JPH0448241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a positioning device that quickly positions a controlled object.

[Prior art]

FIG. 1 shows a typical configuration of a positioning device, in which 100 is a type wheel of a printer and other objects to be controlled, which are controlled by a servo motor 10. As shown in FIG. A position signal detector 11 consisting of an inductosin, a photo sensor, etc. is directly or indirectly coupled to the rotating shaft of the servo motor 10, and detects two periodic position signals having a 90° phase difference. Each position signal detected by the position signal detector 11 is appropriately amplified by amplifiers 12 and 13 and becomes input to an actual speed signal generation circuit 14 and a command speed signal generation circuit 15. The actual speed signal creation circuit 14 is a circuit that creates an actual speed signal whose amplitude increases or decreases in proportion to the speed of the motor 10 from the position signal.
This is created by, for example, differentiating a total of four signals, two position signals and their inverted signals, and sampling each differentiated signal one after another. Further, the actual speed signal generation circuit 14 generates a zero-crossing signal of one of the position signals and outputs it as a pulse (unit movement amount pulse) d indicating the unit movement amount of the motor 10. This unit movement pulse d becomes an input to a calculation device (not shown), and the motor 1
This is used to count the moving distance of 0, which will be described later. Command speed signal generation circuit 1
5 consists of a kind of digital-to-analog conversion circuit, which uses a full-wave rectification of the above two position signals as its reference voltage, divides it by the speed instruction value b given from the outside, and corresponds to the speed instruction value b. Outputs a command speed signal at the specified amplitude level. A comparison circuit 16 calculates the difference between the actual speed signal and the command speed signal, and the result is input to an inverter 17. The inverter 17 either directly supplies the output of the comparator circuit 16 to the motor drive circuit 18 or outputs the output from the comparator circuit 16 to the motor drive circuit 18 in response to a rotation direction instruction signal a given from the outside.
This is a circuit that inverts the polarity of the output of and supplies it to the motor drive circuit 18. The servo motor 10 is rotated in the positive or negative direction by the motor drive circuit 18, and its speed settles down to approximately the speed command value b.

Therefore, as the moving distance of the controlled object 100 progresses, the speed instruction value b is made variable to gradually lower the level of the command speed signal until it reaches the target point and zero, thereby achieving positioning control. Note that the stop command c is issued by the command speed signal generation circuit 15 so as to directly output a position signal as a command speed signal when the controlled object 100 reaches the vicinity of the destination.
This is used to instruct precise positioning control.

The typical positioning device has been described above, but when the controlled object is a type wheel, for example, and a type wheel is selected from a group of type characters arranged on its circumference, the device is When rotating a type wheel, the direction of rotation is generally determined from the positional relationship of the type on the type wheel, and then the type wheel is rotated the shortest distance from the current position to the commanded position to position the selected type at the printing position. A method is adopted to do so. FIG. 2 is a block diagram for explaining the conventional method.

In FIG. 2, reference numeral 21 inputs the unit movement pulse d obtained by the actual speed signal generation circuit 14 in FIG. With the up/down counter turned down, the contents of the counter will indicate the current position of the type wheel. Reference numeral 22 denotes a read-only memory (ROM) which, when a character code corresponding to the next printed character to be printed is inputted through the signal line e, outputs a position code indicating the placement position of the printed character on the type wheel. . This ROM22
In other words, the position code output from the input wheel indicates the next commanded position (stop) of the type wheel, and the output of the up/down counter 21 (current position information) is also input to the difference calculation unit 23. becomes. The difference calculation unit 23 is an up/down counter 2
The difference between the current position information given from ROM 22 and the command position information given from ROM 22 is calculated, and a rotation direction command signal a is created as follows. That is, when the difference between the current position information and the commanded position information is positive, and the difference is less than half of all the characters placed on the type wheel, the rotation direction instruction signal a is used to move the type wheel in the positive direction ( For example, it outputs a signal for rotating in a clockwise direction), and if the difference number is more than half of the total number of printed characters, it outputs a rotation direction instruction signal a in a negative direction (for example, counterclockwise). Also, if the difference between current position information and command position information is negative,
The rotation instruction signal a having the opposite relationship to the above is output when the difference number is less than half of the total number of printed characters on the type wheel and when it is more than half. This rotational direction instruction signal a is given to the inverter 17 in FIG.

