JPH07177319A - Color image reader - Google Patents

Abstract

PURPOSE:To provide a color image reader capable of shortening time from the lighting of an original illuminating lamp up to the start of reading and executing high speed scanning operation. CONSTITUTION:At the time of outgoing scanning operation (area 115) including an unstable area in the light quantity of an original illuminating lamp after starting prescanning operation by means of an optical system, the existence of an original, the position and the size of original are detected, and at the time of incoming scanning operation (area 116) in which the light quantity of the lamp is stabilized, original color information is read out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading apparatus which illuminates an image original with light and reads a color image by the reflected light.

[0002]

2. Description of the Related Art Generally, in a color image reading apparatus which illuminates an image original with an image illumination lamp and reads a color image by the reflected light, various originals are scanned before scanning for color image reading. Pre-scanning is performed to read information (for example, presence / absence of a document, document size, document position) and image color information. Conventionally, the reading operation of document information and color information performed at the time of the prescan has been performed at the time of the prescan forward movement operation.

In the prescan, the document information such as the document size can be read even when the light amount of the image illumination lamp is unstable, but it is sufficiently controlled to read the color information of the document image. A stable amount of light is required. Therefore, in order to start the reading operation during the pre-scan, it is necessary to wait until the light amount becomes stable.

[0004]

However, in the method of waiting until the light quantity of the original illumination lamp is stabilized in order to start the reading operation at the time of prescan as in the above-mentioned conventional example, the starting point of the reading operation is However, there will be a delay until the amount of light stabilizes. Therefore, there is a problem that there is much waste in time, the sequence time of the device becomes long, and the speeding up of the device is hindered.

The present invention has been made in order to solve the above problems, and provides a color image reading apparatus capable of performing a high-speed scanning operation by shortening the time from the lighting of a document illumination lamp to the start of reading. The purpose is to

[0006]

In order to achieve the above-mentioned object, the present invention is a color image reading apparatus for irradiating an image original with light and reading a color image by the reflected light thereof. In a color image reading apparatus having a reading movable portion for performing an operation of reading an image original, and performing scanning for reading information of the image original by the reading movable portion, the image original is turned on in synchronization with the start of the forward operation of the scan. A document illumination lamp that irradiates light onto the document and turns off in synchronism with the end of the backward scan operation of the scan, and a document information detection unit that detects readable document information by the unstable light amount immediately after the original illumination lamp is turned on during the forward scan operation of the scan. And a color information reading unit for reading color information of the image original at the time of the scan return path operation. It is an.

[0007]

According to the above construction, in the reciprocating operation for scanning, the original information detecting means performs the operation of detecting the original information other than the color information by the original information detecting means under the unstable light quantity immediately after the original illumination lamp is turned on. During the returning operation, the color information reading means performs the color information reading operation under the stable light amount of the document illumination lamp.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a timing chart for explaining a difference in system between a prescan operation performed by a color image reading apparatus according to an embodiment of the present invention and a prescan operation performed by a conventional color image reading apparatus. FIG. 1A shows a conventional example, and FIG. 1B shows this example.

In both figures, 101 and 111 show the relationship between the pulse (pps) of the pulse motor for operating the optical system and time, and 102 and 112 show the relationship between the light quantity of the document illumination lamp and time. Further, t1 and t1 'are the points of time when the irradiation light of the original illumination lamp is applied to the front end of the original image in the pre-scan forward operation, and t2 and t2' are the original light of the original illumination lamp in the pre-scan forward operation. This is the point of time when the rear edge is irradiated. That is, the shaded portion 1
Reference numerals 05 and 115 represent times during which the document illumination lamp illuminates the document image area during the prescan forward operation. Also, t
Reference numeral 3 denotes a time point when the light emitted from the document illumination lamp is applied to the front end of the document image in the prescan return path operation, and t4 is a time point when the light emitted from the document illumination lamp is applied to the rear edge of the document image in the prescan return path operation. The shaded area 116 indicates the time during which the document illumination lamp illuminates the document image area during the scan return path operation. Further, te indicates the end point of the prescan by the conventional method, and te 'indicates the end point of the prescan by the color image reading apparatus according to the present embodiment.

The conventional prescan is shown in FIG.
As shown in (a), the reading of the image front end is started at time t1 after the light amount of the document illumination lamp is stabilized, and the image rear end is read from the reading start time t1 when the image front end is read. The image presence / absence, the document position, the document size, and the color information are read at time 105 until the trailing edge time t2. After that, the returning operation was performed, and the prescan was completed at the time point te.

On the other hand, in this embodiment, as shown in FIG. 1B, the original position and the original size are read during the forward scan operation including the area where the light amount of the original illumination lamp is unstable after the start of the prescan operation. To be This is because the document position and the document size can be detected even if the light amount of the document illumination lamp is not stable. Since the light amount of the document illumination lamp is already stable during the scan return path operation, the document color information is read, and the prescan ends at time te ′. In this way, the pre-scan other than the color information reading operation, which requires a stable light quantity, is not used as the waiting time until the light quantity of the document illumination lamp is stabilized, and the entire pre-scan is performed. The time required for the operation is defined as the prescan end time te ′ in this embodiment.
From the conventional prescan operation end time te to Δ
It is possible to shorten by t Δt = te−te ′.

Next, the color image reading apparatus capable of performing the prescan in a shorter time as compared with the conventional one as described above will be described in detail below.

FIG. 2 is a block diagram showing the schematic arrangement of the color image reading apparatus according to this embodiment.

This apparatus includes a document table glass 202 on which the document 201 is placed, and a document 201 placed on the document table glass 202.
A document table cover 203 for holding down the document table is provided below the document table lamp 203 and the first mirror table 204.
, Second mirror base 205, imaging lens 206, R
Color CCD (fixed image element) line sensor (hereinafter referred to as line sensor) 207 having three color separation filters (not shown) of (red), G (green), and B (blue) 207
And an image processing circuit 208. A mirror 210 is mounted on the first mirror stand 204,
Mirrors 211 and 212 are fixed to the second mirror base 205, respectively. The image processing circuit 208 has a CP
The U 213 is connected, and its operation is controlled by the CPU 213. Further, the original illumination lamp 209 is connected to the first and second mirror bases 2 via a drive circuit (not shown).
Reference numerals 04 and 205 denote the CPU 21 via a drive mechanism (not shown).
3, the operation is controlled.

The CPU 213 outputs the signal S1 indicating that the optical path is in the backward path operation at the time of the backward path operation of the optical system, and at the timing described later, the video clock signal VCL.
K, a video enable signal VE, and a reference signal CSO necessary for processing in the slice level determination circuit are output.

Further, the first mirror table 204 and the document illumination lamp 209 are twice as fast as the second mirror table 205 and the document 201 placed on the document table glass 202.
To scan.

Document 2 placed on the platen glass 202
01 is illuminated by a document illumination lamp 209. The reflected light is guided by the mirrors 210, 211, 212 and forms an image on the line sensor 207 via the imaging lens 206. The reflected light is converted into full color information by the color separation filter of the line sensor 207 as R component, G component,
After being decomposed into the B component, it is sent to the image processing circuit 208. By repeating the electrical scanning (main scanning) by the line sensor 207 and the mechanical scanning (sub-scanning) by the document illumination lamp 209 and the mirrors 210 to 212, the image information of the entire region of the document is read. In the image processing circuit 208, the input image information is subjected to predetermined image processing and output as an image signal to a printer or the like connected to the outside.

FIG. 3 is a block diagram showing a schematic configuration of the image processing circuit 208. The image processing circuit 208 is an analog / digital conversion circuit (hereinafter, referred to as an A / D conversion circuit) that converts an input analog signal into a digital signal.
302, a shading correction circuit 303 that performs shading correction, a slice level determination circuit 304 that determines a slice level of an image signal used for a document position or document size detection operation described later, a main scanning address counter 305, and a sub-scanning address counter 305. Scan address counter 306
And an image color information recognition circuit (hereinafter referred to as ACS circuit) 3
07 and a document position / size detection circuit 308. Each component is connected to and controlled by the CPU 213.

The slice level determination circuit 304 is reset by the video clock signal VCLK to start its operation, and the slice level signal C output from the CPU 213.
The slice level is determined based on SO. The determined slice level is input to the document position / size detection circuit 308 and used to detect the position, size, etc. of the document, as described later.

The main scanning address counter 305 is a CPU
An address signal Ax corresponding to an address in the main scanning direction X on the platen is counted by counting the video clock signal VCLK output from the CPU 213, which is initialized by the video enable signal VE output from the CPU 213. Is output. In addition, the sub-scanning address counter 306 detects the CPU from the original table reference position SP described later.
By counting the video enable signal VE output from 213, the address signal Ay corresponding to the address on the document table in the sub-scanning direction Y is output. Address signals output from both address counters 305 and 306 are input to a document position / size detection circuit 308, respectively.

The ACS circuit 307 is a circuit for recognizing whether a document image is a color image or a monochrome image. The ACS circuit 307 is activated by a signal S1 output from the CPU 213 during the prescan return path operation of the optical system and recognizes color information of the image. Perform processing to That is, the ACS circuit 307 is controlled so as to operate only during the return path operation in which the signal S1 is input during the prescan.

When the prescan forward path operation is started, the image information of the original 201 is converted into image signals (R, G, B).
It is input to the A / D conversion circuit 302 via the line sensor 207. Here, the input image signal (R, G, B)
After being converted into a digital signal, the shading correction circuit 303 corrects variations in the output of the line sensor 207 and the output of the document illumination lamp 209 included in the image signal. The image signals (R, G, B) subjected to the shading correction are input to the slice level determination circuit 304 and the ACS circuit 307. The slice level determination circuit 304 determines a slice level for recognizing the image signal based on the slice level signal CSO input from the CPU 213 and the image signal (R, G, B). The determined slice level is used as a slice level signal SL together with the main scanning address signal Ax output from the main scanning address counter 305 and the sub scanning address signal Ay output from the sub scanning address counter 306 to detect the document position / size. It is input to the circuit 308. In the document position / size detection circuit 308, the input signal S
Based on L, Ax, and Ay, the document position and document size are determined as described later, and are output as a document position address signal DAP and document size signal Ds, respectively.

At this time, since the signal S1 is not input from the CPU 213 to the ACS circuit 307 to which the image signal (R, G, B) after shading correction is input,
The operation of determining the color information of the original is not performed.

Next, when the pre-scan returning operation is started, the shading-corrected image signals (R, G, B) are input to the slice level determining circuit 304 and the ACS circuit 307 as in the above-described pre-scan forward operation. The slice level signal SL determined by the slice level determination circuit 304 is applied to the main scanning address counter 3
05 and the address signals Ax and Ay output by the sub-scanning address counter 306 are input to the document position / size detection circuit. At this time, the ACS circuit 307 has been activated by the signal S1 output by the CPU 213 in response to the backward movement operation, and it is determined whether the original image is a color original or a monochrome original by a method described later, The result is output as the ACS signal ACS.

The document detecting operation, the document size discriminating operation, the document position detecting operation, and the document color information reading operation which are performed in the prescan in the above structure will be described below.

First, a document detecting operation for detecting the presence or absence of a document will be described with reference to FIG. FIG. 4 is a diagram showing the arrangement of optical systems for explaining the document detection operation.

The lower surface of the original table cover 203 is mirror-finished so that light is not irregularly reflected. The original illumination lamp 209 is composed of two illumination lamps, and is arranged so that the light emitted from one illumination lamp is reflected by the lower surface of the original table cover 203 toward the other illumination lamp. The mirrors 210 to 212 guide the reflected light of the document illumination lamp 209 to the line sensor 207. As shown in FIG. 4A, the platen glass 2
If there is no original on 02, the light emitted from the original illuminating lamp 209 does not diffusely reflect.
Does not receive the reflected light of the document illumination lamp 209. At this time, the portion of the line sensor 207 that does not receive the reflected light (the portion where there is no document) is determined by the document position / size detection circuit 308 to be a black portion. Further, as shown in FIG. 4B, when there is a document 201, the document illumination lamp 209
The irradiation light of the laser light is diffusely reflected by the original 201 and is reflected by the mirror 210.
The light is guided to the line sensor 207 by ˜212. Therefore, the presence / absence of a document can be detected depending on whether or not the reflected light is guided to the line sensor 207.
At this time, the portion of the line sensor 207 that receives the reflected light of the original 201 is determined by the original position / size detection circuit 308 to be the portion where the original exists.

Next, the document size determining operation and the document position detecting operation will be described with reference to FIGS. In FIGS. 5 and 6, S is the original platen glass 202, M, M ′.
Is the original 201 placed on the original table glass 202.
An arrow X indicates a main scanning direction, an arrow Y indicates a sub scanning direction, and SP indicates a document table reference position of the document table glass 202.

When the originals M and M'placed in this way are scanned during the forward scan operation of the optical system, the original position / size detection circuit 308 is the same as the original presence / absence detection operation described above.
Thus, it is determined that the portion receiving the reflected light from the original 201 is the original M or the original M ′. The originals M and M ′ are white originals.

In FIG. 5, for scanning in the main scanning direction, the output of the line sensor 207 first changes from a black image to a white image, and the document coordinate Xmin closest to the starting point of main scanning and the line sensor 207. The output of is changed from the white image to the black image last, and the document coordinate Xmax farthest from the starting point of the main scanning is detected. For scanning in the sub-scanning direction, the position Ymin at which the output of the line sensor 207 first changes from a black image to a white image and the position at which the output of the line sensor 207 finally changes from a white image to a black image. Ymax is detected. Then, the coordinates P1 (Xmin, Ymin) are recognized as the document position, and the coordinates P1 (Xmin, Ymin) and the coordinates P2 (Xm) are recognized.
A rectangle whose diagonal is a line connecting (ax, Ymax) is recognized as the document size.

Further, as shown in FIG. 6, even when the original M'is placed obliquely, as in the case of FIG. 5, line scanning is performed in the main scanning direction. Sensor 2
07 output first changed from black image to white image,
The document coordinate Xmin ′ closest to the starting point of main scanning, and the document coordinate Xmax farthest from the starting point of main scanning at which the output of the line sensor 207 finally changed from a white image to a black image.
′ Is detected, and for scanning in the sub-scanning direction, the position Ymin ′ at which the output of the line sensor 207 first changes from the black image to the white image, and the output of the line sensor 207 finally changes from the white image to black. Position Ymax changed to image
'Is detected. Then, the coordinate P3 (Xmin ', Y
min ′) is recognized as the document position, and the coordinate P3 (Xm
in ', Ymin') and P4 (Xmax ', Ymax
A rectangle having a diagonal line connecting the line ′) is recognized as the document size.

The document position / size detection circuit 308 performs the document position / document size detection operation. FIG. 7 is a block diagram showing a schematic configuration of the document position / size detection circuit 308. In the figure, a document position / size detection circuit 308 includes flip-flop circuits (hereinafter referred to as F / F) 701, 702, and 704 to 71.
3, an AND circuit 703, and arithmetic circuits 714 and 715.

The image signals (R, G, B) corrected by the shading correction circuit 303 are input to the terminal A of the F / F 702, and at the same time, the slice output from the slice level circuit 304 via the F / F 701. The level signal SL is input to the terminal B of the F / F 702. F / F70
2, the slice level signal SL input from the terminals A and B is compared with the image signals (R, G, B), and based on the result, it is determined whether the document area is currently scanned.
Alternatively, it is determined whether the area is a non-document area. That is, the above-described discrimination between the black image and the white image is performed by the image signals (R, G,
This is performed depending on whether the signal level in B) is higher than the slice level. If the image signal level is higher than the slice level SL, it is determined that the area is the original area, and F / F7
A document detection signal DA is output from 02.

The original detection signal DA is supplied to the AND circuit 70.
Input to 3. In the AND circuit 703, the original detection signal DA is output as a DAC signal in synchronization with the video clock signal VCLK sent from the CPU 213.
The DAC signal is input to the F / F 704 and F / F 709.

The main scanning address counter 305 inputs the main scanning address signal Ax to the F / F 704, and the address of the original area in the main scanning direction is output to the circuit in the next stage in response to the input of the DAC signal. It

F / Fs 705 and 706 are circuits for obtaining the minimum address value from the address input from the F / F 704. The maximum address value is preset in the F / F 706 at the start of prescan, and the preset value is compared with the input address in the F / F 705. Here, when the address is smaller than the preset value, this address value is stored in the F / F 706, and the last input address value is F / F as the minimum address value Xmin.
It is stored in F706.

F / Fs 707 and 708 are circuits for obtaining the maximum address value from the address input from the F / F 704. The F / F 708 has been cleared to zero at the start of pre-scan, and the address and F / F 708 input
The value in is compared by the F / F 707. When the input address is larger than the value in the F / F 708, the input address is stored in the F / F 708, and the stored value is sequentially compared with the input address to store a large address value. . By repeating the comparison and storage of the address values in this manner, the maximum address Xmax of the main scanning original Ax is finally stored in the F / F 708.

As for the sub-scanning address signal Ay, the minimum address value Ymin and the maximum address value Ymax of the sub-scanning address are detected by the F / Fs 709 to 713 as in the above-described main scanning address, and the F / F 71 is respectively set.
1, 713.

A document position address signal DAP (Xmin, Ymin) is generated from the main-scanning minimum address value Xmin and the sub-scanning minimum address value Ymin thus detected.

Further, in the arithmetic circuit 714, the detected main scanning minimum address value Xmin and main scanning maximum address value X are detected.
The calculation shown in Expression (1) is performed using max and the arithmetic circuit 715 detects the detected minimum sub-scanning address value Ymi.
The calculation shown in Expression (2) is performed using n and the sub-scanning maximum address value Ymax, and the document size signal Ds (Dsx, Dsy) is obtained from these calculation results.

Dsx = Xmax-Xmin (1) Dsy = Ymax-Ymin (2) The document position address signal DAP (Xmin, Ymin) and the document size signal Ds (Dsx, Dsy) are stored in the CPU 2.
13 or an externally connected printer or the like.

Next, the document color information reading operation performed during the pre-scan return path operation will be described with reference to FIG. As described above, this operation is performed by the ACS circuit 307 activated by the S1 signal output from the CPU 213 in response to the prescan return path operation.

FIG. 8 is a block diagram showing a schematic structure of the ACS circuit 307. In the figure, an ACS circuit 307
Is a flip-flop circuit (hereinafter referred to as F / F) 80
1, a maximum value calculation circuit 802, and a minimum value calculation circuit 803
And an image type discrimination circuit 804 in which a lookup table is stored in advance.

Image signal after shading correction (R,
G, B) are input to the F / F 801, and the AN shown in FIG.
In response to the DAC signal output from the D circuit 702, that is, only the image signal in the original area is input to the maximum value calculation circuit 802 and the minimum value calculation circuit 803. The maximum value arithmetic circuit 802 extracts the maximum value Max (R, G, B) from the input image signals (R, G, B), and the minimum value arithmetic circuit 803 extracts the minimum value Min (R, G, B). ) Is extracted. Maximum value Max (R, G, B) and minimum value Min
(R, G, B) is input to the image type discrimination circuit 804. In the image type discrimination circuit 804, the maximum value Max (R,
G, B) and the minimum value Min (R, G, B) are respectively determined to be within the area 901 or the area 902 shown in FIG.

During the backward operation, the original position / size detection circuit 308 determines the original position and size as in the forward operation. The output signals DAP and Ds at this time are output by the CPU 213. It is invalidated.

FIG. 9 is a diagram showing an example of a discrimination area diagram for discriminating between a monochrome image and a color image, which is stored in a lookup table in the image type discrimination circuit 804. In the figure, an area 901 is a monochrome image area,
Area 902 shows a color image area. The image type is determined by taking the minimum value Min (R, B, G) on the X axis and the maximum value Max (R, B, G) on the Y axis. The document type determined by the image type determination circuit 804 is A
The CS signal is output to a printer or the like connected to the outside.

As described above, according to this embodiment,
Pre-scan that reads the original information such as the original position and original size that does not require a stable amount of light until the amount of original illumination lamp light stabilizes. Since the original color information reading operation that requires a stable light amount is performed during the backward movement operation, it is possible to easily realize the speedup of the prescan operation, which has a limit in the conventional prescan operation.

In this embodiment, the document position, document size, etc. are read in the forward path of the prescan operation performed before the actual document reading operation, and the color information of the document is read in the backward path. The present invention may be applied during the scanning operation to read the original information that does not require a stable light amount such as the original position and the original size in the forward path, and read the original color information in the backward path.

[0050]

As described above, according to the present invention, in the scan reciprocating operation of the reading movable section, the original information detection that does not require a stable light quantity is performed during the forward operation in which the light quantity of the original illumination lamp is not stable. By performing the operation, the color information reading operation that requires a stable light amount is performed at the time of the return path operation in which the light amount of the original lighting lamp is stable, so that a wasteful time until the light amount of the original lighting lamp is stabilized is eliminated, An effect that a high-speed scanning operation can be performed is obtained.

[Brief description of drawings]

FIG. 1 is a timing chart for explaining features of the present invention with respect to a prescan operation that has been conventionally performed.

FIG. 2 is a block diagram showing a schematic configuration of a color image reading device according to the present invention.

FIG. 3 is a block diagram showing a schematic configuration of the image processing circuit shown in FIG.

FIG. 4 is an explanatory diagram for explaining a document detection operation.

FIG. 5 is an explanatory diagram for explaining a document position detecting operation and a document size determining operation.

FIG. 6 is an explanatory diagram for explaining a document position detecting operation and a document size determining operation when a document is placed obliquely.

FIG. 7 is an electric circuit diagram showing a schematic configuration of a document position / size detection circuit shown in FIG.

8 is a block diagram showing a schematic configuration of a document color information recognition circuit shown in FIG.

FIG. 9 is a diagram showing a color determination area for determining whether a document is a monochrome document or a color document.

[Explanation of symbols]

204 First Mirror Table (Reading Movable Section) 205 Second Mirror Table (Reading Movable Section) 208 Image Processing Section (Document Information Detection Unit, Color Information Reading Unit) 209 Document Illumination Lamp 305 Main Scan Address Counter (Document Information Detection Unit) 306 Sub-operation address counter (original information detecting means) 307 Original color information determining circuit (original information detecting means) 308 Original position / size detecting circuit (color information reading means) 804 Image type determining circuit (color information reading means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04N 1/04 101 1/19

Claims (1)

[Claims] 1. A color image reading device which irradiates an image original with light and reads a color image by the reflected light, the color image reading apparatus having a reading movable section for performing the reciprocating operation to read the image original. In a color image reading apparatus for performing a scan for reading information of the image original by a reading movable portion, the color image reading apparatus illuminates in synchronization with the start of the forward operation of the scan, irradiates the image original with light, and synchronizes with the end of the backward operation of the scan. An original illumination lamp that is turned off, an original information detecting unit that detects readable original information by an unstable light amount immediately after the original illumination lamp is lit during the scan forward operation, and color information of the image original during the scan backward operation A color image reading device comprising: color information reading means.