JPS63204870A - Original scanner - Google Patents

Abstract

PURPOSE:To improve the accuracy of the adjustment of the leading end of image data and the serviceability by constituting the titled scanner so that a counting means counts pulses with the detection output of a detection means for reference, and the scanning of an original is controlled based on the value of said counting and the number of pulses stored in a memory means. CONSTITUTION:An output SCHP from a sensor 240 for the detection of the home position of an optical system is inputted to a CPU 500, and an inversed signal, the inverse of SCHP is inputted to the gate terminal G of a counter 509. Accordingly, the counter 509 counts pulses ENCP generated by an encoder 510 corresponding to the rotation of a motor during a time when the optical system is not in its home position. During a time when the optical system is stopped, the CPU 500 presets an arbitrary value C0 in the counter 509, then drives the optical system. The counter 509 starts counting down from the value C0 every pulse of the pulse ENCP at the time when the optical system leaves its home position, and supplies an INT-signal to the CPU 500 at the time of reaching zero. As a result, an excellent control signal can be formed without increasing the number of sensors for the detection of the optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a document scanning device used in a copying machine or the like.

[Conventional technology]

2. Description of the Related Art Conventionally, as a document scanning device used in a copying machine or the like, one is known that scans the entire surface of a document placed on a fixed document table by moving a mirror, a lens, etc. using a motor or the like.

In order to perform good document scanning in such an apparatus, it is necessary to move the optical system at a constant speed. however,
A time delay occurs from the start of movement of the optical system in a stopped state until the optical system reaches the required speed. Therefore, by setting the stop position (home position) of the optical system to a position slightly in front of the leading edge of the document and starting movement from that home position, the optical system is configured to have a constant speed when it reaches the leading edge of the document. There is.

Therefore, such a configuration requires at least a sensor for detecting that the optical system is at the home position and a tip sensor for detecting that the optical system has reached the leading edge of the document.

Further, the output of the image tip sensor that detects when the optical system reaches the leading edge of the document is also used as a reference signal for document scanning, and various controls are performed using this reference signal. Therefore, if the position of this image tip sensor is not accurate, control using the reference signal cannot be performed well.For example, when using the scanned image as a reference signal for recording on a recording material, There are inconveniences such as mismatch between the leading edge of the document and the leading edge of the recorded image, or loss of images.

However, it is difficult to accurately adjust the position of this image tip sensor, and furthermore, when an image is enlarged and scanned, the positional deviation of this sensor causes a large adverse effect.

〔the purpose〕

The present invention has been made in view of the above points, and an object of the present invention is to avoid increasing the number of sensors for optical system detection (and to enable the formation of good control signals). .

〔Example〕

The present invention will be described below based on preferred embodiments with reference to the drawings.

FIG. 1 shows an embodiment of an image reading apparatus to which the present invention is applied, in which 101 is a document table, 102 is a document holder, 103 is a COD for image reading consisting of a plurality of light receiving elements arranged in a line, and 104 is an image reading device. is a fluorescent lamp for illuminating originals, 105-1
07 is a mirror, 108 is an imaging lens, and 109 is a motor. A motor 109 moves a fluorescent lamp 104 and mirrors 105 to 107 to sub-scan the original in the Y direction, and images of the original are sequentially formed on the CCD 103 . 11
1 is a standard white plate for obtaining data for shading correction, a fluorescent lamp 104 illuminates this standard white plate 111, and a fluorescent lamp 104 and a mirror are placed at a position where the reflected light from the standard white plate 111 is guided to the CCD 103. The state where 105 to 107 are present is called the optical system home position. A sensor 112 detects that the optical system including the fluorescent lamp 104 and the mirror 105 is at the home position.

FIG. 2 is a block diagram of a control section of the document reading apparatus shown in FIG.

In the image reading unit 501, the reflected light of the document illuminated by the fluorescent lamp 511 is read by the CCD 103, photoelectrically converted, and amplified.
Shading correction is performed after A/D conversion. The shading-corrected image signal is sent to the image processing unit 502. The processing unit 502 temporarily stores the image signal in a shift memory,
Conversion and movement in the main scanning direction according to CPU500 commands.
After editing such as trimming 122 king, VIDE
Output as O from connector JR of the reader. The output image signal is sent via a cable 513 to a so-called connector JR of a laser printer 520 as a sub-scanning synchronizing signal VSYN.
It is input together with C. The fluorescent lamp 511 is the fluorescent lamp driver 5
The lighting is controlled by 03, and the CPU 500 is 0N10FF.
The command and its lighting rate are given to the driver 503.

The printer 520 outputs 1 based on the input V[)EO times signal.
Image recording is performed line by line, and a horizontal synchronizing signal BD synchronized with the image recording for each line is output from the printer 520 and input to the clock generator 512 via a cable 513, where it locks the CCD transfer and reads the shift memory. /Write clock etc. are generated and the image reading unit 501
and is supplied to the image processing unit 502.

The CPU 500 is connected to a ROM 504 and a RAM 505 that can be backed up by a battery, and controls the above blocks, the operation section 205, the motor driver 257, and the like.

240 is a sensor sensor for detecting the home position of the optical system described above. Its output S CI (P is input to the CPU 500, and its inverted signal S CHP is input to the counter 5
It is input to the gate terminal G of 09. That is, counter 5
09 is a pulse EN generated from the encoder 510 according to the rotation of the motor when the optical system is not at the home position.
Count CP.

While the optical system is stopped, the CPU 500 presets an arbitrary value C8 in the counter 509 and then drives the optical system. counter 50
9 is a pulse ENC when the optical system leaves the home position.
Counting down starts from C8 every pulse of P, and when it reaches O, an INT signal is given to the CPU 500.

Referring to FIG. 3, an optical drive system and a motor driver 257 consisting of two mirrors will be explained. A first mirror 243 equipped with a mirror 104 and a fluorescent light 105, Mirror 1
Optical pulleys 250, 252 and 25 for providing movement force to each of the second mirror units 242 equipped with 06.107
1.253 is provided. These pulleys 250.25
2. A pulley pairing with 251 and 253 is also provided on the back side (not shown). Each pulley is rotated by an optical system drive DC motor 248 via a drive shaft pulley 247 .

Each mirror 243, 242 is fixed to a wire 246 driven by a respective pulley. Pulleys 252 and 253
The diameter ratio is 2:l, and one mirror 243.242 moves at a speed ratio of 2:1.

When the optical system is stopped, the CPU section 500 outputs the drive signal SCM.
When D becomes "O", the drive circuit 260 is turned off and the motor 248 does not rotate.

When the optical system moves forward, when the drive signal SCMD becomes "B" and the advance signal SCFW becomes "1", the drive circuit 260 is turned on.
Then, a positive voltage is applied to the motor 248 to rotate it in the forward direction.

On the other hand, the forward CPU unit 500 provides speed data 5CDT in accordance with the magnification ratio, and determines the frequency of the clock output from the oscillator 258. In addition to this clock, the speed control circuit 259 includes a pulse generator 25 located on the rotating shaft of the motor 248.
Pulse ENC proportional to the rotation speed of the motor 248 from 8
P is fed back, and the result of comparing the phase and frequency of these two signals is sent to the drive circuit 260 to control the motor 248 at a constant speed. In this example, 22.5 mm/se
c to 600 mm/sec, which is 180 mm/sec at the same magnification.

When moving backward, the drive signal SCMD becomes "B" and the forward signal 5CF
When W becomes "0", the drive circuit 260 applies a negative voltage to the motor 248, causing it to rotate in the reverse direction. At this time, the speed is constant at 800 mm/sec regardless of the magnification.

A plate 245 is attached to the first mirror unit 243, and when this plate crosses the home position sensor 240, which is a photointerrupter, it is detected that the optical system is at the home position. The positional relationship between the home position sensor 240 and the optical system will be explained with reference to FIG.

FIG. 4(b) shows the optical system stopped at the home position. From this state, it starts moving forward in the Y direction by the above-mentioned means, and then the optical system moves forward as shown in FIG. 4(a). A main scanning line perpendicular to the sub-scanning Y direction corresponding to the document table reference point (image leading edge) is reached, and reading of the image of the document 202 is started from this point on.

The relationship among the signals at this time is shown in FIG. 5CHP is the output of the sensor 240, SCMD is the drive signal, 5CFW is the forward signal, and VIDEO is the image signal. Also, VSYNC
is an interval signal that guarantees VIDEO and VSYN
The rising edge of C controls the paper registration in the printer 520.

Further, the pulse ENCP is imported into the CPU section 500, and the pulse ENCP is processed by the preset number of pulses.
is counted to detect that the optical system has reached the leading edge of the image shown in FIG. 4(a).

Pulse ENCP is proportional to the rotation speed of the motor 248, that is, proportional to the moving distance of the optical system.
It is not necessary to consider the rising section to the steady speed of 48,
Easy to control. Further, in this embodiment, since the resolution is high such that one pulse is 51.2X yr/3200S0.05mm, the accuracy is also dramatically improved.

The sequence for reading an image using the above configuration will be explained with reference to the flowchart of FIG. 6.

When reading, first, the counter 50 calculates the number of pulses CNT 1 corresponding to the distance from the home position to the image light end, which is set and stored in the backup RAM 505 as described later.
Set to 9 (601). Next, the speed data according to the magnification, 9SCDT, and SCMD=SCFW for the start of forward movement.
=1 is given to the motor driver 257 (602).

As a result, the counter 509 starts accurately counting the pulses ENCP after leaving the home position, no matter where the optical system starts within the home position.

