JPS6025661B2 - damper device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damper device, and by controlling its excitation current using a plunger solenoid device, the strength and response characteristics of the damper can be easily set and adjusted to arbitrary values. The purpose is to provide a damper device.

Generally, when starting play from the stop mode of a tape recorder, the magnetic tape is suddenly tensioned from a slack state, causing the tension arm to rotate rapidly and greatly, resulting in the tape coming off the tension arm, guide roller, etc. Sometimes.

Also, even if it didn't come off, there was a spring attached to the tension arm, which caused a lot of vibration, and the magnetic tape did not run stably at the beginning of play mode. Furthermore, when ejecting the cassette holder, if the cassette holder is rotated rapidly, the cassette holder will vibrate and adversely affect the mechanism. For this reason, conventionally, mechanical dampers such as mechanical air dampers have been used to eliminate the above phenomenon, but these are somewhat mechanically complex and require highly viscous dampers to obtain the desired shock absorption properties. When using a damper, the time during which the damper is acting is considerably longer than the time required for impact prevention, making it difficult to obtain the desired damper characteristics in a short period of time. there were. The present invention eliminates the above-mentioned drawbacks, and each embodiment of the device of the present invention will be described below with reference to the drawings.

FIG. 1 shows a specific circuit of an embodiment of the main part of the device of the present invention.

In the figure, reference numeral 1 denotes a sliding resistor having an actuator 2 that slides between terminals A and C. This actuator 2 is connected to terminal B and is normally located on the terminal A side. Q, , Q2 are NPN transistors constituting an unbalanced differential amplifier, and a parallel circuit consisting of a resistor R and a diode D is connected between the base of the transistor Q2 and the above terminal B. The connection point between the base of and the parallel circuit consisting of R, , and D is grounded via a capacitor C. Terminal B is also connected to transistor Q via resistor R2.
connected to the base of. The collector of transistor Q2 is connected to the base of PNP transistor Q via a resistor. The collector of this transistor Q3 is a resistor R
3. The above transistor Q via the capacitor C2 in series.
, is connected to the base of the NPN transistor Q, and is further grounded via a resistor R4. A solenoid 3 is connected between the emitter of the transistor Q and ground. FIG. 2 shows a plan view of an embodiment of a mechanism in which the damper device shown in FIG. 1 is applied to a tension arm of a tape recorder.

In the figure, the same parts as in FIG. 1 are given the same reference numerals.
4 is attracted by a plunger when the solenoid 3 is energized, and when it is not energized, it is pulled out by the clockwise rotational force of the tension arm 7, which rotates against the spring force of the spring 5.

The plunger 4, together with the slider 2, is connected to a connecting portion 6 which rotates integrally with the tension arm 7, thereby controlling the rotation of the tension arm 7 about the rotation axis 7a. A magnetic tape 8 is attached to a guide pin 7b at the tip of the tension arm 7.

Next, the operation of the device of the present invention will be explained with reference to FIGS. 1 and 2. In this embodiment, the sudden rotation of the tension arm 7 at the start of play is suppressed (the suction operation of the plunger 4 is controlled). be.

That is, when the magnetic tape 8 is slack as shown in the second figure in the stop mode, the slider 2 is in a position close to the terminal A of the sliding resistor 1 as shown in FIG. As a result, the DC power supply voltage is applied to the base of the transistor Q through the resistor R2 without being substantially divided by the sliding resistor 1, and is applied to the base of the transistor Q2 through the diode D. and is applied to capacitor C. Therefore, the resistor R of the capacitor C is short-circuited by the conductive diode D, so that the capacitor C is instantly charged to approximately the DC power supply voltage. Also at this time, transistor Q
, , Q2 have substantially the same base potential, and transistors Q3 and Q4 are in an off state. Next, in the play mode, at the start of the play mode, the tension arm 7 is suddenly rotated clockwise in FIG. 2, and the slider 2 is directed toward the terminal C shown in the first diagram.

Therefore, the base potential of the transistor Q decreases because the DC power supply voltage is divided by the sliding resistor 1. Also, since diode D is reverse biased, capacitor C,
The charged charges are discharged through the resistor R and the resistor between the terminals B and C of the hyperdynamic resistor 1. That is, transistor Q2
The base potential of the terminal gradually decreases according to a discharge time constant determined by the values of the capacitor C, the resistor R, and the resistance between the terminals B and C. However, since the value of the resistance between the terminals B and C is selected to be sufficiently smaller than the value of the resistance R, the discharge time constant is mainly determined by the resistance R,
, capacitor C, may be considered to be determined by the respective values of capacitor C.
At the start of play, the slider 2 rapidly moves toward the terminal C side as mentioned above, but the rate at which the base potential of the transistor Q due to this movement decreases is equal to the base potential of the transistor Q2 according to the above-mentioned discharge time constant. Since the discharge time constant is selected to be sufficiently larger than the rate of decline, the transistor Q2 is close to on at the start of play. As a result, a large collector current flows through the transistors Q3 and Q, and a large excitation current flows through the solenoid 3. Therefore, the plunger 4 is suddenly attracted with a large stroke, and works together with the spring force of the spring 5 to suppress clockwise rotation of the tension arm 7. In addition,
The above discharge time constant is chosen to be 4.0 times the time constant of the change in tape tension caused by the gradual change in windings of the reel (indicated by 9 in FIG. 2).

Therefore, when the slider 2 gradually moves toward the terminal C side due to a change in tape tension corresponding to a change in the tape winding diameter during the normal play mode, the capacitor C during the stop mode. When the charged charge is discharged, the voltage across the capacitor C, that is, the base potential of the transistor Q2, becomes the transistor Q.
, is approximately equal to the base potential of . Therefore, transistors Q2, Q, and Q4 are all off, and no excitation current flows through solenoid 3, so plunger 4 is not attracted. Therefore, in this case, based on the normal rotation of the tension arm 7, tension servo is performed to keep the tension arm 7 constant by the spring force of the spring 5. If the tape tension suddenly decreases for some reason, the tension arm 7 will suddenly try to rotate counterclockwise in FIG. 2 due to the spring force of the spring 5.

In this case, the slider 2 rapidly moves from the terminal C toward the terminal A. Therefore, even if this movement is so rapid that it is smaller than the discharge time constant, the base potential of the transistor Q increases, so that the diode D is always forward biased and the resistor R is short-circuited. As a result, capacitor C is charged instantly.

Therefore, in this case, the base potentials of transistors Q, , Q2 become equal. Therefore, as mentioned above, the transistor Q
2 to Q4 are each off, and solenoid 3 has a damper.
An effective exciting current does not flow, and no suction operation is performed. Therefore, the tension arm 7 is rotated in all directions by the spring force of the spring 5 without being subjected to damper action by the plunger 4, and the connecting portion 6 displaces the freely displaceable plunger 4. These operations are the same even when the tape tension is slowly decreased. In this way, the pupil of the present invention performs a damper operation only in response to a sudden increase in tape tension that is smaller than the discharge time constant of the capacitor C.

It should be noted that during play mode there is usually no sudden increase in tape tension beyond a constant tape tension.

Further, the strength of the damper is determined by setting the base current value of the transistor Q4. Further, the response characteristics are determined by setting the discharge time constant of the capacitor C. FIG. 3 is a schematic side view of an embodiment of a mechanism in which the device of the present invention is applied to a cassette holder. The same parts as in FIG.

In FIG. 3, 11 is a cassette holder, and when it is not locked by the locking mechanism 12, the spring 1
The plunger 4 is kept stationary at the position shown in FIG. 3 by the force of the spring 3, and the plunger 4 whose tip is fixed to a part of the side surface of the cassette holder 11 is pulled out at this time. Further, at this time, the slider 2 is located extremely close to the terminal C. Therefore, the base potential of the transistors Q, , Q2 is approximately zero, and no excitation current flows through the solenoid 3. next,
When a cassette is inserted into the cassette holder 11 and the cassette holder 11 is pushed downward in FIG. As it moves, it moves to the terminal A side. Therefore, the base potential of transistor Q increases, and as diode D becomes conductive, capacitor C is instantly charged, and the base potential of transistor Q2 also increases. Therefore, the base potentials of the transistors Q, Q2 are substantially equal, and no excitation current flows through the solenoid 3 as described above. Therefore, cassette holder 1
1 is locked by the locking mechanism 12 without being subjected to damper action by the solenoid 3 and flange 4.
Next, when ejecting the cassette holder 11, by releasing the lock by the locking mechanism 12, the cassette holder 11 is moved around the shaft 14 by the spring 1''.
Since the slider 2 rapidly rotates counterclockwise due to the spring force, the slider 2 is rapidly moved in the direction of the terminal C along with this rotation.

As a result, as mentioned above, the base potential of the transistor Q rapidly decreases compared to the base potential of the transistor Q2, so that the transistor Q2 is almost turned on.
Excitation current flows through the solenoid 3. As a result, the plunger 4 is attracted and exerts a damper effect on the cassette holder 11. For this reason, the cassette holder 11
It is possible to prevent a phenomenon in which vibration occurs due to sudden rotation of the cylinder. Since the excitation current level during ejection gradually decreases, the attraction force of the solenoid 3 gradually decreases, and the cassette holder 11 is gradually rotated counterclockwise in FIG. 3. In reality, the plunger 4 is attracted while vibrating at a period determined by the inertia caused by the attraction of the solenoid 3 and the spring constant of the spring 5 or 13.

Therefore, in order to quickly attenuate and absorb the vibrations of the plunger 4, the circuit shown in the first diagram is provided with a series circuit consisting of a resistor R3 and a capacitor C2 as a negative feedback circuit. The gain is decreasing. Furthermore, in the circuit shown in FIG.
If the voltage across the solenoid 3 does not become zero due to variations in the transistors even if the base voltages of , Q2 are kept at the same potential, the voltage across the solenoid 3 cannot be reduced to zero, for example, through a constant voltage diode in the opposite direction from the connection point between the resistor R and the cathode of the diode The base potential of the transistor Q2 may be made lower than the base potential of the transistor Q in advance by connecting the capacitor C to the connection point between the capacitor C and the base of the transistor Q2.

In this case, the transistor Q2 can be reliably turned off in a stable state. Furthermore, the apparatus of the present invention is shown in FIGS. 2 and 3.
It goes without saying that the invention is not limited to the case shown in the figure, and can also be applied to damper mechanisms such as the top cover of the turntable and the door.

As described above, the damper device according to the present invention has a plunger that is attracted in accordance with the excitation current level of the solenoid, and is attracted or withdrawn in accordance with an external force that provides a damper action when the solenoid is not energized. a position voltage generating means for generating a voltage; and a voltage is supplied from the position voltage generating means, and this voltage has a small rise time constant and a fall time constant that is relatively larger than the rise time constant. and an excitation current control means for controlling the excitation current level of the solenoid by the voltage obtained by comparing the output voltages of the position voltage generation means and the time circuit, respectively. Since the excitation current level changes only in response to a change in the output voltage of the position voltage generating means that is smaller than the time constant, the desired damper can be applied in a short time to sudden displacement of the external mechanism warmed by the plunger. Since the plunger is electrically controlled, there is little deterioration over time, and reliability can be improved compared to conventional methods.Also, by controlling the excitation current mentioned above, the strength of the damper can be increased. It has the advantage that the sheath response characteristics can be easily set and adjusted to any value.

[Brief explanation of the drawing]

FIG. 1 is a specific circuit diagram of an embodiment of the main part of the device of the present invention,
Fig. 2 is a plan view of an embodiment of the mechanism in which the device of the present invention is applied to a tension arm of a tape recorder, and Fig. 3 is a schematic diagram of an embodiment of the mechanism in which the device of the present invention is applied to a cassette holder. FIG. 1...Sliding resistor, 3...Solenoid, 4
...Plunger, 7...Tension arm, 1
1...Cassette holder, 12...Lock mechanism. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Position voltage generating means that generates a voltage corresponding to the position of the plunger that is attracted or pulled out in response to an external force that is attracted in accordance with the excitation current level of the solenoid and that provides a damper action when the solenoid is not energized; a time constant circuit that is supplied with voltage from the position voltage generating means and outputs the generated voltage by giving the generated voltage a small rise time constant and a fall time constant that is relatively larger than the rise time constant; The excitation current control means controls the excitation current level of the solenoid by the voltage obtained by comparing the output voltages of the position voltage generation means and the time constant circuit, respectively, and the position voltage is smaller than the falling time constant. A damper device characterized in that the excitation current level is configured to change only in response to a change in the output voltage of the generating means.