JPH0563905A - Method and device for driving scanner - Google Patents

Abstract

PURPOSE:To reduce the memory capacity by generating an acceleration pattern using the distance of an approach for rising to an object speed to each magnification so as to reduce the speed overshoot at rising. CONSTITUTION:A stepping motor is employed for a drive motor. A scanner control CPU 301 calculates an object speed from a designated magnification and whether a full step drive or a half step drive (drive angle) is discriminated based on an object speed. A slow-up table is generated in a storage means through the cooperation of a 16bit timer 801 and a compare match register 802 based on the result of comparison of a comparator 803. Since a table in which all approach from the start of scanning till a tip of a picture is used for a slow-up distance is generated in a memory for each time corresponding to the magnification, speed overshoot at rising is reduced and the memory capacity is saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner driving device for a digital copying machine or the like, and more specifically, a slow-up (acceleration) table having a slow-up area for the entire approach distance is stored in a memory every time corresponding to a variable magnification. The present invention relates to a scanner driving device and method for eliminating the overshoot at the time of rising and reducing the memory capacity.

[0002]

2. Description of the Related Art Conventionally, in a scanner driving device using a stepping motor, one pattern table for slow-up (acceleration) is prepared, and a constant speed is reached when a target speed is reached based on the pattern table. The slow-up control was performed. Also, 25 to 400%
A slow-up table was prepared for each 1% of the scaling ratio of.

[0003]

However, in the scanner driving apparatus as shown above, the speed is raised to the target speed without using the entire approach distance as shown in FIG. However, there is a problem that the overshoot of is likely to occur. In addition, preparing a slow-up table for each 1% at a scaling factor of 25 to 400% requires a large-capacity memory, which is not economical.

The present invention has been made in view of the above, and reduces the memory capacity and the creation of a slow-up (acceleration) pattern for effectively using the approach distance to rise to the target speed for each magnification. The purpose is to

[0005]

In order to achieve the above object, the present invention provides a scanner driving method using a stepping motor as a driving motor, in which a target speed corresponding to a specified scaling factor and a target speed are set. Provided is a scanner driving method for calculating a slow-up pattern in which the entire run-up area is an acceleration area based on a corresponding driving step angle and creating a slow-up table corresponding to the slow-up pattern in correspondence with the scaling factor. It is a thing.

Further, in a scanner driving device using a stepping motor as a drive motor, a control means for calculating a target speed from a designated scaling factor and determining a drive step angle from the target speed, and an approach area from the drive step angle. (EN) A scanner driving device provided with a slow-up pattern creating means for calculating a slow-up pattern having all acceleration regions and creating a slow-up table in a storage means in correspondence with the scaling factor.

Further, in a scanner driving method using a stepping motor as a driving motor, a step angle of full step or half step is judged according to a target speed calculated or selected from a designated scaling factor, and at the start of scanning. Set or select the drive frequency, the target drive frequency, and the number of steps for the approach distance, and add the drive frequency to the value obtained by dividing the difference between the target drive frequency and the drive frequency at the start of scanning by the number of steps. The timer value obtained by dividing the clock frequency by the driving frequency is stored in the storage means as the next driving frequency, and the processing is performed when the step number is 1
The present invention provides a scanner driving method in which a slow-up pattern, which is a target speed based on the approach distance, is created in correspondence with the scaling ratio by executing the reduction by one by one.

[0008]

According to the scanner driving method of the present invention, a slow-up pattern in which the entire run-up area is the acceleration area is calculated based on the target speed corresponding to the specified scaling ratio and the drive step angle corresponding to the target speed. A slow-up table corresponding to the slow-up pattern is created in correspondence with the scaling ratio.

In the scanner driving apparatus according to the present invention, the target speed is calculated from the scaling factor designated by the control means, and the drive type (drive step angle) of full step or half step is determined from the target speed. The slow-up pattern creating means calculates a slow-up pattern in which the entire approach area is the acceleration area from the drive step angle, and creates a slow-up table corresponding to the scaling ratio.

