JPH11122988A - Pulse motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily and accurately drive a pulse motor by reducing the load of a CPU 41 for controlling the slow-up and slow-down of a pulse motor. SOLUTION: An uncoded data frame that is a combination of bit MSB=0 for indicating that there is no coding and data for prescribing phase excitation switching timing and a coded data frame, that is the combination of bit MSB=1 for indicating that there is a coding and five coding data CODE 0-4 (COCE 0-4) are retained in a ROM 42, a CPU 41 reads the data frame and gives it to a motor control 45, and the motor control 45 decodes the coded data when MSB is equal to 1, thus generating a phase excitation pulse. Phase excitation is switched five times, based on the coded data of a single coded data rate. The coded data are differential value data for indicating differential values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse motor driving device, and more particularly, but not exclusively, to driving a pulse motor at a constant speed after starting a speed at a high acceleration and a high deceleration. TECHNICAL FIELD The present invention relates to a pulse motor driving device that lowers the speed with a motor. This pulse motor driving device is used, for example, in a scanner that reads an original image and generates an image signal.

[0002]

2. Description of the Related Art For example, in a digital copying machine, when a copy start key is pressed while a document is set on a contact glass, a carriage (movable part) integrated with a mirror, a light source and the like of a scanner is moved. , A timing belt, a pulley and other power transmission mechanisms
The image surface of the original on the contact glass is optically scanned by being driven in the horizontal direction by the scanner, and the reflected light image from the image surface is connected to the light receiving surface of the CCD image sensor via each mirror and lens including the above-mentioned mirror. The image is converted, and the analog image signal generated by the image sensor is converted into digital data (image data). The image data is converted into image data for printing by an image processing circuit and applied to a laser printer, which forms an image on transfer paper.

Incidentally, a pulse motor is generally used as a scanning drive motor of a scanner. As is well known, this pulse motor applies a phase excitation signal (pulse) to the motor driver, so that the motor driver applies a drive pulse to the pulse motor, thereby providing the pulse motor.
In order to rotate this pulse motor at the self-starting frequency or higher, slow-up (starting from stop to constant speed) control and slow-down (falling from constant speed to stop) are performed. ) Needs control.

[0004]

For example, in the case of scanning drive of a scanner of a copying machine, performing all slow-up control and slow-down control by a microprocessor that controls the entire copying machine requires a large load on the microprocessor. In particular, when other processing (control processing other than the pulse motor control of the copying machine) is performed in parallel, the frequency of the driving pulse of the pulse motor cannot be increased so much. There was a disadvantage that the speed could not be increased.

Therefore, for example, Japanese Patent Application Laid-Open No. 63-202580
As shown in Japanese Patent Application Laid-Open Publication No. H11-107, the microprocessor performs pulse motor control when the pulse motor slows up and slows down.
There has been proposed a motor control device for a printer that controls the driving of a motor and controls the motor at a constant speed by a motor control circuit provided with a microprocessor.

However, in such a conventional motor control device, the load on the microprocessor during the constant speed driving of the pulse motor is reduced, but when the pulse motor is slowed up or slowed down (particularly in the vicinity of the constant speed region). The load on the microprocessor in (1) is not reduced, and it is not possible to expect a sufficiently high speed of the rotation of the pulse motor, especially a reduction in the slow-up and down periods.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its first object to reduce the load on the pulse motor drive control of a microprocessor, and to provide a pulse motor with high speed and high accuracy. A second object is to enable driving.

[0008]

[Means for Solving the Problems]

(1) A series of pulses (φA,
storage means for storing data corresponding to the cycle of φB,
2) a microprocessor (41) for sequentially reading data from the storage means, a pulse generation means (45) for generating a pulse corresponding to the data after the data read by the microprocessor is written, and a pulse generation means And a pulse motor driving means (46) for driving the pulse motor by a pulse from the storage means (42), the storage means (42) stores at least encoded data (CODE 0 to 1 + MSB) The pulse motor driving device is characterized in that the pulse generation means (45) has means (451 to 457) for decoding the encoded data. In addition, in order to facilitate understanding,
The reference numerals of the corresponding elements of the embodiment shown in the drawings and described later are added for reference.

According to this, since the data is encoded, the data amount is drastically reduced, the capacity of the storage means (42) can be reduced, and the cost can be reduced. Microprocessor (4
The burden of data reading in 1) is reduced.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(2) The storage means (42) stores an uncoded data frame consisting of a combination of a bit (MSB) indicating uncoded data and data defining the pulse period. And a coded data frame composed of a combination of a bit (MSB) indicating that the data is coded data and a plurality of (5) sets of coded data (CODEs 0 to 4). When a non-coded data frame is written, the pulse generating means (45) generates a pulse based on the data defining the pulse period in the data frame, and sends the pulse to the microprocessor (41). A request to write a data frame is issued. When an encoded data frame is written, the first encoded data (CODE 0) in the encoded data frame is decoded, and a pulse is generated based on the decoded data. And repeats this in order until the last coded data (CODE 4), and decodes the last coded data (CODE 4). Wherein the generating a pulse based on the data the microprocessor (41) to the next de - Tafure - requires writing beam.

According to this, one encoded data frame is
A plurality of (5) pulse generation processes are automatically performed by the pulse generation means (45) based on the encoded data of the system (CODE 0 to 4), and the microprocessor (41) performs one pulse generation. Compared to the case of reading uncoded data frames which require one data transfer per pulse generation processing, the work load becomes one-fifth (5) and the load of the microprocessor (41) is reduced. This greatly reduces the motor speed, and enables high-speed operation control of the motor, in particular, high-speed acceleration control and high-deceleration speed reduction control. When used in an image forming apparatus, the productivity of image formation is improved.

(3) The encoded data represents a difference value of the data decoded earlier in time series with respect to the value represented by the decoded data. According to this, the decoding logic is simple, and the decoding means can be easily configured.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0014]

FIG. 1 shows the configuration of a control unit of a digital copying machine equipped with an embodiment of the present invention. The embodiment of the present invention includes a microprocessor (CPU) 41 and a ROM serving as a storage unit.
42, a motor control 45 as a pulse generating means and a motor drive 46 as a pulse motor driving means. The pulse motor 51 to be driven drives a carriage integrated with a mirror and a light source of a scanner for reading an original image of a digital copying machine via a power transmission mechanism such as a timing belt and a pulley. is there. In this carriage drive, the speed is increased from a home position (HP) to a constant speed at a high acceleration in a short time (slow-up).
Then, for a long distance (for example, the length of the document), maintain a constant speed, decelerate at a high deceleration (slow down), stop the carriage (the above is the forward stroke: document scanning), and reverse. It is required that the HP be driven to return at high speed (return stroke).

The ROM 42 has a phase excitation pulse (φA, φA, φ) for performing the above-described forward and backward motor driving.
(Inversion, φB, inversion thereof), that is, phase switching timing data. CP
U41 sequentially reads a series of data from the ROM 42
42 and is given to the motor control 45.
5, the level of each phase excitation signal (φA, its inversion, φB, its inversion) is changed from 1 (high level H) to 0 (low level L) at the timing (elapsed time) specified by the given data.
Or vice versa. Thereby, each phase excitation signal becomes a pulse, that is, a phase excitation pulse. These pulses are given to the motor drive 46, which turns on (energizes) / off (deenergizes) each phase of the pulse motor 51 in response to the phase excitation pulse, that is, pulse driving. As a result, the motor 51 rotates. The rotation speed corresponds to the phase switching speed (phase excitation pulse period), and the rotation direction is determined by the order of energization (excitation phase order) for each phase.

One reciprocation of the carriage includes a forward acceleration section from the start of the forward movement to a constant speed, a forward constant speed section (document scanning section), a forward deceleration section, and a backward acceleration section from the start of the backward movement to the constant speed. , A deceleration section and a deceleration section in which the vehicle decelerates and stops at the HP. Forward constant speed section (document scanning section)
Also, in the constant speed section, it is only necessary to perform the phase switching at a constant period, so that it is not necessary to sequentially read a series of data from the ROM 42. Therefore, the ROM 42 need only be provided with phase switching timing data necessary for the forward acceleration section, forward deceleration section, reverse acceleration section, and reverse deceleration section.

For phase switching timing data, that is, phase excitation cycle data, 16-bit data is generally used in many cases when driving a scanner. Therefore, in this embodiment, 16 bits are used. Hereinafter, this 16-bit group is called a data frame.

FIG. 2 shows the data structure of the data frame. One frame has a 16-bit configuration. The most significant bit (hereinafter MSB) indicates whether the data of this frame is coded data or actual data. When the MSB is 1, it means that the next 15 bits are coded data. In this embodiment, the coded data represents a difference value of data to be decoded earlier in time series with respect to a value represented by decoded data (corresponding to actual data). Also,
One (one set) of encoded data is 3 bits, and a total of five encoded data CODE0 to CODE4 are included in one data frame.

When the MSB is 0, the subsequent 15 bits are one piece of real data (uncoded data).

The first data frame of a series of data frames (data frame group) addressed to the forward acceleration section in the ROM 42 is the actual data serving as a base when the carriage is forward accelerated (driving starts). Since the data is required, the MSB is a real data frame of 0, and the subsequent data frame is an encoded data frame of 1 in the MSB. However, the difference value is 3
The part that cannot be represented by bits is the actual data frame whose MSB is 0. The data frame group destined for the reverse acceleration section is the same as that for the forward acceleration section. However, since the motor drive speed is different between the forward stroke and the return stroke, additional
The deceleration characteristics are also different, so the data of the data frame group
The number of tab frames differs, and the values represented by the data in the data frames also differ.

The data frame group addressed to the forward deceleration section is a coded data frame whose MSB is 1, since the speed is reduced from a constant speed. However, where the difference value cannot be represented by 3 bits, the MSB is 0 for the actual data frame. The data frame group destined for the deceleration section is the same as that for the deceleration section.

The CPU 41 designates the above-mentioned data frame group in accordance with the section in which the carriage is located, sequentially reads out the data frames in the group from the ROM 42, and controls the motor. Give to 45.

Each group includes data for designating acceleration / deceleration and data for designating the direction of motor rotation (the order of phase switching). Decoding is performed and a control signal is given to the motor control 45 to set the phase sequence (motor rotation direction) of the pulse generated by the motor control 45, but the description of the phase sequence setting is omitted.

FIG. 3 shows a functional configuration of the motor control 45. The illustration of the functional units related to the phase sequence (motor rotation direction) setting is omitted. Next, the internal function of the motor control 45 will be described with reference to a flowchart (FIG. 5).

FIG. 4 shows an outline of the pulse motor drive control of the CPU 41, and FIG. 5 shows a control unit CP of the motor control 45.
The outline of the pulse generation control of U451 will be described. Hereinafter, FIG.
Please refer to FIG. 4 and FIG.

When the CPU 41 activates a start signal to the motor control 45, the control unit CPU 451 of the motor control 45 activates a data request signal to the CPU 41 (step 1 in FIG. 4 and step 11 in FIG. 5). , 12). In the following, the word “step” is omitted in parentheses, and step No. Write only numbers.

When the data request signal becomes active, CP
The U41 reads the first data frame from the data frame group previously selected by the CPU 41 in the ROM 42 and writes the first data frame into the data register 452 of the motor control 45 (2, 3 in FIG. 4).

When the data is written, the control unit CPU 45
1 checks the MSB of the data register 452, and
Is considered as real data (the first data
(Tab frame is actual data), real data (CODE0
To CODE4) to the base register 455 via the selector 454.
Is transferred to the pulse generator 458 via the selector 457 (13 to 17 in FIG. 5).

The pulse generator 458 sets a phase excitation signal φA or the like which is an output to the motor drive 46 at the start point (start) level, and when the time represented by the given data elapses, the phase excitation is started. The data request signal is supplied to the control unit CPU 451 by switching the level of the signal φA and the like. In response, the control unit CPU 451 proceeds to step 12 in FIG.
The CPU 41 requests the next data frame from the CPU 41, and the CPU 41
Reads the next data frame from the ROM 42 and writes it into the register 452 (2, 3 in FIG. 4).

When the MSB becomes 1, the control C
When the acceleration signal from the CPU 41 is active (acceleration is specified), the PU 451 first specifies the first coded data CODE0 (15, 19, 2 in FIG. 5).
0), it is added via a selector 453, and a subtractor 456
1a) In the adder / subtractor 456, subtract the value represented by CODE0 (3 bits) from the value of the base register 455 (previous output value) (21 in FIG. 5); 2a) Value of the subtraction result ( This time value) is the selector 457
Through to the pulse generator 458. At the same time, the data is transferred to the base register 455 via the selector 454. That is, the data in the base register 455 is updated to the current value (decoded data). Pulse generator 45
8 indicates that the phase excitation signal φA
And a data request signal is given to the control unit CPU 451 (22 in FIG. 5); 3a) The control unit CPU 45 responds to the data request signal.
1 designates the next coded data (23 in FIG. 5), and when there is the next coded data, the same as 1a) above, except that CODE 0 is the coded data just specified. Read as
And then carry out the above 2a) in the same way to obtain the book 3a)
Leads to. Here, when there is no next encoded data (the above processing has been executed up to CODE 4), the control unit CPU 451 operates.
Requests the CPU 41 for the next data frame (FIG. 5).
23, 24, 25, 12); While the start signal is active, the above processing is repeated.

On the other hand, when the acceleration signal from the CPU 41 is inactive, the control unit CPU 451 first specifies the first coded data CODE0 (26 in FIG. 5), and 1b) the value of the base register 455 (1). CO to previous output value)
The value represented by DE0 (3 bits) is added (2 in FIG. 5).
7); 2b) The value of the addition result (current value) is transferred to the pulse generator 458. At the same time, base register 455
Also to forward. That is, the data of the base register 455 is updated to the current value. When the time indicated by the current value has elapsed, the pulse generator 458 switches the level of the phase excitation signal φA and the like, and outputs a data request signal to the control unit CPU.
3b) in response to the data request signal.
1 designates the next coded data, and when there is the next coded data, the same as 1b) above, except that CODE 0 is
It is read and executed with the encoded data designated this time, and the above 2b) is executed in the same manner to reach the book 3b). Here, when there is no next encoded data (the above processing has been executed up to CODE 4), the control unit CPU 451 requests the CPU 41 for the next data frame (29, 30, 3 in FIG. 5).
1, 12); While the start signal is active, the above processing is repeated.

As described above, when the data frame is an encoded data frame, the CPU 41 reads the data frame from the ROM 42 only once for every five excitation phase switchings.
What is necessary is just to read out the frame and give it to the motor control 45, and the required work amount is reduced to 1/5 of the case of the actual data frame.
The data amount of the ROM 42 can be reduced, and
As a result, the acceleration and deceleration of the pulse motor 51 can be performed at a higher speed (in a shorter time).

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a control system of a copying machine equipped with an embodiment of the present invention.

FIG. 2 is a plan view showing a data structure of a pulse motor drive control data frame stored in a ROM 42 shown in FIG.

FIG. 3 is a block diagram showing a functional configuration of a motor control 45 shown in FIG.

FIG. 4 is a flowchart showing an outline of a control operation of a motor control 45 by a CPU 41 shown in FIG. 1;

FIG. 5 is a flowchart showing an outline of a phase excitation pulse generation process of a control unit CPU 451 shown in FIG. 3;

[Explanation of symbols]

 452: Data register 453: Data selector 454: Data selector 455: Base register 456: Adder / subtractor 457: Data selector

Claims (3)

[Claims] 1. A storage means for storing data corresponding to a cycle of a series of pulses applied to a pulse motor, a microprocessor for sequentially reading data from the storage means, and a data after the data read by the microprocessor is written. And a pulse motor driving means for driving the pulse motor by a pulse from the pulse generating means, wherein at least the coding means is stored in the storage means. A pulse motor driving apparatus characterized in that the encoded data is stored, and wherein the pulse generating means includes means for decoding the encoded data. 2. An uncoded data frame comprising a combination of a bit indicating uncoded data and data defining a cycle of the pulse, and a coded data. And a coded data frame composed of a combination of a plurality of sets of coded data. The pulse generating means writes an uncoded data frame. In response to this, a pulse is generated based on the data defining the pulse period therein, requesting the microprocessor to write the next data frame, and the encoded data frame is written. , The first coded data therein is decoded, a pulse is generated based on the decoded data, and the pulse is sequentially repeated in the same manner until the last coded data. Is decoded and a pulse is generated based on the decoded data. Microprocessor next de - Tafure - requires writing beam; of claim 1, wherein Parusumo - motor driving device. 3. The encoded data according to claim 1, wherein the encoded data represents a difference value of data to be decoded earlier in time series with respect to a value represented by decoded data. Item 3. A pulse motor driving device according to Item 2.