JPS6336236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor drive control circuit that controls the drive of a motor in response to command signals that are intermittently applied from the outside, and in particular, a motor drive control circuit that controls the drive of a motor in response to command signals that are intermittently applied from the outside. The present invention relates to a motor drive control circuit that performs control.

For example, when a DC motor is repeatedly driven in response to command signals intermittently applied from the outside, it is required to suppress the temperature rise of the DC motor to below a certain value. In order to meet these demands, it is necessary to provide a margin for the motor output, or
It is conceivable to have a configuration that includes a cooling mechanism for the DC motor, but in such a configuration,
There have been problems in that the structure becomes more complicated and noise increases due to the increased size of the DC motor or the provision of a cooling mechanism. In order to deal with this problem, conventional methods have been to detect the temperature of the DC motor using a sensor, and to stop driving the DC motor when the detected temperature exceeds a certain value, regardless of the external command signal. However, this configuration causes the inconvenience that during repeated driving of the DC motor, the driving is inadvertently stopped and the stopped state continues for a relatively long time until the temperature of the DC motor cools down. . In addition, conventionally,
Based on the pre-measured DC motor characteristics, its DC
Although control has been carried out so that the drive cycle of the motor does not become faster than a certain cycle, this configuration has the disadvantage that the repetitive drive speed of the DC motor becomes slow.

The present invention has been made in view of the above circumstances, and its purpose is to increase the repetitive drive speed of the motor, eliminate the risk of the motor being stopped inadvertently while it is being driven, and to To provide a motor drive control circuit that eliminates the need to provide a margin for output or provide a cooling mechanism dedicated to the motor.

An embodiment in which the present invention is applied to an electronic typewriter will be described below with reference to the drawings. First, in FIG. 1 showing the schematic configuration of the main parts of an electronic typewriter, 1 is a platen, 2 is a linear motor having a movable element 4 that linearly reciprocates on a stator 3, and 5 is the linear motor 2. The print head 5 is placed on a movable element 4. The print head 5 includes a print wheel 8 formed by radially arranging a large number of arm members 7 having character elements 6 at their tips, and a print wheel 8 that rotates the print wheel 8. It is configured to include a DC motor 9, which is a controlled object of the present invention, for performing a character selection operation, and a printing hammer 10.
By hitting the character element 6 at the printing position with 0, the printing paper 1 is printed via the ink ribbon 11.
2. Characters are printed on the top.

On the other hand, in FIG. 2, which shows in block form only the portions of the control system of the electronic typewriter that are directly related to the gist of the present invention, reference numeral 13 indicates the CPU ( (corresponding to the control means in the present invention), 1
4 is a keyboard section of an electronic typewriter equipped with a large number of keys (not shown); 15 is a detection section for detecting the moving position of the linear motor 2; and 16 is a detection section for detecting the rotational position and rotational speed of the DC motor 9. This is the detection part for The CPU 13 controls the linear motor 2 based on the program, the command signal Sc, which is print information intermittently given each time the keyboard section 14 is operated, and the detection signals S ₁ and S ₂ from the detection sections 15 and 16. , a DC motor 9, a printing hammer 10, a motor for one rotation of the platen, that is, a motor for feeding printing paper, a motor for feeding the ink ribbon 11, a motor for moving the ink ribbon 11 up and down (none of the motors are shown), etc., are connected via a driver 17. drive.

However, in the following, the DC by CPU13
The details of drive control of the motor 9 will be explained with reference to the flowchart of FIG. 3 and the time chart of FIG. 4. In addition, in Fig. 4, the command signal
The output timing of Sc is shown in a, the rotational speed _V0 of the DC motor 9 is shown in b, and the output timing of the ready signal So indicating that driving of the DC motor 9 is permitted is shown in c.