The scanner driving method according to the present invention is
Determines the drive type, either full step or half step, corresponding to the target speed calculated or selected from the specified scaling factor, and sets or selects the drive frequency at the start of scanning, the target drive frequency, and the number of steps for the approach distance. Then, the value obtained by adding the drive frequency to the value obtained by dividing the difference between the target drive frequency and the drive frequency at the start of scanning by the number of steps is set as the next drive frequency, and the clock frequency is divided by the drive frequency to obtain the timer value. Store in storage device. The processing is executed one by one until the number of steps becomes one, and a throw-up pattern that is a target speed is created according to the approach distance in correspondence with the scaling factor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing the main configuration of the scanner device. Reference numeral 101 is an exposure lamp that serves as a light source for illuminating the original, 102 is a first mirror that guides the reflected light of the original illuminated by the exposure lamp 101, and 103 is an original in which the exposure lamp 101, the first mirror 102, etc. are integrally configured. The first carriage 103 for scanning the first carriage 103 and the second carriage and the third mirror 104 are integrally formed to scan the document.
The second carriage that guides the reflected light from the image forming lens 105 to the image forming lens 105, the image forming lens 105 that forms an image of the reflected light on the next image sensor 106, and the image sensor 106 that converts the reflected light of the received document into an electric signal ( Solid-state image sensor: CC
D) and 107 are stepping motors for scanning and driving the first carriage 103 and the second carriage 104, which are five-phase stepping motors. 108
Is a first drive belt for scanning and driving the first carriage 103, and 109 is a second driving belt for scanning and driving the second carriage 104.
A drive belt, 110 is a stepped pulley that transmits drive to the first drive belt 108 and the second drive belt 109, 111 is an idle pulley that stretches the first drive belt and freely rotates.
Reference numeral 112 denotes an idle pulley which stretches a second drive belt to freely rotate, 113 denotes a drive belt which transmits the driving force of the stepping motor 107 to a drive shaft 114, and 114 rotates the stepped pulley 110 coaxially fixed on both sides. Drive shaft, 11
A drive pulley 5 is provided on the drive shaft 114 and transmits a rotational force to the drive shaft 114 by the drive belt 113.

In the above, the second carriage 10
No. 4 has the second optical path length of the image formed on the image sensor 106.
Since it is folded back by the mirror and the third mirror to make it constant,
The rotation ratio of the stepped pulley 110 is set to 1: 2 so that the first carriage 103 moves at half the speed.

In the scanner device constructed as described above, the rotational force is transmitted to the drive pulley 115 via the drive belt 113 by the rotation of the stepping motor 107. When the rotational force is transmitted to the drive pulley 115, the stepped pulley 110 is rotated by the drive shaft 114, and at the same time, the first drive belt 108 and the second drive belt 109 are rotated, so that the first carriage 103 and the second carriage 104 respectively. Moving. At this time, the exposure lamp 103 is turned on to expose and scan a document (not shown), and the reflected light is guided from the first mirror 101 to the imaging lens 105 by the second mirror and the third mirror in the second carriage 104, Imaging lens 10
An image is formed on the image sensor 106 by 5 and converted into an electric signal.

FIG. 2 is an explanatory view showing a main cross section of the scanner device shown in FIG. In the figure, 201 is a contact glass made of transparent glass on which a document to be copied is placed, 202 is a reference white plate arranged on the home position side from the leading edge of the image, 203 is a shield plate of the first carriage 103, and the home is detected. It is a photo interrupter that outputs a position signal.

In the scanner device configured as described above, the photo interrupter 203 is the first carriage 10.
The shield plate provided at 3 detects the start position of the first carriage 103 and generates a home position signal. The start position of the first carriage 103 can be known from this signal. Further, after scanning the read document with exposure, the first carriage 103 is returned to the position where the home position signal is generated, so that the scan is always started from a fixed position. Further, at the timing when the first carriage 103 reaches this home position, SL is set.
An EAD signal (a signal from the scanner motor control CPU 301 in FIG. 3) is generated. In addition, the first carriage 10
The position of 3 can be known by how many times the phase excitation pattern is switched from the home position.

FIG. 3 is a block diagram showing a control system of the scanner driving device according to the present invention. A scanner motor control CPU 301 controls the stepping motor 107 in response to each input signal (a signal from the main CPU, a home position signal) and ON / OFF control of the exposure lamp 101, and a constant current 302 is a constant current. Constant current circuit for output control, 303 and 304 are FE of motor driver
T (field effect transistor), 305 is a comparator.

In the control system of the scanner driving device constructed as described above, the scanner motor control CPU 301
Is serially communicated with a main CPU (not shown), and when receiving a scan start command from the main CPU, drives the stepping motor 107 to perform exposure scanning. When the first scanner 103 returns to the home position, it sends a scan end command to the main CPU. At this time, the scanner motor control CPU 301
Controls ON / OFF of the exposure lamp 101. Also,
The scanner motor control CPU 301 sends to the image processing unit (not shown) the reading timing of the reference white plate 202 to be read for the correction of the light amount distribution of the exposure lamp 101 after the scan is started by the SREAD signal.

FIG. 4 shows a scanner motor control CPU 301.
It is a full-step drive pattern that is output more. This is because the 0.72 ° stepping motor 107 rotates every time one step is advanced, and 0 to 9 at the time of forward rotation.
Steps are sequentially switched, and the process returns to step 0 and is repeated. At the time of reverse rotation, the step is switched to the reverse of that at normal rotation.

FIG. 5 shows a scanner motor control CPU 301.
It is a half-step drive pattern that is output more. This is because the 0.36 ° stepping motor 107 rotates every time one step is advanced, and during forward rotation, it is sequentially switched from 0 to 19 steps, and then returns to 0 step and is repeated. At the time of reverse rotation, the step is switched to the reverse of that at normal rotation. This half-step drive generally produces less vibration during rotation of the stepping motor 107 than full-step drive, and drives at half-step during low-speed rotation. At the time of high speed rotation, the timing of switching the phase excitation pattern becomes faster, so that the arithmetic processing speed of the scanner motor control CPU 301 cannot keep up. Therefore, at the speed where it is necessary to switch the phase excitation pattern at a timing of about 200 μsec or less,
Drive in full steps.

FIG. 6 is a numerical table showing a concrete example of the switching timing of the phase excitation pattern for each magnification according to the present invention. Here, the linear velocity (mm / se) corresponding to the scaling factor (%)
c), phase excitation switching timing (μsec), and drive pattern are shown. In this embodiment, the diameter of the stepped pulley 110 that drives the first scanner 103 shown in FIG. 1 is φ30 mm, and the timing belt is set to a reduction ratio of 1: 2. When the linear velocity of 103 is 85 mm / sec, the scaling factor is 25% to 400%, and the top speed on return is 500 mm / se.
c. As shown in FIG. 6, full-step driving is performed for a linear velocity of 250 mm / sec or more.

With respect to the phase excitation pattern, a constant current chopper is applied by the constant current circuit 302 shown in FIG.
Stepping motor 107 with S-FETs 303 and 304
To drive. Rs in the figure is a current detection resistor, and the voltage generated in this resistor and the voltage determined by the divided voltage of the resistors R ₁ and R ₂ are compared by the comparator 305 to generate a signal for the constant current chopper. To do. In the stepping motor 107, the current and the torque are in a substantially proportional relationship, and the current value for the required torque can be determined by the resistors R ₁ and R ₂ . However, the stepping motor 107
As the generated torque increases, the vibration of the stepping motor 107 itself increases, which adversely affects the read image and also increases the amount of heat generated. The required torque becomes particularly large during acceleration / deceleration, but the required torque is small because the image reading timing is constant. Therefore, in the constant speed region, the current down (CD) signal is generated from the scanner motor control CPU 301 to set the constant current value low. FIG. 7 is a graph showing a velocity diagram at the same magnification scan in this case.

FIG. 8 is a block diagram showing the configuration of a slow-up (acceleration) control system inside the scanner motor control CPU 301 according to the present invention. In the figure, 801 is a 16-bit timer that counts a time interval for switching a phase excitation pattern to a compare match register 802, 802 is a compare match register that creates a slow-up pattern for accelerating to a target speed by inputting an output time interval of the phase excitation pattern, Reference numeral 803 is a comparator.

In the above, the scanner motor control CPU
The output of the phase excitation pattern from 301 uses a 16-bit timer 801 and a compare match register 802 inside the scanner motor control CPU 301. A time interval for switching the phase excitation pattern is set in the compare match register 802, and the scanner motor control CPU 301 is interrupted by a compare match signal with the 16-bit timer 801, and the 16-bit timer 801 is cleared. The scanner motor control CPU 301 outputs the next phase excitation pattern in the interrupt process, and sets the time interval for outputting the next phase excitation pattern in the compare match register 802.

Further, as shown in the slow-up (acceleration) diagram of the stepping motor 107 in FIG. 9, the slow-up (acceleration) must be finished before the image front end,
As shown in FIG. 9, the throw-up (acceleration) distance in this case is 30 mm from the home position. In addition, it is preferable to execute the slow-up (acceleration) as gently as possible, and when the speed is rapidly raised, an overshoot of the velocity occurs (a in FIG. 9), which appears as a jitter at the leading edge of the image. Therefore, in the present invention, the slow-up (acceleration) shown in FIG.
A slow-up pattern (time interval sequentially set in the compare match register 802) table for accelerating to the target speed of the stepping motor 107 using all the distance of 30 mm is created in advance before starting the scan.

FIG. 10 is a flowchart showing an example of slow-up (acceleration) control according to the present invention. In the figure,
First, the target speed of the stepping motor 107 is calculated from the scaling factor designated by the main CPU (not shown) (S1001). The target speed corresponding to this scaling factor may be set in advance in a table and selected. Next, based on the target speed, it is determined whether full-step driving or half-step driving as shown in FIG. 6 (S1002), and a predetermined setting corresponding to the driving is executed. In the case of full step drive, the drive frequency f _S at the start of full step drive, the target drive frequency f _T , and the number of steps required for 30 mm movement are set (S1003). Also,
In step S1002, in the case of half step drive, the drive frequency f _S at the start of half step drive, the target drive frequency f _T , and the number of steps required for 30 mm movement are set (S1004). Also,
Drive frequency f _S at each start, target drive frequency f
_T and the number of steps required for 30 mm movement may be tabulated in advance and selected.

Next, n = 1 is set (S1005), the driving frequency f _S at the start is subtracted from the target driving frequency f _T , and the Δf value is calculated by dividing by the step number step required for 30 mm movement (S1006). .. The next drive frequency f _S is obtained by adding the calculated Δf value and the drive frequency f _S at the start (S1007). Therefore, the clock frequency f _C of the 16-bit counter 801 is changed to the next drive frequency f _S.
The timer value Tn set by the next compare match register 802 is divided by _S (S1008), and the RAM (Random Acces) in the scanner motor control CPU 301 is divided.
s Memory) to reduce the number of steps required to move 30 mm by one (S1009), and n = n + 1 (S1010).
It is checked whether the step is 1 (S1011),
If step = 1 is not satisfied, the process returns to step S1006, and s
Repeat the process until step = 1, and conversely, step
When p = 1, the clock frequency f _C of the 16-bit counter 801 is divided by the next drive frequency f _T to obtain the timer value Tn (slow-up pattern) to be set for the nth compare match (S1012). As a result, a slow-up pattern having a target speed at a slow-up distance of 30 mm is created.

Further, the scanner motor control CPU 301
Completes the slow-up (acceleration) by sequentially reading out the slow-up pattern Tn by the scan start command from the main CPU (not shown) and setting it in the compare match register 802.

After the slow-up (acceleration), the distance corresponding to the document size is scanned, and the movement distance is obtained by counting the number of times the phase excitation pattern is switched (interruption number). After moving a predetermined distance, slowdown (deceleration) is performed based on another slowdown pattern table (prepared in advance). And at the time of stopping, 10 msec-100
Turn off msec excitation. This is a process for returning again if a step out occurs. That is, even if the return drive is started without turning off the excitation in the step-out state, the stepping motor 107 is still in the step-out state.
Will be out of control.

After the excitation is turned off, slow-up (acceleration) is performed based on another previously prepared slow-up pattern table for return. During the return operation, it is possible to know the position of the carriage by counting down each time the phase excitation pattern is switched, from the moving distance (the number of times the phase excitation pattern is switched) counted during scanning. When the carriage position returns to the stop position, slowdown (deceleration) is started based on another previously prepared slowdown pattern table. Further, since the carriage starts from the home position, the home position sensor 203 is just input after the end of the return (moving distance counter = 0), and at that time, the stepping motor 1
The driving of 07 is stopped. At this time as well, the excitation is turned off until the start of the next scan at the time when it is considered to have stopped, and heat generation and current consumption of the stepping motor 107 and the driver are suppressed.

If step out occurs during scanning or return, the home position signal will not turn ON after the end of return because the predetermined distance has not been moved. Therefore, when the home position signal is turned on during the return operation, the excitation is turned off immediately.
The signal from the home position sensor 203 may be input as an interrupt signal to the scanner motor control CPU 301, and if the return is not completed during the interrupt process, it is determined as abnormal and the excitation is turned off. Also, if the home position signal is not turned on at the end of the return, it is considered abnormal and the excitation is turned off.

[0031]

As described above, according to the scanner driving apparatus of the present invention, the slow-up (acceleration) table in which the entire run-up distance from the start of scanning to the leading edge of the image is set as the slow-up area is made to correspond to the variable magnification. Since it is created in the memory every time, a slow-up (acceleration) pattern that effectively uses the approach distance to rise to the target speed is created for each magnification to reduce the speed overshoot at the start and reduce the memory capacity. Reductions can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main configuration of a scanner device according to the present invention.

FIG. 2 is a sectional view showing a main configuration of a scanner device according to the present invention.

FIG. 3 is a block diagram showing a control system of a scanner driving device according to the present invention.

FIG. 4 is a table showing full-step drive patterns output from the scanner motor control CPU according to the present invention.

FIG. 5 is a table showing half-step drive patterns output from the scanner motor control CPU according to the present invention.

FIG. 6 is a numerical table showing a specific example of the switching timing in the phase excitation pattern for each magnification according to the present invention.

FIG. 7 is a velocity diagram during a 1 × scan according to the present invention.

FIG. 8 is a block diagram showing the configuration of a slow-up (acceleration) control system inside the scanner motor control CPU according to the present invention.

FIG. 9 is a graph showing slow-up (acceleration) of a stepping motor according to the present invention.

FIG. 10 is a flowchart showing an operation example of slow-up (acceleration) control according to the present invention.

[Explanation of symbols]

 107 Stepping motor 301 Scanner motor control CPU 801 16-bit timer 802 Compare match register

Claims (3)

[Claims] 1. A scanner driving method using a stepping motor as a drive motor, wherein an entire run-up area is set as an acceleration area based on a target speed corresponding to a specified scaling ratio and a drive step angle corresponding to the target speed. A scanner driving method characterized in that a slow-up pattern is calculated and a slow-up table corresponding to the slow-up pattern is created in correspondence with the scaling factor. 2. A scanner driving device using a stepping motor as a drive motor, wherein a target speed is calculated from a designated scaling factor and a drive step angle is determined from the target speed; and a run-up area based on the drive step angle. A scanner driving device comprising: a slow-up pattern creating unit that calculates a slow-up pattern with all acceleration regions and creates a slow-up table in a storage unit in correspondence with the scaling factor. 3. In a scanner driving method using a stepping motor as a driving motor, a step angle of a full step or a half step is determined in accordance with a target speed calculated or selected from a designated scaling ratio, and at the start of scanning. Set or select the drive frequency, the target drive frequency, and the number of steps for the approach distance, and add the drive frequency to the value obtained by dividing the difference between the target drive frequency and the drive frequency at the start of scanning by the number of steps. A timer value obtained by dividing the clock frequency by the driving frequency is set as the next driving frequency, and the timer value is stored in the storage means, and the processing is executed by reducing the number of steps by one until the step number becomes 1 and the target is set by the approaching distance. A scanner driving method, wherein a speed-up slow-up pattern is created in correspondence with the scaling factor.