JPH01256267A - Picture reader - Google Patents

Abstract

PURPOSE:To allow the reader to cope with the operation even at step-out by comparing an applied pulse number to a stepping motor required when a carriage passes by a step-out detection sensor with a prescribed pulse number and confirming the position of the carriage when the prescribed pulse is applied to the stepping motor so as to detect step-out at reversing. CONSTITUTION:A CPU 32 compares the pulse number P1 when the carriage 4 passes by a step-out detection sensor 18 at forward drive with a specified pulse number P2 (read from a memory 33) when the carriage 4 passes by the step-out detection sensor 18 when no step-out takes place, and discriminates it as the occurrence of step-out when relation of P1<P2 exists. The CPU 32 checks whether or not the carriage 4 passes by the step-out detection sensor 18 when the specified pulse number P2 is reached at reversing. Thus, when the carriage 4 does not pass by the step-out detection sensor 18 at the point of time when the specified pulse number P2 is reached, it is discriminated to be step-out at reversing. Thus, step-out at reversing is detected easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image reading device that optically scans a document surface by driving a scanning optical system using a stepping motor to read a document image.

(Background of the Invention) In an image reading device that optically reads a document, a motor is used to scan a light source. In particular, in color image reading devices, DC motors and AC
A stepping motor is used instead of the motor.

Figure 3 shows the torque-speed characteristics of a stepping motor. It is an i characteristic diagram. In this figure, (A) starts and starts in synchronization with the pulse given to the stepping motor.
This is a self-starting area where stopping and reversing can be performed. Further, (B) is a through region in which when the input pulse of a motor that is started in the self-starting region and is rotating synchronously is gradually increased, the motor can rotate synchronously at an input frequency that is higher than the self-starting characteristic. In addition, the pull-in torque is the maximum torque generated when the motor starts without losing synchronization with the frequency of the input pulse, and the escape torque is the maximum torque generated when the motor starts without losing synchronization with the frequency of the input pulse. This is the maximum torque that the motor can generate without losing synchronization when increasing .

In an image reading device that uses a stepping motor as a driving source for a scanning optical system, an exposure light source and the like of the scanning optical system are driven in a predetermined speed pattern (relationship between moving distance and speed).

As shown in FIGS. 4(a) to (C), this speed pattern consists of a rising part A, a constant velocity part B, and a falling part C, and the pattern of the rising part and the falling part C is as follows. The stepping motor is selected to be in the self-starting region so that it can move in as short a time as possible without causing tax adjustments or the like. Further, the distance that the light source of the scanning optical system moves, that is, the scanning distance changes depending on the document size\) and the magnification change. Therefore, in such a case, as shown in FIGS. 6(a) to 6(c),
The light source of the scanning optical system, etc. is driven using speed patterns having different lengths. In the conventional apparatus, data for obtaining a speed pattern corresponding to each scanning distance is stored in a memory, and data for providing a corresponding speed pattern is read out according to the scanning distance to drive the scanning optical system.

In addition, if the optical system reads an image during forward movement and returns to the home position during backward movement, the constant link section B during the backward movement will increase its speed (faster than during the forward movement), and the through area of the stepping motor will increase the speed. It may be driven.

(Problems to be Solved by the Invention) In conventional devices, equivalent consideration has not been given to the case where the stepping motor loses synchronization.

For example, we will explain the case where the stepping motor loses synchronization when the optical system is moving forward (when reading an image).The moving distance of the optical system is determined by the number of pulses given to the stepping motor.Therefore, the tax adjustment has been made. As a result, the optical system moves only a distance shorter than the specified moving distance. At this time, the controlling CPU cannot detect this step-out. Therefore, when the optical system returns by the set pulse during the return movement, There was a problem in that the machine passed the home position where it was supposed to stop and collided with the side plate of the device, causing damage.

Further, step-out may occur when the optical system returns to the home position after image reading is completed.

During return movement, the stepping motor is generally driven at high speed in the through area outside the self-starting area, so once the stepping motor is adjusted, it cannot be driven again with subsequent pulses and the optical system must be returned to the home position. There was also the problem that it was not possible.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to realize an image reading device that can also be used for tax adjustment of stepping motors.

