JPH0334137B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a variable speed playback device, and in particular, in a playback device such as a VTR, it is possible to start variable speed playback in which a magnetic tape is played back at a tape running speed different from that at the time of recording. The present invention relates to a variable speed playback device that detects operations such as dial rotation and automatically performs operations.

PRIOR TECHNOLOGY As is well known, in a helical scan VTR, a recorded magnetic tape is played back at a tape running speed different from that at the time of recording (including when the running speed is zero). Variable speed playback is possible to obtain images with different movements. The playback speed of this variable speed playback ranges from slower than the tape running speed during recording to about 10 times faster, and the playback direction is the same direction as the tape running speed during recording. direction)
and a direction opposite to that during recording (reverse direction).

Conventionally, during this variable-speed playback, a search dial 1 as shown in Fig. 1 is rotated, and variable-speed playback in an arbitrary playback direction and playback speed is determined by the rotation angle. By standing still at a certain position, still motion playback was performed in which the magnetic tape running speed was zero.

Problems that the invention aims to solve However, in the past, pressing play button 2
After setting the VTR to play mode, in order to shift from this play mode to variable speed playback mode (search mode), first press search button 3, then turn search dial 1 to the position where the desired playback speed and playback direction are obtained. It was necessary to operate. That is, conventionally, in order to shift from another mode to the variable speed playback mode, the search button 3 had to be pressed once, which caused a problem of poor operability. Furthermore, in the past, the search dial was a multi-contact rotary switch, which was configured to change the playback speed step by step, resulting in malfunctions due to switch chattering, etc.
In addition, a custom-made and complicated switch mechanism is required, and the playback speed can only be changed in steps.

Therefore, the present invention solves the above problems by generating a continuously changing voltage by operating an operating member such as a search dial, and automatically setting the variable speed playback mode by detecting the fluctuation of this voltage. The purpose of the present invention is to provide a variable speed playback device that solves the problem.

Means for Solving the Problems The present invention provides an operating member that outputs a voltage that continuously changes depending on its moving position, and a minimum voltage when the input voltage supplied from the operating member is a midpoint voltage. a voltage characteristic conversion circuit that outputs an output voltage and a reproduction direction instruction signal according to an input/output characteristic that outputs a voltage other than the minimum voltage when the input voltage is other than the midpoint voltage; a voltage change detection circuit that detects the presence or absence of a change in the output voltage of the voltage characteristic conversion circuit that occurs in response to a change in the moving position and outputs a speed change mode signal; and a reproduction speed instruction that corresponds to the output voltage of the voltage characteristic conversion circuit. and a circuit for outputting a signal, and is configured to run the magnetic tape at a speed according to the speed instruction signal and in a direction according to the reproduction direction instruction signal when the variable speed reproduction mode signal is supplied. , one embodiment thereof will be described below with reference to FIGS. 2 to 5.

Embodiment FIG. 2 is an external perspective view of an embodiment of the device of the present invention.
FIG. 3 shows a partially enlarged front view of the main part of FIG. 2.
In both figures, a search dial 5 is provided on the right side of the front panel surface of the variable speed playback device 4. Further, a cassette insertion/removal opening/closing door 6 is provided at the upper center of the front panel surface. As shown in FIG. 3, this opening/closing door 6 consists of an upper opening/closing door 6a and a lower opening/closing door 6b.The cassette is moved in the direction of arrow _X1 in FIG. By pushing the opening/closing doors 6a and 6b to the inner part of the device 4, the opening/closing doors 6a and 6b are respectively rotated toward the inside of the device 4 and opened.
Note that when the cassette is loaded into the device 4,
The upper opening/closing door 6a is rotated in the original direction to close the cassette insertion/removal opening. By pressing the eject button, the upper opening/closing door 6a is rotated to open the cassette insertion/removal port. Further, 7 is a power switch.

As shown in FIG. 3, the search dial 5 is provided with a scale 5a that indicates its rest position, and on the casing surface of the device 4, along the circumference of the search dial 5, there are scales indicating playback speed values, etc. is provided. ``STILL'' at the top center indicates the playback speed position scale during still motion playback, in which playback is performed by stopping the running of the magnetic tape. Also, as the search dial 5 is rotated clockwise from this scale "STILL", the playback speed (tape running speed) increases, and the tape running direction becomes "FWD".
As shown, a scale is provided to indicate the forward direction. Also, as the search dial 5 is rotated counterclockwise from the "STILL" scale, the playback speed increases, and "REV" indicates that the tape running direction is the opposite direction to that during recording. A scale is provided.

Furthermore, among the above scales, "X1" is 1 in the forward direction.
This indicates the double speed playback position, and "X-1" indicates the single speed playback position in the reverse direction. Forward 1x speed playback position “X”
When the scale 5a of the search dial 5 matches "1", playback is performed at the same tape running direction and tape running speed as during normal playback performed by pressing the normal playback button 8. However, during normal playback, the servo circuit is It operates in phase synchronization with the synchronization signal in the input video signal, but the difference is that during the forward 1x speed playback described above, servo is applied using the output signal of the built-in oscillator as a reference signal.

Next, to explain the signal system of the present invention, the fourth
The figure shows a circuit diagram of an embodiment of the device of the present invention.
In the figure, the search dial 5 is a variable resistor whose resistance value is varied according to its rotation angle, and one end is a resistor.
It is connected to the input terminal of the power supply voltage +12V via R ₁ , and the other end is grounded via resistor R ₂ . Therefore, when the search dial 5 is rotated, the resistance value changes according to the rotation angle, and a voltage that continuously changes depending on the rotation angle is extracted from the slider.
The output voltage of the search dial 5 is supplied to a voltage characteristic conversion circuit 9, where it is given an input/output characteristic as shown in FIG. That is, when the scale 5a of the search dial 5 is brought to a standstill at the position indicated by "STILL" in FIG. 3, for example,
A voltage Vs at the midpoint of the variable range is taken out from the search dial 5, and this voltage Vs is converted by the voltage characteristic conversion circuit 9 to the minimum voltage shown as Vs ₀ in FIG. 5 and output. The input/output characteristics shown in Figure 5 are:
The input voltage from search dial 5 is the midpoint voltage Vs
When the minimum value Vs is ₀ , the output voltage increases as the input voltage becomes greater than Vs, and the output voltage increases as the input voltage becomes smaller than Vs.

Further, when the input voltage is Vs, the voltage characteristic conversion circuit 9 outputs a low level signal to both output terminals 10 and 11, and when the input voltage is higher than Vs, the search dial 5 is lower than the scale "STILL". outputs a high level forward direction designation signal to the output terminal 10, assuming that the rotation direction is also rotated clockwise;
On the other hand, when the input voltage is smaller than Vs, the search dial 5 is rotated counterclockwise and the scale 5a is detected to be on the left side of the "STILL" position, and a high level reverse direction designation signal is output. Output terminal 11
Output to. Note that the other terminal of the terminal 10 or 11 to which the above-mentioned designation signal is output is at a low level.

The voltage characteristics shown in FIG. 5 are imparted by the voltage characteristic conversion circuit 9 and the extracted voltage is divided into three branches, one of which is connected to an NPN transistor _Q1 via a resistor _R3 .
after being delayed by an integrator circuit consisting of resistor R ₄ and capacitor C ₁
The signal is supplied to the base of the NPN transistor _Q2 , and the remaining one is outputted as a reproduction speed instruction signal to the output terminal 15 through the operational amplifier 14 constituting a voltage follower. The emitter of the transistor Q ₁ is grounded through a resistor R ₅ and connected to the non-inverting input terminal of the operational amplifier 12, and is also connected to the inverting input terminal of the operational amplifier 13 through a circuit consisting of a diode D ₁ and a resistor R ₇ . It is connected. on the other hand,
The emitter of the transistor Q ₂ is grounded via a resistor R ₆ , and connected to the inverting input terminal of the operational amplifier 12 via a circuit consisting of a diode D ₂ and a resistor R ₈ , and is further connected to the non-inverting input terminal of the operational amplifier 13 . connected directly to.

Therefore, transistors Q ₁ and Q ₂ are emitter followers, respectively, and operational amplifiers 12 and 13
acts as a comparator. Operational amplifier 1
The output terminals 2 and 13 are connected to diodes D ₃ and D ₄ respectively.
The anodes of the diodes D ₃ and D ₄ are connected in common and connected to the input terminal of the power supply voltage 12V through the resistor R ₉ , while the anodes of the diodes D 3 and D 4 are connected to the cathode of the Zener diode D ₅ . . Zener diode D ₅ is operational amplifier 12,
If 13 is used with a single power supply, the low level will not be 0V, so this is provided to compensate for this. The anode of the Zener diode D ₅ is a resistor
The series-to-parallel converter 16 is grounded via R ₁₀ while the
It is connected to the.

With the above circuit configuration, the operational amplifier 12 outputs the emitter output voltage of the transistor Q ₁ and the output voltage from the emitter of the transistor Q ₂ after a fixed time delay corresponding to the time constant determined by the product of the values of the resistor R ₄ and the capacitor C ₁ . The level of the voltage dropped by the forward drop voltage of the diode D ₂ is compared with the voltage dropped by the forward drop voltage of the diode D 2 .
The voltage obtained by subtracting the forward drop voltage of diode D ₁ from the emitter output voltage of Q ₁ and the delayed voltage taken out from the emitter of transistor Q ₂ are compared in level. Therefore, search dial 5
When Q 1 and Q 2 are stationary, there is no change in their output voltage, and the emitter output voltages of transistors Q ₁ and Q ₂ are approximately equal to each other.
Operational amplifiers 12 and 13 are operated by the voltage drop of D ₁ and D ₂
Since both inverting inputs of the operational amplifiers 12 and 13 are set to be small, both output signals of the operational amplifiers 12 and 13 are at a high level. Therefore, when the search dial 5 is stationary, the diodes D ₃ and D ₄ are both reverse biased and off, and the output of the serial/parallel converter 16 is also a constant value and does not change.

On the other hand, when the user rotates the search dial 5 to the desired playback direction and playback speed scale position, the output voltage of the search dial 5 changes from the value at the previous scale position to the desired playback direction and playback speed scale position. Changes to position value. The voltage after this change is output from the voltage characteristic conversion circuit 9 to the output terminal 10 or 11 as a playback direction instruction signal depending on the voltage value, and the characteristics shown in FIG. The signal is outputted to the output terminal 15 via the operational amplifier 14 as a signal. Also, at the same time,
The voltage corresponding to the _new scale position of the search dial 5 extracted from the voltage characteristic conversion circuit ₉ with the characteristics shown in FIG.
After being delayed for a certain period of time by an integrating circuit consisting of _C1 , it is supplied to the base of transistor _Q2 .

The voltage input to the base of the transistor Q ₁ is extracted from its emitter after impedance conversion and is supplied to the non-inverting input terminal of the operational amplifier 12, while being supplied to the operational amplifier 13 through a circuit consisting of a diode D ₁ and a resistor R ₇ . Supplied to the inverting input terminal. On the other hand, the delayed voltage input to the base of the transistor Q ₂ is extracted from its emitter after being subjected to impedance conversion, and is supplied to the non-inverting input terminal of the operational amplifier ₁₃ .
and operational amplifier 1 through a circuit consisting of resistor R ₈
It is supplied to the inverting input terminal of No. 2. Therefore, each input voltage at the non-inverting input terminal of the operational amplifier 12 and the inverting input terminal of the operational amplifier 13 immediately changes from its previous value by a new operation of the search dial 5, and the input voltage at the inverting input terminal of the operational amplifier 12 immediately changes from its previous value. The input voltages at the non-inverting input terminals of the operational amplifier 13 change from their previous values at a time delayed by a predetermined time by the integrating circuit from the time when the search dial 5 is newly operated.

As a result, if the output voltage of the voltage characteristic conversion circuit 5 becomes higher than the previous value due to a new rotation operation of the search dial 5, for example, the operational amplifier 13 A negative pulse that is at a low level for a certain delay time is extracted. On the other hand, when the output voltage of the voltage characteristic conversion circuit 5 changes to a smaller value than the previous value, a negative polarity pulse similar to the above is taken out from the operational amplifier 12.

