JP2561147B2 - High speed search servo circuit - Google Patents

Description

The present invention relates to a high-speed search servo circuit used in a capstan motor or reel motor control device of a digital audio tape recorder (hereinafter referred to as DAT) or the like.

[Prior Art] When a fast forward (FF) / rewind (REW) search operation (hereinafter collectively referred to as a search operation) is performed in a DAT, a play (PLAY) is set to a 1 × speed and a stop (STOP) is performed. ) Time, the tape speed changes from 0x speed, and during PLAY, from 1x speed to 200x speed. on the other hand,
It is necessary to read the subcode signals such as the song number and the playing time even during the search.

[Problems to be Solved by the Invention] By the way, if the tape speed is suddenly raised at the time of the search operation as described above, the sub-code signal may be missed at an instant due to an excessive force applied to the tape. Get higher

The present invention solves such a problem, and it is possible to increase the tape speed stepwise at the time of the start of the search operation to prevent the tape from being unreasonably applied, and to accurately read the subcode. An object of the present invention is to provide a high speed search servo circuit suitable for a digital audio tape recorder or the like.

[Means for Solving the Problems] In order to achieve the above object, the present invention is used in a capstan motor or reel motor control device of a digital audio tape recorder, etc. An integrator circuit that takes in the search control signal, an A / D converter that digitizes and outputs the output signal of the integrator circuit, a multiplexer that sequentially switches the output according to the count output, and a capstan motor or reel motor. The frequency signal from the frequency generator connected to is divided to generate several kinds of frequencies, and a counter for outputting to the multiplexer in parallel for each frequency and a voltage output inversely proportional to the frequency from the multiplexer are taken out. The output is given as a drive signal for the capstan motor or reel motor. A FV converter, the capstan motor or reel motor, the frequency generator, the counter, the multiplexer, and the FV.
The converter forms a servo loop.

[Operation] In the above configuration, a count output is obtained from the A / D converter by the output of the integrating circuit that receives the command signal at the rising edge of the search operation. With this count output, the frequency from the capstan motor or reel motor is obtained. The frequency-divided output of the signal is sequentially selected and extracted from the higher frequency, and this frequency signal is inversely converted into a voltage by the FV converter. This converted voltage gradually increases in voltage. By applying this output to the capstan motor or reel motor, the speed can be increased stepwise and smoothly. Therefore, when it is used for driving a motor of a digital audio tape recorder, the signal read by the reproducing head is not missed.

[Embodiment] A high-speed search servo circuit used in a capstan motor controller as an embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3.

The high-speed search servo circuit mainly includes a search speed variable circuit 1 that feeds back the frequency (FG) signal of the capstan motor 11 to change the speed. The variable search speed circuit 1 converts an output signal of the integrating circuit 2 into a digital signal, and an integrating circuit 2 that takes in a search (FAST) switching signal from a capstan motor controlling microcomputer (microcomputer) circuit 9. A / D with 3-bit count output
The converter 3, the multiplexer 4 whose output is sequentially switched according to the count output, the FG signal amplifier 5 for amplifying the FG signal from the frequency (FG) generator 12 connected to the capstan motor 11, and this FG signal The binary counter 6 that divides and outputs to the multiplexer 4 and the output of the multiplexer 4 are input, and the output of the F / V converter 7 and the output of the F / V converter that can output the output in inverse proportion to this input are amplified. , Amplifier 8 for outputting signal for driving capstan motor 11 at high speed
Consists of

The microcomputer circuit 9 outputs a signal for switching and operating the changeover switch SW at the time of PLAY, FF / REW, and search, and at the same time as described above, at the time of high speed, the integration circuit 2 outputs the high speed (FAST) changeover signal.
Output to. The drive amplifier 10 drives the capstan motor 11 by receiving the output selected by the changeover switch SW during PLAY and high speed.

FIG. 2 shows a specific configuration example of the search speed variable circuit 1. The integrating circuit 2 is composed of a capacitor C1, a resistor R1 and a transistor, and the A / D converter 3 is composed of comparators A1 to A7, exclusive OR circuits E1 to E7 and OR circuits O1, O2, O3, etc. Is called. The multiplexer 4, the binary counter 6 and the FV converter 7 are composed of an IC chip. The logical table of the A / D converter 3 is shown in the table below. Fig. 3 shows the high-speed (FAS
T) signal, the output of the integration circuit 2, the output of the A / D converter 3, the selection operation of the multiplexer 4, and the speed chart of the capstan motor 11 are shown.

The operation of the high speed search servo circuit will be described below with reference to the time chart of FIG. When a search operation command is input to the microcomputer 9, the FAST switching signal from the microcomputer 9 is switched from "H" to "L". This signal is taken into the integration circuit 2 and integrated, and the A / D converter 3 produces a 3-bit count output as shown in the figure, which is input to the multiplexer 4.

On the other hand, the output of the FG signal amplifier 5 from the capstan motor 11 is divided into eight stages by the binary counter 6,
It is input to the multiplexer 4. In the multiplexer 4, in synchronization with the count output of the A / D converter 3, it is divided into eight stages of 1/1, 1/2, 1/4, 1/8, ... 1/128 from the binary counter 6. The divided frequencies are selected in order from the high frequency. Then, the output is input to the FV converter 7. this
The FV converter 7 outputs a signal voltage inverted to a low voltage when the frequency is high. Therefore, this output becomes a high voltage sequentially from a low voltage and is sent to the amplifier 8. Further, the output of the amplifier 8 is given to the drive amplifier 10 via the switch SW selecting the search operation, and the capstan motor 11 is turned on. To drive. As a result, the capstan motor 11 gradually increases in speed to 1x speed, 2x speed, 4x speed, 8x speed ... 256x speed. In this way, high-speed driving can be started up in multiple stages.

[Advantages of the Invention] As described above, according to the present invention, the speed of the capstan motor or the reel motor can be sequentially increased at the time of start-up of high-speed drive such as tape search. Is no longer applied,
The sub-code is accurately read from the reproducing head in a digital audio tape recorder or the like, and a correct song can be selected without causing a malfunction when the desired song is cued.

[Brief description of drawings]

FIG. 1 is a block diagram of a high speed search servo circuit according to an embodiment of the present invention, FIG. 2 is a detailed block diagram of a main part of the circuit, and FIG. 3 is a time chart for explaining the operation of the circuit. 2 ... Integrator circuit, 3 ... A / D converter, 4 ... Multiplexer, 6 ... Binary counter, 7 ... FV converter, 11 ...
… Capstan motor, 12 …… FG generator.

Claims (1)

(57) [Claims] 1. A servo circuit used for a capstan motor or reel motor control device in a digital audio tape recorder or the like for a high speed search of a tape, and an integrating circuit for taking in a control signal for the high speed search and its integrating circuit. A / D that digitizes output signals and outputs counts
A converter, a multiplexer whose output is switched in sequence according to the count output, and a frequency signal from a frequency generator connected to a capstan motor or reel motor are frequency-divided to create several types of frequencies, and each frequency is connected in parallel. A counter for outputting to the multiplexer, a voltage output inversely proportional to the frequency from the multiplexer, and an FV converter for providing this output as a drive signal for a capstan motor or reel motor. A high-speed search servo circuit in which a motor, a frequency generator, a counter, a multiplexer, and an FV converter form a servo loop.