JP3136184B2 - Pen controller of pen recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pen control device for a pen writing recorder that records a waveform following a measurement signal input on a recording sheet with a pen.

[0002]

2. Description of the Related Art Conventionally, a servo mechanism using a DC or AC servomotor is often used for driving control of a pen of this kind of pen writing recorder. However, since a servomotor is relatively expensive and a drive circuit is complicated, use of a stepping motor used for a printer or a plotter has recently been attempted.

[0003]

However, a stepping motor is easy to use for position control that operates at a constant speed like a printer or plotter, but when used for servo control that requires follow-up control, the stepping motor has a high resonance frequency. Noise may be particularly loud, or the torque and inertia may cause loss of synchronism if the acceleration limit is exceeded. There was a problem. Accordingly, it is an object of the present invention to provide a pen control device of a pen writing recorder in which a stepping motor is used for a servo mechanism without causing the above-described noise and step-out.

[0004]

According to the present invention, as shown in FIG. 1, a stepping motor 5 connected to a pen, measurement signal input means 1, and a current position of the pen are provided. Pen position detecting means 6, a target step number calculating means 2 for calculating a target step number in the stepping motor 5 corresponding to a deviation between the target position corresponding to the measurement signal and the current position of the pen, and a predetermined drive A drive control means 4 for driving the stepping motor 5 in a cycle; and a memory 3 in which a drive frequency within the drive cycle is set and stored in advance corresponding to a target number of steps of the stepping motor and a current value of the drive frequency. And the drive control means 4 performs the stepping by the drive frequency extracted from the memory 3 based on the target number of steps and the current drive frequency. It was assumed to drive the over five other.

According to a second aspect of the present invention, a drive voltage value within a drive cycle is further stored in the memory in advance, and the drive control means draws the drive frequency from the memory based on the target number of steps and the current drive frequency. Further, the stepping motor is driven by the driving voltage value.

[0006]

According to the first aspect of the present invention, the stepping motor is driven by extracting the drive frequency within the preset drive cycle from the memory based on the target number of steps and the current drive frequency. The control process is performed quickly without step-out. According to the second aspect, since the drive voltage value is further stored in the memory, the stepping motor can be driven with an optimum voltage in consideration of noise and followability.

[0007]

FIG. 2 shows the configuration of an embodiment of the present invention. An analog measurement signal is input to the CPU 21 via the A / D converter 11 at a driving cycle of 100 mSEC. The CPU 21 has a memory 3 in which drive data set in advance is stored.
0 is connected, and a feedback signal from a potentiometer 40 for detecting the position of the pen 7 is further input. The frequency divider 42 and the counter 43 are connected to the CPU 21, and the output of the frequency divider 42 is input to the driver 45 of the pen moving stepping motor 50. The forward / reverse input of the driver 45 is set from an external I / O port. Here, an Intel 82C54 is used for the frequency divider 42 in mode 1 (rate generator mode), and its clock input is 614.4 KH.
z is supplied. For the counter 43, 82C54 is used in mode 0 (interrupt mode at the end of counting). Further, TD62803 manufactured by Toshiba can be used for the driver 45.

The output of the frequency divider 42 is further input to a counter 43 via a NAND circuit 47. A start signal from the CPU 21 is input to the NAND circuit 47 as the other input. The output of the counter 43 is connected to the gate of the frequency divider 42 via the inverter 48. The driving data extracted from the memory 30 by the CPU 21 is written in the frequency divider 42, and the target number of steps is written in the counter 43.

As shown in FIG. 3, the driving data is obtained from the number of pulses from the current position of the pen 7 to the target position and the current value of the driving frequency (PPS) of the stepping motor 50.
The drive PPS value of the motor to be taken during the drive cycle is stored in the memory 30. In this example, a case is shown where the maximum value of the driving frequency is 400 PPS and the maximum change width is 300 PPS. As described above, these data are calculated and set in advance based on the drive limit of the stepping motor 50 so as to avoid the resonance frequency and to prevent the acceleration (PPS / S) from becoming excessive. At this time, it is desirable to set the frequency division value in the frequency divider 42 so that the fraction of the pulse does not occur with respect to the interrupt cycle.

In the embodiment apparatus configured as described above, the measurement signal is converted into a digital value by the A / D converter 11 and read into the CPU 21 for each driving cycle. C
In the PU 21, the deviation between the current position of the pen 7 based on the feedback signal from the potentiometer 40 and the target position calculated based on the A / D converted measurement signal is calculated as the number of pulses. Drive data is extracted from the memory 30 based on the number of pulses to the target position, the PPS value of the drive data is written to the frequency divider 42, and the target number of steps is written to the counter 43 as a set value.

