JPH0548541B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a video tape recorder (hereinafter referred to as
Regarding magnetic recording and reproducing devices such as (referred to as VTR),
In particular, it relates to a mode switching device. [Technical Background of the Invention] In VTR and audio tape recorders, the mode switching operation of a mode switching mechanism that switches the operating mode of a set can be controlled by a rotating cam that is rotationally driven by a motor. many. [Problems with Background Art] Incidentally, in recent years, as sets have been made smaller and their added value has been improved, the number of modes to be switched and controlled by the rotary cam has increased significantly. As a result, the rotation angle range of the rotary cam assigned to each mode becomes extremely small, and there is no margin for mode switching control. Therefore, when the rotation of the motor is stopped at the rotational position of the cam corresponding to the desired mode, the motor may overrun due to variations in the motor drive voltage, phase shifts in the stop pulse, and changes in mechanical load over time. When this occurs, the cam cannot be stopped at a predetermined position, and the set mode may deviate from the desired mode. [Purpose of the Invention] The present invention has been made to address the above-mentioned circumstances, and is capable of stopping a rotary cam at a desired rotational position with a simple configuration without adding a motor brake circuit or a mechanical brake mechanism. An object of the present invention is to provide a mode switching device for a magnetic recording/reproducing device that can perform the following steps. [Summary of the Invention] The present invention provides a method for controlling the cam surface of a unidirectional rotating cam for mode switching operation control near the end of the cam rotation direction of the rotation angle region assigned to each mode.
A protruding stopper is formed. [Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a plan view showing the overall configuration of one embodiment. Reference numeral 11 is a rotary cam with the fulcrum 12 as the rotation axis, and the upper surface thereof has two cam surfaces 11 and 11.
1, 112 are formed, a third cam surface (not shown) is formed on the lower surface, and a gear surface 113 is further formed on the outer peripheral surface. 13 is a motor, and the rotational torque of this motor 13 is determined by the belt 14 and the gear 1.
The power is transmitted to the rotating cam 11 via a power transmission mechanism consisting of components 5 to 21, etc., and drives the rotary cam 11 to rotate in one direction. A rotary switch 22 detects the rotational position of the rotary cam 11, and its configuration is as shown in the perspective view of FIG. That is, this rotary switch 22 rotates the large gear 222 so that the main gear 221 rotates in synchronization with the rotating cam 11.
The number of teeth of the small gear 223 is set. A contact brush member 224 is attached to the main gear 221, and as the main gear 221 rotates, the contact brush member 224 rotates and slides on a switch pattern formed on a printed circuit board 225. ing. As a result, the rotational position of the rotary cam 11 is output as a code signal _S1 onto the common terminal a and terminals b to e. This code signal _S1 is input to the microcomputer 23 as shown in FIG. When the code input matches the mode designation input _S2 input using a keyboard or the like, the microcomputer 23 applies a motor stop pulse P to the motor drive circuit 24 to stop the motor 13. Here, an example of a mode switching mechanism controlled by the rotating cam 11 will be described with reference to FIG. 26 is a lever that is rotationally driven by the second cam surface 112 in the direction of arrow C←→D, and 27 is a lever that is driven by the third cam surface to rotate in the direction of arrow C←→D. E
This is a slider that is slidably driven in the ←→F direction. The slider 25 drives a tape tension servo mechanism 28, a loading mechanism (not shown), etc., and the lever 26 drives a brake mechanism 31 of the reel stands 29, 30, a drive mechanism 32 of the reel stands 29, 30, etc. The slider 27 drives the pinch roller lock mechanism 34 and the like. Note that 34 is a cylinder equipped with a rotating head. Here, the features of this invention will be explained. FIG. 1 shows the rotary cam 11 and the slider 25 which is slidably driven by the first cam surface 111 of the rotary cam 11. slider 2
5 is engaged with the cam surface 111 via a pin 251. Further, the slider 25 is always urged in the direction of the arrow B shown in the figure by the spring 35, and this pushes the cam 1
1 rotational load. A protruding stopper 36 is formed on the cam surface 111 as appropriate. This stopper 36 is connected to the cam 11 assigned to each operation mode, as shown in FIG.
It is formed near the end of the cam rotation angle direction X in the rotation angle region. In FIG. 6, the horizontal axis shows the rotation angle θ of the cam 11, and the vertical axis shows the shift amount of the slider 25, and the rotation angle range θ _a to θ _b specifies a certain mode, for example, the playback mode. It is a corner area. In the characteristic curve Z shown in FIG. 6, a point P corresponds to the stopper 36. The height of the stopper 36 is such that when the motor 13 is being driven to rotate, the pin 251 can easily overcome it, and the rotational drive is stopped and the motor 1
During the period when pin 3 is rotating due to inertia, pin 2
51 is set to such a value that it cannot overcome the strike 36. Therefore, for some reason, the motor 13 overruns, and the rotational position of the cam 11 falls outside the rotational angle range θ _a of the desired mode.
Even if you try to exceed θ _b , the pin 251 will stop at the stopper 3.
Cam 11 for not being able to overcome 6
A brake is applied to the rotation of the motor to ensure that the desired mode is set. The above description has been made using the first cam surface 111 as a representative, but it goes without saying that the same applies to the second cam surface 112 and the third cam surface. [Effects of the Invention] As described above, according to the present invention, the rotary cam can be reliably stopped at a desired rotational position and a predetermined mode can be set using a simple configuration that only requires a protruding stopper on the cam surface. It is possible to provide a mode switching device for a magnetic recording/reproducing device that can perform the following.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing characteristic parts of an embodiment of the present invention, FIG. 2 is a plan view showing the overall configuration, FIG. 3 is an exploded perspective view of the rotary switch shown in FIG. 2, and FIG. The figure shows the motor control section, Figure 5 is a plan view showing an example of the mode switching mechanism, and Figure 6
The figure is a characteristic diagram for explaining the operation of FIG. 1. DESCRIPTION OF SYMBOLS 11... Rotating cam, 12... Fulcrum, 13... Motor, 22... Rotary switch, 23... Microcomputer, 24... Motor drive circuit, 36... Stopper, 111, 112... Cam surface.

Claims (1)

[Scope of Claims] 1. A rotary cam that is rotationally driven in one direction by a motor and controls a mode switching operation of a mode switching mechanism; and a rotational drive of the rotary cam by the motor according to the rotational position of the rotary cam. A magnetic recording/reproducing device comprising: a motor control means for controlling the operation; and a stopper formed in a projection shape on the cam surface of the rotary cam near the end of the rotational direction of the cam in a rotational angle region assigned to each mode. Device mode switching device.