(Means for Solving the Problems) The present invention solves the above problems in an image reading device that optically scans a document surface and reads a document image by driving a scanning optical system using a stepping motor. a stepping motor driving means for applying a driving pulse to the scanning optical system; a sensor provided on the scanning direction side near the reference stop position of the scanning optical system to detect whether or not the scanning optical system has passed during return scanning; and a control means for controlling the stepping motor so as to return the scanning optical system to the reference stop position when the step-out detection means detects the 1152 scale of the stepping motor. The tax adjustment detection means detects forward movement by comparing the number of driving pulses required to return the scanning optical system to the position of the sensor and the number of driving pulses actually required to return the scanning optical system to the position of the sensor. a forward movement adjustment detection means for detecting [ of the time], and a detection result of the sensor when the driving pulse necessary to return the scanning optical system to the position of the sensor is applied to the stepping motor to detect the escape during the backward movement. It is characterized by comprising a step-out detection means during double movement for detecting out-of-step.

(Function) In the image reading device of the present invention, the number of drive pulses required for the scanning optical system to reach the sensor is determined based on the number of driving pulses actually required to drive the scanning optical system to the sensor position. The out-of-step detection means detects out-of-step of the stepping motor from the number of pulses or the position of the scanning optical system. When step-out is detected, the control means returns the scanning optical system to the reference stop position (home position).

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing the electrical configuration of the main parts of an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing the mechanical configuration of an embodiment of the present invention.

First, in FIG. 2, 1 is a platen glass on which a document 2 is placed, 3 is a slide rail installed in the horizontal direction (sub-scanning direction in FIG. 2), and a carriage 4 is disposed so as to be movable on this slide rail 3. It is set up. Reference numeral 5 denotes a halogen lamp as an exposure light source, which is installed on the carriage 4 so that its tube axis is perpendicular to the plane of the paper of FIG. Reference numeral 6 denotes an actuator provided on the carriage 4, and the carriage is driven by a wire secured to the actuator 6. 7 is a mirror that receives the reflected light from the source B'i2, 8 is a mirror 9a, 9b is a 9
A movable mirror unit is arranged in a V-shape with an opening angle of 0°, 1o is a stepping motor for driving, and 11 to 15 are booleans around which wires are wound. The carriage 4
The actuator 6 is locked to the wire 16 and the pulley 1
The support shafts 4 and 15 are attached to the movable mirror unit 8. The way the wire 16 is stretched is, for example,
After locking one end of 6 to the left side wall of the device in the figure, pulley 14
．． After winding it around the pulley 13, and then winding it several times around the pulley 11 driven by the stepping motor 10 via the bell 1~, it winds it around the pulley 12, locks it to the actuator 6, winds it around the pulley 15, and then winds it around the pulley 11 driven by the stepping motor 10 via the bell 1~. Use the method of locking to one side wall.

Therefore, when the stepping motor 1o starts moving, the pulleys 11 to 15 rotate, and the carriage 4. The movable mirror units 8 are shown in the horizontal direction in FIG. 2, respectively.

It will move at a speed of V/2.

17 is a home position sensor for detecting whether the carriage 4 is at the home position (reference stop position);
Reference numeral 18 denotes a step-out detection sensor that is disposed at a predetermined position in the sub-scanning direction near the home position sensor 17 and detects the occurrence of step-out in the stepping motor 10 depending on whether the carriage 4 passes at a predetermined timing. . These home position sensors 17. The step-out detection sensor 18 performs detection when the actuator 6 provided on the carriage 4 passes near the sensor. A lens 21 receives reflected light from the document surface via mirrors 7.9a and 9b;
23 and 24 are dichroic prisms for separating the light that has passed through the lens 21; R-ch (red channel) images and C-ch (cyan channel) images separated by the dichroic prism 22 are respectively on the light-receiving surface. R-ch CCD, C-ch CC connected to
It is D. These C0Ds 23 and 24 function as line image sensors, and detection elements are arranged in a direction (main scanning direction) perpendicular to the paper surface of FIG.

This embodiment has a configuration in which one page of color image data is read in three scans, and in the first scan, C0D
The output of CCD 23 is used to obtain red image data, the second scan uses the output of CCD 24 to obtain blue image data, and the third scan uses the outputs of CCD 23 and 24 to obtain black image data. ing.

