JPS642265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device that scans and reads a document by line scanning.

Conventionally, as a configuration for changing the scanning speed, a configuration is known in which a black signal and a white signal are detected from the density of an image, and all-white line portions are skip-scanned.

However, in this type of device, if there is a black signal, that part is always scanned, so even if you want to read and scan only a part of the image information, you cannot skip operations such as reading and scanning from the middle of the image information. However, the disadvantage is that it takes extra time to read the image information.

Therefore, it is known that marks are placed on documents to indicate areas that do not need to be scanned, but in this case, not only do the documents get dirty, but the marks once set cannot be changed.

The present invention aims to eliminate the drawbacks of the prior art described above, and includes a reading means that moves to read image information from a document, a register means for storing a reading start position signal and a reading end position signal, and a register means for storing a reading start position signal and a reading end position signal. A counting means for counting pulses related to the movement, and determining whether the reading means has reached a reading start position and a reading end position based on a position signal stored in the register means and a pulse counting operation of the counting means. and a movement control means that controls the moving speed and direction of the reading means according to the judgment result of the judgment means, and the movement control means is configured to control the reading means to start reading from a starting position. The reading means is moved at a first speed until the determination means determines whether the reading means has reached the position, and the determination means determines that the reading means has reached the reading start position from the reading end position. During the interval, the reading means is moved at a speed slower than the first speed, and when the reading means reaches the reading end position and the reading scan is completed, the reading means is started at a speed faster than the second speed. The present invention provides an image reading device that is characterized in that it can be returned to its original position.

Next, the present invention will be explained based on examples.

In FIGS. 1 and 2, a document to be recorded placed on a document table 1 is illuminated by a light source 2, such as a halogen lamp or a fluorescent lamp. The illuminated light image passes through a reflection mirror 3, a shading correction plate 4, a spectral correction filter 5, and an imaging lens 6, and is formed on a linear reading sensor 7. Since the reflecting mirror 3 is intended to shorten the length of the optical system under the document table 1 by bending the optical path, it is omitted if there is sufficient space and there is no need to bend the optical path. The shading correction plate 4 is a slit-shaped plate whose aperture size is different between the center and the periphery to correct unevenness in brightness between the center and the periphery of the optical axis, that is, unevenness in the amount of light from the light source and unevenness in the amount of transmitted light from the lens system. be. Excluded if shading correction is not required. The spectral correction filter 5 is used to match the emission spectrum of the light source and the spectral sensitivity of the reading sensor 7 to obtain reading spectral characteristics close to the visual sensitivity. It goes without saying that the shading correction plate 4 does not necessarily have to be located at the position shown in the figure, but may be provided at the optical path opening of the light source shielding plate 8 that prevents the light from the light source from leaking outside. Further, the purpose of the spectral correction filter 5 may also be achieved by subjecting the imaging lens 6 to surface treatment.

The imaging magnification of the imaging lens 6 is determined by the size of the sensor 7, and in this embodiment, the sensor 7 is a CCD.
It was done on a reduced scale. The optical system described above is held in a housing 9 to prevent stray light from outside. The housing 9 is connected to a pair of supports 10 and 11, one of the supports 10 having a gear-shaped inner wall is engaged with a screw rod 13 which is rotated by the drive of a reading sub-scanning motor 12, and the other support 11 is It is engaged with the rail rod 14. By driving the reading sub-scanning motor 12, the reading housing 9 is moved to the screw rod 1.
3 and the rail rod 14 to perform sub-scanning for image reading.

Furthermore, a head arm 16 for connecting a marking head 15 is connected to the housing 9. Marking head 15 is an inkjet head in this embodiment. The sub-scanning motor 12 is a stepping motor in this embodiment. Therefore, when a predetermined pulse is applied to the stepping motor, the motor rotates by a predetermined angle, and the casing moves by a predetermined distance.

As will be described in detail later, the stepping motors are driven at different frequencies. When reading a document, it is driven at a frequency that is synchronized with the recording side, but when moving to the reading start position of the document or performing a skip operation, it moves at a faster frequency.

The recording side will be further explained based on FIG.

The recording paper 18 stored in the paper feed cassette 17 is taken out from the paper feed cassette 17 by a pick-up roller 19, and is transferred to the rotating drum 22 by the paper feed roller 20 and the guide plate 21.
guided to the surface. The rotating drum 22 has a small hole on its surface, and is sucked by a suction pump 23 from a suction pipe (not shown), and rotates at a substantially constant speed by transmitting the rotation of a motor 24 via a timing belt 25. Since the rotating drum 22 is rotating at a faster speed than the paper feeding speed by the paper feed roller 20, the paper 18, which was initially sliding while being attracted to the surface of the rotating drum 22 under braking by the paper feed roller 20, When the paper is released from the paper feed roller 20, it is completely wrapped around the rotating drum. Therefore, the paper 18 rotates together with the rotating drum 22. As the rotary drum 22 rotates, the marking head 15 performs main scanning recording, and together with the reading side housing 9 performs sub-scanning recording parallel to the axis of the rotary drum 22.
Copy the original image onto paper. When copying is completed, suction is removed by a valve (not shown) and the paper 18 is released from the surface of the rotating drum 22. Due to the elastic force of the paper 18, separation of the paper from the drum surface begins at the leading edge of the paper. Therefore, by releasing the suction just at the timing when separation starts at the opening of the guide plate 27, the leading edge of the paper can be caught at the leading edge of the opening of the guide plate 27. When the paper that has been rotating at high speed is released from the surface of the rotating drum 22, it is discharged onto the sliding plate 29 by centrifugal force and is received on the tray 30. Guide plates 26, 27
and 28 serve as guides when feeding and discharging the paper 18. Further, an opening is provided in a part of the guide plate 28, and a paper detector 39 is provided for detecting the position of the paper.
is provided, and the output of this detector 39 is used as a line sync signal.

In FIG. 2, a rotating drum 22 is supported by drum supports 31 and 32, and a motor 24, e.g.
The rotation of the synchronous motor is transmitted by the timing belt pulleys 33, 34 and the timing belt 25 and rotates. Also, one end of the rotating drum 22 is
The air is sucked by a suction pump 23 connected to an air valve 35 and an air pipe 36. The suctioned air is exhausted through a filter 37 for removing paper dust and muffling noise. Furthermore, at the other end of the rotary drum 22 there is a rotary encoder 3 which generates a rotational pulse signal in relation to the instantaneous position of the rotary drum 22.
The marking head 15 is driven according to the timing of the rotation pulse signal to perform a recording operation. By using the rotation pulse signal of the rotary encoder 38 as the clock pulse for recording, even if the rotation of the rotating drum 22 is slightly uneven, recording is performed at a timing that corresponds to the instantaneous position of the drum. Accuracy can be relaxed. In the embodiment, 2048 pulses are generated from the rotary encoder 38 during one period of the rotating drum 22.

Next, sub-scanning control will be further explained.

FIG. 3 is a diagram for explaining how to specify the start and end of copying for a document. When not copying, the reading and recording position is normally at the home position HP, which is located away from the original. When a command is given to specify the copy start position SP and end position EP and make a copy, the reading case 9
The marking head 15 then begins to move. And a higher frequency than the sub-scanning frequency f ₂ during copying
At _f1 , the sub-scanning motor is driven and moves close to the designated copying start position SP. When the designated copy start position approaches, the frequency of the sub-scanning motor decreases to the divided frequency of the rotation pulse based on the rotation of the rotary drum. Then, when the position counter of the sub-scanning motor reaches the specified position, the drive pulse of the sub-scanning motor is set at a frequency obtained by dividing the rotation pulse from the rotating drum.
Can be switched to f ₂ . Therefore, during copying, sub-scanning movement is performed in accordance with the rotation of the rotary drum. As a result, even if there is uneven rotation of the rotating drum, the sub-scanning movement is performed accordingly, so that no misalignment occurs between the reading side and the recording side.

When the copying progresses and reaches the copying end position EP, the sub-scanning drive frequency is switched internally and stopped, and this time the frequency f ₁ is higher than that during copying (however, the phase is reversed), that is, it returns to the home position at a faster speed. Return.

FIG. 4 illustrates changes in the driving frequency of the sub-scanning motor. In FIG. 4, the horizontal axis is the time, and the vertical axis is the frequency. Since the sub-scanning drive motor rotates according to the number of pulses applied, the vertical axis can be considered to be the sub-scanning speed. Further, negative means movement in a direction opposite to the direction of movement during copying. Period a is a start-to-search period in which the reading housing and marking head start moving from the home position HP and move to the copying start position SP, and b is a copying period. c is a stop period and d is a return period. In Figure 4, the copy area is explained for one part, but when specifying two or more copy areas for one original, the first copy period is followed by the second search period. This is the period of entering, and then finally stopping and returning in the same manner.

Next, sub-scanning control will be explained based on the block circuit diagram of FIG. In FIG. 5, a pulse signal from a rotational pulse generator 38 is inputted to a terminal 40 in accordance with the instantaneous rotational position of the rotating drum. The input pulse signal is applied to the sub-scanning drive motor 4.
The signal is sent to a discrimination circuit 42 through a frequency divider 41 for matching the amount of rotation of the rotary drum 6 with the rotation of the rotary drum. The frequency divider 41 is configured to frequency divide the number of pulses derived during one revolution of the rotating drum to obtain the number of pulses necessary for the sub-scanning drive motor 46 to move by the required sub-scanning resolution element. .

The internal oscillator 44 generates pulses for the search period, stop period, and return period under the control of the sub-scanning control circuit 43.

The discrimination circuit 42 is a frequency divider 41 based on rotation pulses.
, or an internal pulse from the internal oscillator 44 is selected and sent to the motor driver 45 to drive the sub-scanning motor 46 .

Further, terminals 47 and 48 are terminals for inputting signals specifying the copy start position and end position, respectively. A method for generating a position signal is, for example, by AD converting the output of an absolute linear encoder or a potentiometer. The designated position is stored in the position designation register 49. On the other hand, for the sub-scanning position, the pulses for sub-scanning driving that have passed through the discrimination circuit 42 are further counted down by a frequency divider 50 to the number of pulses corresponding to the number of scans.
This is counted and recognized by the position counter 51.

Therefore, the sub-scanning control circuit 43 and the discrimination circuit 42 compare the contents of the position designation register 49 and the position counter 51, apply an internal pulse to the motor from the home position HP to the start position SP, and start the motor. A divided pulse is applied from position SP to end position EP,
Between the end position EP and the home position H, the frequency is controlled so as to apply internal pulses.

The frequency division ratio of the frequency divider 41 will be explained based on an example. The rotating pulse generator generates 2048 pulses in one revolution of the rotating drum. The marking head is an inkjet head consisting of eight orifices. Therefore, in one rotation of the rotating drum, 8
During the main scanning of the book, the reading sensor also moves by 8 sub-scan resolutions and reads 8 main scans. On the other hand, the sub-scanning motor 46 rotates once with 640 pulses and is connected to this motor. The screw pitch of the screw rod is 1mm. If the sub-scanning resolution pitch is 0.1 mm, the sub-scanning will be performed by 0.8 mm in one rotation of the rotating drum. Therefore, the number of pulses to drive the sub-scanning motor during one rotation of the rotating drum is 640×
Since 0.1×8=512 pulses, the frequency divider 41 divides the input pulse into 1/4. Also, to make high-resolution copies with a sub-scanning resolution pitch of 0.05mm, use 1/8
Divide the frequency into The selection is made by a command from the control circuit 43. In general, the pulse required for one rotation of the sub-scanning motor is Ps, the screw pitch of the screw rod is l, the number of markings on the marking head is N,
When the sub-scanning resolution pitch is lr, the rotating drum is 1
The number of pulses Pr of the sub-scanning motor required to perform N sub-scans during rotation is Pr = Ps/l x lr x N, so the frequency division ratio is 1 of the rotating pulse generator.
When the number of pulses per cycle is Pe, it is Pr/Pe.

Further, the frequency division ratio of the frequency divider 50 is N/Pr=l/Ps×lr. In the example, the resolution of 0.1mm is 1/64,
At 0.05mm resolution, it is 1/32. Pr/N does not necessarily have to be an integer, but is preferably an integer in order to simplify the circuit.

As described above, according to the present invention, the reading start position and end position can be arbitrarily set and changed without staining the original, and the set range can be reliably read and scanned.

Moreover, since the reading means is returned to the starting position after completing the reading scan from the reading start position to the end position, unnecessary movement of the reading means after reading is completed can be prevented, and the time required to complete the reading scanning process can be shortened. I can do it.

[Brief explanation of the drawing]

1 and 2 show a copying and recording apparatus according to the present invention, FIG. 1 is a side view, FIG. 2 is a front view, FIG. 3 is a front view showing the document table, and FIG. 4 is a sub-scanning motor. An explanatory diagram showing the applied signal frequency, FIG. 5 is a control circuit diagram of the control device of the copying machine. Here, 7 is a reading sensor, 12, 24 and 46 are motors, 15 is a marking head, 22 is a rotating drum, 41 and 50 are frequency dividers, 43 is a sub-scanning control circuit, and 49 is a position designation register.

Claims (1)

[Scope of Claims] 1. A reading device that moves to read image information from a document; a register device that stores a reading start position signal and a reading end position signal; and a counter that counts pulses related to the movement of the reading device. means for determining whether the reading means has reached a reading start position or a reading end position based on a position signal stored in the register means and a pulse counting operation of the counting means; and a movement control means for controlling the moving speed and direction of the reading means according to the determination result, and the movement control means is configured to cause the reading means to start from a start position and reach the reading start position by the determination means. The reading means is moved at a first speed until the determination is made, and the reading means is moved at a speed faster than the first speed until the determination means determines that the reading means has reached the reading start position to the reading end position. When the reading means is moved at a slow speed and the reading means reaches the reading end position and finishes the reading scan, the second
An image reading device characterized in that the reading means is returned to the starting position at a speed faster than the speed of the image reading device.