JPH0138644Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device, and particularly to a control device that controls a certain controlled object in accordance with the operation of a plurality of operation switches, for example.

FIG. 1 is a schematic circuit diagram showing an example of a conventional VTR. In the figure, the VTR 1 includes a signal processing section 12 having processing circuits for video signals, audio signals, etc. and servo circuits for various motors, a mechanism section 13 that drives tape running, etc., and a signal processing section 12 and a mechanism section 13. and a microcomputer 14 that performs control. Operations such as playback, recording, fast forwarding, rewinding, and stopping of the VTR 1 can be performed using the remote control section 2. A plurality of operation switches 21 of the remote control section 2
Depending on which switch a to 21e is closed, the potential of the output 3 of the remote control unit 2, that is, the potential of one input of each of the comparators 15a to 15e changes. Further, the potential of the other input of each comparator 15a to 15e, that is, the reference potential, is set to the resistor 16a to 16f.
It is applied by dividing the resistance by . Therefore,
By appropriately selecting the resistance values of the resistors 16a to 16f and the resistors 22a to 22e, the operating switch 21a
The outputs of the comparators 15a to 15e can be selectively set to high level depending on which one of the comparators 15a to 15e is closed. The outputs of the comparators 15a to 15e are input to the input means 14 of the microcomputer 14.
a to the CPU 14b. CPU14
b determines which of the operation switches 21a to 21e has been operated based on the output states of the comparators 15a to 15e, and outputs a corresponding control signal to the signal processing unit 12 via the output means 14c.
Alternatively, it is given to the mechanism section 13.

Incidentally, in the above-mentioned VTR, the number of comparators required corresponds to the number of operation switches installed. For this reason, it becomes necessary to increase the number of comparators each time the operation function is increased, making the device complicated and expensive. Furthermore, as the number of comparators increases, the number of signals input to the microcomputer 14 also increases. Therefore, a microcomputer with a large number of terminals must be used, making the device expensive. If a microcomputer with a small number of terminals is used, the number of terminals that can be used for other purposes will be limited, making it impossible to effectively utilize the functions of the microcomputer.

Therefore, the purpose of this invention is to provide a control device that does not require a large number of comparators even when the number of operation switches increases, and also requires a small number of signals input to a control means such as a microcomputer. It is.

In summary, the idea is to apply a pulse signal of a constant period to a CR time constant circuit whose time constant is changed in stages according to the operation of an operating switch, and to synchronize the output of the CR time constant circuit with a preset reference voltage. The time from the edge of the pulse signal to when the above match is detected is measured. Based on the measurement result, it is determined which operation switch was operated, and based on the result of the determination, The control target is controlled accordingly.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 2 is a schematic circuit diagram showing an embodiment of this invention. In configuration, the VTR 100 includes a signal processing section 112, a mechanism section 113, and a microphone computer 114, which is an example of a control means. The microcomputer 114 includes a CPU 114b and an output means 1.
14c and pulse generating means 114d.
Note that the CPU 114b has a function of measuring time, but in FIG.
It is represented by a block as TC. Power supply 118
is used as a power source to drive the microphone computer 114, and a resistor 1 is connected to both ends of it.
17 and 119 series circuits are connected. The voltage generated at the connection point between the resistors 117 and 119 is applied to one input terminal of the comparator 115 as a reference voltage.

On the other hand, the pulse signal a output from the pulse generating means 114d is given to the time measuring means TC and also to the buffer 120. The output of buffer 120 is applied to capacitor 121. This capacitor 121 is an integrating capacitor, and cooperates with the resistors 22a to 22e of the remote control unit 2 to form a CR time constant circuit. Also, this CR
Operation switches 21a to 21 related to the time constant circuit
e is connected. Operation switches 21a to 21e
switches the resistance value connected in parallel to the capacitor 121 according to the operation. By this, CR
The R component of the time constant circuit is increased or decreased, and the time constant is switched in steps. The output of the CR time constant circuit, ie, the output b generated at the connection point between the capacitor 121 and the resistor 22a, is applied to the other input terminal of the comparator 115. The comparator 115 compares the reference voltage described above and the output voltage b of the CR time constant circuit, and detects whether or not they match. Comparator 11
The output c of 5 is given to the time measuring means TC.

FIG. 3 is a waveform diagram of signals at various parts in the circuit of FIG. 2. The operation of the circuit shown in FIG. 2 will be explained below with reference to FIG.

The pulse signal a output from the pulse generating means 114d is passed through the buffer 120 to the capacitor 1.
Given to 21. Charge is accumulated in the capacitor 121 when the pulse signal a is at a high level. Conversely, when pulse signal a becomes low level,
The buffer 120 becomes open and the capacitor 12
The charge accumulated in 1 is discharged. Therefore, the voltage b at the output end of the buffer 120, that is, the voltage b at the output terminal of the buffer 120, that is,
The output voltage b of the CR time constant circuit gradually decreases. At this time, it depends on which switch among the operation switches 21a to 21c is being operated.
Since the CR time constant of the CR time constant circuit is different, the voltage b
The lowering speed differs depending on the operating state of the operating switches 21a to 21e. When the voltage b matches the reference voltage, the comparator 115 gives a pulse c as shown in FIG. 3 to the time measuring means TC.

Here, the time t1 from the fall of the pulse signal a until the pulse is output by the comparator 115 is
is determined by the falling rate of voltage b, that is, the CR time constant during discharge. In other words, the operation switch 21
Depending on which switch from a to 21e is closed,
Time t1 changes. The time measurement means TC is this time t1
Measure. Then, the CPU 114b determines which of the operation switches 21a to 21e has been operated based on the measurement result of the time measurement means TC, and performs a corresponding control operation.

In the above embodiment, the speed of discharging when the capacitor 121 is discharged is measured to determine which operation switch is operated, but conversely, the charging speed during charging is measured to determine which operation switch is operated. It can also be determined whether the operation switch has been operated. In this case, the CR time constant of the charging path of the capacitor 121 may be changed according to the operation of the operation switch.

As described above, according to this invention, even if the number of operation switches increases, only one comparing means is required, and the structure can be simplified and an inexpensive device can be obtained. Furthermore, since only one signal is input to the control means, an inexpensive control means with a small number of terminals can be used, and the input/output terminals of the control means can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram showing an example of a conventional VTR. FIG. 2 is a schematic circuit diagram showing an embodiment of this invention. FIG. 3 is a diagram showing signal waveforms at various parts of the circuit of FIG. 2. In the figure, 21a to 21e are operation switches;
114 is a microcomputer, 114b is
CPU and TC are time measuring means, 114d is a pulse generating means, and 115 is a comparator.

Claims (1)

[Claims for Utility Model Registration] (1) A control device that controls a controlled object according to the operation of a plurality of operation switches, comprising: a pulse signal generating means for generating a pulse signal of a constant period; and a pulse signal generating means for receiving the pulse signal. , and a CR time constant circuit whose time constant is switched in stages according to the operation of the operating switch; and a comparison means for comparing the output of the CR time constant circuit with a preset reference voltage and detecting that they match. , a time measuring means for measuring the time from the edge of the pulse signal until the matching is detected by the comparing means, and determining which operation switch has been operated based on the measurement result of the time measuring means. death,
A control device comprising a control means for controlling the control target according to the determination. (2) The CR time constant circuit includes an integrating capacitor that receives and integrates the pulse signal at one end thereof, and a resistor circuit that is connected in parallel to the integrating capacitor and has a plurality of dividing points. 2. The control device according to claim 1, wherein each of the operating switches is inserted between a corresponding dividing point of the resistor circuit and the other end of the integrating capacitor.