JP3006183B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image scanner,
The present invention relates to an image reading apparatus that can be used in a facsimile apparatus or the like, and more particularly to an apparatus that has a variable reading width.

[0002]

2. Description of the Related Art There are two types of conventional image reading apparatuses: a contact type and a reduction optical system. The contact-type reading device has a configuration in which a lens array is interposed between a light receiving surface of a line sensor and a subject, and reads an image formed through the lens array, and can reduce the thickness of the shape. . The compact image reading device is CCD
And the like. A reduction lens is interposed between the light receiving surface of the reading unit and the subject, and the image reduced by the reduction lens is read, so that the shape of the reading unit can be reduced.

[0003]

The close contact type device requires a line sensor having a length equal to the width of the document to be read, and has a problem that the width is large. Although the shape of the sensor itself may be small in the reduction-type device, an optical distance for reduction by the reduction lens is required, and there is a problem that the length in the vertical direction becomes long.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems relating to the conventional contact type and reduced type image reading apparatuses, and to make the width variable according to the width of the original. An object of the present invention is to provide an image reading device having a minimum width and a short vertical length.

[0005]

For this reason, in the present invention, the first and second slidable arrangements are parallel to each other and one of them has an overlapping portion with the other. Line sensors (6a, 6
b), and in the overlap portion, in order to validate one of the read signals of the first and second line sensors (6a, 6b), the first and second line sensors (6
a, 6b) for detecting the positional relationship (28, 3
0).

[0006]

The reading width can be adjusted in accordance with the width of the document by sliding one line sensor 6a with respect to the other line sensor 6b. Line sensor 6a
In the overlap portion between the line sensors 6a and 6b, only the output of one of the line sensors is validated, so that the positional relationship between the line sensors 6a and 6b is
Detected by 0.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention, an image scanner manually moved on a document surface, will be described below with reference to the drawings. FIG. 1 is an external view of this embodiment.
1 shows an image scanner according to the present invention. A slit 2 extending in the width direction is formed on the upper surface of the image scanner 1, a lever 3 for changing the reading width is projected from the slit 2, and a reed switch 4 is provided. The image scanner 1 includes cases 5a and 5 fitted coaxially and slidably.
b. The lever 3 is moved according to the width of the document to be read, and the amount by which the case 5a projects from the case 5b is adjusted. After the reading width is adjusted, the image scanner 1 is held perpendicular to the document so that the reading surface below the image scanner 1 is close to or in close contact with the target document. Then, it is manually moved in the sub-scanning direction in that state. At this time, an image scanned while the reed switch 4 is pressed is obtained as an electric image signal. The output image signal is converted into a binary signal, and then supplied to a processing device such as a computer via a predetermined interface (not shown).

FIG. 2 is an exploded view of the internal mechanism of the image scanner 1. In FIG. 2, 6a and 6b
Is a line sensor composed of a MOS or CCD, 7a and 7b are lens arrays for forming an image of a subject such as a document on the line sensor in a one-to-one manner, and 8a and 8b are LED arrays as illumination light sources. However, in FIG. 2, the illustration of the LED array 8a is omitted for simplicity. Line sensor 6a, lens array 7a and LED
The array 8a is attached to holding hardware 9a, 10a and 11a, and the line sensor 6b, the lens array 7b and the LED array 8b are connected to the holding hardware 9b, 10b and 1a.
1b. These line sensors 6a, 6
b, lens arrays 7a, 7b, LED arrays 8a, 8b
Are arranged in parallel with each other at a predetermined interval in the width direction.

The lever 3 for expanding and contracting the reading width includes:
The shaft 12 has a base inserted therethrough. The shaft 12 is supported between the holding fittings 9b and 11b. Lever 3
When the user slides, one reading mechanism including the line sensor 6a, the lens array 7a, and the LED array 8a slides in the width direction. In order to detect the slide amount in this case, the photo interrupter 13a,
An encoder composed of a rotary plate 13b and a rotary plate 14 is provided. Further, rollers 15a and 15b for moving the image scanner in the sub-scanning direction are provided. One roller 15a is rotatably supported by the holding fitting 9a, and the other roller 15b is rotatably supported by the holding fitting 9b.
Supported by The rotation of the roller 15 a is transmitted to the rotating plate 17 via the belt 16. The rotating plate 17 forms an encoder together with the photo interrupter 18 for detecting the amount of movement in the sub-scanning direction.