FIG. 1 shows a configuration in which a halogen lamp 5 provided on a carriage 4 is moved at a predetermined speed pattern. In this figure, 31 is the stepping motor 1 mentioned above.
A driver that drives
(hereinafter referred to as CPtJ) 32, the stepping motor 10 is rotationally driven. 3
3 is a memory in which the basic pattern of the pulse train applied to the stepping motor 10 is stored, and its contents are stored in the cPU 32.
It is read out by

When there is an instruction to read an image from the operation unit (not shown), C
The PU32 is connected to the stepping motor 1 by the driver 31.
0 and executes image reading. First, move the scanning optical system such as the light source from the home position in the sub-scanning direction (
Image reading is performed by moving the image forward (forward and backward). After reading this, drive the stepping motor in the opposite direction (backward motion)
and return the scanning optical system to its home position. When reading a color image, this operation is repeated three times.

First, a case will be described in which a tax adjustment occurs in the stepping motor during forward movement. The moving distance of the carriage 4 and the movable mirror unit 8 is determined by the number of pulses given to the stepping motor 10. Therefore, the carriage 4 and the movable mirror unit 8 only scan a distance shorter than the predetermined distance. Therefore, this reading will be bad. Then, the CPU 32 determines the number of pulses P1 at the time when the carriage 4 passes the step-out detection sensor 18 during the backward movement.
and a prescribed number of pulses P2 (read out from the memory 33) at the time when the carriage 4 passes the step-out detection sensor 18 in the case where no tax adjustment occurs. If step-out occurs during forward movement and the scanning movement distance is short, the carriage 4 passes the step-out detection sensor 18 when the number of applied pulses P1 is less than the specified number of pulses P2. Therefore, if Pi < P2, it is determined that a tax adjustment has occurred during the forward movement. Then, the CPU 32 drives the stepping motor 10 to stop the carriage 4 at the home position. By doing this, you can prevent it from returning too much,
Furthermore, it is also possible to prevent damage to equipment due to excessive return of the carriage 4. In addition, here, the specified number of pulses P2
varies depending on the scanning distance (read size), but includes mechanical errors in the scanning system.

Next, we will explain the case where a tax adjustment occurs at the time of return.

During the backward motion, the stepping motor is driven at high speed outside the self-starting region, so once a step-out occurs, it will not be restarted with subsequent pulses.

Therefore, the CPU 32 checks whether the carriage 4 has passed the step-out detection sensor 18 when the specified number of pulses P2 is reached. Therefore, if the carriage 4 has not passed the step-out detection sensor 18 at the time of the specified pulse number P2, it is determined that the step-out has occurred during the backward movement, and the stepping motor 1
0 is given a pulse in the self-starting region to return the carriage 4 to the home position at a constant speed. By doing this, ff52W4 during the backward movement can also be easily detected and recovered.

(Effects of the Invention) As described in detail above, in the present invention, the number of pulses applied to the stepping motor required when the carriage passes the step-out detection sensor is compared with a predetermined number of pulses, Also, by checking the position of the carriage when a predetermined pulse is applied to the stepping motor, it is possible to detect adjustment during return movement, and in the event of a step-out, the carriage is returned to the home position. . Therefore, according to the present invention, it is possible to realize an image reading device that can also be used for tax adjustment of stepping motors.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the electrical configuration of the main parts of an embodiment of the present invention, Fig. 2 is a block diagram showing the mechanical structure of an embodiment of the invention, and Fig. 3 is a characteristic diagram of a stepping motor. ,
FIG. 4 is an explanatory diagram of the speed pattern. 2... Original 4... Carriage 5...
・Halogen lamp 6...actuator 8...
] Moving mirror unit 10...Stepping motor 17...Home position sensor 18...Step-out detection sensor 31...Driver 32...
...CPU 33...Memory patent applicant
Konica Co., Ltd. Ceremony Clerk Patent Attorney Fuji Ijima 1 person Figure 1 Figure 3 Speed [l)l:l SJ

Claims (1)

[Claims] In an image reading device that optically scans a document surface and reads a document image by driving a scanning optical system using a stepping motor, there is provided a stepping motor drive means for applying a drive pulse to the stepping motor, and a reference stop for the scanning optical system. A sensor that is provided on the scanning direction side near the position and detects whether the scanning optical system has passed during scanning return; a step-out detection means that detects step-out of the stepping motor; and a step-out detection means that detects step-out of the stepping motor. control means for controlling a stepping motor to return the scanning optical system to a reference stop position when step-out of the sensor is detected; forward movement step-out detection means for detecting step-out during forward movement by comparing the number of driving pulses required to actually return the scanning optical system to the position of the sensor;
and step-out detection means for detecting step-out during backward movement based on the detection result of the sensor when a drive pulse necessary for returning the scanning optical system to the position of the sensor is applied to the stepping motor. An image reading device characterized by: