JPS62258551A - Color picture reader - Google Patents

Abstract

PURPOSE:To prevent color shift due to the shift of tip of a picture and to output an excellent color picture by applying prescanning before plural scannings in a color picture reader reading a color picture through the plural number of times of scanning of an original. CONSTITUTION:A detection means 130 detects that a scanning means 100 is at the scanning start position P. A positioning means 140 uses the said detection output at the start to position the scanning means 100 near the scanning start position P. A pre-scanning control means 150, after the said positioning, applies the prescanning to the scanning means 100. After the prescanning, the scanning means 100 is subject to plural number of times of scannings to the original M to read a color picture. Thus, the stop of start condition is matched at the 1st reading scanning and the 2nd and succeeding read scannings, then the color mis-alignment due to the deviation of picture tip is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color image reading device, and more particularly to a color image reading device that reads a color image by scanning a document multiple times.

[Conventional technology]

Conventionally, when obtaining a hard copy of a color image, for example, in a color printer using a thermal transfer method or an electrophotographic method, it is usually Y (yellow) and 1M (magenta).

A hard copy of a full-color image is obtained by a so-called subtractive color mixing method in which C (cyan) and 8K (black) color developing materials are successively superimposed.

In this case, Y image 1M image, 0 image - image,
B11 images must be superimposed on the recording medium (recording paper) with high precision. For example, even if there is a misalignment (abbreviated as color shift) of about 0.1 mm between each image, the color image will be blurred and the sharpness will be affected. There was a problem that the color lacked strength and the color became muddy, resulting in a decrease in saturation.

When reading or forming a color image, the first time is to read an image of one color component of the document, for example, a yellow component, and form a yellow image, then read an image of a magenta component, form a magenta image, and then sequentially print a cyan image. , and the black component. Therefore, in order to obtain a color image without color shift, it is essential that the beginnings of each image overlap with high precision.

Therefore, at regular intervals, color images read by a color image reading device (hereinafter referred to as color league) are sequentially printed out in real time to a color image forming device (hereinafter referred to as color printer) that forms images of each color. or in cases where it does not have image memory.
The color reader needs to read document image information at regular intervals. In other words, in a color reader, it is necessary to have reproducibility in each image reading scan, and in particular, in order to accurately overlap the leading edge of each image with a color printer, it is necessary to adjust the variation in the arrival time from the scanning start position to the leading edge of the document. It is necessary to limit the time range to Δtsec in four image reading scans. Here, the time range △jsec and the scanning speed Vsmm
The product of /sec is the image leading edge shift width ΔXmm. In order to make the color shift caused by this shift of the leading edge of the image less noticeable, it is necessary to suppress the width ΔxII1m to at least about 0, 1, or m.

(Problem to be Solved by the Invention) Here, in order to reduce the variation in the arrival time, it is necessary to make the speed rise characteristics uniform and to reduce the variation in the scanning start position.However, when the power is turned on, it is necessary to In the initial state, such as immediately after scanning, the position where the document scanning unit is stopped is unclear, so the document scanning unit is positioned at the scanning start position (home position) (see 11.P.
(referred to as a search) is preferable.

The operation of the motor as a driving means for driving the scanning unit that performs scanning at this time is generally different from the operation in the return path after scanning for document reading, and the scanning unit and drive transmission system are in a stopped state when reading the document. This is different from the stopped state after scanning.

Therefore, 11. Since the scan start position and speed rise characteristics are different between the first scan after P search and the second and subsequent scans, in conventional color image recording devices, the color of the document read in the first scan is different. There is a problem in that the colors are outputted to the color printer with a shift, and as a result, the color printer forms an image with the colors shifted.

[Means for solving problems]

The present invention solves this problem and reduces the variation in the arrival time from the scan start position to the leading edge of the document between the first scan and the second and subsequent scans after H, P search. Accordingly, it is an object of the present invention to provide a color image reading device capable of outputting a good color image while preventing color shift due to image tip shift.

Therefore, in the present invention, as shown in FIG. 1, in a color image reading device that reads a color image by scanning a document M multiple times with a scanning means 100 for guiding the document image to an image reading sensor, Scanning means 100
a driving means 110 for driving the scanner in the scanning direction S; a scanning control means 120 for performing multiple scans when reading a color image; a detecting means 130 for detecting that the scanning means 100 is at the scanning start position HP; A positioning means 140 that positions the scanning means 100 in the vicinity of the scanning start position P at the initial stage using force, and a pre-scanning control means 150 that causes the scanning means 100 to pre-scan after positioning and before starting multiple scans. .

(Function) That is, according to the present invention, after positioning the scanning means 100 and performing a pre-scan, multiple reading scans are performed. It is now possible to match the stop or start conditions with the image, thereby preventing color shift due to image edge slippage.

(Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment in which the present invention is applied to a digital color image reading device will be described below. Further, it is assumed that a stepping motor is used as the drive source of the scanning unit.

FIG. 2 shows an example of the configuration of a digital color image reading device which is an embodiment of the present invention.

Here, 21 is a document scanning unit, and irradiation lamp 2
2, rod array lens 23, reading sensor 24, A/
It includes a D converter 25, a signal line 26, a reflection mirror 27, and the like. 1 is a stepping motor, and 29a is a pulley fixed to the output shaft of the stepping motor 1.

29b is a pulley fixed to the shaft 30. A toothed belt 31 is wound around pulleys 29a and 29b.

Pulleys 32 and 33 are fixed to the shaft 30, and work together with idle pulleys 32a and 33a to drive wires 32b and 33b, respectively. 34 and 35 are springs, which urge the idle pulleys 37a and 33a, respectively, in the red mark direction in the figure, and apply tension to the wires 32b and 36b, respectively. 36 is a metal fitting fixed to the document scanning unit 21, and is connected to the wire 33b via a member 37. Reference numerals 38 and 39 denote scanning rails, which guide the document scanning unit 1-21 in the direction S in the figure.

FIG. 3 is a view taken in the direction of arrow A in FIG. 2, and the same members as in FIG. 1 are given the same reference numerals.

In this figure, 40 is a document table glass, and 41d is a sliding member relative to the rail 39. 41a to 41c are sliding members with respect to the rail 38, and sliding members 41b and 4
1c are held facing each other by a plate spring 42 and a mounting plate 43 fixed to the document scanning unit 21, respectively, so that the sliding members 41b and 41c are pressed against the scanning rail 39 to sandwich the scanning rail 39,
This limits movement of the document scanning unit 21 in the direction of the arrow.

FIG. 4 is a view taken in the direction of arrow B in FIG. 2, and the same members as in FIGS. 2 and 3 are given the same reference numerals.

In this figure, 45 is a signal line, and the reading sensor 2
The output of 4 is sent to the A/D converter 25.

When the stepping motor 1 is rotated forward or reverse to move the original scanning unit 21 linearly in the S direction, if the number of rotations of the stepping motor 1 is n and the diameter of the pulleys 29a and 29b is ram, then the original scanning unit 2
The scanning speed (moving speed) 1 is given by the following equation.

v=πr n [mm/sec] ・・−・−(
1) FIG. 5 shows an example of the configuration of a drive control circuit for the stepping motor l used in this embodiment. Here, lO is a driver control circuit, which controls various parts according to the processing procedure described later in FIG. 8 for drive control of the stepping motor l, Crt, etc.
In addition to the various processing procedures performed by llll, ROM 12 stores data for pulse generation, and RAM has a work area.
13, an operation display circuit 14 including a receiving section for command input by an operator and a display section for notifying the device status, a pulse generating circuit 15, a latch circuit 16, a buffer circuit 17, a timer circuit 18, etc. A driver circuit 19 generates motor driving pulses and supplies them to the stepping motor 1.

Crtll receives a command to start scanning and a designation of scanning specifications from the operation display circuit 14, and reads the ROM 12 or R
Frequency data 01/l- of generated pulses is sent from the AM 13 to the pulse generation circuit 15 for setting. The pulse generation circuit 15 supplies a pulse signal 03 of a set frequency to the driver circuit 19 in response to the command signal D2 from cputt. Further, after counting the pulse signal D4 and outputting the number of pulses to be output, the CPt1ll sets the frequency of the next pulse in the pulse generation circuit 15. On the other hand, a signal D5 that controls the rotational direction of the stepping motor l and the on/off of the current is supplied to the driver circuit 19 as a signal D6 via the latch circuit 16 and the buffer circuit 17. The driver circuit 19 receives the signal D6 and the pulse signal D.
4, a motor drive pulse signal 07 suitable for driving the stepping motor 1 is supplied to the stepping motor 1 to control its rotation and stop.

Note that the stepping motor 1 is configured to rotate at a certain angle (hereinafter referred to as a step angle. In this example, this step angle is 0.72 degrees) with respect to one signal D6. The rotational movement of the document scanning unit 1 and the linear movement of the document scanning unit 21 correspond to each other. Also,
By electrically controlling the relationship between the number of signals D6 and the frequency, the relationship between the position of the document scanning unit 21 and the B moving speed can also be electrically controlled.

Next, with reference to FIGS. 6, 7 (A) and (B),
Of the positioning control of the document scanning unit l-21 to the stop position (next scan start position), positioning control operations when the power is turned on and when an error occurs will be described.

FIG. 6 is a sectional view of a main part of the document scanning unit 21, and the same parts as in FIG. 1 are given the same reference numerals.

In this figure, SRI is a home position sensor, which is disposed at the home position HP and recognizes the stoppage by detecting the actuator plate AP provided at the bottom of the document scanning unit 21. SR2 is a document leading edge sensor, which is disposed above the document leading edge position DTOP, and detects that the document scanning unit 21 is located at the document light a;13 position DTOP by detecting the actuator plate AP. Note that d indicates the width of t' to the actuator plate, a indicates the left end of the actuator plate AP, b indicates the right end of the actuator plate, and °C indicates 15R2-SRI l, respectively.

However, if the movable distance of the actuator plate AP to the left is e, then o<e<d<l.

FIGS. 7(A) and 7(B) are waveform diagrams illustrating the scanning state transition diagram of the actuator plate AP shown in FIG. fJ6 and the decay time to the stop position. In the same figure (A), ca
sel-case 4 indicates each state transition, and 8IIEAI-AIIEA4 correspond to each state transition.

In the same figure (B), the horizontal axis is the scanning position X, and the vertical axis is the time t.
, ΔX1 indicates the maximum vibration width, and ΔX2 indicates the arrival time until the allowable stop error ts reaches the allowable stop error ΔX2, respectively.

casel is a case where the left end a of the actuator plate AP is located to the left of the home position sensor SRI,
At this time, the IIP signal (home position sensor SRI
The DTOP signal (signal output when the document leading edge sensor SR2 detects the actuator plate AP) is at the "H" level, and the DTOP signal (the signal output when the document leading edge sensor SR2 detects the actuator plate AP) is at the "L" level.

In case 2, the left end a and right end of the actuator plate AP are the home position sensor SRI and the document leading edge sensor S.
This is a case in which the signal is located between R2 and R2, and at this time, both the HP signal and the DTOP signal are at the "high" level.

Case 3 is a case where the left end a of the actuator plate AP is located to the left of the document leading edge sensor SR2, and the right end is located to the right of the document leading edge sensor SR2.
The signal becomes "L" level, and the DTOP signal becomes "H" level.

Case 4 is a case where both the left end a and the right end of the actuator plate AP are located on the right side of the document leading edge sensor SR2, and at this time, both the HP signal and the DTOP signal are at the "L" level.

In the casel process, the original scanning unit 21 is moved forward in the SF force direction at a low speed, and when the IIP signal reaches the °L" level state, it is moved backward at a low speed in the 58 direction, and the 11P
Stop when the rising edge of the signal is detected.

In case 2, the document scanning unit 21 is moved backward at a medium speed and stopped when the rising edge of the IIP signal is detected.

In the casa3 process, the original scanning unit 21 is moved backward at a medium speed, moved backward at a low speed when the DTOP signal reaches the "L°° level state," and stopped when the rising edge of the HP signal is detected.

In the process of case 4, the document scanning unit 21 is moved backward at high speed, moved backward at low speed when the DTOP signal is in the "H" level state, and stopped when the rising edge of the IIP signal is detected.

FIG. 8 shows an example of a motor control procedure according to this embodiment.

First, it is determined whether ++p (g is in the °゛H''' level state or not (step S1), and if the determination is affirmative, the document scanning unit 21 is advanced at a low speed (step S2).
, waits for the up signal to reach the "high" level state (step S3). When the level becomes "L", the unit 21 is moved backward at low speed (step S4), and the low speed backward movement is repeated until the IIP signal rises (step S5).

When the rising edge of the IIP signal is detected, the unit 21 is stopped at that spot, and then a briscan process (step 516), which will be described later, is performed, and it waits for an instruction to start reading.

On the other hand, if a negative determination is made in step Sl, D
It is determined whether the TOP signal is at the "H" level (step S6), and if the determination is affirmative, the unit 21 is moved backwards at medium speed (step S7), and the DTOP signal is set at "L".
Step 58) repeats medium-speed reverse movement until the DTOP signal reaches the "L" level state. When the DTOP signal reaches the "L" level state, the process returns to Step S4.

If a negative determination is made in step S6, the unit 21 is moved backward at low speed (step S9), and then) the IP
Determine whether the damage signal has risen (step 510)
). Here, if the determination is affirmative, the process moves to step 515. On the other hand, if the judgment is negative, which of the home position sensor SRI and document leading edge sensor SR2 is 'J5 If! I
t fl to the side of the actuator temporary AP 1 + iii d
It is determined whether the document scanning unit 21 has moved backward by the distance obtained by subtracting the distance (step Sit), and if the determination is negative, the process returns to step S9, and if the determination is affirmative, the process returns to DTOP.
Determine whether the signal is at °°H'° level (
Step 512). If the judgment is affirmative here, step S
Return to step 7, and if the judgment is negative, move backward at high speed (step 5)
13), the process returns to step 512.

In this way, the processing up to step S15 ensures that 1
Since the document scanning unit 21 is automatically stopped at the home position HP at a low speed, positioning accuracy is high.
When the original scanning unit 21 reaches the home position HP, the stepping motor 1 receives a stop command, but the original scanning unit 21 first vibrates with the maximum vibration width Δxl, and attenuates at the arrival time ts, and the allowable stop error Δ Stop at x2.

Further, since the speed is set in three stages, even if the document scanning unit 21 is far to the right from the home position HP, it can be stopped at the home position +IP in a short time and with high precision.

Figure 9 shows the case of H0P search, normal document scanning,
For example, the relationship between the position X and speed V of the document scanning unit 21 when reading an A4 size document in the same magnification mode is shown.

Generally, when scanning a document, in order to rotate the stepping motor 1 at high speed, it is preferable to gradually increase (slow-up process) and lower (slow-down process) the driving frequency of the stepping motor 1. On the other hand, when performing l(,P search, the position of the document scanning unit 21 is unknown at the initial time such as when the power is turned on, and when slow-up processing and slow-down processing are performed, reversal, deceleration, etc. based on position judgment, Since control such as stopping becomes complicated, the stepping motor 1 is rotated by constant speed control and speed switching within the self-starting frequency by the processing up to step S15.Therefore, during original scanning and during IP search, the stepping motor 1 is The speed (acceleration) of the document scanning unit 21 before the position HP is different.

