a)
CCD with W filter attached as shown in
The signal (71W) from the sensor is input to the integrator (591a). The signal (71Y) from the CCD sensor to which the Y filter as shown in FIG. 11 (b) is attached is input to the integrator (591b). The signal (71C) from the CCD sensor as shown in FIG. 11 (c) is input to the integrator (591c).

Charges are accumulated in capacitors (not shown) included in the integrators (591a), (591b) and (591c).
As shown in FIG. 12, integrators (591a), (591b), (591c)
The integration operation is performed during the time t ₀ when the signal is input to. When the integration is completed, the voltage value at this time as shown by the solid line in FIG. 12 is held and sent to the amplifiers (531a), (531b) and (531c).

The integrators (591a), (591b), (591c) have the following effects. For example, as shown in FIG.
Consider a case where noise is added to the signal before being input to (591a), (591b), and (591c). When such a signal is input to the integrators (591a), (591b), (591c), as shown by the dotted line in FIG. 12, even if there is a slight variation in the integrated value, the influence of noise is almost eliminated. .

In this way, the signals free from the influence of noise are supplied to the amplifiers (531a), (531b) and (531c). The individual amplification factors of these amplifiers (531a), (531b), (531c) are adjusted so that the output voltage for each color is the same. Therefore, when the outputs of the amplifiers (531a), (531b), (531c) are all white images, the signal of the same voltage V ₂ is output.

Such a signal is supplied to the selector (541a). The selector (541a) is a kind of switch. This selector (541a) performs a switching 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, from the selector (541a), as shown in FIG.
Time-divided signals as shown in (a), (b), and (c) are multiplexed and output.

The signal thus time-divided is supplied to the A / D converter (542a). Three amplifiers (531a), (531a
A single A / D converter (542a) is used in a time division manner corresponding to (b) and (531c). The A / D converter (542a) is expensive, and the smaller the number, the better.

The output of the A / D converter (542a) is stored in the storage section (55).
Is stored in. As described above, this storage unit (55) is a memory (121W), (121Y), (121C) for each of white, yellow and cyan.
Is prepared. Further, the storage section (55) is provided with a gate. This gate has selectors (541a) to (541a).
It corresponds to the signal switching in h). That is, the A / D converter (5
Digital signals from 42a) to (542h) have their gates opened according to the color of the filter attached to the CCD sensor, and memories (121W), (121W) for each of white, yellow and cyan.
It is stored in Y) and (121C). This memory (121W), (121Y),
(121C) does not mean that 2048 × 8 signals are stored.
Since the filters of the same color are attached to the two CCD sensors as described above, the number of signals is halved. Furthermore, 3
Since the signals are completely separated and stored for each color, the number of signals stored in the memories (121W), (121Y), and (121C) for each color becomes one third. Therefore, the memory for each color (121
W), (121Y), and (121C) only need to have the ability to store only one-sixth the number of signals of all CCD sensors.

The memory (121W), (121Y) for each color,
The signal stored in (121C) is supplied in parallel to the read memories (122W), (122Y), and (122C) having the same storage capacity. This read memory (122W), (122Y), (122C)
Note the following when reading from. Figure 15
As shown in, the first to eighth CCD chips (11a) to (11h) are 17 CCD sensors on the scanning line for image reading.
0 Element Spectral overlap. Therefore, it is necessary to read out while removing this portion.

In this embodiment, when the first and eighth CCD chips (11a) to (11h) are provided by the hybrid technique, the overlapping portion can be seen. Therefore, the pixels corresponding to this overlapping can be removed. However, CCD chips (11a) to (1
1h) When referring to a pixel above, it refers to a group of six CCD sensors to which W, C, and Y fillers are attached.

For example, as shown in FIG. 16, from the left end of the first CCD chip (11a) to the n-th pixel, the second CCD chip (11b) does not overlap, and from the (n + 1) th pixel to the second pixel. The case of overlapping with the CCD chip (11b) will be described. In this embodiment, all C filters are attached to the (n + 1) th and subsequent pixels.

Each of the memories (121W), (121Y), (121C) and the read memories (122W), (122Y), (122C) stores one signal for one pixel. Thus (n + 1) th to (a n ₀ th pixel.) End of the pixel on the CCD chip (11a) signals up may be removed. This may be skipped during reading. This skip is used when reading from the read memories (122W), (122Y), and (122C) for each color. To identify the overlapped portion, for example, in the case of the W signal, after hybridizing, the CCD color sensor reads a document with a thin vertical line of about 80 μ, and the W
When the digital signal from the memory is D / A converted and output as an analog value, the output signal is obtained as two signals.
This can be easily done by removing the address of the memory at the rear end of the sensor.

Next, where to arrange the above circuits will be described. In this embodiment, the input section (51) is provided on the ceramic substrate (12). However, in FIG. 1, first to eighth C
Only the CD chips (11a) to (11h) are shown. Integrator
The (52), the amplification section (53), the A / D conversion section and the storage section (55) are not provided on the substrate (12) constituting the contact sensor, but are provided outside the substrate (12). Then, these circuits and the input section (51) are electrically connected by a cord.

This advantage is as follows: (i) CCD chips (11a) to (11h), sampling hold circuits (56a) to (56h), and differential amplifiers (57a) to (57a)
(58h) Since the linear light sources (31a), (31b), and the focusing rod lens arrays (21a), (21b) are provided integrally with the substrate (12), they are lightweight.

(Ii) Since the input section (51) is provided on the substrate (12), a significant signal component is amplified from the substrate (12), so the influence of noise is reduced. (Iii) Since the integration (52) is provided in the circuit outside the substrate, the influence of noise can be substantially eliminated.

