JP2746585B2 - Scanning device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning device used for recording and reading of a facsimile, a printer, and the like. 2. Description of the Related Art A conventional scanning device will be described below. FIG. 3 is a schematic perspective view showing a recording apparatus to which an example of a conventional scanning apparatus is applied. This recording apparatus is provided with a pair of feed rollers 1 driven by a step motor capable of intermittent feeding (not shown) at a predetermined interval. The feed roller 1 moves the medium 2 to be scanned in the sub-scanning direction indicated by an arrow a.
In the direction of. Between the pair of feed rollers 1, a guide shaft 3, an anti-vibration shaft 4, and a recording timing index (hereinafter, referred to as an index) 5 forming a scale are each indicated by an arrow “b” in the main scanning direction.
It is arranged parallel to the direction. The index 5 is provided with a first slit 6 indicating the start and end of recording and a second slit 7 indicating the recording timing for each bit at a position corresponding to the recording position of the recording paper 2 by etching or the like.
A carrier 8 is mounted on the guide shaft 3 so as to be able to move forward and backward. The carrier 8 is driven by a step motor (not shown),
It is moved in the main scanning direction while being guided by the guide shaft 3 and the retaining shaft 4. The carrier 8 includes a recording head 9 serving as a scanner and first and second detectors 10 and 1 for reading the scale of the index 5.
With one. The first detector 10 detects recording start and end timings, and the second detector 11 detects information corresponding to the recording timing of each bit. In the recording apparatus configured as described above, while the recording paper 2 is stationary, the carrier 8 is forward-scanned in the direction of arrow b to perform recording of a predetermined width.
The recording paper 2 is moved in the direction by a predetermined width. Then, while the recording paper 2 is stationary, the carrier 8 is re-scanned in the direction opposite to the arrow b to perform recording of a predetermined width, and when this recording is completed, the recording paper 2 is moved by a predetermined width in the direction of the arrow a. Hereinafter, the same operation as described above is repeated to obtain a predetermined image on the recording paper 2. In the above-described image recording, for example, as shown in FIG. 5, when a single movement of the carrier 8 records an m-bit row in the main scanning direction and an n-bit row in the sub-scanning direction, The position of the carrier 8 is confirmed based on the reading value of the index 5 by the detectors 10 and 11, and the deviation of the recording timing of the forward scan and the backward scan is controlled by referring to the confirmation result. Problems to be Solved by the Invention However, according to such a configuration, every time the scanning element moves in the main scanning direction, a shift occurs in the main scanning direction as shown in FIG. 5, and as a result, the image quality is significantly deteriorated. There was a problem of doing. The above problem arises for the following reasons. That is, in this type of conventional scanning apparatus, generally, tens to hundreds of scanning elements are arranged in the sub-scanning direction, but the scanning elements have an error of a predetermined angle with respect to the accurate sub-scanning direction. In many cases, a step shift in the sub-scanning direction occurs at each of the first bit and the n-th bit of the scanning element in each scan. As a result, when a continuous scanning line or the like is scanned in the sub-scanning direction, a shift in the main scanning direction occurs in the recorded image or the read image, and the image quality is significantly reduced. The error of the angle θ is caused by a manufacturing error of the scanner, an error of attaching the scanner to the carriage, and the like. In mounting the scanner on the carriage, the angle θ
In some cases, a mechanical adjusting means is provided to reduce the error of the above, but the mechanical adjusting means is complicated and expensive, and it is difficult to perform fine adjustment. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a scanning apparatus capable of preventing deterioration of image quality without providing an expensive and complicated scanning mechanism for correcting inclination of a scanning element in a sub-scanning direction. The purpose is to provide. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention comprises a plurality of scanning elements arranged in the sub-scanning direction, and a scanning means movable in the main scanning direction with respect to the medium to be scanned. Moving means for moving the scanning means in the sub-scanning direction, and control means for positioning the recording start position of the first line of the current scanning by the scanning means near the scanning start position of the last line of the previous scanning. It is. According to the present invention, by changing the scanning start position by a distance corresponding to the inclination of the recording pixel array or the reading pixel array with respect to the sub-scanning direction by the above-described configuration, it is possible to prevent a recording deviation or a reading deviation in the main scanning direction, Images can be obtained. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a scanning device according to an embodiment of the present invention, and the same members as those in FIG. In FIG. 1, reference numeral 1 denotes a feed roller composed of two rollers disposed adjacent to each other, and the feed roller 1 is driven by a step motor (not shown) to be scanned and inserted between the two rollers. The medium 2 is transported in the direction of arrow a, which is the sub-scanning direction. 3
