JPH07121048B2 - Scanning device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning device applied to recording or reading an image, and more particularly to a scanning device for performing scanning while reciprocating a scanning element.

2. Description of the Related Art FIG. 5 is a schematic perspective view of a mechanical portion of a conventional scanning device of this type. This scanning device is applied to an image recording device. While the scanning element is reciprocated in the arrow b direction (main scanning direction), the scanning element sequentially scans the recording paper 40, and the scanning element scans in the arrow a direction ( The recording of n pixels arranged in the sub-scanning direction) is performed.

The main scan for recording is performed by moving the scanning element, while the sub-scan is performed by intermittently feeding the recording paper 40 in the direction of arrow a. The intermittent feeding of the recording paper 40 is performed by driving the pair of upper and lower feed roller pairs 41 and 42 by a step motor (not shown) capable of intermittent feeding.

Between the upper and lower feed roller pairs 41 and 42, a guide shaft 43, a steady shaft 44, and a recording timing index (hereinafter, referred to as index) 45 that forms a scale are provided in parallel with the arrow b direction. On the index 45, left and right first slits 46 indicating the start and end of recording and a large number of second slits 47 indicating recording timing for each pixel (bit) are formed by a method such as etching. A carrier 48 is mounted on the guide shaft 43 so as to be able to move back and forth.

The carrier 48 is driven by a motor (not shown) and reciprocates in the direction of arrow b (main scanning direction) while being guided by the guide shaft 43 and the steady rest shaft 44. In addition, carrier 48
The recording head 49 as the above-mentioned scanning element, the first detector 50, and the second detector 51 are provided.

The first detector 50 reads the first slit 46 on the index 45 to detect the recording start and end timings, and the second detector 51 reads the second slit 47 to detect the recording timing for each pixel. To do.

In such a configuration, while the recording paper 40 is stationary, the carrier 48 is moved in the right direction (forward movement), and a scanning (recording) timing signal is continuously given to the drive circuit of the recording head 49 so that the recording head 40 moves. By 49, recording is sequentially performed with n pixels in the sub-scanning direction as a scanning unit. When the recording by the forward movement is completed, the recording paper 40 is moved by a predetermined width in the direction of the arrow a, and then the scanning timing signal is continuously supplied to the drive unit of the recording head 49 while moving the carrier 48 to the left (returning movement). The recording is performed with a predetermined width. When the recording by the backward movement is completed, the recording paper 40 is moved by a predetermined width, and the recording by the forward movement is started.

FIG. 6 is an explanatory diagram of this recording, and m columns (main scanning direction) × n rows (sub scanning direction) by one forward movement or backward movement.
Image is recorded. The generation time of the scanning timing signal during the forward movement or the backward movement is controlled by confirming the position of the carrier based on the reading value of the index 45 by the first detector 50 and the second detector 51.

The scanning (recording) pitch by such a scanning device varies depending on the application, but when applied to the recording section of a facsimile apparatus, the scanning pitch is small, for example, 0.125 mm, and highly accurate scanning timing control is possible. Is required. However, it is difficult to manufacture the high-density, high-accuracy index 45 that meets such requirements, and it is inevitable that the index 45 is expensive. As a result, the cost of the entire scanning device increases.

It is also possible to generate the recording timing signal at a constant time interval while the carrier is moving, without controlling the generation timing of the scanning timing signal by detecting the slits corresponding to the scanning pitch. In this case, since it is not necessary to provide a high-density slit in the index, the index becomes inexpensive.

However, as shown in FIG. 7, scanning (recording) deviations in the main scanning direction occur between the forward movement and the width movement, and the continuity of the boundary between the recording portion due to the forward movement and the recording portion due to the sub movement is maintained. The image quality may be deteriorated and the image quality may be significantly deteriorated. FIG. 8 is a graph in which the scanning deviation measured by such an actual device is plotted for each main scanning position.

Such scanning deviation in the main scanning direction is mainly due to imperfections of the carrier drive mechanism. That is, since the carrier moving speed is not strictly uniform in the scanning range, even if the period of the scanning timing signal is strictly kept constant, the scanning pitch becomes uneven. This variation in scanning pitch is not so large when only one of the forward movement and the backward movement is considered. However, since the movement speed of the carrier varies in the case of the forward movement and the case of the backward movement, the variation in the scanning pitch naturally differs. As a result, there is a portion in which variations in the scanning pitch in each moving direction are emphasized, and the recorded image becomes extremely unnatural.