Therefore, when the search dial 5 is rotated anew, the values of both the output voltages of the search dial 5 and the voltage characteristic conversion circuit 9 change, and as a result, the negative electrode remains at a low level for a certain period of time from the time the search dial 5 is operated. A signal pulse is output from either one of the operational amplifiers 12 and 13. This negative pulse is supplied to the serial-to-parallel converter 16 through a diode D ₃ or D ₄ and further through a circuit consisting of a Zener diode D ₅ and a resistor R ₁₀ . As a result, the serial-to-parallel converter 16 converts the input negative polarity pulses into serial-to-parallel signals and then outputs the converted signals to, for example, a microcomputer (not shown) as a variable speed reproduction mode (search mode) signal via the output terminal 17.

When the microcomputer receives this variable speed playback mode signal, it operates in the same way as when the search button is pressed until another mode signal is supplied.
Rotate a capstan motor (not shown) at a speed according to a reproduction speed instruction signal from output terminal 15, and rotate the capstan motor in a direction according to an output instruction signal from output terminal 10 or 11. At the same time, the reproducing head is controlled to be switched from the rotary head for normal reproduction to the rotary head for variable speed reproduction. Since such control operation is well known, detailed explanation thereof will be omitted.

Therefore, if the device is in the normal playback mode immediately before a new rotation operation of the search dial 5 is performed, the search dial 5 will be automatically changed by simply rotating the search dial 5 a new time without pressing the search button. It is possible to shift to a variable speed playback mode with a newly specified direction and speed. Also,
If the device is in the variable speed playback mode immediately before the search dial 5 is rotated anew, the device enters the variable speed playback mode in the newly designated direction and speed.

Note that the present invention is not limited to the above-described embodiments, and for example, a variable resistor that linearly moves the scale position may be used instead of the search dial. Any operating member may be used as long as the output voltage changes continuously according to the moving position (low resistance value) by the moving operation.

Effects As described above, according to the present invention, a voltage that continuously changes according to the moving position of the operating member is generated and output as a signal indicating the playback direction and speed, and the change in the output voltage is detected and automatically activated. Since the variable-speed playback mode is set to the variable-speed playback mode, it is no longer necessary to press the search button when switching from another mode to the variable-speed playback mode, which was required in the past.This improves operability. Since the component is a variable resistor whose output voltage changes continuously, there are no switch contacts like in the past, preventing malfunctions due to switch chatter, etc., and the operating component is a single variable resistor. Because it's done,
It can be constructed at low cost without the need for custom-made switches such as multi-contact rotary switches or complicated mechanisms, and has features such as being able to ensure reliability because the number of mechanical parts such as switches can be reduced. It is something.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of the panel surface of the main part of a conventional device, Fig. 2 is a perspective view showing the external appearance of an embodiment of the device of the present invention, and Fig. 3 is an embodiment of the main part of Fig. 2. FIG. 4 is a circuit system diagram showing one embodiment of the device of the present invention, and FIG. 5 is a diagram showing an example of input/output characteristics of main parts in the circuit system shown in FIG. 4. 1, 5...Search dial, 6...Cassette insertion/removal opening/closing door, 9...Voltage characteristic conversion circuit, 10...
... Forward direction designation signal output terminal, 11 ... Reverse direction designation signal output terminal, 12, 13 ... Operational amplifier for comparator, 14 ... Operational amplifier for voltage follower, 15 ... Playback speed instruction signal output terminal, 17
...Search mode signal output terminal.

Claims (1)

[Scope of Claims] 1. A variable speed playback device that plays back previously recorded signals on a magnetic tape at a tape running speed different from that during recording, comprising: an operating member that outputs a voltage that continuously changes according to its moving position; Output voltage according to input/output characteristics that outputs a minimum voltage when the input voltage supplied from the operating member is a midpoint voltage, and outputs a voltage other than the minimum voltage when the input voltage is other than the midpoint voltage. and a voltage characteristic conversion circuit that outputs a reproduction direction instruction signal; and a voltage that detects the presence or absence of a change in the output voltage of the voltage characteristic conversion circuit that occurs in response to a change in the moving position of the operating member and outputs a variable speed reproduction mode signal. a change detection circuit; and a circuit that outputs a playback speed instruction signal according to the output voltage of the voltage characteristic conversion circuit, and when the variable speed playback mode signal is supplied, the speed and the playback according to the speed instruction signal are supplied. A variable speed playback device characterized in that it is configured to run a magnetic tape in a direction according to a direction signal.