JP2541961B2 - Document scanning device - Google Patents

Description

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, there is known a document scanning device which scans a document placed on a fixed document table by moving a mirror, a lens or the like by 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, there is a time delay from the start of movement of the optical system in the stopped state until the optical system reaches the required speed. Therefore, the stop position (home position) of the optical system is set to a position slightly ahead of the leading edge of the document, and the movement starts from the home position so that the optical system has a constant speed when it reaches the leading edge of the document. Has been done.

Therefore, in such a configuration, at least a sensor for detecting that the optical system is present at the home position and an image tip sensor for detecting that the optical system has reached the leading edge of the document are required.

The output of the image sensor which detects that the optical system has reached the leading edge of the document is also used as a reference signal for document scanning, and various controls are performed using the reference signal. Therefore, if the position of the image tip sensor is not accurate, the control using the reference signal cannot be satisfactorily executed. For example, when the scanned image is used as a reference signal for recording on a recording material, There is an inconvenience such that the leading edge of the document does not match the leading edge of the recorded image, or the image is missing.

However, it is difficult to accurately adjust the position of the image tip sensor, and further, the position shift of the sensor causes a great adverse effect during the enlarged scanning of the image.

〔Purpose〕

The present invention has been made in view of the above points, and an object of the present invention is to provide a document scanning device capable of scanning a document without misalignment without increasing the number of sensors for detecting an optical system. It is a thing.

〔Example〕

Hereinafter, the present invention will be described 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. Reference numeral 101 is a document table, 102 is a document holder, and 103 is an image reading CC including a plurality of light receiving elements arranged in a line.
D, 104 are fluorescent lamps for illuminating the original, 105-107 are mirrors, 108
Is a lens for image formation, and 109 is a motor. By moving the fluorescent lamp 104 and the mirrors 105 to 107 by the motor 109, the document is sub-scanned in the Y direction, and document images are sequentially formed on the CCD 103. 111 is a standard white plate for obtaining data for shading correction, the fluorescent lamp 104 illuminates this standard white plate 111, and the reflected light from the standard white plate 111 is guided to the CCD 103. The state with 105 to 107 is called an optical system home position. 112 is a fluorescent lamp 104 and a mirror
It is a sensor that detects the presence of an optical system consisting of 105 at the home position.

FIG. 2 is a block diagram of the control unit 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, widened, and subjected to the A / D conversion post-fading correction. The image signal subjected to the shading correction is sent to the image processing unit 502. In the processing unit 502, the image signal is temporarily stored in the shift memory, and the main scanning direction conversion, movement, trimming, editing such as masking are performed in accordance with the CPU500 command, and then as a VIDEO, the connector J of the reading device is used.
Output from R. The output image signal is input to the connector JR of the so-called laser printer 520 via the cable 513 together with the sub-scanning synchronization signal VSYNC. Lighting of the fluorescent lamp 511 is controlled by the fluorescent lamp driver 503, and the CPU 500 gives an ON / OFF command and its lighting rate to the driver 503.

The printer 520 records an image for each line based on the input VIDEO signal, and the printer 520 outputs a horizontal synchronization signal BD synchronized with the image recording for each line, and the cable 51
Input of clock generator 512 via 3 where CC
D transfer clock, shift memory read / write clock, etc. are generated and supplied to the image reading unit 501 and the image processing unit 502.

CPU500 is ROM 504, RAM 505 that can be backed up
Is connected to control the block and operation unit 205, the motor driver 257, and the like.

Reference numeral 240 is a sensor for detecting the home position of the optical system. The output SCHP is input to the CPU 500, and the inverted signal {circle over ()} is input to the gate terminal G of the counter 509. That is, the counter 509 counts the pulse ENCP generated from the encoder 510 according to the rotation of the motor when the optical system is not in the home position.

While the optical system is stopped, the CPU 500 drives the optical system after presetting an arbitrary value C ₀ in the counter 509. The counter 509 starts counting down from C _{0 for} each pulse of the pulse ENCP when the optical system leaves the home position, and when it reaches 0, INT
Signal is given to CPU500.

An optical drive system including two mirror bases and a motor driver 257 will be described with reference to FIG. Optical pulleys 250, 252 and 251, 253 are provided to give a moving force to each of the first mirror stand 243 including the mirror 104 and the fluorescent lamp 105 and the second mirror stand 242 including the mirrors 106 and 107. Pulleys paired with these pulleys 250, 252, 251, and 253 are 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 stand 243, 242 is fixed to a wire 246 driven by each pulley. The diameter ratio of pulleys 252 and 253 is
At 2: 1, the mirror stands 243 and 242 move at a speed ratio of 2: 1.

