JP2736142B2 - Automatic adjustment device for electronic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an automatic adjustment device for an electronic device using a motor, and a rotary variable device such as a variable resistor or a variable capacitor which is rotated by the motor. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic adjustment device for an electronic device that prevents breakage of an element when the element attempts to rotate beyond a rotation range.

<Prior Art> Electronic devices require minute adjustments in the manufacturing process and in calibration after a certain period of use in order to provide or maintain desired functions and characteristics. This adjustment is generally performed by rotating a variable element such as a variable resistor or a variable capacitor. As a means for this, there are a manual method and a method by automatic control. The manual method is a method in which the adjuster manually adjusts by visual judgment or the like, and the automatic control method is a method in which the motor is adjusted by an electric detection means.

<Problems to be Solved by the Invention> In the above-described automatic adjustment, there are cases where adjustment cannot be performed within the rotation range of the variable element due to factors such as failure of other components or deterioration with time of the variable element itself. ,
In the case of manual adjustment, the rotation stops when the variable element reaches the end of rotation, but in the case of automatic adjustment by the motor, if the predetermined adjustment is not achieved even when the end of rotation is reached, the rotation operation by the motor continues, and finally the variable The element is destroyed because it exceeds the rotation range. To prevent this, it is only necessary to stop the rotation of the motor when the variable element reaches the end of rotation, but if the stop is delayed for a short time due to the large torque, the variable element may be destroyed, It is necessary to quickly detect that the end of rotation has been reached and stop the motor.

In view of the above-mentioned need, the present inventor has previously described a voltage amplifier for amplifying a voltage obtained by current-to-voltage conversion of a load current flowing through a motor, a filter for passing only a specific frequency component of the output of the voltage amplifier, and an output of the filter. A sample-and-hold circuit that stores the data at a certain time interval, a voltage shift circuit that shifts the output of the filter, a comparison circuit that compares the output levels of the sample-hold circuit and the voltage shift circuit, and an output from the comparison circuit. An automatic adjusting device for electronic equipment, comprising: a storage circuit for storing signals; and a relay for interrupting a current path of the motor by an output signal of the storage circuit (Japanese Patent Application No. 1-14254).
4) proposed. However, the circuit according to the present invention has a problem that, besides the fact that the variable element has reached the end of rotation, the start and deceleration of the motor accompanying the adjustment operation of the variable element are also detected and the motor is stopped. Was.

SUMMARY OF THE INVENTION In order to solve the above-described problems, the present invention is to provide an automatic adjusting device that selectively detects only that a variable element has reached a rotation end and stops a motor.

<Means for Solving the Problems> In order to achieve the above object, the present invention relates to an automatic adjustment device for electronic equipment that adjusts a rotary variable element to a predetermined value by using a motor as a driving means. A voltage amplifier for amplifying a voltage obtained by converting a current into a voltage, a filter for passing only a specific frequency component of the output of the voltage amplifier, a sample and hold circuit for storing the output of the filter at fixed time intervals, and an output of the filter. , A first comparator for comparing the output levels of the sample-hold circuit and the voltage shift circuit, and a second comparator for comparing the output of the filter with a reference voltage and outputting a signal for a predetermined time. A comparison circuit, a logic circuit for processing output signals from the first comparison circuit and the second comparison circuit, and the logic circuit And a relay for interrupting the current path of the motor by the output signal of the storage circuit.

<Operation> The following is defined among the driving voltage V of the motor, the back electromotive force E of the motor, the load current I of the motor, the armature resistance R of the motor, the number of magnetic fluxes per pole of the motor φ, and the number of rotations N of the motor. Have a relationship.

V = E + IR (1) E = KφN (2) From such a relationship, when the variable element reaches the end of rotation, the load on the motor increases, and the rotational speed of the motor decreases,
E in equation (2) decreases, and accordingly, I in equation (1) increases. That is, when the variable element reaches the end of rotation, the load current I of the motor changes. Also, when the motor is started, accelerated, decelerated, and the like, the load current I of the motor also changes. The change in the load current caused by these factors is larger than the change caused by the variable element reaching the end of rotation.

The present invention utilizes this phenomenon to constantly monitor the load current I of the motor, thereby detecting that the variable element has reached the end of rotation and stopping the motor. In the present invention, the load current I of the motor is converted into a voltage, and the voltage output having only the voltage change accompanying the above phenomenon is amplified and extracted by the voltage amplifier and the filter so as to be easily detected. This output is input to a sample-hold circuit and a voltage shift circuit, and the output from the sample-hold circuit and the voltage shift circuit is compared and determined by a first comparison circuit to detect a change in the load current I of the motor due to the above phenomenon. Is done. In addition, when the amplified output is input to the second comparison circuit, the change in the load current of the motor caused by starting the motor is larger than the change in the load current of the motor caused by the variable element reaching the end of rotation. Is used to detect a change in the load current I of the motor due to something other than that the variable element has reached the end of rotation. Then, detection signals from the first comparison circuit and the second comparison circuit are input to the logic circuit, and only the change in the load current I of the motor due to the variable element reaching the end of rotation is detected. The motor is stopped by turning off the relay incorporated in the current path of the motor.

Embodiment An embodiment of the present invention will be described below in detail with reference to FIGS.

As shown in FIG. 1, the automatic adjustment device of the present embodiment includes a variable element 4 inside an electronic device 5 by an adjustment driver 3 connected to a rotating portion of a motor 2 via a reduction gear.
Is rotated at a few rpm to adjust the electronic device. One end of the drive terminal of the motor 2 is
The other end is connected to a resistor 7 via a relay 6, one end of the resistor 7 is grounded, and one end is connected to a voltage amplifier 8, and the voltage amplifier 8 has a cutoff frequency of 1 Hz.
Is connected to a filter 9 which is a third-order active low-pass filter.

The filter 9 is connected to a sample hold circuit 10 and a voltage shift circuit 11, and the sample hold circuit 10 and the voltage shift circuit 11 are connected to a first comparison circuit 12.
The sample and hold circuit 10 includes a VCO 10a, as shown in FIG.
It comprises a monostable multivibrator 10b and an analog switch 10c.

The filter 9 is connected to a second comparison circuit 18 and a logic circuit 19, and the first comparison circuit 12 and the second comparison circuit 18 are connected to the logic circuit 19. The second comparison circuit 18 includes a Schmitt trigger circuit 13, a monostable multivibrator 14,
The logic circuit 19 includes an AND circuit 16 and a logic circuit 15. Further, the logic circuit 19 is connected to a flip-flop circuit 17 which is a storage circuit, and the flip-flop circuit 17 is connected to the relay 6.

Hereinafter, the operation in the present embodiment will be described for the case where the motor 2 rotates forward.

Now, it is assumed that the variable element 4 is automatically adjusted by the adjustment circuit 3 by the drive circuit 1 based on the feedback of the adjustment result of the variable element 4, and the motor 2 is temporarily stopped and restarted. . The load current flowing through the motor 2 is converted into a voltage by a resistor 7 that does not affect the motor 2 and is amplified by a voltage amplifier 8.
The voltage output waveform at this time has a waveform as shown in FIG. 4A, and the change in the load current due to the change in the rotation speed in the mV order is hidden in the current fluctuation accompanying the rotation in the V order. When this output passes through the third-order active low-pass filter 9 used particularly for increasing the attenuation gradient, 1HZ
The above components are cut to form a waveform Z from which noise is removed as shown in FIG. 4 (b), and as shown in FIG. 4 (c), the load current associated with the stop, start and rotation termination of the motor 2 Output having only a waveform due to the change of

This output is applied to a voltage shift circuit as shown in FIG.
An output waveform X, which is obtained by shifting the output waveform Z that has passed through the filter 9 by 11 by C volts, is generated, and a sample-and-hold circuit is formed.
At 10, the monostable multivibrator 10 according to the signal output at the time T ₂ from the VCO 10 a shown in FIG.
The output waveform Z Charge ₁ hour T according to T ₁ hour signal shown in FIG. 5 (b) issued from b, T ₂ -T ₁ hour memory waveform Y is made. Then, both the waveforms X and Y are compared by the first comparison circuit 12, and when the waveform X exceeds the waveform Y, a binary Hi level signal shown in FIG. 5D is output.

The output waveform Z that has passed through the filter 9 shown in FIG. 2A is input to the Schmitt trigger circuit 13, and when the output waveform Z exceeds a preset level of a and b, the output waveform Z shown in FIG. ) as shown in a signal is output, the signal as shown in FIG. 2 (c) is stretched in the T ₄ hours by monostable multivibrator 14. As shown in FIG. 2 (a), the change due to the stop and start of the motor 2 is sharper and larger than that at the end of rotation, and is accompanied by a gradual change for stability. Depending on the setting, only the signal accompanying the stop and start is output, and the signal is maintained during the stabilization time by further extending the time.

The signals from the first and second comparison circuits are
The AND circuit 16 outputs a signal that is ANDed with the Lo level in FIG. 2C and the HI level in FIG. 2D.
The logic circuit 15 detects the rotation direction of the motor 2 and determines the cause of the load current change due to the change in the rotation direction. Since the signal from the first comparison circuit 12 is composed of the signal of the end of rotation and the stop and start of the motor 2, and the signal from the second comparison circuit 18 is composed of the signal of the stop and start of the motor 2, the AND circuit 16 Output only the signal at the end of rotation.

When the signal from the AND circuit 16 is input to the flip-flop circuit 17 having a storage capability, the state of the flip-flop circuit 17 becomes Lo as shown in FIG.
State, whereby the relay 6 is turned off, this state is maintained, the current path of the motor 2 is cut off, the motor 2 is stopped, and the reset signal is output because the flip-flop circuit 17 has a storage capacity. As long as there is no input, the motor 2 is not driven even if there is a signal from the drive circuit 1, and the destruction of the variable element 4 is prevented.

In the above description, it is assumed that only the motor stop and start operations are the causes of the rotation speed change until the end of rotation is reached. However, in actual use, the deceleration operation due to the adjustment by the variable element 4 approaching the target value is also performed. , Repeat operation of start / stop of motor 2 due to drift fluctuation of measured value indicating adjustment result, repeat operation of deceleration → stop → start → acceleration → deceleration → stop → reversal start from overshoot-like operation due to inertia of motor 2, etc. All the fluctuations of the load current due to these are removed by the second comparison circuit 18.

In this embodiment, after the variable element 4 reaches the end of rotation, about 1
In 2 seconds, the motor 2 stops, but as shown in FIG. 5 (c), the voltage due to the load current increases during the time B from the point S at which the end of rotation is reached to the point at which the variable element 4 is destroyed. Since there is a time during which no load is imposed, the time A until the motor 2 stops is set in consideration of this.

When the motor 2 rotates in the reverse direction, the voltage must be shifted to the GND side as shown in FIG. 6, but this is adjusted by detecting the rotation direction by the logic circuit 15. The level from a to b is shown in FIG.
Variable element 4 is energized by the corresponding load current to the second view after the time T ₄ in FIG. 2 (c) to the maximum value b 'of the voltage due to the load current (a) when it is destroyed as shown in a value or more, more T ₄ by the voltage change by a slight load current other than termination waveform shifted waveform X is the memory Y
Is determined in consideration of a shift width C which is determined so as not to exceed.

By performing the operation described above, the adjustment of the variable element 4 was performed without being destroyed by the apparatus of the present embodiment.

<Effects of the Invention> According to the present invention, it is possible to accurately and quickly detect only the end of the variable element from a change in the load current of the motor, so that the variable element can be prevented from being destroyed during automatic adjustment of the electronic device. , The reliability of automatic adjustment is improved, and complete automation becomes possible.

[Brief description of the drawings]

1 is a block diagram of the embodiment, FIG. 2 is a diagram for explaining the operation of the embodiment, FIG. 3 is a configuration diagram of a sample and hold circuit of the embodiment, and FIG. 4 is a voltage waveform before and after passing through a filter of the embodiment. FIG. 5 is a diagram for explaining signal output from the first comparison circuit of the embodiment, and FIG. 6 is a diagram showing a shift in the case of reverse rotation of the embodiment. 6 ... Relay, 8 ... Voltage amplifier 18 ... Comparison circuit, 9 ... Filter 19 ... Logic circuit, 10 ... Sample hold circuit, 17 ...
Flip-flop circuit 11: Voltage shift circuit, 12: Comparison circuit

Claims (1)

(57) [Claims] 1. An automatic adjusting device for an electronic device for adjusting a rotary variable element to a predetermined value by using a motor as a driving means, comprising: a voltage amplifier for amplifying a voltage obtained by current-to-voltage conversion of a load current flowing through the motor; A filter that passes only a specific frequency component of the output of the amplifier, a sample and hold circuit that stores the output of the filter at fixed time intervals, a voltage shift circuit that shifts the output of the filter, the sample and hold circuit, and the voltage A first comparison circuit that compares and determines the output level of the shift circuit, a second comparison circuit that compares the output of the filter with a reference voltage and outputs a signal for a fixed time, the first comparison circuit, and the second comparison circuit. A logic circuit that processes an output signal from the comparison circuit, a storage circuit that stores the output signal from the logic circuit, and an output signal of the storage circuit. Automatic adjusting apparatus of an electronic device characterized by comprising a relay for interrupting the current path of the motor by.