As the counter 509 counts up, the INT signal becomes “
1" (603), it is known that the optical system has reached the front end of the image, so it starts outputting VSYNC and VIDEO (604). Also, the counter 509 calculates the number of pulses CNT2 calculated according to the image length. (605).When the INT signal becomes "1" again by the count up of the counter 509 (606), it is known that the optical system has reached the rear end of the image, so VSYNC and V
The output of IDEO should be prohibited (609), and the optical system should be stopped (SCMD=O) (608).

After that, in order to reverse the optical system, SCMD=1°5C
Set FW=O (611). 5CHP=1, that is, when it is detected that the optical system has returned to the home position (612
), the optical system is stopped (613), and the process ends.

The timing chart according to the above sequence control is shown in the seventh figure.
As shown in the figure.

Using FIGS. 8 and 9, step 601 in FIG.
The adjustment of the number of pulses CNTl corresponding to the distance between the home position and the leading edge of the image will be explained. First, FIG. 8 shows an example of the operation section 205. The operation unit 205 includes a start key 800 for instructing to start image reading, a stop key 801 for instructing to stop reading, a numeric keypad 802 for setting numerical values such as the number of readings, a clear key 803 for clearing the number set on the numeric keypad 802, Function key 804, number display 805 that numerically displays the number of readings,
a density display 806 that displays the set image reading density;
It has a density key 807 for setting the image reading density, a magnification display 808 for displaying the set reading magnification, a magnification setting key 809 for setting the reading magnification, a size display 810, and a size selection key 811.

Normal display 805 and 808 have one each, 100% is the 9th
It is displayed as shown in Figure (a). Here, when the function key 804 is pressed, the display 805 is displayed as shown in No. 9(a).

Here, when you press the function key 804, a display 805 appears.
becomes "FOI" as shown in FIG. 9(b), indicating that it is the first function mode. In this example, “F
"OI" is the setting mode for the pulse number CNT l. At this time, the display 808 displays the data read out from the backup RAM 505 (FIG. 2) as, for example, "600" as shown in FIG. 9(b). .The operator is shown in Figure 9 (
C) or (d), enter this value using the plus/minus key 8
09, the data can be changed by one count, that is, by about 0.05 mm, and written into the RAM 505 at the same time.

In this way, the image is output while changing the data in units of about 0.05 mm until the leading edge of the document matches the leading edge of the printed paper. The adjusted data is retained in the RAM 505 even when the power is turned off.

That is, in FIG. 10, (a) shows an original, (b) shows an example of a good image output, and for example, if the output image is (e)
In the case like (d), the pulse number CNTl is increased, and in the case (d), the pulse number CNTl is decreased so that the output image becomes as shown in (b).

Although this embodiment has been described with a configuration in which the document table is fixed and the mirror and the like are moved, it is also applicable to a configuration in which the mirror and the like are fixed and the document table is moved. Furthermore, it is applicable not only to a configuration in which an original image is photoelectrically read by an image sensor such as a COD, but also to the optical system control of a conventional copying apparatus that forms an image by directly exposing a photosensitive member to the reflected light of the original image. Needless to say.

〔Effect of the invention〕

As explained above, by adopting a configuration in which pulses proportional to the rotation speed of the motor for moving the optical system are counted based on the home position, and various timing signals are formed based on the counting results, the leading edge of the image can be adjusted. Accuracy and serviceability were improved.

[Brief Description of the Drawings] Fig. 1 is a configuration diagram of an image reading device to which the present invention is applied;
The figure is a block diagram showing the circuit configuration of the document reading device, Figure 3 is a configuration diagram related to optical system movement, Figure 4 is a diagram showing the relationship between the optical system and sensor position, and Figure 5 is a timing chart showing signal output. 6 is a flowchart showing the reading operation, FIG. 7 is a timing chart showing signal output in the reading operation, FIG. 8 is an external view of the operation section, FIG. 9 is a diagram showing the display state, and FIG. The figure shows the adjustment operation, 103 is a CCD, 104 is a fluorescent lamp, 105 to 07 is a mirror 257 is a motor driver, 500 is a CPU section, 50
4 is a ROM, 505 is an R/'M, and 509 is a counter.

Claims (3)

[Claims] (1) A movable optical system that scans a document, a motor that moves the optical system, a detection means that detects that the optical system is in a predetermined position, and a generator that generates a pulse depending on the distance traveled by the optical system. means, a counting means for counting pulses from the generating means, and a storage means for storing the number of pulses corresponding to a distance from the predetermined position to a document scanning start reference position, and the counting means is configured to detect pulses from the detecting means. A document scanning device characterized by counting pulses using output as a counting reference and controlling scanning of the document based on the counted value and the number of pulses stored in the storage means. (2) A document scanning device according to claim (1), further comprising a changing means for changing the number of pulses stored in the storage means. (3) The document scanning device according to claim (1), wherein the counting means counts the pulses from the generating means at least when the detecting means is not detecting the optical system.