When the drive data is written, the counter 43
Becomes LOW, the gate of the frequency divider 42 is opened, and the frequency dividing operation is started. When this frequency division output is output, the CPU 2
A start pulse in the same direction as the divided output from 1 is sent to the NAND circuit 47 and added to the count. The start pulse is inserted because the stepping motor 50 rotates one step more than the set value of the counter 43 without this start pulse. Thus, the step motor 50 rotates by the number of steps that matches the set value (target value) written in the counter 43. When the counter 43 reaches the set value, its output becomes HIGH, the gate of the frequency divider 42 is closed, the pulse output to the driver 45 is stopped, and the rotation of the step motor 50 is stopped.
If the drive cycle ends before the set value is reached, a new set value up to the target position is written to the counter 43 at the next interrupt cycle, and while repeating the above flow, the target position corresponding to the measurement signal is returned. Is driven.

According to this embodiment, since the stepping motor 50 is controlled and driven at the drive frequency set within the drive limit of the motor, step-out is performed by using an inexpensive stepping motor instead of an expensive servomotor. Therefore, there is an effect that smooth servo control of the pen is ensured without occurrence of the pen. Further, there is an advantage that the driving circuit of the motor is simpler. Further, in order to obtain the drive data, the drive limit does not need to be obtained from the calculation every time the drive cycle is performed, and it is only necessary to extract the drive limit from the memory. Therefore, the load on the CPU is small and the processing speed is increased.

In the above embodiment, an example has been shown in which the A / D conversion and the driving data writing to the stepping motor driving are performed synchronously in the same driving cycle. However, the present invention is not limited to this. It is also possible to perform an interrupt process of a fixed period which is a fractional value or a multiple value of the A / D conversion period.

FIG. 4 shows a second embodiment in which a power control circuit 46 is further connected to a pen moving stepping motor 50 in addition to the configuration of the previous embodiment. The stepping motor has a large torque at low speed rotation and the reverse at high speed rotation.However, it is desirable that the torque at high speed rotation is large for high-speed follow-up. Become.

For this reason, the number of pulses from the current position of the pen 7 to the target position and the driving frequency (PP) of the stepping motor 50 are stored in the memory 30 'connected to the CPU 21'.
With respect to the current value of S), the drive voltage value of the stepping motor 50 is set and stored together with the motor drive PPS value. The CPU 21 'sends this drive voltage value to the power control circuit 46 as a command for each drive cycle, and the stepping motor 50 is driven at a high drive voltage at high PPS. Thus, the optimum drive voltage is set according to the drive frequency of the stepping motor 50, so that there is an effect that the high-speed followability and the noise at low speed are further improved.

[0016]

As described above, the present invention provides a memory in which the drive data of the drive frequency within the drive cycle is preset and stored in correspondence with the target number of steps of the stepping motor for moving the pen and the current value of the drive frequency. And the stepping motor is controlled to drive the stepping motor. Therefore, even when the stepping motor is used, the step-out does not occur and the pen can be smoothly servo-controlled. In addition, an inexpensive stepping motor can be used, and the drive circuit is simpler than a servomotor. Further, since the control driving means only needs to fetch the driving data from the memory, there is no need to obtain the driving limit by calculation for each driving cycle, so that there is an advantage that the load is reduced and the processing speed is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an example of drive data stored in a memory.

FIG. 4 is a diagram showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement signal input means 2 Target step number calculation means 3 Memory 4 Drive control means 5 Stepping motor 6 Pen position detection means 11 A / D converter 21, 21 'CPU 30, 30' Memory 42 Divider 43 Counter 45 Driver 46 Power control circuit 47 NAND circuit 48 Inverter 50 Stepping motor 60 Potentiometer

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01D 15/24 H02P 8/14

Claims (2)

(57) [Claims] 1. A stepping motor connected to a pen, measurement signal input means, a pen position detection means for detecting a current position of the pen, and a deviation between a target position corresponding to the measurement signal and the current position of the pen. Target step number calculating means for calculating a corresponding target step number in the stepping motor; drive control means for driving the stepping motor at a predetermined drive cycle; and a target step number of the stepping motor and a current value of a driving frequency. A memory in which a drive frequency within the drive cycle is set and stored in advance, wherein the drive control means uses the drive frequency extracted from the memory based on the target number of steps and a current drive frequency to control the stepping motor. A pen control device for a pen writing recorder. 2. A stepping motor connected to a pen, measurement signal input means, pen position detection means for detecting the current position of the pen, and a deviation between a target position corresponding to the measurement signal and the current position of the pen. Target step number calculating means for calculating a corresponding target step number in the stepping motor; drive control means for driving the stepping motor at a predetermined drive cycle; and a target step number of the stepping motor and a current value of a driving frequency. A memory in which a driving frequency and a driving voltage value within the driving cycle are set and stored in advance, and the driving control means drives the driving frequency extracted from the memory based on the target step number and a current driving frequency. And a driving voltage value for driving the stepping motor. Place.