Therefore, in this example, after the document scanning unit 21 is positioned at the home position IIP, one reciprocating scan (prescan) is performed in the normal document scanning mode shown in FIG. 8 in the process of step 516.

At this time, the number of pulses of the pulse signal o3 (i.e., 04) is made to be the same on the outward and return passes, and the rotation angle of the stepping motor 21 is made to be the same on the outward and return passes. The stop position at this time is different from the stop position in the LP search mode, but the difference is within a distance equivalent to one step angle of the stepping motor 1 at most. In this prescan, in principle, image reading is not performed in this example, but if there is a preprocessing request such as document position detection, corresponding processing can be performed.

After completing such pre-scanning (step 516), the state waits for an input from the operation display circuit 14, and when an image reading command is given by keystrokes or the like, the original is scanned in synchronization with an output device such as a color printer. The document scanning unit 21 is driven in this mode, and the document image is read and the color printer sequentially outputs it four times.

In this embodiment, a stepping motor is used as the driving source for the document scanning unit 21, but it is of course possible to use a DC motor, a near motor, or the like.

Further, in the above embodiment, the home position 1. After detecting P and positioning the original scanning unit 21, the reproducibility of original scanning is achieved by performing bridging.For example, as shown in FIG. By arranging a sensor equivalent to the home position sensor SRI at the return position ff1PR and positioning the document scanning unit 21 at the return position, the document scanning unit 21 is positioned to the home position IIP on the return trip shown in FIG. It can also provide reproducibility. Further, in this embodiment, the original was scanned by moving the original scanning unit 21 on which the reading sensor 24 was mounted, but the present invention can also be applied to a configuration in which a mirror or the like that guides the image to the fixed reading sensor 24 is moved. You can also.

[Results of invention]

As explained above, according to the present invention, the stopped state of the library performing the first original scanning (stopped state of the original scanning unit and drive transmission system) and the stopped state after the first original scanning , so the first original f
The reproducibility between the A scan and the second and subsequent document scans is better, that is, the variation in the arrival time from the scan start position to the leading edge of the document is small, and therefore a high-quality color image without color shift due to image leading edge deviation is obtained. We have achieved a color image reading device that can output .

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 is a perspective view showing an example of the configuration of a color image reading device as an embodiment of the present invention. FIGS. 1. FIG. 5 is a block diagram showing a configuration example of the drive control circuit of the stepping motor shown in FIG. 1. FIG. 6 is a cross-sectional view of main parts of the document scanning unit. FIG. 7 (A)
and (B) are respectively a waveform chart for explaining the scanning state transition diagram of the actuator plate and the decay time to the stop position shown in FIG. 6, and FIG. 8 is an example of the motor control processing procedure according to the embodiment. The flowchart shown in FIG. 9 is 11. λ indicates the relationship between the position and speed of the document scanning unit in P search mode and document scanning mode.
, in the eastern part of the country. DESCRIPTION OF SYMBOLS 1...Stepping motor, 10...Driver control circuit, 11...CPIJ, 12...ROM. 13... RAM, 14... Scanning display circuit, 15... Pulse generation circuit, 16... Latch circuit, 17... Buffer circuit, 18... Timer circuit, 19... Driver circuit, 21... Original scanning unit. 7 Figure 1 Figure 6 SS SF Figure 7

Claims (1)

[Scope of Claims] In a color image reading device that reads a color image by scanning a document multiple times with a scanning device for guiding the document image to an image reading sensor, a drive for driving the scanning device in a scanning direction. scanning control means for performing the plurality of scans when reading the color image; detection means for detecting that the scanning means is at a scanning start position; and using the detection force to start the scanning at an initial stage. A color image reading device comprising: positioning means for positioning the scanning means near the position; and pre-scanning control means for causing the scanning means to pre-scan after the positioning and before starting the plurality of scans. .