JPH04322199A - Controller of stepping motor - Google Patents

Abstract

PURPOSE:To drive a stepping motor with the pulse output being controlled by software, using a two-channel timer, which is built in an MPU loaded for controlling the device. CONSTITUTION:In the stepping motor control of a device loaded with an MPU, the MPU300 is equipped with a timer A, which calculates the control profile of the acceleration, the constant velocity, and the deceleration of a stepping motor and synchronizes the acceleration/deceleration control speed change position based on this control profile, and a timer B, which sets the frequency of the pulse output. It sets the time where a certain time is added to the read value of the timer A at the time of start, and from the next, it sets the next timer value being calculated at the point of time when the set time has passed. It sets the frequency of the next pulse output by applying timer conformity interruption to the timer B at the point of time when the set time of the timer A has passed, and can connect the next pulse output without disturbing the waveform of the previous pulse output.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor control device for accurately conveying a document in a recording apparatus such as a copying machine, a printer, or a facsimile machine.

0002

[Prior Art] In recent years, recording devices have been developed with higher accuracy, higher speed, and smaller size, and automatic document feeders have been developed as a means to efficiently perform various job functions. Improvements are being made in functionality and performance.

The automatic document feeder automatically sets the document on the platen glass, and is usually provided as an option so that the user can selectively install it on the base machine. This device feeds the originals set on the original tray one by one through the transport path from the original entrance in accordance with the timing of image processing, transports them onto the platen glass using an endless belt, and after reading the original image, sends them through the ejection transport path. The original is ejected to the original ejection tray.

This automatic document feeder is broadly divided into a tray section for placing originals before and after processing, a loading section for feeding the originals, a registration section for placing the originals at fixed positions on the platen glass, and a registration section for placing the originals at a fixed position on the platen glass. It consists of a document discharge section that removes documents from above the platen glass. Each of the above sections has an independent or dependent transport roll mechanism for transporting the document, and a DC motor or a stepping motor is used as the drive system for this transport roll mechanism.

Conventionally, in order to place a document on a platen crow, a belt motor is activated by a document exchange signal, and the belt motor is stopped by an output from a sensor that detects the document. When a stepping motor is used as the belt motor, it must be driven within a self-starting region to perform high-speed and highly accurate laying control. If an attempt is made to drive the motor at an acceleration exceeding this self-starting range, the disturbance in the applied pulse waveform will cause step-out, making it impossible to rotate. Therefore, in a stepping motor, drive control is generally performed in which the speed is sequentially changed through a plurality of acceleration or deceleration steps in an acceleration region leading to the maximum speed region or a deceleration region in which the motor stops within a predetermined time from the maximum speed region.

[0006]

[Problem to be Solved by the Invention] By the way, in order to prevent disturbance of the pulse waveform at the switching point of each step,
The stepping motor driver is equipped with an external pulse control LSI, and is configured to write a timer value from the CPU to this LSI, and output pulses at a predetermined frequency to the stepping motor based on this timer value. . However, in controlling a small stepping motor, there is a problem in that solving the problem using hardware such as a pulse control LSI increases the cost.

An object of the present invention is to provide a stepping motor control device that drives a stepping motor with a pulse output controlled by software using a two-channel timer built into an MPU installed to control the device. It is to be.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a stepping motor control device provided in a device controlled by an MPU, which provides acceleration and constant speed of the stepping motor. In addition to calculating the control profile for deceleration, it also has a timer A that synchronizes the acceleration/deceleration control shift position and a timer B that sets the frequency of pulse output.The timer is set by adding a certain time to the reading value of timer A at the start time. Then, set the next timer value calculated at the time when the set time has elapsed, and
an MPU that executes a process of setting the frequency of the next pulse output by issuing a timer match interrupt to timer B when the set time has elapsed; It consists of a driver that drives the motor by switching.

