JPS5946404B2 - plunger solenoid device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plunger solenoid device, which allows the plunger to be suctioned slowly over a desired period of time, thereby preventing noise caused by instantaneous suction, and preventing sudden suction. It is an object of the present invention to provide a plunger solenoid device that can be applied to loads where it is inappropriate to be operated.

Plunger solenoid devices conventionally used in tape recorders have an on/off operation, which creates an unreasonable load on the plunger solenoid device.

For example, when a plunger solenoid device is used to press the pinch roller against the capstan, the impact force generated when the pinch roller and the capstan are pressed during play mode is considerable and can shorten the life of the capstan bearing. This was one of the causes. In addition, since the plunger is instantaneously attracted, noise (mechanical click sound) is generated, and the pinch roller is not stopped instantaneously by braking, resulting in slight vibration (overshoot), which is undesirable. For this reason,
Previously, mechanical click noise and pinch roller overshoot had to be reduced using mechanical air dampers. This makes conventional tape recorders somewhat mechanically complex, and when a highly viscous material is used to obtain the desired shock-absorbing properties, the duration of the damper's action is longer and shorter than the time required to prevent the shock. The disadvantage was that the desired damper characteristics could not be obtained. The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

FIG. 1 is a plan view of the mechanism in stop mode of an embodiment of the device of the present invention applied to a cassette tape recorder, FIG. 2 is a plan view of the main parts of the mechanism in play mode shown in FIG. The figure is a specific circuit diagram of one embodiment of the main part of the device of the present invention, and the same parts in each figure are given the same reference numerals. In FIGS. 1 and 2, 1 is a sliding resistor whose resistance value can be varied by changing the position of the slider 2, and 3 is a spring 5 that attracts the plunger 4 when energized and returns when not energized.
This is a solenoid by which the plunger 4 is pulled out.
The slider 2 and the tip of the plunger 4 are connected via a connecting piece 6 so that they can be displaced integrally. Further, a pin 7 is installed at the tip of the plunger 4, and each of the pins 7 has an arm 8, which has an elongated hole at the tip.
9 are engaged with each other. The arms 8, 9 are provided with pinch rollers 10, 11 at the ends opposite to the elongated holes, and are configured to be rotatable about shafts 8a, 9a. In addition, in FIG. 3, the sliding resistor 1 has a structure in which a slider 2 slides between terminals A and C, and the slider 2 is connected to the terminal B and the base of an NPN transistor Q1 via a resistor. It is connected to the.

The NPN transistor Q2 constitutes an unbalanced differential amplifier together with the transistor Q1, and the collector of the transistor Q2 is connected to the base of the PNP transistor Q2 via a resistor. Further, the base of the transistor Q2 is connected to a positive DC power supply voltage input terminal via a resistor R1, and is grounded via a capacitor C1, and is also connected to a contact a of a changeover switch SW. This changeover switch SW has contacts A and b, the contact b is a blank contact, the movable contact piece is grounded, and is configured to be switched in conjunction with the operation switch of the tape recorder. Further, a resistor R2 is connected in parallel to the capacitor C1. The collector of the transistor Q3 is a resistor R3 and a capacitor C2.
is connected in series to the base of the transistor Q1, and is connected to the base of the NPN transistor Q4, and is further grounded through a resistor R4. A solenoid 3 is connected between the emitter of the transistor Q4 and ground. First, the operation of the apparatus of the present invention in the stop mode will be explained with reference to FIGS. 1 and 3. The changeover switch SW is closed and connected to the contact a side.

As a result, the capacitor C1 and the resistor R2 are each short-circuited to ground, and the base potential of the transistor Q2 becomes the ground level. At this time, the slider 2 is located on the terminal C side. Since transistor Q2 is off, transistor Q
3, Q4 is also off. Therefore, the collector current of the transistor Q4, that is, the excitation current of the solenoid 3 does not flow.
As shown in FIG. 1, the plunger 4 is pulled out by the spring force of the return spring 5. As a result, pinch roller 1
0 and 11 are located within the force set 12, and the magnetic tape 13 is not brought into sliding contact with the heads 14 and 15, but remains housed within the force set 12 as shown in FIG. Next, the operation of the present invention apparatus in the play mode will be explained with reference to FIGS. 2 and 3. In the play mode, the changeover switch SW is switched to the contact b side. As a result, the DC power supply voltage is applied to the base of the transistor Q2 via the integrating circuit made up of the resistors Rl and R2 and the capacitor C1. Therefore, the base potential of the transistor Q2 is the resistor Rl,
According to the charging time constant of capacitor C1 (this value can be arbitrarily set) determined by the respective values of R2 and capacitor C1, the voltage gradually increases toward the power supply voltage value divided by resistors R1 and R2. Therefore, the collector currents of transistors Q2 and Q3 also gradually rise in accordance with the charging time constant. As a result, the excitation current of the solenoid 3 gradually increases in accordance with the charging time constant, the plunger 4 is gradually attracted accordingly, and the slider 2 gradually moves toward the terminal A side. Therefore, the base potential of transistor Q1 also gradually increases. The plunger 4 is slowly attracted by the excitation current flowing through the solenoid 3, and the pinch rollers 10, 11
When pressed against the carburetor stans 18 and 19, the plunger 4
Suction operation stops.

In this state, the base potential of the transistor Q2 is higher than the base potential of the transistor Q, and a constant excitation current flows through the solenoid 3. At this time, even if the slider 2 reaches the terminal A, the base potential of the transistor Q is fixed by the Zener diode connected between the terminal A and the DC power supply +DC, and the base potential of the transistor Q1 is fixed. does not become higher than the base potential of transistor Q2.

This means that the base potential of transistor Q1 is
If the base potential of transistor Q2 becomes higher than the base potential of transistor Q2, the voltage between the base and emitter of transistor Q2 becomes lower than the voltage between the base and emitter of transistor Q1, and as a result, transistors Q3 and Q4 are turned off and solenoid 3 is attracted. This is because the state cannot be maintained. However, the resistance Rl
, R2, and the resistor connected between the terminal B and the base of the transistor Q1, the Zener diode can be omitted by appropriately selecting the respective constants.

Further, due to the suction operation of the plunger 4, the arms 8 and 9 are rotated in a predetermined direction about the shafts 8a and 9a, respectively, as shown in FIG. is extracted from the force set 12,
It is brought into sliding contact with the heads 14 and 15.

In this way, the plunger 4 is slowly attracted, so there is no mechanical clicking sound or overshoot of the pinch roller. In addition, the plunger 4 actually uses inertia due to the suction of the solenoid 3 and the spring 5.
It is gradually attracted while vibrating with a period determined by the spring constant of.

Therefore, in this embodiment, a series circuit consisting of a resistor R3 and a capacitor C2 shown in FIG. This is done to prevent oscillation. In this case, the frequency characteristics of the negative feedback circuit are
It is selectively set as appropriate depending on the magnitude of the vibration period. In the above embodiment, the case where the device of the present invention is applied to draw out the magnetic tape 13 in the force set 12 has been explained, but the device of the present invention is not limited to this, and can be applied to other methods such as ejecting the force set holder. It can also be applied to various uses. Further, the reference variable voltage applied to the base of the transistor Q2 is obtained by an integrating circuit in the above embodiment. However, it may be obtained by other methods, and it does not matter whether the change is analog or digital. As described above, the plunger solenoid device according to the present invention includes a position voltage generating means that generates a voltage corresponding to the attraction position of the plunger that is attracted in accordance with the level of the excitation current of the solenoid, and a position voltage generating means that generates a voltage that corresponds to the attraction position of the plunger, regardless of the position of the plunger. The solenoid is controlled by the voltage obtained by comparing the voltages from the position voltage generation means and the voltage generation means, which generate a voltage whose level gradually changes from the start of the suction operation of the plunger, and the position voltage generation means. excitation current control means for controlling the excitation current level to gradually change; a return spring for the plunger; and a frequency of vibration determined by the inertia caused by attraction of the solenoid and the spring constant of the return spring for the plunger. The negative feedback means has a frequency characteristic that acts to lower the gain by the excitation current control means and negatively feeds back the voltage obtained by comparison by the excitation current control means to the output side of the position voltage generation means. The suction can be performed slowly in response to changes in the level of the changing voltage, thereby preventing the generation of noise caused by instantaneous suction, and the time from the start of suction to the completion of suction is controlled by the level of the changing voltage. It can be obtained arbitrarily by setting the rate of change, and it can be applied to loads where sudden operation is inappropriate, such as pinch rollers, and it can eliminate the need for conventionally used mechanical air dampers. The damper action can be exerted for a sufficient period of time to prevent impact, and since the plunger is electrically controlled, it is more reliable and less prone to aging over time than when mechanically controlled. can reduce the gain of the entire circuit, thereby allowing the plunger to be suctioned slowly in a stable state without causing it to vibrate at a period determined by the inertia of the solenoid's suction and the spring constant of the spring. It is something that you have.

[Brief explanation of the drawing]

1 is a plan view of the mechanism in the stop mode of an embodiment of the device of the present invention applied to a force setting type tape recorder; FIG. 2 is a plan view of the main parts of the mechanism in the play mode of FIG. 1; The figure is a specific circuit diagram of an embodiment of the main part of the device of the present invention. 1...Sliding resistor, 3...Solenoid, 4...Plunger, 5...Return spring, 12...Force setting , 13...
・Magnetic table.

Claims (1)

[Claims] 1. A position voltage generating means that generates a voltage corresponding to the attraction position of the plunger that is attracted in response to the excitation current level of the solenoid, and a voltage that gradually changes in level from the start of the attraction operation of the plunger regardless of the plunger position. A variable voltage generating means that generates a voltage, and an excitation current that controls the excitation current level of the solenoid to be gradually changed by a voltage obtained by comparing both the generated voltages from the position voltage generating means and the variable voltage generating means, respectively. control means;
The excitation current control means has a frequency characteristic that acts to reduce the gain with respect to the frequency of vibration determined by the return spring of the plunger and the spring constant of the return spring of the plunger due to inertia due to attraction of the solenoid. 2. A plunger solenoid device comprising negative feedback means for negatively feeding a voltage obtained by comparison between the two to the output side of said position voltage generating means, and configured to slowly attract said plunger.