JPH0937039A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read an original corresponding to a selected reading mode by arranging a CCD for reading the black part of the original and a multicolor contact sensor for reading the color part of the original, and changing the clock pulse frequency of the CCD. SOLUTION: A CCD 10 for reading the black part of the original and a multicolor contact sensor 13 for reading the color part of the original are arranged in the same direction to an original feeding path, and one side or both the sides of the original are read corresponding to the (monochromatic/ multicolor) reading mode. Then, the clock pulse frequency not on the side of the multicolor contact sensor 13 but on the side of the CCD 10 is changed separately for the case of using only the CCD 10 and the case of using both the multicolor contact sensor 13 and the CCD 10. Namely, since the storage time of the CCD 10 is varied so that the storage time of the CCD 10 can be reduced rather than the storage time of the contact sensor 13, the optimum original reading can be performed corresponding to the reading mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device suitable for reading a monochrome / multi-color document.

[0002]

2. Description of the Related Art For example, in a device disclosed in Japanese Patent Laid-Open No. 3-240361, a contact type image sensor (hereinafter referred to as a contact sensor) is provided on one side of a document feeding path, and a reduction optical system CCD linear is provided on the opposite side. Image sensor (hereinafter,
By arranging a CCD), the images on both sides of the original can be read simultaneously by passing the document once, and by placing a contact sensor on the upper side of the conveyance path and a CCD on the lower side, the conveyance path can be easily opened. It is configured to easily perform jam removal work. With such a configuration, operability and maintainability are improved, and space saving and cost reduction are realized. In this apparatus, since the contact sensor and the CCD are used to simultaneously read the image information on the front and back of the document at the same document conveyance speed, the clock pulse frequency is determined according to the contact sensor having the slow clock pulse frequency due to the characteristics of the sensor. . Further, when the CCD is used to read only the front side of the document, the clock pulse frequency is similarly determined according to the contact sensor. Further, it is conceivable to construct a document reading device corresponding to a monochrome / multicolor document by using a multi-color contact sensor instead of the contact sensor. In such a double-sided original reading device, when a monochrome single-sided original is read by a CCD, for example, in order to avoid a delay in reading time,
It is necessary to consider the clock pulse frequency to match the CCD.

[0003]

In the above prior art, C
Since the clock pulse frequencies of the CD and the contact sensor are not switched, there is a problem that the original reading time is delayed when only the front side of the original is read by the CCD. Furthermore, in order to realize a device that can handle multi-color originals using a multi-color contact sensor,
Depending on the reading mode, it is necessary to switch the sensor driving clock, correct the density, switch the sub-scanning direction transport speed, and the like. An object of the present invention is to provide a multi-color contact sensor and CCD, and a selected reading mode (monochrome / multi-color).
An object of the present invention is to provide a document reading device capable of reading a document according to the above. In addition to the above purpose, it is also an object to set an arbitrary image quality according to the reading mode of the original.
In addition to the above-mentioned object, another object is to perform optimum document reading by changing the scanning speed in the sub-scanning direction according to the reading mode of the document. Further, in addition to the above-mentioned object, another object is to make the accumulation time of the CCD variable according to the reading mode of the original and perform the optimum original reading so that the reading time is not delayed even when only the CCD is used for reading. . Another object of the present invention is to provide a double-sided document reading device that includes a multi-color contact sensor and a CCD and can read a double-sided document according to a selected reading mode (monochrome / multi-color).

[0004]