In this embodiment, the input section provided on the substrate (12)
As (51), only the differential amplifier (17) is mainly provided, but it is needless to say that this can be appropriately modified and selected according to the implementation, but as is clear in this embodiment as well. Since the output of the photoelectric conversion element is directly calculated before being output to the outside, the calculation itself is accurate, and the degree of freedom is high because it is not restricted.

Further, since the 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 may be used. In fact, CCD is 2 when 2048 elements are formed on one chip.
It is common for three to three defective elements to occur. In this case, it was discarded as a defective product, but if it is used in this way, it is equivalent to that there is substantially no defective element even if it is a defective element. This is more effective when reading a black and white document.

When there are no defects, the S / N ratio increases when the signals from the two CCD sensors are used. However, 1
The pixels may be read by three CCD sensors. At that time, W, Y, and C filters are attached to the CCD sensor one by one. When scanning a black and white document, 1 pixel is 1C
It may be read by a CD sensor.

Furthermore, if filters of the same color are attached to one pixel, color separation can be surely performed even if there is some error in attaching the filters.

The circuit features of this embodiment are summarized as follows.

(I) Resistant to noise.

(Ii) The number of A / D converters is small.

(Iii) It is possible to adjust the signal for each color.

(Iv) The number of constituent elements provided on the moving substrate is small and does not hinder the movement of the substrate. The advantages of (i) and (iv) are related, and the weight of the substrate is light because only the input part (51) for extracting only the signal corresponding to the color and appropriately amplifying the signal is provided on the substrate.

The signal obtained here is integrated by a signal line into an integrating unit.
Since it is sent to (52), even if noise is picked up on the signal line,
The noise is erased in 2).

Since the amplifying section (53) amplifies the noise after the noise is erased, the influence of noise is not shown.

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.

In this embodiment, the CCD transfers the signal, but the CCD has a high transfer speed. Also, for example, when reading a document of A4 size, C of this size is used.
Eight Cs as in this embodiment rather than using one CD
Since the CD is used to perform signal transfer in parallel, the transfer time is shorter. As for the signals that have been read extra, it is sufficient to select the reading of the signals from the reading memories (122W), (122Y), and (122C) as described above, and the large C
The time required for reading is the same as when one CD is used.

The embodiments of the present invention have been described above, but the embodiments are not restricted in any way. In the embodiment, the photoelectric conversion element array and the transfer unit are realized by the CCD, but a CTD (Charge Transfer Device) is used.
May be used. For example, BBD (Bucket Brigade Devic
e), CID (Charge Injection Device), LCD (Ligh
tCoupled Device), PCD (Plasma Coupled Device),
It is a scanter. Further, the photoelectric conversion element rows may be arranged in three rows so as to cover the reading area without arranging them in a zigzag manner, and any plural arrangement may be adopted.

The optical system is not limited to the focusing rod lens array. The number of light sources may be one instead of two, and is not limited to the number. Also, as the light source, a fluorescent lamp, an LED (Lig
ht Emitting Diode).

[0068]

As described above, according to the present invention, it is possible to obtain a read signal that is not affected by noise applied to the signal line.

Further, since the predetermined function is assigned to the circuit provided on the substrate, the output of the photoelectric conversion element is directly processed, and the processing with a higher degree of freedom can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement of eight CCD chips, which is an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a positional relationship between a CCD chip and a converging rod lens array.

FIG. 3 is a schematic cross-sectional view of a contact sensor for explaining image formation on a CCD chip.

FIG. 4 is an assembly diagram when a substrate provided with a CCD chip is configured as a contact sensor.

FIG. 5 is a perspective view of a contact sensor.

6 is a side view of the contact sensor shown in FIG.

FIG. 7 is a diagram showing how to attach a filter onto a CCD sensor.

FIG. 8 is an electric circuit diagram of the contact sensor.

FIG. 9 is a diagram showing a signal serially output from a CCD chip in an electric circuit diagram.

FIG. 10 is a diagram showing a signal from a CCD sensor in an electric circuit diagram.

FIG. 11 is a diagram showing signals from a CCD sensor in an electric circuit diagram.

FIG. 12 is a diagram showing a signal after integration in an electric circuit diagram.

FIG. 13 is a diagram showing signals before integration in an electric circuit diagram.

FIG. 14 is a diagram showing time-divided signals in an electric circuit diagram.

FIG. 15 is a diagram showing a storage unit.

FIG. 16 is a diagram showing an overlap of CCD chips.

[Explanation of symbols]

(11a), (11b), (11c), (11d), (11e), (11g), (1
1h) ... CCD chip (21a), (21b) ... Focusing rod lens array (31a), (31b) ... Linear light source

Claims (1)

[Claims] 1. A light source, a substrate provided to face an original document irradiated with light from the light source, a plurality of photoelectric conversion elements provided on the substrate, and the photoelectric conversion element from the original document. An optical system arranged to receive the reflected light of, and means for relatively moving at least the substrate and the document, and a predetermined process is applied to the output from the photoelectric conversion element in accordance with the movement by this means. In the reading device including a circuit for performing the predetermined processing, among the circuits for performing the predetermined processing, a circuit that samples and holds the output signals of the plurality of photoelectric conversion elements, and a differential amplifier circuit that amplifies the signal from the sample and hold circuit. A unitary structure is provided on the substrate on which the photoelectric conversion element is provided, the analog signal from the differential amplifier circuit is converted into a digital signal, and the digital signal is provided outside the substrate. Reader and to store the parts.