Now, in the flowchart of FIG. 3, in the "drive start/first timer operation start" step (a), in response to the input command signal Sc, the DC At the same time as starting the motor 9, a first timer operation for measuring the driving time (indicated by Td in FIG. 4) is started. After this, in the determination step (b), when it is determined that the desired character element 6 is rotationally driven to the printing position and the driving of the DC motor 9 has ended, the first timer operation is stopped and the "addition" step ( C). In the "addition" step (c), the first timer operating time, that is, each driving time Td of the DC motor 9 is added to the duty timer time X, which will be described later. In this case, the duty timer time ), the drive time Td may be multiplied by n (n>o) and added. In the "second timer operation start" step (d) following the "addition" step (c), the second timer operation is started to measure the rest time of the DC motor 9 (indicated by Ts in FIG. 4). In the subsequent determination step (e), it is determined whether or not the duty timer time X is zero. At this time, if X=0, the process immediately moves to the "send ready signal So" step (f), and
If ≠0, the process moves to the "standby" step (g), and in this "standby" step (g), the waiting time T (see Fig. 4) corresponding to the duty timer time X is determined by a predetermined routine. After the standby time T has elapsed, the process moves to the "send ready signal So" step (f). In this case, the above waiting time T is
For example, an approximate function formula (T=f(X)) obtained based on temperature rise characteristic data of the DC motor 9 measured in advance.
It can be obtained by substituting the duty timer time X into the above functional formula. In addition, in the "standby" process (g),
DC as above for storage elements such as ROM etc.
The temperature rise characteristic data of the motor 9 may be stored in association with the multi-stage duty timer time X, and the standby time T may be obtained by reading out the stored data. The ready signal So is transferred to the "Send ready signal So" step (f).
In the determination step (H) after the is sent, when it is determined that the command signal Sc from the keyboard section 14 has been input, the second timer operation is stopped and the process shifts to the "subtraction" step (R). be done. In addition, ready signal So
disappears when the command signal Sc is input. In the "subtraction" step (re), the second timer operating time, that is, each stop time Ts of the DC motor 9, is subtracted from the duty timer time X. Incidentally, in this "subtraction" step (2), the pause time Ts may be multiplied by m (m>o) and subtracted. In the determination step (N) following the "subtraction" step (I), it is determined whether the duty timer time If X<O (that is, YES), the duty timer time X is initialized to zero through the "initialization" step (l), and then The process moves to step (a) ``Start driving/Start first timer operation''. That is, when the duty timer time X becomes negative, in other words, when the rest time Td of the DC motor 9 becomes sufficiently long, the duty timer time X is returned to the initial state. On the other hand, "Start"
In the "initialization" step (W) following step (W), the duty timer time X is also initialized to zero, and after this, the "second timer operation start" step (D)
will be moved to In addition, the DC motor 9 receives the ready signal.
The drive is configured to start only when the So signal is output and the command signal Sc is input. Therefore, the ready signal So is output as shown at timing to in Fig. 4. The DC motor 9 does not start driving even if the command signal Sc is previously input, and the DC motor 9 starts driving only when the ready signal So is output thereafter.

As described above, after the duty timer time teeth,
The rest time Ts is subtracted from the duty timer time X, and the driving time Td is added to the duty timer time X during the period in which the DC motor 9 is driven (however, if the duty timer time When the discrimination process (nu)
and the "initialization" step (l) are sequentially executed to return the duty timer time X to zero). As a result,
The state in which the duty timer time
In other words, this corresponds to a state in which the ratio (ΣTd/ΣTs) of the total sum ΣTs of the driving times Td to the total sum ΣTs of the rest times Ts is equal (1/1 state). Therefore, in the determination step (e) for determining whether the duty timer time When the value exceeds "1", a "standby" step (g) is executed, and a standby time T corresponding to the duty timer time X is set.

According to the present embodiment described above, in the "addition" step (c), the duty timer time In the subsequent determination step (E), it is determined whether the duty timer time X added or subtracted as described above is zero or not. The configuration is such that the total sum of Ts is compared with ΣTs, and it is determined whether the ratio of ΣTd to ΣTs is below a certain value. This constant value is "1" in this example, and the subtraction process
In (li), the pause time is multiplied by m and subtracted, and the addition process
In (c), when the drive time is multiplied by n and added, it is m/n. If ΣTd/ΣTs exceeds a certain value at this time, a waiting time T is set in the "standby" step (g), and the sending of the ready signal So is delayed by this waiting time T, so that ΣTd/ΣTs remains constant. The configuration is such that control is performed so that the value is less than or equal to the value. Also,
The configuration is such that the DC motor 9 does not start driving even if the command signal Sc is input from the outside during a period from when the DC motor 9 ends to when the ready signal So is output, that is, during the standby time T. Therefore, the rest time Ts of the DC motor 9 automatically changes in proportion to the length of the drive time Td, and in this way, the temperature rise of the DC motor 9 is suppressed to below a certain value. While the drive is controlled.

In the above embodiment, the DC motor 9 of the electronic typewriter was controlled, but the control object is of course not limited to this.

According to the present invention, as is clear from the above explanation, when controlling the intermittent drive of the motor, the temperature rise is kept at a constant value based on the ratio between the actual drive period and the stop period of the motor. Since the motor drive cycle can be variably controlled so that the motor drive cycle does not exceed a certain cycle, the motor's repetitive drive speed is faster than the conventional configuration, which controls the motor drive cycle so that it does not exceed a certain cycle. Unlike the conventional structure in which the motor is stopped when the temperature rise exceeds a certain value, the motor is not inadvertently stopped while it is being driven. Of course, there is no need to provide a margin for the motor output or to provide a dedicated cooling mechanism for the motor.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a perspective view of the main parts of an electronic typewriter, FIG. 2 is a block diagram showing the main parts of the control system, FIG. 3 is a flowchart, and FIG. is a time chart. In the figure, 9 is a DC motor, 13 is a CPU (control means), and Sc is a command signal.

Claims (1)

[Claims] 1. In a motor drive control circuit that drives and controls a motor in response to command signals intermittently applied from the outside, the total sum of the motor's rest time and the sum of the motor's drive time are compared, and the In a state where the ratio of the sums of drive times exceeds a certain value, each time the motor finishes driving, until the standby time determined according to the ratio of the sums has elapsed, the motor is operated based on an external command signal. A motor drive control circuit comprising a control means for prohibiting driving of the motor.