[0009] Also, a two-channel timer built into the MPU is used to perform registration control to decelerate the belt based on the sensor output obtained by detecting the trailing edge of the document while the document is being pulled in, and to place the document at a fixed position on the platen glass. In the stepping motor control device, the MPU reads the value of timer A at the rising edge of the sensor output, sets a time that corrects the reading error of this timer value, and then calculates the time after the set time has elapsed. The present invention is characterized in that it is configured to set a timer value and also to interrupt timer B when this time elapses to set the frequency of the next deceleration pulse output.

0010

[Operation] Sets the pulse output start time by adding a certain time to the value of timer A at the start time. Based on this pulse output start time, accurate shift positions for the next and subsequent stages are calculated to create a motor control profile. As the next set time, the calculated shift position times are set in sequence. When this set time elapses, an interrupt is applied to timer B, which resets timer B and sets the frequency of the next pulse output, so the next pulse output can be connected without disturbing the waveform of the previous pulse output. .

In document registration control, an interrupt is generated at the rising edge of a pulse output based on the sensor output for detecting the trailing edge of the document, and the value of timer A is read at a readable edge at the time of the interrupt. This timer value is corrected so that it can be handled by software, and this corrected time is set. The set time for the next stage is determined by a pre-calculated deceleration motor control profile. The frequency of the deceleration pulse output is set by an interrupt from timer A when the set time has elapsed.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment is applied to a copying machine, which is constructed by combining a base machine with additional devices such as a double-sided automatic document feeder and a sorter. As shown in FIG. 2, the copying machine has a base machine 1 equipped with a double-sided automatic document feeder (DADF) 2 and a sorter 3.
This base machine 1 controls the mechanical section including attached devices according to the job set by the console panel 4,
After image processing is performed on the specified size paper supplied from the tray 5 based on the image information read from the document sent by the DADF 2, the paper is ejected and the image-processed paper is processed in the sorter 3. The system is configured to perform sorting.

[0013] Also, the outline of the copying machine will be explained with reference to FIG. A photosensitive drum 7 is arranged inside the copying machine. In the figure, the photoreceptor 8 is formed in a layered manner on the outer peripheral surface of the photoreceptor drum 7. This photosensitive drum 7 is connected to a drive device (not shown) so as to rotate in the direction of the arrow. On the outer periphery of the photosensitive drum 7, a charge corotron 9 and developing devices 11, 1 are arranged.
2. A transfer corotron 13 and a cleaning device 15 are arranged. In this copying machine, the photosensitive drum 7
As the photoreceptor 8 rotates in the direction of the arrow, the photoreceptor 8 is uniformly charged by the charge corotron 9, and then the exposure point 16
When exposed to light, an electrostatic latent image is formed. Exposure point 16
A light image of a document (not shown) placed on a platen glass 17 placed on the top surface of the copying machine is incident on the photocopying machine. For this purpose, an exposure lamp 19 and a plurality of mirrors 20 and optical lenses 21 that transmit reflected light from the surface of the original illuminated by the exposure lamp 19 are arranged. It is now possible to do so.

The photoreceptor 8 on which the electrostatic latent image has been formed is then developed by a developing device. The toner image formed on the photoreceptor 8 is transferred onto a sheet of paper by a transfer corotron 13, thermally fixed between a heat roll 23 and a pressure roll 24, and then transported out. On the other hand, the photoreceptor 8 is cleaned by a cleaning device 15 and is reused. On the other hand, the paper 27 stored in the supply tray 25 disposed in the copying machine or the paper 27 that is manually fed along the manual feed tray 28 is sent out by the feed roll 29 or 31 and guided by the transport roll 32. It passes between the photosensitive drum 7 and the transfer corotron 13. At this time, the toner image is transferred onto the paper 27. The paper 27 after the transfer passes between the heat roll 23 and the pressure roll 24 and is thermally fixed. Then, it passes between the transport rolls 32 and is delivered to the sorter 3, which is a delivery tray. Note that the intermediate tray 33 is used for double-sided or multiple copying.

