JPH0560776A - Rotating-direction detecting apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] Simplification of rotation direction detection device. A forward rotation detection for detecting the level of the second or first signal of the frequency signal generator with respect to the edge of the level of the first or second signal obtained from the frequency signal generator according to the rotation of the rotating body. A circuit, a reverse detection circuit that detects the level of the first or second signal with respect to the edge of the level of the second or first signal, and a holding circuit that holds the detection result of each detection circuit as a digital signal, A forward rotation, a reset circuit for resetting the forward rotation or reverse rotation detection circuit to an initial state after a fixed time from each detection time point of the reverse rotation detection circuit, the forward rotation of the rotating body from the output level of the holding circuit, It is characterized in that the reverse rotation is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a main rotation signal obtained from a frequency generator attached to a rotating body and a sub-rotation signal having a phase difference with respect to this signal to determine the rotation direction of the rotating body. The present invention relates to a rotation direction detecting device for discriminating, and is particularly used for detecting the traveling direction of a tape of a VTR (video tape recorder).

[0002]

2. Description of the Related Art With respect to the traveling direction of a tape of a conventional VTR, the traveling direction may be determined by detecting the rotation direction of a capstan motor that controls the traveling of the tape. For this purpose, for example, a first signal (rotation signal) CFGA obtained from the frequency signal generator of the capstan motor and a second signal (rotation signal) CFGB having a phase difference with respect to this signal CFGA are used. To use. The relationship of these signals during normal rotation is shown in FIG. 4, and the relationship during reverse rotation is shown in FIG.

In the conventional rotation discriminating method using these signals, the signals CFGA and CFGB are respectively inputted to the microcomputer, and the first edge 11 of the signal CFGA,
The level of the signal CFGB at 21 and the second edge 12 and 22 and the level of the signal CFGA at the third edge 13 and 23 and the fourth edge 14 and 24 of the signal CFGB are
There is a method of detecting that the polarities are inverted between the normal rotation of FIG. 4 and the reverse rotation of FIG. 5 by software. However, as described above, when a microcomputer is used to detect the rotation direction, it is necessary to develop dedicated software.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rotation direction detecting device which can detect the rotation direction of a rotating body such as a motor with high accuracy without using software.

[0005]

According to the present invention, the second or the second of the frequency signal generators corresponding to the edge of the level of the first or second signal obtained from the frequency signal generator in response to the rotation of the rotating body is provided. A forward rotation detection circuit that detects the level of the first signal, a reverse rotation detection circuit that detects the level of the first or second signal with respect to the edge of the level of the second or first signal, and a detection circuit of each of the detection circuits. A holding circuit that holds the detection result as a digital signal; and a reset circuit that resets the normal rotation or reverse rotation detection circuit to an initial state after a fixed time from the detection points of the normal rotation or reverse rotation detection circuit, respectively. It is characterized in that normal rotation and reverse rotation of the rotating body are detected from the output level of the circuit. That is, according to the present invention, the rotation direction of the rotating body is detected using each of the circuits described above, and can be detected without using software as in the conventional case.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of the same embodiment, and FIG. 2 is a timing chart showing the operation of this circuit. Signal CFGA here
And CFGB are the main rotation signal obtained from the frequency signal generator attached to the rotating body and the sub-rotation signal having a phase difference from this signal, which are the same as those shown in FIGS. 4 and 5. The D-type flip-flops 3A to 3D receive the signal CFG.
A normal rotation detection circuit 1 for detecting the normal rotation of the rotating body is constituted by A and CFGB. The D-type flip-flops 3E to 3H form a reverse rotation detection circuit 2 that performs the same reverse rotation detection. I1, I2
Is an inverter, and the flip-flops 3A to 3H read the corresponding data input D at the rising edge of the clock input CK. Further, the node N1 receives the signal CF.
At the rising edge of GA, it becomes "H" (high) level,
The node N2 is "H" at the falling edge of the signal CFGA.
Level, the node N3 becomes “H” level at the rising edge of the signal CFGB, and the node N4 becomes the signal CFG.
At the falling edge of B, it becomes "H" level.

The NOR circuit 31 includes flip-flops 3A ...
The NOR of the outputs Q of the 3D is obtained, and the NOR 32 of the outputs Q of the flip-flops 3E to 3H is obtained. The RS flip-flop 33 includes NOR circuits 31 and 32.
Is used as the first and second inputs, and the output Qo is transmitted. Reference numerals 33a and 33b are NAND circuits (negative logical product circuits). The reset circuit 34 outputs a reset pulse after a predetermined time has elapsed since the output of the NOR circuit 31 or 32 was input.

In FIG. 1 and FIG. 2, the forward rotation detecting operation is as follows. When the signal CFGA rises at the edge 41a, the D-type flip-flop 3A reads the data D (in this case, "H"), the output of the NOR circuit 31 becomes "L" (low) level, and therefore the output of the RS flip-flop 33. Qo is uniquely "H". After that, when a fixed time 45 elapses, a reset pulse 46 is output from the reset circuit 34, and the flip-flops 3A to 3A.
Since D is reset and these outputs Q all become "L", the output of the NOR circuit 31 returns to "H", that is, the initial state, but the NAND circuit 33b of the flip-flop 33 does.
Since the output of the flip-flop is "L", the flip-flop 3
The output Qo of 3 holds "H". After that, CFGA,
The NOR circuit 31 and the reset circuit 3 each time the normal rotation is detected at the edges 43a, 42a, 44a of the CFGB.
The output of No. 4 repeats the operation between the edges 41a and 43a, and the output Qo of the flip-flop 33 holds "H" to hold the normal rotation detection state.

In FIGS. 1 and 2, the reverse rotation detecting operation is as follows. When the signal CFGB rises at the edge 43b, the flip-flop 3G reads the data input D, the output of the NOR circuit 32 becomes "L", and the output of the NAND circuit 33b of the flip-flop 33 becomes "H". The output Qo of the flip-flop 33 becomes "L". When a reset pulse is output from the reset circuit 34 after the elapse of the fixed time 45, the flip-flops 3E to 3E
H is reset, all of these outputs Q become "L", and the output of the NOR circuit 32 returns to "H", that is, the initial state. However, the NAND circuit 3 of the flip-flop 33
When both inputs of 3a are "H", output Q of NAND circuit 33a
o holds “L”. After that, signals CFGA, CFGB
Whenever the reverse rotation is detected at the edges 41b, 44b, 42b of the NOR circuit 32, the outputs of the NOR circuit 32 and the reset circuit 34 repeat the operation between the edges 43b, 41b.
The output Qo of the flip-flop 33 holds "L" and holds the reverse rotation detection state.

According to the above embodiment, the rotation direction can be detected without using software on the microcomputer as in the conventional case. In addition, a plurality of edges (41a to 44a for forward rotation, 41
The detection accuracy is improved by detecting the rotation direction in steps b to 44b).

The present invention is not limited to the embodiments, but various applications are possible. For example, the portion of the RS flip-flop 33 of FIG. 1 shown in FIG.
Even if it is replaced with the flip-flop 51, the same operation can be obtained. The flip-flop 51 inputs the “H” level to the data input D of the D-type flip-flop 54,
The output of the NOR circuit 31 of FIG. 1 is input to the clock input CK via the inverter 52, the output of the NOR circuit 32 is input to the reset input R via the inverter 53,
The output Q is the detection output Qo. Further, in the present invention, the forward rotation detection element (3A to 3D) and the reverse rotation detection element (3E
.About.3H) is not limited to the number of examples.

[0012]

As described above, according to the present invention, the rotation direction of the rotating body can be detected by the circuit without using software on the microcomputer as in the prior art. In addition, by detecting the rotation direction at each of the plurality of edges of the first and second signals of the frequency signal generator provided in the rotating body, both during the forward rotation and the reverse rotation detection, the rotation direction detection accuracy is improved. There is.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a timing waveform chart showing the operation of the circuit.

FIG. 3 is a partial circuit diagram of FIG.

FIG. 4 is a signal waveform diagram at the time of forward rotation detection obtained from a frequency signal generator of a conventional capstan motor.

FIG. 5 is a signal waveform diagram at the time of reverse rotation detection obtained from a frequency signal generator of a conventional capstan motor.

[Explanation of symbols]

1 ... Forward rotation detection circuit, 2 ... Reverse rotation detection circuit, 3A to 3H ... D
Type flip-flops 31, 32 ... NOR circuit, 33 ...
RS flip-flop, 34 ... Reset circuit, I1, I
2 ... Inverter, N1 to N4 ... Detecting node where edge of rotation signal becomes “H”.

Claims (4)

[Claims] 1. A positive for detecting the level of the second or first signal of the frequency signal generator with respect to the edge of the level of the first or second signal obtained from the frequency signal generator in response to the rotation of the rotating body. A reverse detection circuit, a reverse detection circuit that detects the level of the first or second signal with respect to the edge of the level of the second or first signal, and a holding circuit that holds the detection result of each detection circuit as a digital signal. And a reset circuit for resetting the normal rotation or reverse rotation detection circuit to an initial state after a fixed time from each detection time point of the normal rotation or reverse rotation detection circuit. A rotation direction detecting device characterized by detecting rotation and reverse rotation. 2. The rotation direction detecting device according to claim 1, wherein the rotating body is a capstan motor that controls the progress of the tape. 3. The rotation direction detecting device according to claim 1, wherein the relative relationship between the levels of the first and second signals is detected by a plurality of edges at the levels of the first and second signals. 4. The outputs of the forward rotation and reverse rotation detection circuits are inputs to the first and second NOR circuits, respectively, and the outputs of the first and second NOR circuits are inputs to the holding circuit. The rotation direction detection device according to item 3.