Is a guide shaft arranged in parallel to the direction of the arrow c which is the main scanning direction, 4 is a vibration-prevention shaft also arranged in parallel, 8 is guided by the guide shaft 3 and is capable of moving back and forth in the direction of the arrow c. The carrier 20 whose vibration is suppressed by the anti-vibration shaft 4 is provided on the carrier 8, and
, A pulley arranged side by side in the direction of the arrow c, a belt wound around the pulleys 21 and 22 and connecting a predetermined portion to the carrier 8, and a pulley 21 for driving the pulley 21 And a motor for rotating forward and reverse, 25 is a carrier left position detector provided at the left end of the guide shaft 3, and 24 is a carrier right position detector also provided at the right end. The devices 25 and 26 detect when the carrier 8 reaches the end of the guide shaft 3. FIG. 2 is a block diagram showing a circuit for controlling the movement of the scanning device. In FIG. 2, 101 is a position detection circuit for detecting the position of the scanner in the main scanning direction, 102 is a main scanning circuit counter for counting the number of main scans of the scanner, and 103 is the output value of the position detection circuit 101 and the main scanning circuit. This is a scan start determination circuit that receives an output value of the scan number counter 102 as an input. The scanning start determination circuit 103 also includes a scanner right movement signal a for instructing the scanner to move rightward, which is an output of the control circuit 104 described later, and a scanner left movement signal for instructing the scanner to move leftward. The movement signal b is input and the scanning start signal e is output. Reference numeral 104 denotes a control circuit for controlling the whole, and a position detection circuit 101 in addition to the signals a and b described above.
, A signal j for initializing the main scanning circuit counter 102, and a signal d for incrementing the main scanning counter 102. A terminal 105 is an input terminal of a signal f for instructing the start of scanning on a page basis, a terminal 106 is an input terminal of an output signal g of the carrier left position detector 25, and a terminal
107 is an input terminal for the output signal h of the carrier right position detector 26. A terminal 108 is an input terminal for the same signal i as the step pulse input to the movement motor 24 of the carrier 8. Terminals 109, 110 and 111 are output terminals for the signals e, a and b, respectively. The operation of the thus configured scanning apparatus of this embodiment will be described below. First, before scanning, an external circuit (not shown) turns on the signal f and inputs the signal f to the control circuit 104 via the terminal 105. The control circuit 104 turns on the signal b when detecting the ON of the signal f. The signal b is input to a driving circuit (not shown) of the motor 24 via the terminal 110, and rotates the motor 24 in the reverse direction to move the carrier 8 to the left. Due to this movement, the scanning can be started from the left end, regardless of the position on the guide shaft 3 where the carrier 8 is at rest before the scanning is started. When the carrier 8 reaches the left end, the carrier left position detector 25 detects this and turns on the signal g. The signal g is input to the control circuit 104 via the terminal 106. When the control circuit 104 detects that the signal g is on, it turns off the signal b and stops the carrier 8.
When the signal b is turned off, the scanning start determination circuit is initialized, and the control circuit 104 turns on the signals c and j to initialize the position detection circuit 101 and the main scanning number counter 102. When the initialization is completed, the control circuit 104 turns on the signal a. The signal a is input from a terminal 110 to a drive circuit of a motor 24 (not shown), and the motor 24 is rotated forward to move the carrier 8 rightward. The step pulse for driving the motor 24 is sent as a signal from the terminal 108 to the position detecting circuit 101.
, And the position detection circuit 101 counts this, and outputs the count value to the scanning start determination circuit 103. Scan start judgment circuit 1
In addition, the output value of the main scanning counter and the signals a and b are input to 03. The scanning start determination circuit 103 determines the scanning start position from these four signals, turns on the signal e, A start of scanning is notified to a scanning circuit (not shown) via a terminal 109. Next, a method of determining a scanning position will be described. First, a case where the carrier 8 moves to the right will be described. Here, FIG. 4 is a schematic diagram showing a scanning example of the scanning device shown in FIG. 3, FIG. 5 is a schematic diagram showing a state of occurrence of a shift amount of a scanning position by a conventional scanning device, and FIG. FIG. 4 is a schematic diagram of a scanning position corrected by the device. As apparent from FIGS. 4 and 5, the scanner 20 has n scanning elements in the sub-scanning direction, and as shown in FIG. For example, in the scanning start position for each scan in the conventional scanning device shown in FIG. 5, the shift between the last line and the start line of the scan is Δl. That is, as shown in FIG. 5, the first pixel of the second scan (the pixel in the first row and the first column, hereinafter referred to as 1-1 pixel) is replaced with the n-th pixel (hereinafter referred to as the first pixel) of the first scan. , N−1 pixels), and the 1-1 pixel of the third scan is shifted by Δl compared to the n−1 pixel of the second scan, and n−1 of the first scan.