FIG. 3 is a block diagram of this embodiment.
Reference numeral 1 denotes a sensor drive pulse generation circuit. Sampling pulse S output from sensor drive pulse generation circuit 21
H and the clock CK are supplied to the line sensors 6a and 6b. The line sensors 6a and 6b read and accumulate images at the cycle of the sampling pulse SH, and output image signals in synchronization with a clock. The output signal SOa of the line sensor 6a is supplied to the binarization circuit 22a of the binarization block 22, and the output signal SOa of the line sensor 6b is output.
b is supplied to the binarization circuit 22b. Binarization block 2
2, the output signals SO of the line sensors 6a and 6b
a and SOb are binarized to a high level or a low level depending on their magnitudes.

The output signal of the binarization block 22 is taken out as output image data via the switching block 23. The switching block 23 includes switching circuits 23a and 23b. The image data Da of the line sensor 6a is gated via the switching circuit 23a, and the image data Db of the line sensor 6b is gated via the switching circuit 23b.

Reference numeral 24 denotes an encoder for detecting the sub-scanning direction, that is, the distance when the scanner 1 moves. The encoder 24 includes the photo interrupter 18 and the rotating plate 17 described above. Encoder 2
4 is supplied to the waveform shaping circuit 25, and the detection pulse Sd from the waveform shaping circuit 25 is supplied to the sensor interval counter 26 as a clock input. The sensor interval counter 26 is supplied with a pulse signal that changes in response to the on / off of the reed switch 4 as a count enable signal. Therefore, while the reed switch 4 is on, the counter 26 counts the detection pulse Sd from the waveform shaping circuit 25.

The count value of the counter 26 is supplied to a comparison circuit 27 and compared with a set value. This setting is
This is a value corresponding to the shift of the reading position of the line sensors 6a and 6b in the sub-scanning direction. That is, since it is difficult to arrange the line sensors 6a and 6b so that the reading positions of the line sensors 6a and 6b are completely coincident with each other, the position in the sub-scanning direction is detected by the counter 26 in order to correct the deviation of the reading position. I have. The switching circuit 23a is controlled by the output signal of the comparison circuit 27. Here, in FIG. 2, the line sensor 6b is provided at a position preceding the line sensor 6a in the sub-scanning direction indicated by the arrow. Therefore, after the line sensor 6a reaches the position read by the line sensor 6b, the switching circuit 23a is turned on by the output of the comparison circuit 27, and the image data Da of the line sensor 6a thereafter is made valid.

Reference numeral 28 denotes an encoder block for detecting the length of the line sensors 6a and 6b along the main scanning direction, that is, a change in the reading width. The encoder block 28 includes the above-described photo interrupter 13.
a, 13b and the rotary plate 14 are provided. The detection signals of the encoders 28a and 28b are supplied to waveform shaping circuits 29a and 29b, respectively, to form detection pulses Sa and Sb. The detection pulses Sa and Sb are supplied to a counter 30 for detecting the sensor expansion / contraction position.

A reset switch 31 is provided in association with the counter 30. As will be described later, the position of the line sensors 6a and 6b after the expansion and contraction is detected by the counter 30. The output of the counter 30 is supplied to the comparison circuit 32. The comparison circuit 32 includes a counter that counts the sampling pulse SH, and compares the count value of the counter with the count value of the counter 30. The switching circuit 23b is controlled by the output signal of the comparison circuit 32.

As shown in FIG. 4, when each of the line sensors 6a and 6b has N pixels,
b, the line sensor 6a slides relatively to
The reading width is expanded or contracted. The minimum value of the reading width is N pixels of the line sensors 6a and 6b alone, and the maximum value is 2N pixels. The reading width can be adjusted in the range of (N to 2N) according to the width of the document. In the overlapped portion indicated by oblique lines in FIG. 4, image data Da of one line sensor, for example, 6a is valid. Therefore, the signals of N pixels read by the line sensor 6a are valid, and the signals of NM (M: the number of pixels of the overlap portion) pixels of the line sensor 6b are valid. The counter 30 generates a value indicating the position NM after the expansion / contraction adjustment. The switching circuit 23b controlled by the comparison circuit 32 includes:
It is necessary to selectively extract valid image data from the line sensor 6b.

As shown in FIG. 5, the rotary plate 14 constituting the encoder 28 has a plurality of slits 33a provided at equal angular intervals along one circle, and equals a plurality of slits 33a along the inner circle. A plurality of slits 33 provided at angular intervals
b are formed. The openings of these slits 33a and 33b overlap in the circumferential direction. The slits 33a and 33b are provided in the photo interrupter 1
3a and 13b respectively. These two photo interrupters 13a and 13b constitute encoders 28a and 28b, respectively.

Since the rotary plate 14 shown in FIG. 5 is used, the detection pulse Sa of the encoder 28a for detecting the slit 33a and the encoder 28 for detecting the slit 33b are provided.
The detection pulse Sb of b is as shown in FIG. As described above, when the lever 3 is operated to move the line sensor 6a and extend the reading width, the rotating plate 14 rotates in the counterclockwise direction ccw. In this case,
As shown in FIG. 6A, the detection pulse Sa is generated with a phase advanced from Sb. When reducing the reading width, the rotating plate 1
4 rotates clockwise cw, and as shown in FIG. 6B, the detection pulse Sb is generated with a phase advanced from Sa.

FIG. 7 shows a more detailed configuration of the counter 30 and the comparison circuit 32 for detecting the expansion / contraction position of the sensor in FIG. In FIG. 7, reference numerals 41a and 41b denote 256-digit counters, respectively, which generate an 8-bit output. Here, the number of pixels N of the line sensors 6a and 6b is set to 2
56. A common reset pulse is generated by the reset switch 31 for the counters 41a and 41b. The counter 41a receives the detection pulse Sb from the encoder 28b supplied to the input terminal 40b as a clock input, and detects the detection pulse Sa from the encoder 28a.
As an enable input. The detection pulse Sa from the input terminal 40a is supplied to the counter 41b as a clock input, and the detection pulse Sb is supplied as an enable input to the counter 41b. While the enable input is at the high level, the counters 41a and 41b
Is incremented by one.

Since the detection pulses Sa and Sb are generated in the phase relationship shown in FIG. 6, the counter 41a outputs the detection pulse Sb to the phase relationship shown in FIG. 6A, that is, when the line sensor is extended. When the count is reduced, the counter 41b counts the detection pulse Sa. Counters 41a and 41b
Is supplied to the subtraction circuit 42. Subtraction circuit 4
2 subtracts the count value of the counter 41b indicating the contraction amount from the count value of the counter 41a indicating the extension amount. Therefore, at the start of expansion / contraction adjustment, the reset switch 31 is turned on, the counters 41a and 41b are reset, and then the lever 3 is slid to perform expansion / contraction adjustment. When the adjustment is completed, the output of the subtraction circuit 42 is output. Indicates the extension adjustment position. The counters 41a and 41b and the subtraction circuit 42 constitute the counter 30 for detecting the expansion / contraction position.

The output signal of the subtraction circuit 42 is supplied to a comparison circuit 43. An 8-bit output of the counter 45 is supplied as the other input of the comparison circuit 43. The counter 45
It is reset by the sampling pulse SH from the input terminal 46, and counts the clock CK from the input terminal 47. The comparison circuit 43 generates a comparison output for controlling the switching circuit 23b. When the output of the subtraction circuit 42 is represented by C and the output of the counter 45 is represented by D, the comparison output is (C> D)
Is a value (for example, high level) for turning on the switching circuit 23b, and a value (for example, low level) for turning off the switching circuit 23b when (C ≦ D).
Since the switching circuit 23b is controlled in this manner,
Only the effective part of the output data Db of the line sensor 6b is output via the switching circuit 23b.

FIG. 8 shows an example of expansion and contraction adjustment of the line sensor. That is, as shown by the solid line, the line sensor 6a
From the initial state where both ends of the lines 6b and 6b are aligned, the line sensor 6a is extended by the distance A as shown by the broken line, and the line sensor 6a is contracted by the distance B as shown by the dashed line. The counter 41a generates a count value corresponding to the increased distance A, and the counter 41b generates a count value corresponding to the reduced distance B. Therefore, the output C of the subtraction circuit 42 corresponds to the length C of the effective portion of the line sensor 6b after the expansion and contraction adjustment. And after the expansion and contraction adjustment,
When the reading operation is performed, the counter 45 counts the clock CK corresponding to the pixel. When the count value reaches C, the counter 45 generates a comparison output that turns off the switching circuit 23b. In this way, only the read output of the length of the effective portion of the line sensor 6b is selected by the switching circuit 23b.

FIGS. 9, 10 and 11 are timing charts showing the operation of this embodiment. The clock CK shown in FIG. 9A and the sampling pulse SH shown in FIG. 9B are supplied from the sensor drive pulse generation circuit 21 to the line sensors 6a and 6b. When the sampling pulse SH goes low, the image information captured by the line sensors 6a and 6b is read out in synchronization with the clock CK. If one line is N pixels, as shown in FIG. 9C,
The signal S1 to SN of each pixel is the output signal SOa or SO
b is sequentially generated from the line sensors 6a and 6b.

FIGS. 10A, 10B, 10C and 1
0D indicates the clock CK, the sampling pulse SH, and the output signals SOa, SOb of the line sensors 6a, 6b shown in FIGS. 9A, 9B, and 9C described above, respectively.
10E is generated from the encoder 24 by the rotation of the rotating plate 17 due to the rotation of the roller 15a. The frequency of the detection pulse Sd corresponds to the speed at which the scanner is moved.
The interval between the rising edge and the falling edge of the detection pulse Sd has a fixed relationship with the scanning distance in the sub-scanning direction.

FIG. 11 shows an operation when the interval between the line sensors 6a and 6b corresponds to four edges of the detection pulse Sd. 11A and 11B show the clock CK and the sampling pulse SH, and FIG.
11D is the image data Da of FIG.
11E is the detection pulse Sd.
It is. Further, FIG. 11F shows ON / OFF of the reed switch 4.
It indicates OFF, and the low level period corresponds to the ON period of the reed switch 4.

While the reed switch 4 is on, the sensor interval detecting counter 26 counts the edges of the detection pulse Sd. When the count value reaches 4, the switching circuit 23a turns on. After this, the line sensor 6
are output via the switching circuit 23a. On the other hand, the image data Db1, Db2,... Of the line sensor 6b are output after the reed switch 4 is turned on, but the switching circuit 23b is controlled by the comparison circuit 32 to control the switching circuit 23b. 23b is turned off and no image data is output, and only image data consisting of pixels of the effective portion (1 to NM) is output.

As described above, the switching circuits 23a,
Although not shown, the image data Da and Db output via 3b are processed by a computer or dedicated hardware for processing the output of the image scanner. That is, the image data Da1 and Db1 are processed as one-line read output, and similarly, Da2 and Db2,.
.. Are processed as one line read output.

In the above-described embodiment, the switching block 23 controls the gate timing of the image data for correcting the interval between the line sensors 6a and 6b and correcting the expansion / contraction position. However, these corrections may be performed by a computer for processing the image data. For position detection, a sensor other than the rotary encoder may be used.

[0029]

According to the present invention, since the reading width of the image sensor can be freely expanded and contracted, the minimum length can be achieved when the image sensor is not used. You can solve the problem you needed.
Further, the height can be reduced as compared with a reduction type using a reduction lens.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of an embodiment of the present invention.

FIG. 2 is a perspective view showing an internal mechanism of one embodiment of the present invention.

FIG. 3 is a block diagram showing signal processing according to one embodiment of the present invention.

FIG. 4 is a schematic diagram used for describing signal processing according to an embodiment of the present invention.

FIG. 5 is a diagram showing a rotary plate used for an encoder for detecting a telescopic position.

FIG. 6 is a waveform diagram of a detection pulse output from an encoder for detecting an extension position.

FIG. 7 is a block diagram showing an electrical configuration for detecting a telescopic position.

FIG. 8 is a schematic diagram used to describe the detection of the expansion / contraction position.

FIG. 9 is a timing chart of one embodiment of the present invention.

FIG. 10 is a timing chart of one embodiment of the present invention.

FIG. 11 is a timing chart of one embodiment of the present invention.

[Explanation of symbols]

 3 Lever for variable reading width 6a, 6b Line sensor 7a, 7b Lens array 13a, 13b, 18 Photo interrupter 14, 17 Rotating plate 23 Switching block 30 Counter for detecting expansion / contraction position

Claims (1)

(57) [Claims] A first and a second line sensor slidably arranged in a state where one of the first and second line sensors is parallel to each other and one has an overlapping portion with respect to the other; An image reading apparatus comprising: means for detecting a positional relationship between the first and second line sensors so as to validate one of the read signals of the first and second line sensors.