JPS6213253Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a reel motor control circuit in a tape drive device such as a video tape recorder (VTR).

The reel motor of the VTR is configured to be selectively applied with a first or second potential so as to be driven at a first or second speed, depending on the designation of the operation mode of the VTR. That is, the first potential (for example, 4V) is applied in play mode, record mode, etc. where the tape transport speed is low, and the second potential (e.g., 8V) is applied in fast forward mode, rewind mode, etc. where the tape transport speed is high. ing.
Generally, a brake is applied to the reel, which is the load of the reel motor, when tape transport is stopped, so this brake must be released before instructing the reel motor to drive. Therefore, conventional VTRs utilize a reel motor control circuit as shown in FIG.

This conventional circuit will be explained below with reference to the time chart shown in FIG.

1 is an external specifying means for specifying the operation mode of the VTR, for example, depending on the specification such as play specification, stop specification, or fast forward specification, the operation mode shown in Fig. 2 a, b, c
Outputs the specified signal as shown in . 2 receives the designation signal from the external designation means 1 and outputs a predetermined control signal, that is, a first controller that instructs the reel motor 3 to be driven.
Control signal generating means for individually outputting a control signal (FIG. 2 d) and a second control signal (FIG. 2 e) instructing the rotational speed of the reel motor 3; In addition to the signals, mode switching signals (not shown) to various mode switching means 4 are generated. Therefore, sensor input is required to grasp the operating status of the VTR, but the explanation of this is omitted. The first control signal (FIG. 2d) is set to a high level with a delay of a predetermined time τ after the input of the designation signal based on the play designation and the fast forward designation. This is provided to ensure the mechanism operation time required for switching. Further, the second control signal (Fig. 2e) is a designation signal (second
(c) is input and becomes high level.

Each control signal is converted to a low level by a designated signal (FIG. 2b) based on the stop designation.

Reference numeral 5 denotes an AND gate which receives the first and second control signals as two inputs, and generates a third control signal for a fast-forward operation as shown in FIG. 2(f). 6 is a first potential applying circuit; 7 is a second potential applying circuit;
The control signal (Fig. 2d) or the third control signal (second
Figure f) Switching transistor with input
When Q ₁ or Q ₂ is conductive, the first and second potentials set by the volume VR ₁ or VR ₂ are expressed as g ₁ and g 2 in Fig. _2.
It is applied to the reel motor 3 as shown in FIG.

In this conventional circuit, in order to apply a second potential (g 2 in Fig. ₂ ) to the reel motor 3 and set it to a fast-forward mode, etc., the third control signal, which is an AND output of the first control signal and the second control signal, is used. The signal is generated using an AND gate 5 separate from the switching transistor _Q1 or _Q2 .

The present invention aims to simplify the circuit configuration and provide an inexpensive control circuit by distributing the function of the AND gate to the transistors constituting the first and second potential applying circuits.

FIG. 3 shows an embodiment of the circuit of the present invention. In the figure, the same components as those in FIG. 1 are given the same reference numbers and their explanations will be omitted. The circuit of the present invention is characterized in that, in order to omit the AND gate 5, the first and second potential applying circuits 10 and 11 are constructed as shown. First potential applying circuit 10
comprises a first switching transistor 12 into which a first control signal (FIG. 2 d) is input to its base electrode, and a first volume 13 to which a constant potential (+B) is applied when the transistor is turned on; The potential applying circuit 11 includes a second switching transistor 14 which inputs a second control signal (FIG. 2e) to its base electrode.
and a second volume 15 to which a constant potential (+B) is applied when the transistor is conductive and when the first switching transistor 12 is conductive, and each volume 13, 15 is provided with a first potential (+B). For example, it is set to output a second potential (for example, 4V) or a second potential (for example, 8V).

Therefore, these first and second potential applying circuits 10, 1
1 is given the first and second control signals shown in FIG. It is possible to output the motor applied voltage as shown in _g3 . This motor applied voltage is applied to the reel motor 3 via a transistor 19 that changes internal impedance depending on the level difference, and controls the rotational speed of the motor. still,
In this embodiment, the speed of the reel motor can be changed in two stages, but the present invention is not limited to this, and the present invention is not limited to this, but the present invention is not limited to this, but the present invention is not limited to this. Needless to say, by arranging the gears, it is possible to change gears in three or more stages.

In this way, the circuit of the present invention is capable of controlling the third control signal to be formed based on the first and second control signals from the control signal forming means.
The control signal is not generated by an AND gate separate from the switching transistors that constitute the first and second potential applying circuits as in the conventional circuit, but the action of this AND gate is shared by the switching transistor. Therefore, the circuit configuration can be simplified and practical.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the conventional circuit, FIG. 2 is a time chart for explaining the operation, and FIG. 3 is a block diagram of the circuit of the present invention. Explanation of main drawing numbers, 1... External designation means, 2...
Control signal forming means, 10, 11...first and second potential applying circuits, 16, 17...supply circuit (OR gate), 12, 14...first and second transistors,
13, 15...1st and 2nd volume.

Claims (1)

[Scope of utility model registration request] external designation means for designating an operation mode of the tape drive device; a first control signal for instructing to drive the reel motor after a predetermined time delay upon receiving a designation signal based on the designation for driving the tape from the external designation means; a control signal forming means for individually outputting a second control signal instructing the rotational speed of the reel motor in response to an input of a designation signal based on a designation for driving the tape at high speed from the external designation means; and the control signal formation means a first transistor that inputs the first control signal from the first transistor to a base electrode, and a voltage divider circuit that forms a first potential when the first transistor is conductive, and when the first control signal is present, the first transistor
a first potential applying circuit that outputs a potential; and a second transistor that inputs the second control signal to a base electrode and is directly connected to the output electrode of the first transistor, and when the second control signal is present. a second potential applying circuit that outputs a second potential based on a power supply applied through the first potential applying circuit when the first potential applying circuit is applying the first potential; A reel motor control circuit comprising: a circuit for supplying a second potential applying circuit output to the reel motor.