As shown in FIG. 4, the console panel 4 has a panel for performing operations such as setting/inputting paper size, magnification, number of copies, etc., starting, stopping, interrupting, and confirming settings. It has buttons as hard keys and buttons as touch keys provided on the display portion corresponding to the functions displayed on the LCD screen. Further, the console panel 4 displays the status of selections and settings when operating the hard keys by means of lamps and the like. FIG. 5 shows the hardware configuration of the copying machine. A user interface (UI) 50 is a MAIN PW that executes settings/input data processing by operating buttons on the console panel 4 and manages the system of this machine.
It sends input data to BA (hereinafter referred to as "MAIN system") and displays it to the user.

A double-sided automatic document feeder (DADF) controller 51 performs control to convey the original onto the platen glass in accordance with the reading timing in order to read image information from both sides of the original. An optical reading device (OPT) controller 52 performs optical reading control of image information designated by a user from a document conveyed onto a platen glass. That is, the DADF transports the document with one side facing the platen glass. Then, the OPT operates and performs the first exposure. Next, when the DADF returns the original after exposure to the tray in the apparatus, it turns it upside down. As a result, when this original is sent out again, the original feeding mechanism and the optical system are controlled so that the opposite side to the previously exposed side is exposed. In the base machine, paper conveyance control and duplex tray drive control are performed in response to a double-sided copy command.

[0017] Static eliminator (ISIL) controller 5
3 controls editing processing such as erasing unnecessary parts from the image information of the original, frame erasing processing for erasing the periphery of the original, and drawing specific information from the image information of the original. An image recording device (IOT) controller 54 performs paper conveyance control,
Manage development process control including paper jam detection and zero rotation. Specific tray (DDM/TRAY [X])
Based on a command regarding double-sided image processing from the IOT, the controller 55 reverses the sheet on which image processing has already been performed on one side and performs image processing on the back side.
Controls the double-sided tray so that it is temporarily on standby until the ro timing, and also controls a specific tray [X] that is handled separately from other trays due to the paper path relationship based on a special tray operation command from the IOT. .

The bin sorter controller 56 includes, for example, two
0 bin sorter is driven by sorting commands from IOT,
Performs control to store paper after image processing carried out from the base machine in a designated bin. The stipple sorter controller 57 performs control for stapling after collating the sheets stored in the bins in response to a binding and sorting command from the IOT. Light Lens Manager (
LLM) 58 is in charge of the overall management of the entire system.
It mainly performs job management such as system timing control to temporally match document image processing and paper transport, and copy mode set by the user. Serial data communication processor (SCP) 59 includes UI, DADF, OPT
It transmits and receives data to and from ISIL using serial communication, and also performs data processing for exchanging data with LLM using parallel communication.

In particular, data exchange between the SCP and the LLM is performed through the dual port RAM built into the SCP. That is, the LLM reads/writes the RAM of the SCP allocated on its own address map, and the SCP reads/writes this RAM to transmit information. The above hardware includes an independent CPU for each function, and the CPU and peripheral LSI constitute an electric circuit board (PWBA). Here, the LLM, SCP, and IOT form the core of the control system of the base machine, and the main control circuit board is composed of the CPU and peripheral LSIs that share each function. less than,
Characteristic parts of the embodiments of the present invention will be explained.

First, the structure of DADF2 will be briefly explained. FIG. 6 shows a cross-sectional configuration of the DADF2. The DADF2 has a tray section installed on the top, a document loading section that automatically transports and processes documents according to various job modes, and a base machine's optical reading device OPT to read the document image by placing the document on a platen glass. It is composed of a document registration section (hereinafter referred to as "registration section") in which the document is placed and a document discharge section which sends out the document after image processing to the tray section. The tray section is provided with a document tray 101 for setting documents and a document discharge tray 102 for storing processed documents.

[0021] As shown in FIG. 8, in the document loading section, there is a feed (prefeed) from the document entrance to a registration roll (hereinafter referred to as "registration roll") for feeding the document 103 set on the tray section. Infeed conveyance path 106, Sada (SA) from the manual feed port to the register roll
DH: semi auto document han
dler) conveyance path 107, a pull-in conveyance path 108 that transports the original onto the platen at a predetermined timing, and a duplex roll that passes through the registration roll and pulls the original into the registration section from the rear end in order to reverse the original during double-sided original processing. A duplex conveyance path 109 is provided for reverse conveyance and conveyance to the upstream side of the registration rolls.

