JPH0731719B2 - Control system for document reading device halfway stop and restart - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] A method of restarting control of a document reading device capable of automatic sheet feeding (ADF) scanning and document scanning (flatbed) scanning is described. The purpose of the present invention is to provide an improved means that can reduce the disturbance of the image seam as compared with the conventional method. Then, the carrier is moved by self-starting or slewing by the distance that the original traveled by the above-mentioned slew-down in the traveling direction of the original, plus the distance required for stable operation of the original. Then, after moving the carrier by self-starting in the direction opposite to the direction of movement of the original by the distance required for stable operation, the fixed-type original is read. Scanning, the document is read for a distance equivalent to the sum of the distances the document advances in slew-down and slew-up in the case of document feeding drive, and then stopped, and then the carrier self-starts or slews in the document traveling direction. To stop at the usual carrier stop position during automatic paper feed scanning, and then drive the document feed in a slew-up direction in the direction of the document.
After the slew-up was completed, it was configured to start automatic paper feed scanning.

[Industrial application field]

The present invention relates to a midway stop / restart control system of a document reading apparatus capable of automatic sheet feeding (ADF) scanning and document fixed (flatbed) type scanning. The present invention relates to a reading control technique that prevents duplication or omission of image reading.

[Conventional technology]

FIG. 8 shows an example of a conventional document reading apparatus having a structure in which ADF reading and flatbed reading to which the present invention is applied are combined.

When performing ADF scanning, the original is sucked from the original intake section, the internal original is fed while being read, and the original is ejected from the original ejection section. On the other hand, in the case of flatbed scanning, the original is set on the flatbed and is scanned in a fixed state.

FIG. 9 is a cross-sectional view of the mechanical section of the document reading apparatus shown in FIG. 8, where 1 is a platen glass, 2 is a pick roller, 3 is a pick spring, 4 is a pad, and 5 is a paper guide. , 6, 7 are feed rollers, 8 and 9 are discharge rollers, 10 is a carrier, 11 is a lamp, 12 and 13 are mirrors, 14 is a lens, 15 is a CCD, 16
Indicates the lead screw.

When performing the above ADF scanning, set the original 1
7 is pulled by the pick roller 2 and the pick spring 3 and is fed by the feed roller 6 so that an image is read when passing through the reading position, and discharged by the discharge rollers 8 and 9 outside. At the reading position, the carrier 10 is stopped at this time, and the light of the lamp 11 illuminates the surface of the document 17. Then, the light reflected from the image on the document surface is read by the CCD 15.

Further, when performing flatbed reading, an original is placed on the platen glass 1, the carrier 10 is moved in the horizontal direction to scan the original surface, and an image is read.

By the way, in order to store the read image data, a memory used as an image buffer is provided in the document reading device or the host to which the document reading device is connected as shown in FIG. , It is common that the document does not have enough storage capacity to store all the image data of the document.

In such a case, a memory overflow occurs during document reading, and a stop signal is output. The document reading device stops document reading halfway, and waits until the host processes the image data and becomes empty, then restarts. The way to start is taken.

However, if the document reading is stopped halfway and restarted in this way, the control characteristics of the mechanical section cause the document to stop too far, or the start is delayed, causing disturbances such as missing seams in the image. There is a problem that the image quality deteriorates.

Conventionally, various measures have been taken in order to eliminate the disorder of the seam of the image, but there are the following, for example.

(1) Back and force method When the document is stopped halfway during ADF scanning, the document is moved back by a predetermined amount at the time of restart, and then the document is moved forward by a predetermined amount and then scanning is started. It offsets the amount and delay time at the start.

Fig. 11 shows the control characteristics of this method. When starting from the stop position, a delay in distance movement occurs during the slew-up T _U , and when stopped, the stop position overshoots during the slew-down T _D. It can be seen from the figure that there occurs. Therefore, when shifting from the midway stop to the start, it is moved in the reverse direction once to correct the delay time and the overshoot amount.

However, when the document is backed, there is a drawback that wrinkles and tears due to shallowness or catching of the document are likely to occur due to the structure of the mechanical portion, for example, points C ₁ , C ₂ and C _{3 in} FIG.

(2) Reading method during slewing The rising and falling of the pulse motor are controlled with a slewing curve that minimizes hunting when stopping document feeding. Then, the driving signal of the pulse motor during the slewing and the original reading signal are synchronized to perform the original reading, so that the disturbance of the seam of the image is minimized. FIG. 12 shows an example of the control characteristics.

However, there is a limit to the selection of the optimal slewing curve due to disturbances such as the installation environment of the document reading device and the paper feed load, and it is difficult to reduce the delay time and the overshoot amount to a sufficient extent, and the image seam The disorder could not be completely eliminated.

[Problems to be Solved by the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved means capable of reducing the disorder of the image seam as compared with the conventional method without backing the original.

[Means for Solving the Problems]

The present invention provides automatic paper feed (ADF) scanning and fixed document (FDF)
B) In a document reading device capable of reading, in the case of stopping and restarting the document during the automatic paper feed reading, by controlling the movement of the carrier,
Achieving good image quality with less distortion of the seam without back movement of the document itself.

That is, the same result as when the document is moved back is obtained by performing the operation of advancing the carrier in the traveling direction of the document by a predetermined distance.

In the present invention, in particular, control is performed so that carrier movement can be performed and cancellation can be performed in consideration of the slew-down and slew-up in document feeding drive and the distance required for stable operation during carrier movement.

: When a stop signal is sent from the host, the reading operation is terminated, the pulse motor for driving the original is slewed down, and the reading stop position on the original is stopped at a position advanced by α from the carrier stop position. .

: During carrier slew-down by self-starting in the direction of original movement (pulse motor operation without slippage within the low pulse frequency range where the pulse motor can follow the input pulse) or slewing. The distance is advanced by the distance .alpha. Plus the distance .beta. Required for stable operation before the next fixed original reading.

: The carrier advances in the self-starting direction opposite to the moving direction of the original, and advances by the distance β at which the operation is stable.

′: Continuously, the reading is started, and after reading the slew-down amount α and the slew-up amount γ of the document driving pulse motor, the scanning is stopped.

: The carrier is set to the normal carrier stop position during automatic paper feed reading, by self-starting or slewing depending on whether it was self-starting or slewing.
Move a distance.

: Starts the pulse motor for driving the document in the direction of travel in a slew-up manner. After the slew-up is completed, the sheet is moved by the distance γ to reach the beginning of the unread area, and the automatic paper feed reading is started from here.

[Action]

As shown in FIG. 1, according to the present invention, when a reading stop occurs due to a memory overflow during the automatic paper feed reading, the reading stop position on the original is determined by the through-down operation of the original drive pulse motor. As described above, the carrier is stopped at a position beyond the normal carrier stop position by a distance α.

Therefore, the carrier is made to follow and move in the document advancing direction. However, the distance .alpha. Advanced by the document through-down as in this case, plus the distance .beta. For stabilizing the operation required when the carrier itself moves. Move by α + β. Carrier movement at this time may be self-starting or slewing.

Next, the original is fixedly read, and the original is left in the same position and the carrier is moved in the opposite direction. When β is moved as in this case, the position on the original where the reading is stopped is reached, so that seamless reading is started from here. The movement of these and 'is done by self-start without slip.

In the fixed document reading of ′, it is possible to return to the automatic paper feeding reading by reading the distance of α originally, but in that case, when the automatic paper feeding reading is restarted, the original driving must be started by the through-up operation. Since it has to be done, the seams will be disturbed again. Therefore, in consideration of the distance γ through which the original travels in a slew-up manner, the carrier γ is additionally fed, and the reading area of the fixed original is within the range of α + γ.

As described below, the carrier is returned by the distance γ to the normal stop position for automatic paper feed reading. The carrier movement at this time is the same as if the movement of was carried out by the self-start without slipping, and the movement of the carrier was canceled if the movement of was carried out by slewing. To slew.

After this, when the memory overrun of the host is resolved, the automatic paper feed reading operation is restarted, and when the document advances by the distance γ due to the document driving slew up, the beginning of the unread area reaches the carrier stop position. Thus, seamless reading is performed.

〔Example〕

FIG. 2 is a diagram for explaining the operation of the first embodiment of the present invention.
The figure is an operation timing chart showing the control characteristics. This first embodiment corresponds to the principle explanatory diagram of FIG. 1, and the numbers indicating the operation procedure in the figure ,.
Indicate the same contents in FIGS. 1, 2, and 3.

In Fig. 2, 1 is platen glass, 2 is pick roller, 4
Is a pad, 6 and 7 are feed rollers, 17 is a document, and
A part of the mechanism of the document reading apparatus in the figure is shown in a simplified manner. The upper part of the platen glass 1 is an operation on the medium (original) side, and is related to the automatic paper feed reading procedure. Also, the lower part of the platen glass is the operation on the carrier side, and is related to the fixed document reading procedure ,. The description of FIG. 1 is cited for each operation.

Further, in FIG. 3, (a) is a document operation, which shows a moving distance of the document. The flat part in the figure shows the position where the stop signal was caused by slewing down due to the stop signal due to memory over. (B) shows the driving pulse of the pulse motor for driving the document, in which slew down and slew up are performed. (C) shows the carrier operation, which advances from the stop position by α + β between the document traveling directions, and then α + β in the opposite direction.
Shows that + γ goes back and further goes by γ. (D) shows a drive pulse of the carrier drive pulse motor. In this example, everything is self-starting. (E) is the read signal of CCD output, the left end of the figure is for automatic paper feed reading,
The center is for fixed original scanning, and the right end is for automatic paper feeding scanning.

The above operation requires high accuracy of the document driving pulse motor and the carrier driving pulse motor. However, in reality, the original driving pulse motor system may be overshooting at the time of stopping or may be too late at the time of starting, and the carrier system may also have the same error of the carrier. An example in which this error can be corrected is shown below.

In order to prevent the deviation due to the accumulation of the above-mentioned errors, it is applied to the normal stop position shown by A in FIG. 2 at a position outside the reading range in the main scanning direction and the carrier return position shown by B in FIG. At the time of stop, by stopping after detecting each mark, the influence of error in the carrier system can be eliminated as much as possible.

FIG. 4 shows the marking of the second embodiment of the present invention based on this, and the markings 18 and 19 are set at positions deviated to the left side from the reading range of the platen glass 1.

Further, in order to prevent the document from going too far in the roller or slipping, the operation of the first embodiment shown in FIG. 2 is performed at the leading end of the document, and the slew-down and stop of the carrier at that time are performed. By detecting the position with respect to the marking in Fig. 4 and using that value as the value of the subsequent reading start position, errors such as paper quality differences and mechanical rattling can be minimized, and You can solve the difference. A second embodiment for this purpose is shown in FIGS.

FIG. 5 shows the operation of the embodiment of the present invention, and FIG. 6 shows its control characteristic. The operation is performed as follows.

When the leading edge of the draft reaches the stop position, it stops after slewing down.

Move the carrier to the carrier return position according to the marking.

The carrier is moved until the leading edge of the document is detected, and the position A is recorded after the detection.

Move the carrier to the return position according to the marking.

The carrier is moved in the opposite direction, and when it reaches position A, reading is started.

The carrier is normally moved to the return position according to the marking.

After the original is slewed up, the reading is started, and thereafter, the same operation as that in the first embodiment is performed when the intermediate stop occurs.

However, when stopped midway, the position accuracy of the reading start position A is increased by the recorded value, and the seam is improved.
In addition, the number of processed sheets can be increased by recording in the EEPROM during the shipping test.

FIGS. 7A and 7B show a third embodiment of the present invention having three markings.

FIG. 7 (A) shows the marking of the third embodiment of the present invention, which includes a carrier return position marking 20, a normal read position marking 21, and a carrier return position marking 22. The positions of the markings 20, 21, 22 are represented by a, b, c, respectively.

The operation when the marking of FIG. 7 (A) is applied will be described with reference to FIG. 7 (B).

 The leading edge of the document is stopped at point l between points a and b.

The carrier is moved by self-starting from the point a to the point b, the position of the point l, that is, the document leading edge position is detected, and the carrier is stopped at the point b. This detects the distance z (depending on the number of pulses).

The original is driven through up, and when the carrier detects the leading edge of the original, it goes through and stops. This stop position is set to point d. At that time, the number of pulses until the tip detection and z
And the difference (denoted by f) is detected.

The carrier is moved by itself in the direction of point c and stopped at point c.

Move the carrier from point c to point b by self-start,
The position d of the leading edge of the document is detected, and the number of pulses (g) between them is detected.

(If the following operations are performed at the time of shipment, set the values of f and g to EE
Although it is stored in the PROM, f and g may be obtained every time the sheet feeding operation is performed and stored in the RAM as in the case of the first embodiment. ) If an intermediate stop occurs, the document is slewed down and stopped.

 Move the carrier to point c and stop it.

The carrier is moved from point c to point b by self-starting, the reading operation is performed when the number of pulses g is counted, and the carrier is stopped at point a.

 The carrier is moved from point a to point b.

 Feed the original through in the feed direction.

Reading is started at the time when the document movement amount moves to the value a between a and b by the number of pulses for which the correction value f is calculated.

〔The invention's effect〕

According to the present invention, it is possible to avoid the document damage when the document is backed in the conventional back and force systems, and the carrier position correction and the document drive system correction improve the reading accuracy and the image quality.

Furthermore, connection with a host with a small amount of memory that has a high frequency of mid-stops, which was not possible in the past, becomes easy, and usability is improved.

[Brief description of drawings]

1 is an explanatory view of the principle of the present invention, FIG. 2 is an explanatory view of the operation of the first embodiment of the present invention, FIG. 3 is a control characteristic diagram of the first embodiment of the present invention, and FIG. 4 is a second embodiment of the present invention. FIG. 5 is an explanatory view of the marking of an example, FIG. 5 is an operation explanatory view of the second embodiment of the present invention, FIG. 6 is a control characteristic view of the second embodiment of the present invention, and FIG. 7A is a third embodiment of the present invention. Marking explanatory drawing, FIG. 7 (B) is an operation explanatory drawing of the third embodiment of the present invention, FIG. 8 is an external view of an example of a conventional document reading apparatus, and FIG. 9 is the document reading apparatus of FIG. Sectional view of the mechanism, Fig. 10 is an explanatory view of the read stop operation due to memory overflow, Fig. 11 is a control characteristic diagram of the conventional back and force method, and Fig. 12 is a control characteristic diagram of the conventional reading method during slewing. . In Fig. 2, 1: Platen glass, 2: Pick roller, 4: Pad, 6, 7: Feed roller, 17: Original.

Claims (3)

[Claims] 1. An automatic paper feed mechanism and a carrier are provided, and an automatic paper feed reading function and an original fixed reading function are provided. In the automatic paper feed reading operation, an automatically fed original is at a normal stop position. In an original reading device that reads by a carrier, if it stops midway during the original reading operation by automatic paper feed scanning, the original feeding drive is slewed down to stop the original, and then the carrier is moved in the moving direction of the original. In addition, the original is moved by self-starting or slewing by the distance that the original traveled by the above-mentioned slew-down plus the distance required for stable operation in the original fixed reading, and then the carrier is set as the original traveling direction. After moving by the distance necessary for the operation to stabilize in the opposite direction by self-starting, scanning with the fixed document type starts The original is read and stopped for a distance equivalent to the sum of the distance the original advances in down and slew-up, and then the carrier is moved in the direction of original movement by self-starting or slewing. Stop at the carrier stop position, then drive the document feed through in the direction of document passage in a slew-up manner, and after completion of the slew-up, start automatic sheet feed scanning. Start control method. 2. The method according to claim 1, wherein a first marking is provided at a normal carrier stop position during automatic paper feed reading, and when the carrier is stopped midway during automatic paper feed reading, the carrier is moved in the document advancing direction. A second marking is applied to the first moving position, and when the carrier is stopped at each of the above positions, the marking is detected and stopped. 3. When feeding a document to a reading position by automatic sheet feeding reading according to claim (2), first, when the leading edge of the document reaches the normal stop position of the carrier, the document is slewed down and stopped. The carrier is moved to the second marking position, then the carrier is moved in the opposite direction until the leading edge of the document is detected, the leading edge detection position of the document is recorded, and then the carrier is moved to the second marking position again. Then, the carrier is moved in the opposite direction, and when the above-mentioned recorded document leading edge detection position is reached, the fixed document reading is started, and from there, the distance that the document advances by slew-down and slew-up in document feeding drive. Read the original for a distance equivalent to the sum of the above, and then stop, then move the carrier to the first marking position and stop, and then perform the original feeding drive in a slew-up direction in the original direction, When the automatic paper feed reading is started after the completion of the loop-up, and then the stop occurs midway, the recorded document leading edge detection position is used as the fixed document reading start position. Restart control method.