JPH05288252A - Cam controller - Google Patents

Abstract

PURPOSE:To increase the accuracies of operation and stopping of a cam, enable smooth operation of the cam and enable high-precision cam control with good accuracy of positioning. CONSTITUTION:Rotation of a worm gear 4 is detected by a reflecting body 8 and a light-emitting/receiving element 9 to obtain a cam rotation detection signal finer than the detection signal of a cam switch 7. A controlling voltage output circuit 10 calculates a counted value of the detection signals obtained and converts the counted value into a voltage to be supplied to a motor 1. The supply voltage is turned on or off according to the output of the cam switch 7 and is supplied to the motor 1 to increase the accuracy of positioning of a master cam 6. A voltage applied to the motor 1 is varied for each cam phase so as to prevent resonance and noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam control device,
In particular, the present invention relates to a cam control device suitable for controlling a drive mechanism of a magnetic recording / reproducing device such as a video tape recorder.

[0002]

2. Description of the Related Art A drive mechanism such as a magnetic recording / reproducing apparatus is required to have high positional accuracy. For this reason, control of such a drive mechanism is performed by the master cam. 6 and 7 show a conventional configuration example of a cam control device that performs various controls by operating the master cam 6. Figure 6
Shows the configuration as seen from above the cam control device, and FIG.
Shows the configuration of the cam control device as seen from the side.

The operation of the cam control device shown in FIGS. 6 and 7 will be described. A loading belt 3 is wound around a loading pulley 2 which is press-fitted into a rotating shaft of a loading motor (hereinafter referred to as a motor) 1, and the driving force of the motor 1 is decelerated via the belt 3 and the worm gear 4 is used. Be transmitted to. Worm gear 4, worm wheel 5, and gear 5A provided coaxially with worm wheel 5.
By the outer peripheral gear of the master cam 6, the transmitted driving force is decelerated to drive and rotate the master cam 6. A groove is provided on the master cam 6, and the master cam 6 controls various levers by operating the lever when the master cam 6 rotates.

The operation control of the master cam 6 is performed by the output signal of the cam switch 7 which is coaxially connected to the master cam 6. That is, the rotation operation of the master cam 6 is converted into a signal by the contact operation inside the cam switch 7, and the start / stop of the motor 1 is controlled by this signal. Figure 8
FIG. 7 is an explanatory diagram of an output signal of the cam switch 7. As shown in FIG. 8, the output signal of the cam switch 7 is turned on (O) depending on the rotation angle of the master cam 6.
N), off (OFF), and there is a level difference depending on the rotation phase. The phase of the master cam 6 is detected by the level difference between the output signals. Normally, the voltage applied to the motor 1 is constant, and a start / stop signal is output from the cam switch 7 according to the angle of the master cam 6. This signal starts and stops the motor 1, and the master cam 6
Is positioned.

[0005]

However, as described above, the master cam 6 performs various lever operations. When the lever operation is performed, the load becomes large, and when the lever operation is not performed, the load is increased. Becomes smaller, the load of the master cam 6 changes depending on the angle. Therefore, since the conventional cam control device controls the operation of the master cam only with the detection signals of the cam rotation angle and the rotation phase, there is a problem that the stop accuracy, that is, the positioning accuracy is limited. Further, since the conventional cam control device starts / stops and operates the motor 1 only with the ON / OFF signal of the cam switch 7 output for each relatively coarse rotation angle, the operation of the cam is awkward. It has a problem that it cannot be operated smoothly. The present invention has been made to solve the above-mentioned conventional problems, and improves the accuracy of starting and stopping the cam, and enables smooth operation, thereby achieving high-precision cam control with good positioning accuracy and the like. An object of the present invention is to provide a cam control device capable of performing the same.

[0006]

The present invention has a cam for controlling equipment, a cam switch for detecting the phase of the cam, and a motor for driving the cam via a speed reduction mechanism. A device for controlling a cam operation by controlling a motor based on an output signal of a switch, for detecting an operation of the motor or the speed reduction mechanism and obtaining a cam rotation detection signal finer than a detection signal of the cam switch. The problem is solved by providing a detector and a power supply control circuit for controlling the power supply to the motor based on the detector output signal.