The document entrance is provided with a nudger mechanism for automatically inserting documents one by one into the tray side and an ingate for stopping the leading edge of the document when the document is set. This in-gate moves up and down to protrude or retract with respect to the document entrance by an in-gate solenoid. That is, the in-gate solenoid turns ON when the document sensor in the tray section detects the first document, causes the in-gate to protrude to the document entrance to catch the leading edge of the document, and turns OFF after a certain period of time or when the ADF start signal is received. It is operated and retracted from the document entrance, allowing continuous feeding of documents.

The feed conveyance path includes a feed roll for feeding the original inserted by the nudge mechanism, and a feed roll that is rotated in the opposite direction to this feed roll to carry the original that comes in overlapped with the original sent by the feed roll. A retard roll is arranged to return the document in the direction of the entrance in cooperation with the feed roll. Further, a registration sensor (hereinafter referred to as "registration sensor") that detects the front edge and rear edge of the document and a size sensor that detects the width of the document are arranged on the feeding path near the registration rolls. A feeder sensor for detecting a manual document and a feeder roll for feeding the document are arranged in the feeder conveyance path, and the manually fed document is conveyed to the registration roll by the feeder roll driven by a feeder sensor signal.

A registration gate is provided in the middle of the pull-in conveyance path to switch from the pull-in conveyance path to the duplex conveyance path in order to invert the document in the registration section and set it on the platen during double-sided document processing. This regigate 1
Reference numeral 38 denotes a plate-like member having a substantially triangular cross section, a rotation axis parallel to the rotation axis of the belt drive roll 110, and a member having approximately the same width as the platen 105. During double-sided document processing, on condition that the first side of the document to be processed is in the registration section, the registration solenoid is energized and the transfer path of the registration gate is switched.

[0025] The cash register section is provided with an endless belt 111 made of rubber and driven by a belt drive roll 110 whose power source is a belt motor. The document that has reached the registration roll is processed for a predetermined period of time related to the distance between the registration roll and the registration position on the platen (hereinafter referred to as the "registration position"), in accordance with the paper transport on the base machine side and the operation timing of the optical reading device. The belt is driven to convey the document 103 in cooperation with the registration rolls, and the trailing edge of the document is stopped at a registration position (see FIG. 8) located at the edge (including the vicinity) of the platen on the document carrying side.

As shown in FIG. 9, the document discharge section is equipped with an exit sensor that detects the document sent from the register section and an exit roll that conveys the document. The belt motor and the exit motor are driven by the original document exchange signal (SCAN END), and the processed original sent from the register section is delivered to the discharge tray 102. During this document ejection, after the trailing edge of the document passes the exit sensor, the exit motor is slowed down to prevent the document from suddenly flying out of the document ejection port. Incidentally, reference numeral 147 is an exit interlock sensor that detects an opening/closing operation of the document discharge section cover when, for example, a jam occurs in the document discharge section.

Here, the motors that drive the rolls of each part are DC motors for the nudger roll, feed roll, and sadder roll for feeding the original, and the duplex roll for reverse conveyance, and the registration roll 134 for pulling in the original, and the belt drive roll. 110 and exits 142 and 143 for ejecting originals, stepping motors are used for highly accurate drive control. In addition, cashier roll 134
is driven by a belt motor so that it rotates at the same linear velocity as the belt.

Furthermore, as shown in FIG. 7, the top cover has an SEF (Sh
ort Edge Feed) 113, LEF (Long Edge
A display section is provided in which LEDs are arranged to notify the user of the document feed) 114, document jam 115, and document set 116. Note that 151 and 152 are ADs that detect opening/closing operations of the top cover when a document jam occurs, for example.
This is an F interlock sensor.

