JP2908803B2 - Exposure equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document scanning device that illuminates an image on a document and guides reflected light to a light receiving unit such as an image sensor or a photosensitive drum.

(Prior art) Generally, in a copying machine, an image scanner, and the like,
A so-called 1: 1/2 document scanning apparatus is used in which a document placed on a platen glass is illuminated by a light source and a mirror, and the reflected light is imagewise exposed on a light receiving unit. This is ninth
As shown in FIG. 10 and FIG. 10, a mobile unit 109, 110 mounted on a pair of shaft-like rails 107, 108 installed in parallel, and two wires a, b are fixed to the mobile unit 109. , The torque of the drive source 111 is transmitted to the wires a and b via the gear group and the drive drum 112, and the moving bodies 109 and 110
It runs on 7,108.

During this traveling, the document P on the platen glass 100 is illuminated by the light source 101 of the moving body 109, and the reflected light is reflected by the mirrors 102, 103, 104 of the moving body 109,
The light is guided to the light receiving unit via the imaging lens 105, and then the reflected light is converted into an electric signal and output to an image processing unit (not shown).

In this case, the moving body 110 is moved with respect to the traveling speed of the moving body 109.
By traveling at half speed, the optical path length from the document surface to the imaging lens 105 is always constant.

By the way, some devices of this type are connected to the host computer while illuminating one document, and are therefore connected to the host computer.
In some cases, it is necessary to repeat reading / suspending at any time. For example, in an image scanner for computer input, when the buffer of the host computer connected to the light receiving unit 106 becomes full, the temporary illumination is interrupted, and the reading of the document P is resumed when the data processing on the host computer is completed.

In general, when rotating the drive source 111, slow-up and slow-down (gradually increasing or decreasing the number of rotations) are used to smoothly connect the stopped state and the steady state. However, in the light receiving unit 106 employing a reading sensor such as a CCD, it is necessary to keep the end time interval (accumulation time) of one line constant. In some cases, the motor must be stopped / rotated at a steady-state rotational speed. That is, if the accumulation time T and the number of pulses of the drive source 111 required for feeding one line are n, the drive source 111 suddenly stops / rotates at a speed of n / T (pps) at the time of stop / start. Let me.

(Problems to be Solved by the Invention) However, when the driving source 111 is suddenly stopped / rotated as described above, the bearings (not shown) of the moving bodies 109 and 110 receiving the rails 107 and 108 are stuck in the rails 107 and 108. As a result, a difference occurs between the left end (on the rail 107 side) and the right end (on the rail 108) of the moving body 110 from the time when the driving signal of the driving source 111 is given to the time when it actually starts moving. As a result, there is a problem that the reflected light guided to the light receiving unit 106 is disturbed and affects the electric signal output to the image processing unit, and the finally obtained image information is incomplete. .

The present invention has been made in order to solve the above-mentioned problems, and by providing a document scanning device with a degree of freedom in a horizontal plane,
It is an object of the present invention to improve the running stability of the document scanning device when the running is restarted after the running is stopped.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a moving body that optically scans a document, and a rail that guides the moving body parallel to the document surface. In a document scanning device that moves while being held at two positions in the longitudinal direction of the rail, the moving body is fitted to the rail via a bearing at a first holding position, and is in contact with the document surface at a second holding position. It is characterized by being held so that it can be displaced only in a parallel direction.

(Operation) According to the operation of the present invention based on the above configuration, the displacement of the moving body at the moment of the start of movement is parallel to the document surface and is a circular motion about the first holding position, so that the moving amount of the moving body is small.

(Example) Hereinafter, the present invention will be described based on the illustrated example. Third
FIG. 4 and FIG. 4 show a schematic configuration of an image reading apparatus to which the present invention is applied. That is, reference numeral 1 denotes a light receiving unit (reading sensor) formed of a CCD or the like, which is disposed inside the apparatus main body 2.
On the other hand, an original placing glass 3 is provided on the upper surface of the apparatus main body 2, and the original P placed on the original placing glass 3 is illuminated by the original scanning device A, and the reflected light is guided to the reading sensor 1. It has become.

The document scanning device A includes a lamp unit (moving body) 5 driven by a wire and a mirror unit (moving body) 6. Reference numeral 7 denotes an imaging lens. The lamp unit 5 includes an illumination lamp L that irradiates the document P, and a first mirror M1 that reflects image reflected light of the surface of the document P illuminated by the illumination lamp L to the mirror unit 6 side. On the other hand, the mirror unit 6 is provided with second and third mirrors M2 and M3 that turn the image light reflected by the first mirror M1 toward the reading sensor 1.

The lamp unit 5 and the mirror unit 6 are supported by rails 8a and flat rails 8b so that they can scan parallel to the optical axis while maintaining a right angle to the optical axis of the lens 7.

Reference numeral 9 denotes a driving source for driving the lamp unit 5 and the mirror unit 6, and the rotation is transmitted to a driving drum 10 via a gear group. Generally, in this type of image reading apparatus, a pulse motor is often used as the drive source 9 because the position control and the speed control are easy. The drive drum 10 has two wires 11a and 1 connected at one point on the way.
1b is wound. One end of each wire is fixed to the lamp unit 5 on the way, and is fixed to the main body by making a half circumference on the pulleys 12a and 12b at both ends of the mirror unit 6. The other end of the wire is connected to the pulleys 12a and 12b by a tension spring 13 so as to make a half circumference. As a result, the vehicle travels at half the speed of the lamp unit 5 based on the principle of the moving pulley of the mirror unit 6, and the optical path length is always kept constant over the entire traveling range.

The lamp unit 5 and the mirror unit 6 are normally set at home positions near the document illumination start position by a home position sensor (not shown).

1 and 2 show the displacement means B provided on the mirror unit 6. FIG. In the figure, 17 is a ring-shaped bearing, 16a, 16b
Is a hole into which the bearing 17 is inserted. One of the holes 16a as the first holding position is formed with a hole diameter to fix the bearing 17 by interference fit, and the other hole 16b as the second holding position.
Has a shape of an oblong hole whose dimension in the vertical direction to the running surface is equal to the hole diameter of 16a and larger in the horizontal direction. Both the depths 16a and 16b are equal to or slightly deeper than the length of the bearing 17. 18 is the bearing 17 inserted in 16b
Is fixed to the main body 16 and presses the end face of the bearing 17. The other end of the lamp unit has a roller K on the flat rail 8b.
At one point.

Therefore, the mirror unit 6 has a length corresponding to the long diameter of the oblong hole 16b,
It has the freedom to swing in the horizontal plane (the direction of the arrow in the figure). For this reason, the displacement of the mirror unit 6 at the moment of the movement start is parallel to the document surface and a circular motion about the hole 16a. Maintain the connection between images.

FIG. 5 is an example of a processing block diagram of read image data of the image reading apparatus shown in FIG. After the analog image signal from the reading sensor 6 is amplified by the amplifier 22,
It is converted to a digital image signal by A / D converter 23,
It is input to the image processing circuit 24. CPU 2 in the image processing circuit 24
The digital image signal is binarized according to the instruction from 7. The CPU 27 supplies a threshold level for binarization and data for shading correction to the image processing circuit using image processing parameters stored in the ROM 28 in advance. Further, it outputs a drive signal to a drive circuit 29 that drives the drive source 9. The output from the image processing circuit 24 is branched into two, one of which is directly connected to the selector 26, and the other of which is connected to the subsequent selector 26 via the buffer memory 25 in accordance with a command from the CPU 27.

An image sensor such as a CCD that constitutes the light receiving unit 6 operates under a clock that is output at regular intervals. Processing one line of image data requires two cycles,
As shown in the timing chart of FIG. 6, the image is read in the first cycle, and the read data is transferred in the next cycle. In the figure, Hsync
Is a read synchronizing signal output every accumulation time T (msec) of the image sensor, and SPM is a pulse motor drive signal output in synchronization with Hsync. In this embodiment, one line is fed by giving four pulses to the pulse motor.

Normally, the selector 26 is directly connected to the image processing circuit 24, and the transfer is performed in the next cycle of the reading, but the data of the line being read at the time when the host computer issues the read interruption instruction is transferred in the next cycle. Is not accepted and transferred after reading is resumed. Therefore, when reading is resumed, the selector 26 is connected to the line buffer 25. First, the image of the last line read before the interruption is transferred, and then the selector 26 is switched to the normal state.

In the image reading apparatus configured as described above, when there is a reading start command from the host computer, a driving pulse synchronized with the reading synchronization signal is given to the driving source 9, and the document scanning apparatus A starts running and reads. The image data is transmitted to the host computer.

The host computer processes the transmitted image signal. If the image signal cannot be processed due to a full buffer or the like, a read interruption command is sent to the reading device. Upon receiving this signal, the reading device temporarily stops the rotation of the drive source 9 and the transmission of the image signal, and enters a standby state. When a read restart instruction is issued from the host computer, reading is restarted again from this position.

7 and 8 show another embodiment of the displacement means B. In the figure, reference numeral 27 denotes a bearing made of a material having excellent wear resistance, such as polyacetal or nylon, and a fitting hole 27a of the rail 8a as a second holding position has an oval shape. This outer shape has the same shape as the mounting hole 28 of the main body 16, so that the major axis of the bearing 27 is always fitted in the horizontal direction with an interference fit.

Note that the pair of bearings 29 provided at the first holding position may have a round hole shape made of the same material.

Furthermore, if there is no problem such as strength or thermal change,
It is also conceivable that the bearings 29, 27 and the main body 16 are integrated and made of the above-mentioned material.

In the above embodiment, the case where the displacement means B is provided on the side of the mirror unit 6 has been described. However, since the stick-slip of the lamp unit 5 may affect the bearing, the present embodiment is also applied to the bearing of the lamp unit 5. The same structure as described in the example may be adopted. Further, the present invention is not limited to an image reading apparatus, but may be applied to a copying machine for guiding reflected light to a photoreceptor as in an electrophotographic system.

(Effect of the Invention) Since the present invention is configured as described above, the displacement of the moving body at the moment of starting the movement is parallel to the original surface and the first movement.
The movement of the moving body is small because of the circular movement centered on the holding position, and the connection of images when reading of the document is restarted from the middle can be maintained. Therefore, when the present invention is applied to an image reading apparatus or a copying machine, the output signal from the light receiving section does not change even if the stop / start operation of the document scanning apparatus is performed in the middle, and the finally obtained image information is not affected. It has an excellent effect of not reaching.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention. FIGS. 1 and 7 are side views of the displacement means, FIGS. 2 and 8 are plan sectional views of the displacement means, and FIG. FIG. 4 is a side sectional view of the image reading apparatus of FIG. 3, FIG. 5 is a block diagram showing a main circuit configuration of the image reading apparatus of FIG. 3, and FIG. 9 is a timing chart showing the operation of the image reading apparatus shown in FIG. 3, and FIGS. 9 and 10 are a plan sectional view and a side sectional view showing a conventional image reading apparatus. Description of reference numerals 1 ... Light receiving section (reading sensor) 5,6 ... Moving body (lamp unit, mirror unit) 8a, 8b ... Rail, 16b ... Long hole 17,27 ... Bearing, 28 ... Hole A … Document scanning device, B… Displacement means P… Document

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 1/04 H04N 1/10 H04N 1/00 G03B 27/50

Claims (1)

(57) [Claims] An original having a movable body for optically scanning an original and a rail for guiding the movable body parallel to the original surface, wherein the movable body is moved while being held at two longitudinal positions of the rail. In the scanning device, the moving body is fitted to the rail via a bearing at a first holding position, and is held at a second holding position so as to be displaceable only in a direction parallel to the document surface. A document scanning device characterized by the above-mentioned.