In order to achieve the above object, the invention according to claim 1 is for reading a CCD for reading a black portion of a document and a color portion of a document in the same direction with respect to a document feeding path. It is characterized by arranging a multi-color contact sensor and performing reading according to the selected reading mode. In addition to the above, the invention according to claim 2 is characterized in that the γ table of the read image processing unit is changed in accordance with the reading mode of the original to obtain an arbitrary image quality. In addition to the above, according to the third aspect of the invention, depending on the reading mode of the original, the sub-scanning is performed so that the original conveying speed is increased when reading a monochrome original and the original conveying speed is decreased when reading a multi-color original. It is characterized by performing optimum document reading according to the reading mode by changing the scanning speed in the direction. In addition to the above, the invention according to claim 4 is, in addition to the above, according to the reading mode of the document, for example, when reading a monochrome document, CC
Change the clock pulse frequency of D so that the CCD accumulation time is shorter than the contact sensor accumulation time.
The characteristic is that the document reading is optimally performed according to the reading mode by making the accumulation time of the variable. Also,
According to a fifth aspect of the present invention, the multi-color contact sensor is arranged on the side opposite to the CCD with respect to the original feeding path, and the CCD clock pulse frequency is changed according to the original reading mode to change the accumulation time of the CCD. Is characterized in that a double-sided original is read.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a CC for reading a black portion of a document in the same direction with respect to the document transport path.
D and a multi-color contact sensor for reading the color portion of the original are arranged, or a multi-color contact sensor for reading the color portion of the original is provided on the original feeding path opposite to the CCD for reading the black portion of the original. It is arranged on the side, and one-sided or two-sided originals are read according to the reading mode (monochrome / multi-color).
Further, when reading a document, (1) when only CCD is used (for single-sided monochrome document), and (2) when both multi-color contact sensor and CCD are used (for color or double-sided document). The clock pulse frequency is switched on the CCD side instead of the multi-color contact sensor side. In the case of (1), regardless of the characteristics of the multi-color contact sensor, the clock pulse frequency is increased according to the characteristics of the CCD, so that only the CCD is used in the reading device using the CCD and the multi-color contact sensor. When used, the original reading speed can be increased. Note that the density correction table (γ table), the conveyance speed in the sub-scanning direction, and the like can also be changed according to the reading mode.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of a document reading apparatus according to an embodiment of the present invention, which is applied to a sheet scanner, but is also applicable to a book scanner. FIG. 2 is a block diagram showing the configuration of the device shown in FIG. This corresponds to the invention described in claim 1. As shown in FIG. 1, the documents 1 stacked on the document table 2 are fed by the document feed roller pair 3. At this time, the first side of the originals is stacked and fed from below, and in the case of a monochrome original, the originals 1 placed on the original table 2 are stacked.
Is transported by the pair of document feed rollers 3 onto the first scanner contact glass 6 along the document transport guide plate 4. The original 1 is placed on the contact glass 6 by the first scanner (shading plate 5, mirror 8, lens unit 9,
After the first surface of the original is read by the CCD 10, the printed circuit board 11 and the like), the original is ejected to the ejection tray 15 by the original ejection roller pair 14. On the other hand, when the original 1 is a two-color or multi-color original, the first one is placed on the contact glass 6.
After reading the first surface of the original with the scanner, the original 1 is conveyed to the shading plate 12 and the position of the multi-color contact sensor 13 of the second scanner, and the image information of a portion other than black of the original 1 is read and then discharged. In FIG. 2, reference numeral 20 denotes a first scanner including the CCD 10 and the like, which reads a black portion of a monochrome original and a multi-color original. 21 is a multi-color contact sensor 13
And the like, which reads a portion other than black of a multi-color original. Further, 22 is a recording unit including a plotter or the like for outputting the read content, 23 is an encoding / decoding unit for encoding the read data of the transmission document and decoding the received image information, and 24 is a communication control unit. Reference numeral 25 is a modulation / demodulation circuit section (modem), 26 is a communication line such as a public line, 27 is a system control section for controlling the entire apparatus, and particularly for controlling reading of monochrome / multi-color originals, 28 is a ten-key pad, operation buttons, etc. Become the operating part,
Reference numeral 29 is a display unit including a display device for displaying the device status, 30 is an image memory for temporarily storing transmission / reception data, and 31 is an interface unit (I / O IF).

Next, a density correction method using the γ table, which is applied to the document reading apparatus of this embodiment, will be described. This corresponds to the invention described in claim 2. In this embodiment, a plurality of γ tables are set according to the reading mode (monochrome / multi-color). FIG. 3 (a)
The γ table (1) shown in (1) is set so that the density of black is emphasized in order to obtain the density of the black portion of the input data, and the density is reduced in the area of the input data to prevent the background stain. It is a thing. Further, the γ table (2) shown in FIG. 3 (b) is set more linearly with smaller density correction as in the γ table (1). Further, in the γ table (3) shown in FIG. 3C, in order to obtain the density of the solid portion in the color portion, the dark portion is emphasized, and the light portion is emphasized in order to prevent blurring. Is set to. At the time of reading an original, as shown in FIG. 4, if the original to be read is a monochrome original (steps 1 and 2), the γ table (1) is set and the original is fed (steps 3 and 4). CCD1 of one scanner 20
At 0, a monochrome original is read (step 5), and the original is ejected (steps 6 and 7). When reading a multi-color original (step 8), C of the first scanner 20 is used.
The γ table (2) is set on the CD 10 side, the γ table (2) is set on the multi-color contact sensor 13 side of the second scanner 21 (step 9), and the document is fed (step 10). Then, the CCD of the first scanner 20
The image data from 10 is subjected to density correction using the γ table (2) (step 11), and the second scanner 2
The image data from the multicolor contact sensor 13 of No. 1 is density-corrected using the γ table (3) (step 12), and the original is ejected (step 13). In this way, it is possible to set the optimum γ tables for monochrome / multi-color originals. The reading mode is set by the operation unit 28 or is set by another device via the line 26.