The DADF having the above structure has the following transport modes. The simplex mode is a transport mode for performing image processing on only one side of documents 103 of the same size. In this simplex mode, the next document 103 is transported to the registration position before the processed document 103 is completely ejected, thereby achieving high-speed processing. The duplex mode is a transport mode for performing image processing on both sides of the document 103. In this duplex mode, the registration gate 1
38 is pulled in and rotated toward the conveyance path side to open the duplex conveyance path 109, and the original image-processed document is conveyed in reverse to this duplex conveyance path 109, and the back side of the document is stopped at the registration position on the platen 105. Performs image processing on the back side of the document.

The mixed size mode is a transport mode for sequentially copying only one side of a plurality of documents 103 of different sizes, and is operated by selecting the mixed image processing function of the base machine main body. Pre-count mode is original 103
This is a transport mode in which documents can be transported in the same way as the simplex mode and the number of originals can be counted. This pre-count mode can be set when only documents 103 of the same size are transported. The parallel original composition (2 in 1) mode is a transport mode in which two originals 103 of the same size are successively transported onto the platen and image processing is performed on the two sheets at the same time. In this 2in1 mode, the document tray 101
After the odd-numbered originals 103 among the originals set in the original are conveyed to just before the platen, the trailing edge of the odd-numbered originals 103 is detected by a registration sensor. Then, by driving the belt motor for a certain period of time, the trailing edge of the document is placed at the registration position, and document conveyance is temporarily stopped at this point. Next, the even-numbered originals 103 are transported in the same manner as the odd-numbered originals 103. Next, the odd-numbered originals 103 are reversely transported by a certain distance to the duplex transport path 109. By arranging the trailing edge of the even-numbered original at the registration position, the even-numbered original 103 is set on the platen after the odd-numbered original 103 without any gap. According to this transport timing, the odd-numbered original 10
Parallel composite image processing is performed for the third and even-numbered originals 103. After this process, the two original documents 103 are discharged.

Next, the operation of DADF will be explained using simplex mode. Figure 10 shows an outline of transport in simplex mode when the original size is LEF, and Figure 11
shows the sequence flow in simplex mode. Here, a case will be described in which three LEF originals are processed. The arrow ↑ in the diagram is ON, the arrow ↓ is OF
It represents F. Place the original on the original tray (Figure 10A)
) Then, the document set signal (DOCS) from the document sensor
NR↑) is sent to the LLM. When the start button is pressed, the DADF receives the ADF start signal (ADF STAR) in simplex mode sent from the LLM.
T) is received, and the operation of pulling the first document from the document tray is started. At this time, the ADF mode signal (AD
F MODE↑) is transmitted. First, in the prefeed operation (FIG. 10B), the document is conveyed to the so-called prefeed position, where it hits the registration rolls.A registration sensor detects the front edge of the document, and this registration sensor signal (REG
ISNR↑) is sent to LLM. However, in the case of the first document, a registration operation is started in which the document is immediately pulled in by the rotation of the registration roll and belt and stopped at the registration position on the platen glass.

In the above registration operation, a copy start signal (COPY START ↑
) to the LLM. LLM is the copy start signal (
A feed signal (F
EED) is an IO that controls paper supply and paper ejection.
Output to T. During this time, the size of the first document is detected, and this document size signal (PAPER SIZEDATA
) and the register sensor signal at the rear edge of the document (REGISNR↓
) is sent to the LLM.

After a predetermined period of time has elapsed after the trailing edge of the document is detected, the document is stopped at the registration position (FIG. 10C), so the IOT adjusts the document image based on the document size data in accordance with the document transport timing. is read. At the same time, the prefeed operation for the second original starts. In other words, during scanning, the prefeed operation for the second document is performed on the condition that the registration sensor signal (REGISNR↓) for the rear edge of the first document and the document set signal (DOCSNR↑) are output (Fig. 10D). is started. This shortens the time required to start the registration operation for the second and subsequent documents, allowing high-speed processing.

DADF exchanges originals (SCAN END)
When the signal is received, 1 as shown in Figures 10E and 10F.
The operation of ejecting the first sheet of original and the 2 at the pre-feed position.
The registration operation for the first original sheet and the prefeed operation for the third original sheet begin. In this operation, 1
The ejection process for the original sheet is to convey it onto a platen glass near the original ejection section. Next, when the third original is transported, the second original is transported over the platen glass, and the original ejection unit is operated so that the first original is transferred to the ejection tray as shown in FIG. 10G. will be sent to. When the processing of the set originals is completed, all the originals on the platen glass are ejected (FIG. 10H).

Next, stepping motor control will be explained. FIG. 1 shows a basic block of stepping motor control using two-channel timer synchronization. MPU2
00 is a computer that controls the device, and has a two-channel timer consisting of timer A and timer B, which are created by frequency-dividing the original oscillation (basic clock). Timer A is a free running counter, and interrupts timer B when the value of timer A matches the counter value set in the output compare register (OCPRT1). This timer A is used for synchronous control at fixed time intervals in the speed change position in the acceleration (step-up) and deceleration (step-down) regions and in the constant speed region. Timer B sets the frequency applied to the stepping motor, and the value of this timer B is stored in the output compare register (OCPR).
When it matches the counter value set in T0), the previous value is reversed, for example, 0 becomes 1, and 1 becomes 0, and this pulse becomes the real-time output (RTO0).
) is output to the driver 201 as a CLK signal.

The driver 201 starts operating in response to the ENB signal from timer A of the MPU, and drives the stepping motor 203 based on the CLK signal. FIG. 12 shows an example of the operation of the stepping motor. In the step-up, the speed is increased by a plurality of predetermined accelerations within a predetermined time t1, for example, three stages of acceleration of plus 1.5G, 0.5G, and 0.23G. Next, during time t2, the rotation is performed at a constant speed by outputting a pulse at a constant frequency. Note that the constant velocity time t2 is not constant and changes depending on the length of the document being transported, so the constant velocity operation is performed when the register sensor detects the trailing edge of the document and a certain period of time tc has elapsed since the sensor output (OFF signal) at this time. Finish it later. The fixed time tc at this time is set by the number of pulses from the time when the trailing edge of the document passes the registration sensor. The number of pulses is registered in the non-volatile memory of the base machine, and here the non-volatile value 1 is 2 pulses (1 pulse is 0.
(equivalent to 138mm).

Step-down is started after a predetermined time tc has elapsed since the OFF signal of the sensor output, and deceleration is performed at a predetermined acceleration, for example, minus 0.83 G within a predetermined time t3. Step-down and each acceleration in step-down are controlled according to a control profile calculated in advance. FIG. b shows a part of a step-up motor control profile with N steps, and after reading the value of timer A based on this motor control profile, data calculation for each step is performed and a table is created. In FIG. 13, the step number (
Step No. ) determines the number of steps in which acceleration/deceleration is to be performed, and the control is configured such that step-up is controlled by N steps and step-down is controlled by M steps.

Frequency (pps) is the number of pulses/second used in the step. Pulse is the pulse output (number of pulses) of the step at the pulse frequency used. The half-cycle time constant is the time (in microseconds) of a half-cycle per pulse set in the OCPR, and is calculated by the following formula. Half cycle time constant = (1/frequency) x 106/clock/
2 The correction value is a value (unit clock) obtained by rounding off the half-cycle time constant so that it can be handled by software. The actual frequency is the actual frequency (pps) determined from the correction value, and is calculated by the following formula. Actual frequency = (1/correction value x 2 x clock) x 106 The timeout (TimeOut) value is the time (microseconds) it takes to output an arbitrary number of pulses at an arbitrary frequency, and is calculated by the following equation. Timeout value=correction value×2×clock×number of pulses 1 step The time constant is the timeout value (unit clock) set in the OCPR, and is calculated by the following formula. 1 step time constant = correction value x 2 x number of pulses By the way,
Step-up and step-down are realized using a pre-calculated motor control profile using an MPU built-in timer.