[0007]

In the present invention, the cam control device detects the operation of the motor or the speed reducing mechanism to obtain a detection signal finer than the detection signal of the cam switch. Based on the obtained detection signal, the power supply to the motor (for example, supply voltage) is controlled. Therefore, it becomes possible to freely control the supply of the power source, for example, the voltage to the motor, more finely than the interval between the ON / OFF signals of the cam switch. Therefore, the accuracy of starting / stopping the cam is improved, smooth operation is possible, and highly accurate cam control with good positioning accuracy can be performed.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 are explanatory views of a cam control device according to an embodiment of the present invention, FIG. 1 is a plan explanatory view of the cam control device, and FIG. 2 is a front explanatory view of the control device. In addition,
The same parts as those of the conventional cam control device shown in FIGS. 6 and 7 are designated by the same reference numerals, and the description thereof will be omitted. Figure 1
As shown in FIG. 2, this cam control device is similar to the cam control device shown in FIGS. 6 and 7, and further includes a reflector or a reflector on a part of the worm gear 4 at predetermined intervals. Alternatively, a reflector 8 having a function equivalent to that is provided,
A cam rotation detector including a light emitting element and a light receiving element 9 that reflects light on the reflector 8 and receives the reflected light of the reflector 8 and outputs a rectangular signal according to the rotation of the worm gear 4 is provided. A control voltage output circuit 10 for controlling the output and voltage value of the voltage supplied to the motor based on the output signal of the cam switch 7 and the output signal of the element 9 similar to those provided in the conventional cam control device. It is provided.

FIG. 3 is an explanatory diagram showing the relationship between the output signal of the cam switch 7 and the output signal of the element 9. As shown in FIG. 3, the signal detected by the element 9 from the rotation angle of the reduction mechanism, that is, the worm gear 4, is a rectangular signal smaller than the output signal of the cam switch 7. Cam switch 7
Is a detector for detecting the rotation angle and rotation phase of the master cam 6, but cannot detect the rotation position between ON and OFF. Therefore, the element 9
Outputs the rotation angle of the worm gear 4 as a rectangular signal. The control voltage output circuit 10 counts high and low of the rectangular signal, and the rotational position of the master cam 6 is determined and detected by the counted number.

By increasing / decreasing the count number serving as a reference for this determination based on the forward rotation and reverse rotation signals applied to the motor, the correlation between the rotational position of the master cam 6 and the count number can be obtained. Further, a backlash occurs due to a combination of two gears (worm wheel 5 and a gear coaxially provided on the wheel 5) between the worm gear 4 and the master cam 6, and if the count number remains as it is, an error occurs in the detection phase. Occurs. Therefore, it is necessary to correct this backlash. In the embodiment, this correction is performed as follows. That is, as shown in FIG. 4, when the power to the motor 1 is turned on, the motor 1 is always rotated in the reverse direction up to the starting point A of the cam switch 7 and the master cam 6 is returned. The motor 1 is turned off at the fall of the starting point A. At this time, since the motor 1 continues to rotate by inertia, the master cam 6 moves to the position C. After the motor 1 is completely stopped (for a certain period of time), the counter is set to 0 and the motor 1 is normally rotated. Next, by reading the count number at the position B where the cam switch 7 is high, the correction value due to the gear backlash can be obtained. This correction value is used only when the motor 1 reversely rotates from the previous rotation, and can be corrected by adding this correction value to the count number. For example, in FIG. 4, if the motor 1 is rotated in the reverse direction at the position D (count number n) of the cam switch 7, the worm gear 4 reversely rotates and the count number (n−S) minus the backlash amount (corresponding to the count number S) is subtracted. After counting, the master cam 6 starts reverse rotation. Therefore, if S is added to the display count number, it is possible to determine that the reverse rotation start position D'and the position D are in the same phase, and the correlation between the count number and the cam phase is obtained.

As described above, the position of the master cam 6 is detected by the count number, and the value of the count number is used to freely change the value of the voltage applied to the motor 1, thereby enabling extremely fine operation control. Becomes In order to perform such operation control, the control voltage output circuit 10 has a configuration shown in detail in FIG. 5, and includes a frequency-voltage converter (FV converter) 11 and a comparator 12, It has a voltage output switch 13. The FV converter 11 converts a rectangular wave signal output from the light emitting and receiving element 9 into a numerical value (counter value) by a counter, and converts the counter value into a voltage value applied to the motor 1. Further, as shown in FIG. 3, the output signal of the cam switch 7 changes its voltage level depending on the rotational position (phase) of the master cam 6, so that the comparator 12 compares it with the reference voltage (VREF). The output of the comparator 12 controls ON / OFF of the voltage output switch 13. Therefore, the output voltage converted from the counter value is applied to the motor 1 as the control voltage of the motor 1 via the switch 13. As described above, since the control voltage output circuit 10 outputs the voltage having the voltage value corresponding to the counter value according to the phase of the master cam 6, it is compared with the conventional motor control by the output of the cam switch 6. The motor 1 can be made to perform a delicate operation.

Further, the load of the master cam 6 differs depending on the phase as described above, and when the load increases, resonance easily occurs in each rotating part, which causes noise to occur easily. On the other hand, in the embodiment, the position of the master cam 6 is digitized by the counter value, and
Since the voltage applied to the motor 1 is changed for each phase of the master cam 6, the above resonance can be avoided,
Moreover, the operation of the cam control device can be smoothly performed.

In the above embodiment, the case where the present invention is implemented by the cam control device having the configuration shown in FIGS. 1 and 2 has been described. However, the configuration of the cam control device according to the present invention is as follows.
The present invention can be applied to any cam control device that is not limited to those shown in FIGS. 1 and 2 as long as it is intended to perform various controls by the cam. For example, the motion detecting element of the deceleration mechanism is, in addition to the light emitting and light receiving element 9,
Various pulse generators can be used. or,
In addition to the worm gear, the element 9 may be disposed near the motor shaft so as to detect the rotation of the motor itself. Further, the speed reducing mechanism is not limited to the one including the worm gear and the worm wheel, and can be applied to any other mechanism such as another speed reducing mechanism and a planetary gear reducing mechanism.

[0014]

As described above, according to the present invention, the accuracy of starting / stopping the cam is improved, the smooth operation is possible, and highly accurate cam control with good positioning accuracy can be performed. Further, by changing the voltage applied to the motor for each cam phase, it is possible to reliably prevent the generation of noise due to resonance with the motor even if the cam load changes depending on the cam phase.

[Brief description of drawings]

FIG. 1 is an explanatory plan view of a cam control device according to an embodiment of the present invention.

FIG. 2 is a front explanatory view of a cam control device of the present invention.

FIG. 3 is an explanatory diagram showing a rectangular wave output signal and a cam switch output signal of a light emitting element and a light receiving element of the cam control device of the present invention.

FIG. 4 is an explanatory diagram showing a cam switch output at the time of forward rotation / reverse rotation, for explaining correction for backlash of the cam control device of the present invention.

FIG. 5 is a block diagram showing a detailed configuration of a control voltage output circuit of the cam control device of the present invention.

FIG. 6 is a plan view showing a configuration of a conventional cam control device.

FIG. 7 is a front view showing a configuration of a conventional cam control device.

FIG. 8 is an explanatory diagram of output signals of a cam switch of a conventional cam control device.

[Explanation of symbols]

 1 Motor 2 Loading Pulley 3 Loading Belt 4 Worm Gear 5 Worm Wheel 6 Master Cam 7 Cam Switch 8 Reflector 9 Light-Emitting and Light-Receiving Element 10 Control Voltage Output Circuit 11 Frequency-Voltage (F-V) Converter 12 Comparator 13 Voltage Output Switch

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location G11B 15/665 101 W 7201-5D 15/675 101 Z 9295-5D

Claims (1)

[Claims] 1. A cam for controlling a device, a cam switch for detecting a phase of the cam, and a motor for driving the cam via a speed reduction mechanism. The motor is controlled based on an output signal of the cam switch. A device for controlling the operation of a cam by controlling, a detector for detecting the operation of the motor or the speed reduction mechanism to obtain a cam rotation detection signal finer than the detection signal of the cam switch, and the detector output. And a control voltage output circuit for controlling the power supply to the motor based on the signal.