On the other hand, the number of differences between the current position information and the command position information calculated by the difference calculation unit 23 (more precisely, the difference between the current position information and the command position information so that it is less than half of the total number of characters on the type wheel (calculated value) is given to the speed level judgment circuit 24. The contents of the up/down counter 21 go up or down for each unit movement of the type wheel, and correspondingly, the difference between the current position information and the commanded position information, that is, the remaining distance from the current position to the commanded position, is sometimes It changes every moment. The speed level judgment circuit 24 outputs a speed instruction value b to gradually reduce the rotational speed of the motor in accordance with the moving distance of the type wheel. This speed command value b becomes an input to the command speed signal generating circuit 15 shown in FIG. When the rotation of the type wheel progresses and reaches the command position, the difference calculation unit 23 outputs a stop command c, and at the same time the speed level judgment circuit 24 outputs a speed instruction value indicating a zero level. Moving on to area control, this is not directly related to the present invention, so a description thereof will be omitted.

In this way, when positioning a controlled object by rotating it in the direction of the shortest distance from the current position to the commanded position, conventionally the difference calculation unit instructs the direction of rotation of the shortest distance from the current position to the commanded position. At the same time as the signal is created, the remaining moving distance of the controlled object, which changes from moment to moment, is continuously taken in one after another to calculate the remaining moving distance of the controlled object one by one. The level judgment circuit indicates the speed level of the motor. For this reason, once a certain command position is given, the next command position cannot be specified until positioning to that command position has been completely completed, and positioning control becomes intermittent. If the object is a type wheel and the target is a printer that rotates the type wheel in the positive or negative direction to position designated characters one after another at the printing position and prints, there is a limit to how much the printing speed can be increased. It was hot.

〔the purpose〕

The present invention was made in order to solve the above-mentioned conventional problems, and it temporarily stores the previous command position information, and when the next command position information is given, the previous positioning operation is not yet completed. Next, the direction in which the motor should rotate next is determined using the value of the previously stored command position information as the virtual current position, and when the previous positioning operation is completed, the motor is driven in the determined direction. The purpose is to start the next positioning operation.

〔composition〕

FIG. 3 is a block diagram showing the principle configuration of the present invention. The difference from FIG.
5 is provided, and a subtraction counter 26 is provided between the difference calculation section 23 and the speed level judgment circuit 24. Here, the previous command position information storage register 25
is for temporarily storing the previous position code (previous command position information) until its content is replaced by the position code newly output from the ROM 22. As in the case of FIG. 2, when the character code corresponding to the type character to be printed next is input through the signal line e, the position code indicating the position of the type character on the type wheel is read from the ROM 22. The command position information is given to the difference number calculation unit 23, and at this time, the contents of the previous command position information storage register 25 are given to the difference number calculation unit 23 as virtual current position information. The difference calculation unit 23 calculates the difference between the virtual current position information and the command position information so that it is less than half of the total number of characters on the type wheel, sets the value in the subtraction counter 26, and , generates a rotation direction indication signal a to rotate the type wheel in the positive or negative direction. A unit movement pulse d is input to the subtraction counter 26, and its content is subtracted every time the unit movement pulse d is applied, indicating the remaining distance from the current position to the command position. . The speed level judgment circuit 24 outputs a speed instruction value b according to the contents of the subtraction counter 26,
The subtraction counter 26 outputs a stop command c when its content becomes zero.

On the other hand, the difference calculation unit 2 which is also a rotation direction determining means
When the difference calculation in step 3 is completed, the value is set in the subtraction counter 26, and the rotation direction instruction signal a is issued, the contents of the previous command position information storage register 25 are changed to the new command position output from the ROM 22. Replaced with information. Then, even if the previous positioning operation is still in progress, i.e., the subtraction counter 2
Even before the stop command is issued from 6, input the next character code through the signal line e,
Correspondingly, the position code output from the ROM 22 is used as new command position information, and the content of the replaced previous command position information storage register 25 is used as virtual current position information, and the start of the calculation of the difference between the two is set as the difference number. The calculation unit 23 is instructed to do so.

FIG. 4 is a block diagram of one embodiment of the present invention, and FIG. 5 is a flowchart for explaining the operation of FIG. 4.

At the start of operation, an initial value is set in the previous command position information storage register 102 through the signal line s, and thereafter it is successively updated with output data from the ROM 101. It is now assumed that command position information “B” is stored in the previous command position information storage register 102. In this state, when the next character code "C" arrives through the signal line e, the ROM
Commanded position information "C" corresponding to the character code appears on the output side of 101. Difference calculation unit 1
03 takes in the command position information "C" through the signal line f, and then reads the content "B" of the previous command position information storage register 102 through the signal line g as the virtual current position information for the command position information "C". Take in and calculate difference number "B-C". Difference calculation unit 10
When the calculation operation in step 3 is completed, the calculation end signal h becomes high, command position information "C" is stored in the previous command position information storage register 102, and the difference number and rotation direction command data are transmitted through the signal line j. It is stored in the buffer register 104.

During this time, the previous positioning operation is still being executed, and the contents of the subtraction counter 105 are sequentially subtracted by the unit movement amount pulse d, and the speed instruction value b corresponding to the contents is subtracted.
is given to the servo control device from the start level determination circuit 107. The positioning operation progresses, the subtraction counter 105 becomes zero, a stop command c is issued, and then,
When the signal l indicating the end of positioning operation becomes high,
The AND condition of AND gate _G2 is satisfied, and the output signal n of the AND gate becomes high. This signal n
becomes high, buffer register 1
The difference number “B-C” stored in 04 is the signal line k
The rotational direction instruction data is newly set in the subtraction counter 105 through the signal line k', and the rotational direction instruction data is set in the rotational direction buffer 106 through the signal line k'. The contents of the rotation direction buffer 106 become the rotation direction instruction signal a, and a speed instruction value b corresponding to the contents of the subtraction counter 105 is created in the speed level judgment circuit 107, and the next positioning operation is started.

On the other hand, when the buffer register 104 becomes empty, the buffer register 104 uses a signal line m to permit the next data input.
is high. At this time, the signal line h indicating the end of the calculation
Therefore, the AND condition of the AND gate _G1 is satisfied, and the signal line i becomes high to instruct the next character data transfer request. As a result, when the character data "D" arrives and the corresponding command position information "D" is output from the ROM 101, the difference calculation unit 103 stores the information stored in the previous command position information storage register 102 at that time. The previous command position information "C" is used as virtual current position information for the above command position information "D" as "C-D".
Calculate. The difference number and rotation direction instruction data obtained by the difference number calculation unit 103 are stored in the buffer register 104, and the command position information "D" is stored in the buffer register 104.
is stored in the previous command position information storage register 102, and waits until the positioning operation being executed at that time is completed.

〔effect〕

As explained above, according to the present invention, when the controlled object moves from the first position to the second position, the controlled object moves from the first position to the second position before being positioned to the first position. The rotation direction of the motor to move to the position can be determined. Therefore, when applied to the positioning control of a type wheel in a serial printer, for example, the positioning of successively designated characters to the printing position is performed continuously, and high-speed operation of the device is achieved. Of course, it goes without saying that the present invention is also applicable to various control devices other than printers.

In the embodiment, only one set of difference number and rotational direction instruction data required for the next positioning control is calculated during operation of a certain positioning control, and it is temporarily stored. However, the previous command position information storage register and By increasing the capacity of the buffer register for difference number and rotational direction instruction data, it is possible to calculate and stack multiple sets of difference number and rotational direction instruction data one after another.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a typical configuration example of a positioning device, Fig. 2 is a diagram showing a conventional method of calculating the difference between the current position and a command position, and Fig. 3 is a diagram showing the principle configuration of the present invention. 4 is a diagram showing an embodiment of the present invention, and FIG. 5 is a diagram showing a time chart for explaining the operation of FIG. 4. 10... Servo motor, 11... Position signal detector, 12, 13... Amplifier, 14... Actual speed signal creation circuit, 15... Command speed signal creation circuit, 1
6... Comparison circuit, 17... Inverter, 18...
Motor drive circuit, 22...read-only storage device, 2
3...Difference calculation unit, 24...Speed level determination circuit, 25...Previous command position information storage register, 26
...Subtraction counter, 100...Controlled object.

Claims (1)

[Claims] 1. Stores a controlled object, a motor for moving the controlled object, and information regarding the position at which the controlled object is to be positioned (hereinafter referred to as command position information). A positioning device comprising a storage means and a means for driving a motor based on the commanded position information and positioning the controlled object, wherein the commanded position information of the storage means is read in advance so that the controlled object is located at the first position. and a rotation direction determining means for determining the rotation direction of the motor for moving from the first position to the second position before moving to the first position when moving from the first position to the second position. A positioning device featuring: