JPH03148911A - Signal generation equipment and blowing device using signal generation equipment - Google Patents

Abstract

PURPOSE:To obtain the cooling air of a capacity corresponding to a temperature by storing a routine inverting the output potential of an output port and a table specifying the relation of an interruption time with respect to the number of execution times for the routine in correspondence with the period and the waveform of a signal. CONSTITUTION:A temperature detection circuit 14 outputs a voltage signal which changes with the resistance change of a temperature detection element 13 to the input port of a micro computer 15. The rectangular pulse signal P of a pulse width which periodically changes in accordance with interruption time is outputted from the output port of the micro computer 15, and the rectangular pulse signal P is inputted to a low pass filter 22. Then, it is shaped in a sine wave signal S and is inputted to a driving circuit 21. Since the driving circuit 21 conducts a sine wave current based on the sin wave signal S, a diaphragm 17 is energized by a solenoid 20 in accordance with the sin wave current and a blower 12 blows the cooling air of the capacity corresponding to the frequency of the sine wave current to a heat sink 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a signal generator and a blower using the signal generator.

(Prior Art) Power amplifiers (hereinafter referred to as amplifiers) such as audio amplifiers house heat-generating devices such as transformers and power transistors in the cabinet, and hot air tends to get trapped inside the cabinet. The cabinet has an air blower that blows cooling air onto a heat sink or the like inside the cabinet, and is equipped with an air blower that controls this blower ff1 using a microcomputer according to the temperature inside the cabinet. As an air blower for such an amplifier, the present applicant has previously proposed an air blower that blows air by bending a diaphragm using a solenoid. This air blower connects a temperature sensor that detects the temperature of a heat sink, etc. to a microcomputer, and the microcomputer outputs a pulse width modulation signal (PWM signal) according to the temperature.This PWM signal is converted into a sine wave signal by a filter circuit. The waveform is shaped and guided to the drive circuit, and the drive circuit energizes the solenoid with a sine wave current.

(Problem to be Solved by the Invention) However, in the above-mentioned blower, the microcomputer generates a control signal according to the temperature according to a predetermined program based on the clock signal, and opens and closes the gate using this control signal. In order to generate a PWM signal using a PWM signal, the above-mentioned program must be constantly executed, and it is essential to speed up the processing and reduce the influence on other programs, which leads to an increase in cost. .

The present invention has been made in view of the above-mentioned problems, and provides an inexpensive signal generator that outputs a signal with a predetermined waveform based on a PWM signal output from a microcomputer.
It is an object of the present invention to also reduce the cost of an air blower by using this signal generator.

(Means for Solving the Problems) The present invention waveform-shapes a pulse width modulation signal whose pulse width periodically changes, which is output from a microcomputer, to form a predetermined waveform having a period corresponding to the period of change of the pulse width. In the signal generating device that outputs a signal, the microcomputer defines a routine for inverting the output potential of an output port and a relationship between the interrupt time and the number of executions of the routine in accordance with the period and waveform of the signal. The gist is to store a table and execute the routine using a timer interrupt at an interrupt time determined based on the table to generate a pulse width modulated signal.

(Function) In the signal generating device according to the present invention, the microcomputer executes the routine to invert the potential of the output port using a timer interrupt to generate the PWM signal, so the routine is not constantly executed. , has little impact on other programs. Therefore, there is less need to increase the speed of the microcomputer, and costs can be reduced. Since the interrupt time for the number of routine executions is stored in a table and the routine is executed at the interrupt time determined by the table, the change characteristics of the pulse width of the PWM signal can also be easily changed by changing the table.

Further, in a blower device using this signal generating device, the signal generating device is inexpensive, and the overall cost can be reduced.

Then, by selecting a table according to the temperature, the microcomputer outputs a PWM signal whose pulse width changes at a cycle according to the temperature, and this PWM signal drives a sine wave current whose frequency changes according to the temperature. Since the circuit energizes the blower, a volume of cooling air corresponding to the temperature can be obtained.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 to 6 show an embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram, FIG. 2 is a circuit diagram, FIG. 3 is a circuit diagram, and FIG.
5 is a flowchart, FIG. 5 is a characteristic diagram, and FIG. 6 is a timing chart.

This embodiment shows a signal generating device applied to the blower device of the amplifier described above.

In FIG. 1, reference numeral 11 indicates a heat sink disposed within the cabinet of the amplifier, and reference numeral 12 indicates a blower that blows cooling air to the heat sink 11. The heat sink 11 has a temperature detection element such as a thermistor! 3 is provided, and this temperature detection element 13 is connected to an input port of a microcomputer 15 via a temperature detection circuit 14. The blower 12 is
A chamber 16a is formed within the case 16 by a diaphragm 17.

16b is separated, and these chambers 16a and 16b are case 1.
It opens toward the heat sink 11 from the air outlet 16c formed in the heat sink 16. A magnet 19 is fixed to the diaphragm 17 via a bracket 18, and a solenoid 20 is disposed on a body (not shown) or the like opposite the magnet 19. The solenoid 20 is connected to a drive circuit 21, and the drive circuit 21 is connected to an output port of the microcomputer 15 via a low-pass filter (waveform shaping circuit) 22. This blower 12 has a solenoid 20
A sinusoidal current, which will be described later, is applied to deform the diaphragm F as shown by the arrow in the figure, and this diaphragm 17
Air is blown by the deformation of Although the temperature detection element 13 and the temperature detection circuit 14 are not required in this embodiment, they will be described in the description of this embodiment because they will be used in other embodiments to be described later.

The temperature detection circuit 14 includes a resistor R and a transistor T, as shown in FIG.
Output to input port 5. The low-pass filter 22 is
As shown in FIG. 2, it consists of an RC type circuit including a capacitor C1, a resistor R, and a transistor T. This low-pass filter 22 has a frequency characteristic as shown in FIG. The waveform of the rectangular pulse signal is shaped. In this embodiment, as shown in FIG.
The low-pass filter 22 smoothes the rectangular pulse signal P and outputs a sine wave signal S. The drive circuit 21 is
As shown in FIG. 2, the solenoid 2o has a diode D, a resistor R, and a transistor T, and a current having substantially similar characteristics to the sine wave signal S manually inputted from the low-pass filter 22, that is, a sine wave current, is supplied to the solenoid 2o. The microcomputer 15 has an A/D converter 15a and a PWM signal generator 15b as a configuration of the present invention.^/D
The converter 15a converts the analog signal output from the temperature detection circuit 14 into a digital signal, and the PWM signal generator sb generates a rectangular pulse signal and outputs it to the waveform shaping circuit 22 by executing a routine to be described later. Furthermore, this PWM
The signal generator 15b is implemented as a function of the microcomputer 15.

Next, the operation of this embodiment will be explained.

This air blowing device executes the routine shown in the flowchart of FIG.
The low-pass filter 22 outputs a sine wave signal S based on the rectangular pulse signal P to the drive circuit 21.

Then, the drive circuit 21 drives the blower 12 based on the sine wave signal S.
A sinusoidal current is applied to the solenoid.

First, the output of the rectangular pulse signal P will be explained. In the microcomputer 15, an interrupt occurs when a time (interrupt time) set by a timer for setting an interrupt time has elapsed, and the step counter is decremented in step Pi. This step counter corresponds to step P, which will be described later.
A predetermined value is set at 3, and 1 is subtracted each time this routine is executed.

In the next step P2, whether the step counter is 0 or not,
That is, it is determined whether or not one loop of processing has been completed. In this step P2, the step counter is 0.
If it is determined that the step counter is not 0, the process of step P4 is executed. Here, one loop is one cycle of the sine wave signal S, that is, one cycle of change in the pulse width of the rectangular signal P.

In step P3, a predetermined value is set in the step counter. The setting value of this step counter (102 in this embodiment) is determined according to the waveform and period of the sine wave signal S (desired signal) obtained by shaping with the low-pass filter 22, and the number of routines set in the step counter is By executing , the rectangular pulse signal P required to obtain -period (1 loop) of the desired signal is obtained. Step P4
Now, from the data table, find the current value of the step counter (
The interrupt time is searched using the count value) as the address, and the interrupt time is set in the interrupt time setting timer. If the desired signal has a sine waveform, use the data table shown below, for example. If the desired signal has a different waveform, such as a triangular one, use the data table if the time change rate or time change amount of the pulse width of the rectangular pulse signal P is different. Use other data tables that have been set.

In the following step P5, the phase of the output of the output port (I
(/L) is reversed to end the interrupt and execute the interrupted main program. Thereafter, when the interrupt time set in step P4 has elapsed, the main program is interrupted again and the processing from step P1 is performed. Therefore, as shown in FIG. 6, the output port of the microcomputer 15 outputs a rectangular pulse signal P with a pulse width that changes periodically in accordance with the interrupt time, and this rectangular pulse signal P is passed through the low-pass filter 22. The signal is then manually shaped into a sine wave signal S and input to the drive circuit 21. And drive circuit 2
1 conducts a sinusoidal current based on the sinusoidal signal S,
The diaphragm 17 is energized by the solenoid 20 according to the sine wave current, and blows cooling air to the heat sink 11 in an amount corresponding to the frequency of the sine wave current.

As mentioned above, in this blower device, the microcomputer 15 generates the pulse signal P by executing the routine shown in FIG. 4 using a timer interrupt, so that the influence on other programs can be minimized. . Therefore, there is little need to increase the speed of the microcomputer 15.
An increase in the cost of the microcomputer 15 can be prevented.

FIG. 7 shows another embodiment of the invention. Note that the same parts as in the embodiment described above are given the same numbers, and illustration and description thereof are omitted.

In this embodiment, the microcomputer 15 executes the flowchart shown in FIG. 7 using a timer interrupt and outputs a rectangular pulse signal P.

First, when an interrupt occurs, in step Pi, the number of executions of the routine is counted by subtracting 1 from the step counter as in the embodiment described above. In the next step P2,
It is determined whether the step counter is 0 or not, and the temperature of the heat sink 11 is read from the output signal of the temperature detection element 13 to determine whether the temperature is high or low. In this step P2,
If it is determined that the step counter is not 0, step P
4. When the step counter is determined to be 0, one step P3 of step P3 (tt to P3(n)) is performed depending on the temperature.
Perform the process (1). In step P3 (1), a counter setting value f1 corresponding to each temperature is set in the step counter. This counter setting value fi corresponds to the frequency of the desired signal and is set to increase in the high temperature range of the heat sink 11.

In step P4, an interrupt time is searched from a data table selected based on the counter setting value fi, using the count value of the step counter as an address, and this interrupt time is set in an interrupt time setting timer. Subsequently, in step P5, the phase of the output port is inverted as in the embodiment described above. Thereafter, the interrupted main program is executed, but when the interrupt time has elapsed, an interrupt is made again from step PI.

In this embodiment, the change period in which the pulse width of the rectangular pulse signal changes, that is, the period of the sine wave signal S output from the low-pass filter 22, is determined according to the step counter value fi, and the solenoid 20 of the blower 12 is connected to the heat sink 11. A high frequency sinusoidal current is applied at high temperatures. Therefore, when the heat sink 11 is at a high temperature, a large amount of cooling air can be blown to the heat sink 11, and heat can be effectively radiated.

In each of the embodiments described above, a solenoid of a blower is exemplified as an object to be driven, but it goes without saying that the present invention can also be applied to devices such as motors.

(Effects of the Invention) As explained above, according to the signal generating device according to the present invention, the microcomputer generates the PWM signal by executing the routine using a timer interrupt, which greatly affects other programs. PWM signals can be generated without any problems, there is no need to increase the speed of the microcomputer, and costs can be reduced.

In addition, a blower device using this signal generator can also reduce the cost of a microcomputer, thereby reducing manufacturing costs.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 6 show an embodiment of the signal generator according to the present invention, FIG. 1 is a schematic configuration diagram of a blower using the signal generator, FIGS. FIG. 3 is a circuit diagram, FIG. 4 is a flowchart, FIG. 5 is a characteristic diagram, and FIG. 6 is a timing chart. FIG. 7 is a flowchart of another embodiment of the signal generator according to the present invention. 12...Blower, 13...Temperature detection element, 14-...
・Temperature detection circuit, tS-...Microcomputer, 2
0...Tsurenoid, 21-...Drive circuit, 22-...Low pass filter (waveform shaping circuit). (Timer interrupt) Subtract 1 from the 1 step counter - Set the number according to the desired signal to the step counter Determine the next interrupt time based on the count value of the step counter and set it to the timer

Claims (2)

[Claims] (1) A signal generating device that shapes a pulse width modulated signal whose pulse width periodically changes output from a microcomputer and outputs a signal with a predetermined waveform having a period corresponding to the period of change of the pulse width. The microcomputer stores a routine for inverting the output potential of the output port, and a table that defines the relationship between the number of executions of the routine and the interrupt time in accordance with the period and waveform of the signal, and performs processing based on this table. A signal generating device characterized in that the routine is executed by a timer interrupt at a predetermined interrupt time to generate a pulse width modulated signal. (2) In a blower device that detects temperature and controls the blowing capacity of the blower according to the temperature, a routine that inverts the potential of the output port and a plurality of routines that define the relationship between the interrupt time and the number of executions of the routine are used. a table, the temperature information is input, one table is selected from a plurality of tables based on the temperature, and the routine is executed at an interrupt time determined based on the table to perform pulse width modulation according to the temperature. A microcomputer that outputs a signal, a waveform shaping circuit that shapes a pulse width modulated signal output from the microcomputer to output a sine wave signal with a period corresponding to the pulse width change period, and this waveform shaping circuit A blower device comprising: a drive circuit that outputs a sine wave having a period corresponding to the sine wave signal to the blower based on the output sine wave signal.