In the case of step-up control, as shown in FIG. 14, when the value of timer A is read on software at the time of control start, it does not become X, but becomes X+a, which includes the software processing time. Calculating the next gear shift position based on this, (X+A1) (X+A1+A2)...
An interrupt does not occur accurately at the position (X+A1+A2+...+AN), and the pulse is shifted. In the next stage and subsequent stages, the pulse width is similarly shifted by a minute, making the pulse width uncertain and causing the motor to step out. Therefore, in the present invention, as shown in FIG. 15, pulse output is started at a time point n0=X+n when a certain time n (using motor pre-excitation time) is added to the value (X) of timer A read at the start time. During this time, the exact value of timer A (n1
=
+A1) (X+n+A1+A2)...(X+n+A1
+A2+...+AN) and outputs an accurate waveform to the motor to perform normal acceleration.

At the shift position, the previous pulse waveform is caused to rise, and the rewriting of timer B and OCPR0 is completed within the time until the fall of the first pulse of the next stage. By performing such processing, the disturbance of the pulse waveform at the switching point is eliminated, and during this time, the time required for setting the next stage is gained, and the fall of the first pulse of the next stage is accurately controlled by the frequency set in OCPR0. You can make it happen. On the other hand, timer A sets the time of the next gear shift position calculated in advance after the interrupt processing to OCPR1. By synchronizing the two timers in this manner, a pulse output without waveform disturbance can be obtained during switching between each step.

In the case of step-down control, in order to start deceleration at a predetermined acceleration from a state of rotation at a constant speed, it is necessary to read the value of timer A in order to connect the switching points of both speeds without disturbing the waveforms. It is necessary to match the waveform of the constant velocity pulse output. In other words, when the value of timer A is read using the OFF signal from the register sensor, the reading is performed at an undefined position from A to D in the pulse cycle, as shown in Fig. 16, and deceleration is started at this timer value. . Since deceleration is started from a state where the time is shifted by a fraction of one pulse, the switching points are not properly connected, which causes step-out.

Therefore, with the OFF signal from the register sensor, R
Interrupt at the rising edge of TO output (arrow position). When this interrupt point is between A to D of the pulse (in the case of D, the first half), the RTO output rising edge R1
When it is the second half of D, the edge R of the next pulse
Lead with 2. Reading in this D area is related to the processing speed of the computer, and if the reading is not completed in time, the value of the next pulse will be read. Therefore, an error of up to one pulse will occur depending on the interrupt position caused by the output of the registration sensor, so in registration control, one pulse is 0.138m.
This appears as an error of m, which is considered the accuracy. Incidentally, even if the value of timer A is read at the rising edge of the RTO output, a time lag of time b actually occurs as shown in FIG. 17. This deviation is corrected by software until the step-down starts, and then the time and frequency according to the deceleration motor control profile are set in each timer.

Document registration control involves calculating the number of pulse outputs, that is, the deceleration motor control profile, based on the distance from the registration sensor position to the registration position on the platen glass, and executing this control profile using the registration sensor output. It is. Further, in the constant speed control after the step-up is completed, timer A generates a timer interrupt at fixed time intervals, and timer B repeatedly sets the same frequency, thereby producing a pulse output with a constant frequency. In this constant speed region, document size detection, which will be described later, is performed using a timer operation.

FIGS. 18 to 21 show flowcharts of MPU processing. Upon receiving an ON signal for driving the belt, such as an ADF start signal or a document exchange signal, the MPU executes a motor control program. First, the value of timer A (
After calculating the motor control profile and creating a speed table for each step (step 101), the control profile for acceleration 1 is read (step 102). Then, set time n1 (=X+n), which is the timer value plus a certain time n (=
05), set the count value of acceleration 1 to OCPR0 (step 106), reset timer B (step 107), start outputting pulses of acceleration 1 from the RTO terminal to the driver (step 108), and start the motor. let

Next, the control profile for acceleration 2 is read (step 109), and time n2 (=n
1+A1) (step 110). time n2
When the acceleration 2 has elapsed (step 111), an acceleration 2 interrupt is generated (step 112), the acceleration 2 count value is set in OCPR0 (step 113), and at the same time, timer B is reset (step 114) and the acceleration 1 pulse is generated. Following the output, pulse output for acceleration 2 is started (step 115), and the motor speed is further increased. After repeating this process and outputting acceleration N pulses (step 116), the constant velocity profile is read (step 117), and similar processing (steps 118 to 122) is performed to output constant velocity pulses (step 116). 123) To be done.