It is shifted by Δl compared to one pixel. Similarly, the first 1
The −1 pixel is shifted by Δl compared to the (l−1) -th n−1 pixel, and is also shifted by Δl compared to the n−1 pixel of the first scan. As described above, since a shift occurs for each scan,
When a straight line is drawn in the sub-scanning direction, the shift is conspicuous. Therefore, the second scan start position is $ 1 with respect to the first scan start position, the third scan start position is 2 $ l with respect to the first scan start position, ...
If the position is shifted by (l−1) Δl with respect to the start position of the second scan, a scan in which the shift is inconspicuous can be realized. In FIG. 2, a scan start determination circuit 103 compares the output of the position detection circuit 101 with a scan start position calculated based on the output value indicated by the main scan number counter 102, and when they match, actual scanning is started. The signal e may be turned on in such a manner. When the scanning proceeds and the carrier 8 reaches the right end, the carrier right position detector 26 detects this and turns on the signal h. The signal h is input from the terminal 107 to the control circuit 104. Control circuit
When the signal 104 detects that the signal h is on, the signal a is turned off, and the carrier 8 stops. When the signal a is turned off, the scanning start determination circuit 103 is initialized, and the control circuit 104 turns on the signal c to initialize the position detection circuit 101, and further turns on the signal d to turn on the number of times of main scanning. Is incremented. Next, the control circuit 104 turns on the signal b, and sets the carrier 8
Starts moving to the left. As in the case of moving the carrier to the right, the position detection circuit 101 counts the signal input to the terminal 108 and outputs the signal to the scanning start determination circuit 103. The scanning start determination circuit 103 determines the scanning start position and turns on the signal e in the same manner as the above-described rightward movement of the carrier, but the following points are different between the rightward movement and the leftward movement.
That is, when scanning to the right, the starting point is
In contrast to this, when scanning in the left direction, △ l
The point is that you need to stop. This operation is performed by the signal a,
Switching is performed by turning b on and off. When the scanning further proceeds and the carrier 8 reaches the left end, the carrier left position detector 25 detects this and turns on the signal g. When the control circuit 104 detects that the signal g is on, it turns off the signal b and stops the carrier 8. When the signal b is turned off, the scan start determination circuit is initialized, and further, the control circuit 104 turns on the signals c and d to initialize the position detection circuit 101,
The main scanning number counter is incremented. Next, the control circuit 104 turns on the signal a, and the movement of the carrier 8 in the right direction is started again, and the same operation as described above is executed for one page. As described above, according to the present embodiment, the carrier left position detector 25 and the carrier right position detector 26 that detect the position of the carrier 38, the position detection circuit 101, the main scanning number counter 102, the control circuit 104, By providing the start determination circuit 103, it is possible to prevent a printing displacement of the printing pixel array in the main scanning direction and obtain a good image. The present invention provides a main scanning number counter for counting the number of times of scanning, a position detection circuit for detecting the position of the scanning element in the main scanning direction, an output value of the main scanning number counter, and a position detection circuit. By providing a scan start determination circuit that determines the scan start position based on the output, the scan start position is changed by a distance corresponding to the inclination of the recording pixel array or the read pixel array with respect to the sub-scanning direction. An excellent scanning device that can develop a smooth image without any trouble and can obtain a good image can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view showing a scanning device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a control circuit of the scanning device,
FIG. 3 is a perspective view of a conventional scanning device, FIG. 4 is a schematic diagram showing a scanning example of the conventional scanning device, FIG. 5 is a schematic diagram showing a state of occurrence of a shift amount by the scanning device, and FIG. FIG. 7 is a schematic diagram of a scanning position that has been set. 8 Carrier, 20 Scanner, 25 Carrier Left Position Detector, 26 Carrier Right Position Detector, 23 Belt,
24: motor, 101: position detection circuit, 102: main scanning frequency counter, 103: scanning start determination circuit, 104: control circuit.

Claims (1)

(57) [Claims] A plurality of scanning elements are arranged in the sub-scanning direction, and scanning means movable in the main scanning direction with respect to the medium to be scanned, moving means for moving the scanning means in the sub-scanning direction, and arranged in the scanning means. Assuming that the amount of shift in the main scanning direction between the first element and the last element of the provided scanning elements is Δl, the pixel position in the main scanning direction in the Nth scan is shifted with respect to the pixel position in the main scan direction in the first scan. A control unit for displacing by an amount corresponding to (N−1) × Δl.