The present invention has been made in view of the above-mentioned problems, and in the case of recording or reading an image by reciprocating movement without using an expensive and highly accurate index, a scanning deviation (recording deviation, reading) in the main scanning direction is performed. It is an object of the present invention to provide a scanning device that can significantly reduce the deviation.

Means for Solving the Problems In order to solve the above problems, the present invention provides data of a scanning cycle preset corresponding to the number of times of scanning or the number of times of passing of a reference position for each of forward movement and backward movement of a scanning element. Accordingly, during the forward movement or the backward movement of the scanning element, the scanning cycle by the scanning element is adjusted according to the moving direction and the number of scanning times from the start of movement or the number of passing times of the reference position. is there.

Operation If the moving mechanism of the scanning element is specified, the scanning deviation characteristic is almost constant and reproducible. Therefore, for example, during the forward movement and the backward movement of the scanning element, the scanning is performed at a constant period to record or read the image, and the scanning deviation is measured from the image. Then, based on this measurement data, the scanning cycle required to minimize the scanning deviation during movement in each direction is set for each number of scans or for each of a plurality of preset reference positions. If the scanning cycle is adjusted as described above according to the data, high-quality image recording or image reading with a small scanning deviation due to the reciprocating movement of the scanning element becomes possible.

The scanning cycle data for each number of scans can of course be set in increments of one, but even if it is set in increments of a plurality of times, it is possible to sufficiently reduce scanning deviation.

Even if the interval between the reference positions is sufficiently larger than the scanning pitch, the scanning deviation can be sufficiently reduced, so that an index or the like for detecting the reference position is inexpensive and sufficient. Also, the interval between the reference positions does not necessarily have to be constant,
The intervals of some reference positions may be wide, and the intervals of other reference positions may be narrow.

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

FIG. 1 is a schematic perspective view of a mechanical portion of a scanning device according to an embodiment of the present invention. This scanning device is applied to an image recording device. FIG. 2 is a schematic block diagram of the control unit of this scanning device.

In FIG. 1, 1 is a recording paper, and 2 is a feed roller pair for conveying the recording paper 1. By driving this feed roller pair 2 by a tipper motor (not shown), the recording paper 1 is sandwiched by the feed roller pair 2 and indicated by the arrow a.
In the sub-scanning direction. Reference numerals 3 and 4 respectively denote a guide shaft and a steady rest shaft which are arranged in parallel with the arrow b direction (main scanning direction).

Reference numeral 5 denotes a carrier, which can be moved back and forth in the direction of arrow b while being guided by the guide shaft 3. The steady rest shaft 4 is a carrier 5
It is provided in order to suppress the shake during movement of the. This carrier 5 is driven by a motor 7 via a belt 6.
Done by 8 and 9 are pulleys.

The carrier 5 is provided with a recording head 11 which is a scanning element for recording scanning. The recording head 11 is configured such that when a scanning timing signal (recording timing signal) is generated,
In this configuration, n recording elements (for example, heating resistance elements) arranged in the sub-scanning direction are driven all at once in accordance with an image signal to perform scanning (recording) for n pixels.

A carrier left position detector 12 and a carrier right position detector 13 are provided at the left and right ends of the guide shaft 3 so that the carrier 5 can detect movement of the guide shaft 3 to the end.

In FIG. 2, reference numeral 21 is a scanning timing generation circuit for generating a scanning timing signal (recording timing signal) SST. The scanning timing signal 21 is given to the drive circuit 22 of the recording head 11 as a scanning (recording) start signal. In addition,
The drive circuit 22 is generally integrated with the recording head 11. Reference numeral 23 is a counter for counting the scanning (recording) timing signal SST.

Reference numeral SNO is a count value SNO of the counter 23 for data of a scanning (recording) timing signal SST, that is, data of a scanning cycle (a time interval from one scanning start time to the next scanning start time).
It is a scanning cycle table stored in association with. This table 24 has an area for forward movement and an area for forward movement. One area is selected by designating the scanning direction (distinction of forward movement and backward movement) by the scanning direction signals CW and CCW, and the count value SCNO is used. By addressing the selected area, the optimum scanning cycle SCYC is output to the current main scanning position.

This scanning cycle data specifies the scanning cycle for each of the forward movement and the backward movement so that the scanning deviation (recording deviation) between the forward movement and the backward movement is minimized for each number of scans.

Specifically, for example, while moving the carrier 5 in the forward movement direction or the backward movement direction, an image is recorded at a constant scanning cycle, and the actual scanning (recording) deviation from the recorded image is counted value SCNO.
The measurement is made in association with (the number of scans). Then, for the range in which the scanning deviation increases to the positive side (right side in the forward movement), the scanning cycle is determined to be smaller than the standard so as to cancel it, and in the range to shift to the negative side (left side in the forward movement). On the contrary, the scanning cycle is set larger than the standard.

It should be noted that such recording deviation is mainly caused by the drive mechanism of the carrier 5, and has a very high reproducibility for each scanning device. Further, in general, the scanning deviation fluctuates relatively slowly, so in practice, even if the scanning cycle is set for each relatively coarse unit, the scanning deviation can be sufficiently corrected. Therefore, as the count value SCNO, the lower one bit or several bits of the output bit of the counter 23 may be used, and the remaining upper bits may be used as the count value SCNO, and the scanning cycle data may be set for each of a plurality of scans.

Reference numeral 25 denotes a control circuit to which a recording operation start signal ST, a detection signal SLFT of the carrier left position detector 12, a detection signal SRIT of the carrier right position detector 13, and a scanning (recording) timing signal SST are input. The control circuit 25 outputs scanning direction signals CW (forward movement), CCW (reverse movement), a clear signal CR for the counter 23, and a timer start signal TST for the scanning timing generation circuit 21. Scanning direction signal CW,
CCW is supplied to the drive control circuit 26 of the motor 7.

The scanning timing generation circuit 21 uses the timer start signal TS
A timer 27 that counts the elapsed time from the time when T occurs, and a comparison circuit 28 that compares the count value TIM of this timer 27 with the value of the scanning cycle SCYC and turns on the scanning (recording) timing signal SST when they match. It consists of

The operation of the scanning device configured as described above will be described below.

When the recording operation start signal ST turns on, the control circuit 25 first
The scanning direction signal CCW for designating the backward movement direction is turned on, and the motor drive circuit 26 causes the motor 7 to rotate in the reverse direction.
As a result, the carrier 5 moves to the left in FIG. When the carrier 5 reaches the left end of the guide shaft 3, the detection signal SLFT of the carrier left position detector 12 is turned on.

When the control circuit 25 detects that the detection signal SLFT is turned on, it turns off the scanning direction signal CCW and turns on the scanning direction signal CW for designating the forward movement direction. As a result, the motor drive circuit 26
Causes the motor 7 to rotate forward, so that the carrier 5 starts to move to the right. Further, the forward movement area of the scanning cycle table 24 is selected. At the same time, the control circuit 25 sends a clear signal.
The counter 23 is cleared by turning on CR. With this, the preparation for printing by the forward movement is completed, and the control circuit 25 starts the control of scanning by the recording head 11.

The control circuit 25 resets the timer 27 by turning on the timer start signal TST after clearing the counter 23,
Start counting. The scanning cycle table 24 outputs a scanning cycle SCYC corresponding to the count value SCNO (here, zero). The comparison circuit 28 of the scan timing generation circuit 21 is
When the scanning cycle SCYC and the count value TIM of the timer 27 match, the scanning timing signal SST is turned on. Thus, the print head 11 is driven by the drive circuit 22 to perform the first scanning (printing).

When the first scanning timing signal SST is turned on, the counter 23 increments by 1. Also the control circuit 25
Turns on the timer start signal TST again. Therefore, the scan timing signal SST is turned off. Than this,
When a time equal to the scan cycle SCYC output from the scan cycle table 24 has elapsed, the comparison circuit 28 finds a match, turns on the scan timing signal SST again, and the second scan is performed.

The counter 23 increments by 1. The control circuit 25 turns on the timer start signal TST again. Therefore, the scan timing signal SST is turned off. From this, when a time equal to the scanning cycle SCYC has elapsed, the scanning timing signal SST is turned on again and the third scanning is performed.

By repeating the same operation, according to the scan cycle data corresponding to the number of scans stored in advance in the scan cycle table 24, the scan cycle is appropriately adjusted according to the main scan position, and the recording is performed by the forward movement. When the carrier 5 reaches the right end of the guide shaft 3, the detection signal SRIT of the carrier right position detector 13 is turned on.

When the control circuit 25 detects that the detection signal SRIT is on, it turns off the scanning direction signal CW to stop the carrier 5, and at the same time turns on the clear signal CR to clear the counter 23. Further, a step motor (not shown) for driving the feed roller pair 2 is controlled so as to feed the recording paper 1 by a predetermined amount.

When the feeding of the recording paper 1 is completed, the control circuit 25 turns on the scanning direction signal CCW to start the leftward movement (backward movement) of the carrier 5. Further, in the scanning cycle table 24, the backward movement area is selected.

After that, the control similar to the case of the forward movement is performed by the control circuit 25, and the image is recorded. Then, when the carrier 5 reaches the left end of the guide shaft 3 and the detection signal SLFT is turned on, the control circuit 25 controls the end of the recording operation by the backward movement, the control of the recording paper feed, and the control of the forward movement.

Although the image is recorded while the recording head 11 is reciprocally moved in this way, the scanning cycle is appropriately adjusted according to the main scanning position as described above. It is possible to obtain a high-quality recorded image by significantly reducing the (scanning deviation in the direction).

FIG. 3 is a schematic perspective view of a mechanical portion of a scanning device according to another embodiment of the present invention, and FIG. 4 is a schematic block diagram of a control portion of the scanning device, wherein the reference numerals in FIG. 1 or FIG. The same reference numerals as in FIG. This scanning device is also applied to the image recording device.

In FIG. 3, an index 30 for scanning timing control is provided along the movement path of the carrier 5. The index 30 is provided with reference position marks 31 at regular intervals, and the interval is the recording pitch (pixel interval in the main scanning direction).
Big enough. The index 30 having such a rough reference position mark can be manufactured at a much lower cost than a conventional high-precision index having a mark for each pixel.

The carrier 5 is provided with a mark reader 32 for setting the reference position mark 31 on the index 30.

In FIG. 4, 33 is a mark detection signal of the mark reader 32.
This is a counter for counting MD. The count value MCNO of the counter 33 is the number of the reference position marks 31 detected in the forward movement or the backward movement, and this is a main value measured roughly with the interval of the reference position marks 31 sufficiently larger than the pixel interval as a unit. Means scanning position.

Reference numeral 34 is a scanning cycle table corresponding to the scanning cycle table 24 in FIG. However, in the present embodiment, since the scanning position is measured with reference to the reference position mark 31 on the index 30,
The scanning cycle table 34 stores the data of the scanning cycle determined in advance so that the scanning deviation between the reference position marks 31 is minimized in separate areas for the forward movement and the backward movement. The area selection is made by the scan direction signals CW, CCW, and the addressing of the selected area is made by the count value MCNO.

The scanning timing generation circuit 21 and the control circuit 25 are the same as those in FIG. Further, each signal of ST, SLFT, SRIT, CW, CCW is the same as the corresponding signal in FIG.

The operation of the scanning device configured as described above will be described below.

When the recording operation start signal ST is turned on, the control circuit 25 first turns on the scanning direction signal CCW, and the motor drive circuit 26 causes the motor 7 to rotate in the reverse direction. When the carrier 5 moves to the left and reaches the left end of the guide shaft 3, the detection signal SLFT of the carrier left position detector 12 turns on.

The control circuit 25 turns on the detection signal SLFT to turn on the scanning direction signal CC.
Scan direction signal C to turn off W and specify the forward movement direction
Turn on W. As a result, the motor 7 rotates forward and the carrier 5 starts moving to the right. Also, scan cycle table
34 outbound areas are selected. At the same time, the control circuit 25 turns on the clear signal CR to clear the counter 33. This completes the preparation for recording by forward movement.

After clearing the counter, the control circuit 25 turns on the timer start signal TST to reset the timer 27 and start counting. The scanning cycle table 34 outputs the scanning cycle SCYC corresponding to the count value SCNO (here, zero). When a time equal to the scan cycle SCYC has elapsed, the comparison circuit 28 determines that the comparisons match and the scan timing signal SS
Turn on T. The first scan (print) by the print head 11 starts.

When the first scan timing signal SST is turned on, the control circuit 25 turns on the timer start signal TST again. Therefore, the scan timing signal SST is turned off.
From this, the scanning cycle output from the scanning cycle table 34
When a time equal to SCYC has elapsed, the scan timing signal SST is turned on again and the second scan is performed.

Although the sequential scanning proceeds in this manner, the counter 33 counts up by 1 each time the mark detection signal is output from the mark reader 32. Therefore, the scanning cycle is reset each time the reference position mark on the index 30 is detected.

By repeating the above-described operation, the recording is performed by the forward movement while the scanning cycle is appropriately adjusted according to the main scanning position. When the carrier 5 reaches the right end of the guide shaft 3, the detection signal SRIT of the carrier right position detector 13 is turned on.

The control circuit 25 turns off the scanning direction signal CW to stop the carrier, and at the same time turns on the clear signal CR to clear the counter 33. Further, a step motor (not shown) for driving the feed roller pair 2 is controlled so as to feed the recording paper 1 by a predetermined amount.

When the feeding of the recording paper 1 is completed, the control circuit 25 turns on the scanning direction signal CCW to start the leftward movement (backward movement) of the carrier 5. Further, in the scanning cycle table 34, the backward movement area is selected.

After that, the control similar to the case of the forward movement is performed by the control circuit 25, and the image is recorded. Then, when the carrier 5 reaches the left end of the guide shaft 3 and the detection signal SLFT is turned on, the control circuit 25 controls the end of the recording operation by the backward movement, the control of the recording paper feed, and the control of the forward movement.

An image is recorded while moving the recording head 11 back and forth in this way, but as described above, the scanning cycle is appropriately adjusted according to the number of times the reference position mark 31 on the index 30 is detected (the number of passages). It is possible to obtain a high-quality recorded image with a small recording deviation (scanning deviation in the main scanning direction), which was a problem of reciprocating movement recording, without using such an expensive and highly accurate index.

The scanning device of each of the above-described embodiments can be applied to an image reading device by providing the carrier 5 as a scanning element with a reading head configured to optically read an original by a photoelectric conversion element instead of the recording head 11. Is.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, according to the data of the scanning cycle preset corresponding to the number of times of scanning or the number of times of passing of the reference position for each of the forward movement and the backward movement of the scanner, During the forward or backward movement of the scanner, in order to adjust the scanning period by the scanner according to the movement direction and the number of scans from the start of movement or the number of passages of the reference position, without using an index, or The use of an inexpensive index has the effect of enabling high-quality image recording or image reading with a small scanning deviation.

[Brief description of drawings]

1 and 2 are schematic perspective views of a mechanical unit and a schematic block diagram of a control unit of a scanning device according to an embodiment of the present invention, and FIGS. 3 and 4 are respective other embodiments of the present invention. FIG. 5 is a schematic perspective view of a mechanical section of a scanning device and a schematic block diagram of a control section, FIG. 5 is a schematic perspective view of a mechanical section of a conventional scanning apparatus, FIG. 6 is an explanatory view of recording by reciprocating movement, and FIG. FIG. 8 is an explanatory diagram of the scanning deviation (recording deviation) in the scanning direction, and FIG. 8 is a graph showing the relationship between the scanning deviation (recording deviation) and the scanning position. 1 ... Recording paper, 2 ... Feed roller pair, 3 ... Guide shaft, 5
... carrier, 6 ... belt, 7 ... motor, 11 ... recording head (scanner), 12 ... carrier left position detector, 13 ... carrier right position detector, 21 ... scanning timing generation circuit, 22 ... recording head drive circuit , 23 ... counter, 24 ... scan cycle table, 25 ... control circuit, 26 ... motor drive circuit, 27 ... timer,
28 ... Comparison circuit, 30 ... Index, 31 ... Reference position mark, 32 ... Mark reader, 33 ... Counter, 34 ... Scan cycle table.

Claims (2)

[Claims] 1. A means for moving a scanning element by generation of a scanning timing signal, and data of a scanning cycle set to a value such that a scanning deviation due to main scanning movement is minimized corresponds to the number of times the scanning timing signal is generated. Storage means for storing in advance, counting means for counting the number of times the scanning timing signal is generated, data of a scanning cycle corresponding to the counted number of times of occurrence is read from the storage means, and based on the data of this scanning cycle And a means for generating the scan timing signal. 2. A means for moving a scanning element in response to generation of a scanning timing signal, an index means provided along a moving path of the scanning element for indicating a reference position at regular intervals, and the scanning element provided on the scanning element. A means for detecting the reference position, and a storage means for preliminarily storing the data of the scanning cycle set to a value such that the scanning deviation between the reference positions of the index means is minimized in association with each reference position, A scanning device comprising: each time the reference position is detected, data of a scanning cycle corresponding to the reference position is read from the storage means, and the scanning timing signal is generated based on the data of the scanning cycle.