Thereafter, when the document is conveyed at a constant speed and the trailing edge of the document passes the registration sensor and the ON signal changes to an OFF signal, the control profile for deceleration 1 is read (Step 1) by reading this OFF signal (step 124).
24). Then, read the value (nd0) of timer A at the rising edge R1 or R2 of the RTO (pulse) output (
Step 126), and software correction is performed before the start of step down (Step 127).

Therefore, the time tc from passing through the registration sensor to the start of step-down is the calculated correction value (n
d1), and has a value of, for example, 115 pulses. This correction value nd1 is set in OCPR1 as the starting point of deceleration 1 (step 128). When time nd1 has elapsed (step 129), a deceleration 1 interrupt is generated (step 130), a count value is set to deceleration 1 in OCPR0 (step 131), and at the same time, timer B is reset (step 132), Pulse output is started (step 133). Processing is performed in the same manner up to M steps, and the final deceleration M pulse output is output (step 13
4) and then stopped (step 135).

[0048]

[Effects of the Invention] As described above, according to the present invention, the MPU
Since the two built-in timers A and B are used to generate accurate pulse outputs for executing the motor control profile, an external timer LSI is not required and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a basic block diagram of the present invention.

FIG. 2 is an external view of the copying machine.

FIG. 3 is a sectional view of the copying machine.

FIG. 4 is a configuration diagram of a control panel of the copying machine.

FIG. 5 is a hardware configuration diagram of a copying machine.

FIG. 6 is a sectional view of the automatic document feeder.

FIG. 7 is a plan view of the automatic document feeder.

FIG. 8 is an enlarged cross-sectional view of the document loading section.

FIG. 9 is an enlarged cross-sectional view of the document discharge section.

FIG. 10 is a diagram illustrating document conveyance in simplex mode.

FIG. 11 is a diagram showing an example of a sequence flow of an automatic document feeder.

FIG. 12 is a diagram illustrating a control profile during acceleration of the stepping motor.

FIG. 13 is a diagram showing an example of data of a control profile during acceleration.

FIG. 14 is a diagram illustrating the timing of reading a timer.

FIG. 15 is a diagram illustrating the read timing of a timer according to the present invention.

FIG. 16 is a diagram illustrating the timing of reading a timer during deceleration.

FIG. 17 is a diagram illustrating a step-down start point during deceleration.

FIG. 18 is a flowchart from startup to acceleration in pulse output processing by the MPU.

FIG. 19 is a flowchart from acceleration to constant velocity.

FIG. 20 is a flowchart from constant velocity to deceleration.

FIG. 21 is a flowchart from deceleration to stop.

[Explanation of symbols]

103 Manuscript 119 Registration sensor 134 Cash register roll 200 MPU 201 Driver 202 Stepping motor

Claims (2)

[Claims] 1. A stepping motor control device provided in a device controlled by an MPU, which calculates acceleration, constant velocity, and deceleration control profiles of the stepping motor, and determines acceleration/deceleration control shift positions. Equipped with a timer A to be synchronized and a timer B to set the frequency of pulse output, a time is set by adding a certain time to the reading value of timer A at the start time, and the next timer value is calculated when the set time elapses. and an MPU that executes processing to set the frequency of the next pulse output by issuing a timer match interrupt to timer B when the set time of timer A has elapsed; A stepping motor control device consisting of a driver that drives the motor by switching to the next pulse output based on a signal. [Claim 2] Registration control that uses a built-in 2-channel timer in the MPU to control the belt deceleration based on sensor output from detecting the trailing edge of the document while the document is being pulled in to place the document at a fixed position on the platen glass. The MPU reads the value of timer A at the rising edge of the sensor output, sets a time that corrects the reading error of this timer value, and then reads the value of timer A, which is calculated at the time when the set time has elapsed. A stepping motor control device configured to set a timer value, and to interrupt a timer B when this time elapses to set the frequency of the next deceleration pulse output.