When the optical system is stopped, the drive signal SCMD is set to "0" by the CPU 500.
Then, the drive circuit 260 is turned off and the motor 248 does not rotate.

When the optical system moves forward, the drive signal SCMD becomes "1"
When SCFW becomes “1”, the drive circuit 260 is turned on, and a positive voltage is applied to the motor 248 to rotate it forward.

On the other hand, when moving forward, the CPU section 500 displays the speed data SC according to the scaling factor.
DT is given to determine the frequency of the clock output by the oscillator 258. The speed control circuit 259, together with this clock, receives the motor 248 from the pulse generator 258 on the rotary shaft of the motor 248.
The pulse ENCP proportional to the rotation speed of
The result of comparing the phase and frequency of these two signals is the drive circuit 26.
Sent to 0 to control the motor 248 to a constant speed. In this embodiment, it is possible to control from 22.5 mm / sec to 600 mm / sec.
mm / sec.

When the drive signal SCMD becomes "1" and the drive signal SCFW becomes "0" during reverse, the drive circuit 260 applies a negative voltage to the motor 248,
Reverse rotation. At this time, a constant speed of 800 mm / regardless of the magnification
sec.

A plate 245 is attached to the first mirror base 243, and the plate crosses a home position sensor 240, which is a photointerrupter, to detect that the optical system exists at the home position. The positional relationship between the home position sensor 240 and the optical system will be described with reference to FIG.

FIG. 4 (b) shows a state in which the optical system is stopped at the home position. From this state, the forward movement is started in the Y direction by the above-mentioned means, and thereafter, the optical system is moved as shown in FIG. 4 (a). Arrives at the main scanning line orthogonal to the sub-scanning Y direction corresponding to the document table reference point (image front end), and thereafter, the reading of the image of the document 202 is started.

The relationship between the signals at this time is shown in FIG. SCHP is a sensor
240 outputs, SCMD is a drive signal, SCFW is a forward signal, and VIDEO is an image signal. Further, VSYNC is a section signal that guarantees VIDEO, and controls the registration of the paper in the printer 520 by the rise of VSYNC.

Further, the pulse ENCP is fetched into the CPU unit 500, and the pulse ENCP is counted by a preset number of pulses to detect that the optical system has reached the image front end shown in FIG. 4 (a).

Since the 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 magnification and the rising section of the motor 248 to the steady speed, and the control is simple. Further, in this embodiment, one pulse is 51.2
Since it has a high resolution of × π / 3200≈0.05 mm, the accuracy is dramatically improved.

A sequence for reading an image with the above configuration will be described with reference to the flow of FIG.

At the time of reading, first, the number of pulses CNT1 corresponding to the distance from the home position to the leading edge of the image, which is set and stored in the backup RAM 505 as described later, is set in the counter 509 (6
01). Next, the speed data SCDT corresponding to the magnification and SCMD = SCFW = 1 for starting the forward movement are given to the motor driver 257 (6
02). This causes the counter 509 to start counting the pulses ENCP exactly after leaving the home position wherever the optical system starts in the home position.

When the INT signal becomes "1" by the count-up of the counter 509 (603), it is known that the optical system has reached the front end of the image, and the output of VSYNC and VIDEO is started (604).
Further, the pulse number CNT2 calculated according to the image length is set in the counter 509 (605). When the INT signal becomes "1" again due to the count-up of the counter 509 (606),
Since you can see that the optical system has reached the rear edge of the image, VSYNC and V
SCMD to stop the output of IDEO (609) and stop the optical system
= 0 (608).

After that, SCMD = 1 and SCFW = 0 are set in order to invert the optical system (611). When SCHP = 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.

A timing chart according to the above sequence control is shown in FIG.

Referring to FIG. 8 and FIG. 9, the above-mentioned FIG.
The adjustment of the pulse number CNT1 corresponding to the distance between the home position image tips in the above will be described. First, FIG. 8 shows an example of the operation unit 205. The operation unit 205 includes a start key 800 for instructing the start of image reading, a stop key 801 for instructing to stop the reading, a ten key 802 for setting numerical values such as the number of times of reading, a clear key 803 for clearing the set number of the ten key 802, and a fan. Function key 804, number display 805 that displays the number of times of reading numerically, density display 806 that displays the set image reading density, density key 80 that sets the image reading density
7, 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.

Each of the normal displays 805 and 808 is displayed 100% as shown in FIG. 9A. Where the funky key
When the user presses 804, the display 805 is displayed as in the ninth (a).

Here, when the function key 804 is pressed, the display 805 becomes "F01" as shown in FIG. 9 (b), indicating that it is the first function mode. In this embodiment, "F01" is the setting mode of the pulse number CNT1. At this time, the display 808 displays the data read from the backup RAM 505 (FIG. 2) as shown in FIG. 9B, for example, "600". The operator adds this value as shown in Fig. 9 (c) or (d).
With the minus key 809, you can change the data in 1-count increments, that is, change the data in units of about 0.05 mm, and write it to 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 original matches the leading edge of the printed sheet. 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 and (b) shows a good image output example. For example, the output image is (c).
In case such as, increase the pulse number CNT1, and (d)
In such a case, the pulse number CNT1 is reduced and adjustment is performed so that the output image becomes as shown in (b).

In the present embodiment, the configuration is described in which the document table is fixed and the mirror or the like is moved, but it is also applicable to a configuration in which the document table is moved while the mirror or the like is fixed. Further, it is applicable not only to a configuration in which an original image is photoelectrically read by an image sensor such as a CCD, but also to an optical system control of a conventional copying apparatus which directly exposes a photosensitive member with reflected light of the original image to form an image. Needless to say.

〔The invention's effect〕

As described above, according to the present invention, it is possible to start the movement from a predetermined position, pass through the document leading edge reference position where no sensor is provided, and move along the document aligned with the document leading edge reference position. The scanning means for exposing and scanning the original by the detecting means, the detecting means for detecting that the scanning means is at a predetermined position, the generating means for generating a pulse according to the moving distance of the scanning means, and the scanning means deviated from the predetermined position. From time to time, counting means for counting the pulses from the generating means, backed up storage means for storing a predetermined number of pulses corresponding to the distance from the predetermined position to the document leading edge reference position, and the predetermined pulse stored in the storage means The adjusting means for manually increasing or decreasing the number, the storage control means for rewriting and storing the predetermined pulse number increased or decreased by the adjusting means in the storage means, and the count value of the counting means are stored in the storage means. The sensor for detecting the scanning means has a signal output means for outputting a signal indicating that the scanning means has passed the reference position of the leading edge of the document in response to the value corresponding to the stored predetermined number of pulses. It is possible to perform document scanning without misalignment without increasing the number of.

[Brief description of drawings]

FIG. 1 is a block diagram of an image reading apparatus to which the present invention is applied, and FIG.
FIG. 4 is a block diagram showing the circuit configuration of the document reading device, FIG. 3 is a configuration diagram relating to the movement of the optical system, FIG. 4 is a diagram showing the relationship between the optical system and the sensor position, and FIG. 5 is a timing chart showing the signal output. 6 and 6 are a flow chart showing the reading operation, FIG. 7 is a timing chart showing the signal output in the reading operation, FIG. 8 is an external view of the operation unit, FIG. 9 is a view showing the display state, and FIG. 10 is a view showing the adjustment operation of FIG. 10, 103 is a CCD, 104 is a fluorescent lamp, 105 to 107 are mirrors, 257 is a motor driver, 500 is a CPU section, 504 is ROM, 505 is RAM, and 509 is a counter.

Claims (1)

(57) [Claims] 1. An exposure scanning of a document by starting a movement from a predetermined position, passing through a document leading end reference position where no sensor is provided, and moving along a document aligned with the document leading end reference position. Scanning means for performing, detecting means for detecting that the scanning means is at the predetermined position, generating means for generating a pulse according to the moving distance of the scanning means, and when the scanning means deviates from the predetermined position Counting means for counting the pulses from the generating means, a backed up storage means for storing a predetermined number of pulses corresponding to the distance from the predetermined position to the document leading end reference position, and a storage means stored in the storage means. Adjusting means for manually increasing / decreasing the predetermined pulse number, and a storage system for rewriting and storing the predetermined pulse number increased / decreased by the adjusting means in the storage means. And a signal indicating that the scanning unit has passed the document leading edge reference position in response to the count value of the counting unit becoming a value corresponding to the predetermined pulse number stored in the storage unit. A document scanning device comprising: a signal output unit for outputting.