Next, a method of changing and changing the document conveying speed in the sub-scanning direction (control method when a two-phase stepping motor is used) according to the reading mode of this embodiment will be described. This is the CCD 10 and the multi-color contact sensor 13
It depends on the clock speed difference. That is, when a monochrome original is read by the CCD 10 of the first scanner, CC
The reading operation is performed by the pixel clock according to the specification of D, but when reading is performed by using the CCD 10 and the multi-color contact sensor 13 at the same time like a multi-color original,
It is necessary to perform the reading operation according to the driving condition of the contact sensor having the slow clock speed. Therefore, the main scanning direction 1
It is necessary to change the document conveyance speed in the sub-scanning direction according to line = accumulation time. Incidentally, this corresponds to the invention described in claim 3. FIG. 5 is a diagram showing a configuration of a driver circuit of a two-phase stepping motor in one embodiment of the present invention, and FIG. 6 is an excitation timing chart thereof. In FIG. 5, reference numeral 51 is a two-phase stepping motor driver, and 52 is a two-phase stepping motor, which inputs a phase excitation pattern signal corresponding to each motor phase from a four-phase input section (A, A, B, B). Stepping motor 52
Is rotated by one step angle in one clock, so that if the number of clocks per unit time is multiplied by four, the rotation angle will be multiplied by four and the document conveying speed will also be multiplied by four. Therefore, the document conveyance speed in the sub-scanning direction is switched and changed at the timing of the phase excitation pattern input signal shown in FIGS. 6A and 6B so as to correspond to the reading by the CCD 10 or the multi-color contact sensor 13. Note that FIG. 6A is a timing chart when the document transport speed is V ₀ with two-phase excitation, and FIG. 6B is a timing chart when the document transport speed is 4V ₀ with two-phase excitation. With such a configuration, as shown in FIG.
For monochrome originals (steps 20 and 21), the original conveying speed in the sub-scanning method is set to 4V ₀ (step 2).
2) A document is fed, the CCD 10 reads it (steps 23 and 24), and the document is discharged (step 2).
5, 26). For color originals (Step 2
7) The document feeding speed in the sub-scanning method is set to V ₀ (step 28), the document is fed and the CCD 10 and the multi-color contact sensor 13 sequentially read (steps 29 to 31), and the document is ejected. (Step 32). The reading mode is set by the operation unit 28 or is set by another device via the line 26.

Next, C according to the reading mode of the present embodiment
A method of setting drive conditions for the CD 10 and the contact sensor 13 will be described. Incidentally, this corresponds to the invention described in claim 4. In this embodiment, as shown in FIG. 1, the CCD 10 and the multi-color contact sensor 13 are arranged in the same direction with respect to the document conveyance path. When reading a multi-color document, the contact sensor drive conditions are set. It is necessary to read according to. That is, normally
For the light source of the contact sensor, an LED or the like is often used for downsizing, but since the amount of light is small, it is necessary to increase the accumulation time in order to obtain an output signal of a certain size. Further, since one contact sensor is composed of a plurality of elements, there are variations in sensitivity and ACDC component between elements, and if the accumulation time is short, variations in the output signal become large. Further, the staggered contact sensor requires the transfer time of the line memory for correcting the spatial deviation of the reading position due to the chip arrangement. For this reason, the standard value of the pixel clock is 3 to 4 times faster in the CCD than in the contact sensor. Therefore, in this embodiment, the driving conditions of the CCD 10 and the multi-color contact sensor 13 are made variable to the optimum set values according to the selected image reading mode (monochrome / multi-color). First, FIG. 8 shows a timing chart of the sensor drive clock and the sensor output. FIG. 8A is a timing chart of CCD drive clock (SH, PH, RS) and CCD output (OS), and FIG. 8B is a multi-color contact sensor drive clock (ST, PHCCD, RH ₁ , RS) and contact. It is a timing chart of a sensor output (OS). FIG.
In FIG. 1, SH (shift pulse) and ST (start pulse) are pulses for driving the shift electrode which passes when the signal charge accumulated in the photosensitive portion is transferred to the transfer portion.
It occurs for each line. PH (clock pulse), P
HCCD.PH ₁ (clock pulse) is a pulse for driving the transfer unit that transfers the signal charge generated in the photosensitive unit to the output unit. Further, RS (reset pulse) is a drive pulse for returning the output section, which converts the signal charge transferred from the transfer section to a voltage, to the initial state for detecting the signal charge. In this embodiment, the CCD driving clock is 3 times faster than the multi-color contact sensor driving clock depending on the reading mode.
Change the clock pulse frequency to be ~ 4 times faster. At the time of reading the original, as shown in FIG. 9, in the case of a monochrome original (steps 40 and 41), the pixel clock is set to 4 times (4f ₀ ) (step 42), the original is fed (step 43), CCD 10 of the first scanner 20
Is read (step 44), and the read original is discharged (steps 45 and 46). In the case of a multi-color original (step 47), the pixel clock is set to f ₀ in accordance with the multi-color contact sensor 13 (step 48), the original is fed (step 49), and first the first scanner 20 operates. After the black portion of the original is read by the CCD 10 (step 50) and then the portion other than black is read by the multi-color contact sensor 13 of the second scanner 21 (step 51), the original is ejected (step 5).
2). The reading mode is set by the operation unit 28 or is set by another device via the line 26.

Next, a double-sided document reading apparatus to which the above embodiment is applied will be described. Incidentally, this corresponds to the invention described in claim 5. In the present embodiment, as shown in FIG. 10, the CCD 1 is provided on the front surface reading side with respect to the original conveyance path.
0 is arranged, and the multi-color contact sensor 13 is arranged on the opposite side of the CCD 10, that is, on the back surface reading side. That is, the mounting positions of the scanner shading plate 12 and the multi-color contact sensor 13 are different from those of the embodiment shown in FIG. The multi-color contact sensor 13 is used to read image data on the back surface of a monochrome original. In addition,
The operation of the other components is the same as in the above embodiment.

[0011]

According to the first aspect of the invention, the CCD for reading the black portion of the original and the multi-color contact sensor for reading the color portion of the original are arranged in the same direction with respect to the original conveying path. Therefore, the reading can be performed according to the reading mode (monochrome / multi-color) arbitrarily selected. According to the second aspect of the present invention, the γ table of the read image processing unit is changed according to the reading mode of the original, so that an arbitrary image quality can be obtained.
According to the third aspect of the invention, since the document conveying speed, that is, the scanning speed in the sub-scanning direction is changed according to the document reading mode, optimum document reading can be performed according to the reading mode. According to the fourth aspect of the present invention, since the accumulation time of the CCD is variable according to the reading mode of the original, it is possible to perform optimal reading of the original according to the reading mode. According to the fifth aspect of the invention, since the multi-color contact sensor can be mounted on the side of the original conveyance path opposite to the CCD, it is possible to read a double-sided original according to the reading mode.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a document reading device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a document reading device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a γ table according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a γ table setting method according to an embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a driver circuit of a two-phase stepping motor in one embodiment of the present invention.

FIG. 6 is a timing chart of a phase excitation pattern input signal of the two-phase stepping motor according to the embodiment of the present invention.

FIG. 7 is a flowchart showing a method of controlling a document transportation speed in the sub-scanning direction when using a two-phase stepping motor in one embodiment of the present invention.

FIG. 8 is a timing chart of a sensor drive clock and output in one embodiment of the present invention.

FIG. 9 is a timing chart showing a method of setting a clock pulse frequency according to an embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a configuration of a double-sided document reading device according to an embodiment of the present invention.

[Explanation of symbols]

1: original document, 2: document table, 3: document feed roller pair, 4: document conveyance guide plate, 5: first scanner shading plate,
6: first scanner contact glass, 7: xenon lamp, 8: first scanner mirror, 9: first scanner lens unit, 10: CCD, 11: printed circuit board, 12:
Second scanner shading plate, 13: multi-color contact sensor, 14: document discharge roller pair, 15: discharge table.

Claims (5)

[Claims] 1. In a document reading device for reading image information of a document by a photoelectric conversion element including a CCD linear image sensor of a reduction optical system and a contact type image sensor of an equal-magnification optical system, a document feeding path for feeding a document is described. A CCD linear image sensor for reading the black portion of the original and a multi-color contact sensor for reading the color portion of the original are arranged in the same direction, and monochrome and color originals are read according to the reading mode. Document reading device. 2. The document reading apparatus according to claim 1, wherein the γ table of the image processing unit is changed according to the reading mode of the document. 3. The original reading device according to claim 1, wherein the scanning speed in the sub-scanning direction is changed according to the reading mode of the original. 4. The storage time of the CCD linear image sensor is arbitrarily changed by changing the clock pulse frequency of the CCD linear image sensor according to the reading mode of the original. 1. The document reading device according to 1. 5. In an original reading device for reading image information of a double-sided original by a photoelectric conversion element including a CCD linear image sensor of a reduction optical system and a contact type image sensor of an equal-magnification optical system, an original feeding path for feeding an original is provided. On the other hand, a multi-color contact sensor for reading the color part of the original is placed on the opposite side of the CCD linear image sensor for reading the black part of the original, and the clock pulse frequency of the CCD linear image sensor is set according to the reading mode of the original. CC by changing
A double-sided document reading device characterized in that the storage time of the D linear image sensor is arbitrarily changed.