JPH0447929Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) This invention is a magnetic recording and reproducing device, especially a broadcasting VTR.
This invention relates to a plunger solenoid for pinch roller crimping.

(Prior art and its problems) In a VTR, a pinch roller presses the tape against a capstan shaft during recording and playback, and the rotation of the capstan shaft causes the tape to run at a desired speed.
At this time, the pinch roller is pressed against the capstan shaft with a pressure of several kilograms, and an electromagnetic solenoid is generally used as the power for this. With the pinch roller drive solenoid, the plunger is attracted when the tape starts running, and there is a collision noise between the plunger and the bottom of the plunger sleeve of the solenoid.Especially in broadcast VCRs, the pressure of the pinch roller is strong.
There was a problem that the tape running started and stopped frequently, resulting in frequent loud noises.

As a countermeasure to this problem, a variable orifice is provided at the bottom of the plunger sleeve of the solenoid, and the airtightness between the plunger and the plunger sleeve is increased, so that the plunger and the plunger sleeve function as a doss pot to soften the impact when the plunger is attracted. It was hot. However, this method
The dimensional tolerances required to maintain airtightness between the plunger and the plunger sleeve are strict, and the structure of the variable orifice is complex, making it expensive and lacking in reliability.

Another disadvantage is that if the orifice used as a dart pot is made smaller, the solenoid suction time, that is, the pinch roller operation time becomes longer, and the starting and stopping characteristics of the VTR deteriorate.

As this pinch roller drive solenoid,
There was also a method of using a rotary solenoid, which produced less suction noise, but this had the disadvantage of being complicated and expensive.

(Purpose) In order to improve these drawbacks, this invention installs an air seal and shock-reducing rubber on the plunger of the solenoid, and applies damping immediately before the suction operation to reduce noise without prolonging the operation time. This is what I did.

(Example) An example of the present invention is shown in FIGS. 1 and 2. In Figures 1 and 2, 1 is a capstan shaft, 2 is a tape, 3 is a pinch roller, 4 is a pinch roller shaft, 5 is a pinch roller arm, 6 is an arm shaft, and 7
is the joint, 8 is the compression spring, 9 is the return spring,
10 is an arm push washer, 11 is an arm return washer, 12 is a spring adjustment nut, 13 is a joint guide, 14 is a pin, 15 is a back up washer, 16 is a V ring, 17 is a plunger, 1
8 is a solenoid, 19 is a plunger sleeve,
20 is the bottom surface of the solenoid sleeve, 21 is the coil housing, and 22 is the V-ring lip portion.

Fig. 1 is a plan view including a cross section of the solenoid-related portion with the pinch roller detached from the capstan, and Fig. 2 is a cross-sectional view of the solenoid-related portion with the pinch roller pressed against the capstan. FIG.

FIG. 1 shows the case where the solenoid 18 is not energized, but in this case, the repulsive force of the compressed return spring 9 causes the joint guide 13 fixed to the tape running board (not shown) and the arm return A force acts to widen the spacing between washers 11.
Then, the arm return washer 11 pushes the pinch roller arm 5, and the pinch roller arm 5 rotates clockwise around an arm shaft 6 fixed to the tape running board, thereby separating the pinch roller 3 from the capstan 1. At this time, the pinch roller arm 5 pushes the arm push washer 10 and moves the joint 7 to the left via the compression spring 8, which is stronger than the return spring 9, and the spring adjustment nut 12. The joint 7 pulls out the plunger 17 from the solenoid 18 via the pin 14, resulting in the state shown in FIG.

When the solenoid 18 is energized from this state, the plunger 17 pulls the joint 7 to the right via the pin 14, and the joint 7 is connected to the spring adjustment nut 12,
The pinch roller arm 5 is rotated counterclockwise via the compression spring 8 and the arm push washer 10 to press the pinch roller 3 against the capstan shaft 1. Since the plunger 17 moves a little further to the right after the pinch roller 3 contacts the capstan shaft 1,
The compression spring 8 is compressed via the pin 14, the joint 7, and the spring adjustment nut 12, and the pinch roller 3 is pressed against the capstan shaft 1 with a specified pressure by this repulsive force. A rubber V ring 1 is fitted into the plunger 17 when it is sucked.
6, as the plunger 17 moves, the lip portion 21 first comes into contact with the front surface of the coil housing 21 holding the solenoid 18. In this state, the plunger 17 and the plunger sleeve 19
A sealed space is created in front of the V ring 16 and the coil housing 21, and as the coil is attracted further, the air trapped in the sealed space is compressed, generating a force in the direction opposite to the direction of attraction. In addition, the lip portion 21
is pressed against the front surface of the solenoid 18, that is, the front surface of the coil housing 21, and deforms as shown in FIGS. 1 and 2. As the V-ring 16 is deformed as shown in FIG.

Therefore, the plunger 17 and the plunger sleeve 1
The speed at which the bottom surface 20 of 9 collides is considerably reduced, and the collision sound is also reduced. Furthermore, since this collision sound also occurs in a closed space, the sound transmitted to the outside is extremely small.

(Effects) As described above, according to the present invention, by simply attaching an air seal rubber such as a simple V-ring to the plunger, the operating noise of the solenoid can be made extremely small, and the damping effect is achieved at the end of the solenoid's suction operation. Since it only has the following characteristics, there is little increase in operating time, and the performance improvement and economic effect are significant.

[Brief explanation of the drawing]

1 and 2 are plan views including a partial cross section of the pinch roller solenoid of the present invention. 1... Capstan, 3... Pinch roller, 5
...Pinch roller arm, 16...V ring, 1
7... Plunger, 18... Solenoid.

Claims (1)

[Scope of utility model registration request] In a plunger solenoid that drives a pinch roller that is pressed against a capstan, and is equipped with a plunger, a plunger sleeve, and a coil housing that holds the solenoid, a rubber-made air seal and shock absorbing rubber is installed in the front part of the plunger. A plunger solenoid for a pinch roller, characterized in that a V-ring is attached so that a space surrounded by the V-ring, the front surface of the coil housing, the plunger, and the plunger sleeve is sealed when the plunger is suctioned.