JPH02303384A - High speed search servo circuit - Google Patents

Abstract

PURPOSE:To increase the tape speed in steps, when searching operation is started, by constituting a high speed search servo circuit with an integrating circuit for taking in a high speed search control signal, an A/D converter, a multiplexer, a FV converter, and the like. CONSTITUTION:Upon provision of a search operation command to a microcomputer 9, output from a frequency generator(FG) signal amplifier 5 is subjected to frequency division in eight steps through a binary counter 6 and fed to a multiplexer 4. The multiplexer 4 selects the divided frequency in the order of frequency. A FV converter 7 outputs a signal voltage inverted into a low voltage for high frequency and feeds the signal voltage sequentially to an amplifier 8 thus driving a capstan motor 11 through a drive amplifier 10. By such arrangement, speed can be increased sequentially and application of excessive force onto the tape can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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).

[Conventional Technique 11r1 D A In 'I', when performing a fast forward (FF)/rewind (REW) search operation (hereinafter collectively referred to as search operation), the play time is changed to 1 @ speed. , if at stop (STOP), O times the speed, PL
The tape speed changes from 1x speed in AY to 200x speed. On the other hand, even when searching, it is necessary to read subcode signals such as song numbers and performance times.

[Problem B to be solved by the invention] By the way, if the tape speed is suddenly increased during the search operation as described above, there is a possibility that the subcode signal will be momentarily read due to excessive force being applied to the tape. becomes higher.

The present invention solves this problem by increasing the tape speed in steps of V1 at the start of a search operation, preventing excessive force from being applied to the tape, and making it possible to read subcodes accurately. The purpose is to provide a high-speed search servo circuit.

[Means for Solving the Problems] In order to achieve the above object, the present invention is used in a capstan motor or single motor control device, and in a servo circuit when searching a tape at high speed, a control signal for high speed search is transmitted. An integrator circuit that captures the output signal, an A/D converter that digitizes the output signal of the integrator circuit and outputs a count, a multiplexer that sequentially switches the output according to the count output, and a frequency signal from the capstan motor or reel motor. It is equipped with a counter that divides the frequency to create several types of frequencies and outputs each frequency in parallel to the multiplexer, and an FV converter that takes out a voltage output from the multiplexer that is inversely proportional to the frequency.

[Function] 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 start of the search operation, and this count output is used to calculate the output from the capstan motor or the single motor. The frequency-divided outputs of the frequency signals are selected and taken out in sequence starting from the higher frequencies, and the frequency signals are inversely proportionally converted into voltages by an FV converter. This converted voltage increases in steps, and by applying this output to the capstan motor or reel motor, the speed can be increased in steps.

[Example] Figure 1 shows a high-speed search servo circuit used in a capstan motor control device as an example of the present invention.
This will be explained with reference to FIGS.

The high-speed search servo circuit mainly includes a search speed variable circuit 1 that feeds back a frequency (FC,) signal from a capstan motor 11 to vary the speed. The search speed variable circuit 1 is controlled by the capstan motor 9, the control 171 microcomputer (microcomputer), and the search from the circuit 9 (
FAST) Integrating circuit 2 that takes in the switching signal and Integrating circuit 2
An A/D converter 3 converts the output signal into a digital signal and outputs a 3-bit counter, a multiplexer 4 whose output is sequentially switched according to the count output, and a frequency (PG) converter connected to the capstan motor 11. An FG signal amplifier 5 that amplifies the FG signal from the generator 12, and this FG
A binary counter 6 that divides the frequency of the doubled signal and outputs it to the multiplexer 4, and an F/V'R conversion that receives the output of the multiplexer 4 and takes out an output that is inversely proportional to this input.
ii7, and an amplifier 8 that amplifies the output of the F/V converter and outputs a signal for driving the capstan motor 11 at high speed.

The microcomputer circuit 9 outputs a signal for switching the changeover switch SW during PLAY, FF/REW, and search, and also outputs a fast (FAST) switching signal to the integration circuit 2 during high speed, as described above.

The drive amplifier 10 drives the capstan motor 11 in response to the output selected by the selector switch SW during PLAY and high speed.

FIG. 2 shows a specific example of the configuration of the variable search speed circuit 1. As shown in FIG. Here, the integrating circuit 2 consists of a capacitor C1, a resistor R1, and a transistor, and the A/D converter 3 consists of comparators A1 to
It consists of A7, exclusive OR circuits E1 to E7, OR circuits 01, 02, 03, etc., and is called a flash type.

The multiplexer 4, binary counter 6 and FV converter 7 are composed of IC chips. In addition, the logic table of the A/D converter 3 is shown in the table below. , the selection operation of the multiplexer 4, and the speed of the capstan motor 11 are shown as time charts.

The operation of the present high speed search servo circuit will be described below with reference to the time chart shown in FIG. 3 above. When a search operation command is input to the microcontroller 9, the FAS from the microcontroller 9
The T switching signal is switched from "g" to "rL". This signal is taken in and integrated by the integrating circuit 2, outputted by the A/D converter 3 as a 3-bit count output as shown, and inputted to the multiplexer 4.

On the other hand, the FG signal amplifier 5 from the capstan motor 11
The output is frequency-divided into eight steps by the binary counter 6 and input to the multiplexer 4.

The multiplexer 4 receives the 1/1 output from the binary counter 6 in synchronization with the count output of the A/D converter 3.
1.1/2.1/4.1/8. ...The frequencies divided into 8 steps of 1/128 are selected in order from the highest frequency.

And what is the output ■? ■Input to converter 7. This FV converter 7 outputs a signal voltage inverted to a low voltage when the frequency is high. Therefore, this output is sent to the amplifier 8 as a high voltage in order from low voltage, and further, the output of the amplifier 8 is given to the drive amplifier 10 via the switch SW which selects the search operation, and the capstan motor 11 is Drive. As a result, the capstan motor 11 increases the speed sequentially from 1x speed, 2x speed, 4x speed, LA speed... 256x speed. In this way, high speed Me can be started up in multiple stages. .

(Hereafter, blank space) Time chart table [Effects of the invention] As described above, according to the present invention, it is possible to gradually increase the speed of the capstan motor or reel motor when starting up a high-speed drive such as a tape search. Because you can
No excessive force is applied to the tape, and subcodes are accurately read from the playback head, allowing for correct song selection without causing malfunctions when locating the beginning of a desired song.

[Brief explanation of the drawing]

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 specific block diagram of the main parts of the circuit, and FIG. 3 is a time chart for explaining the operation of the circuit. 2... Integral 0 path, 3... A/D converter, 4... Multiplexer, 6... Binary counter, 7... F
V converter, 11... Capstan motor, 12...
FGI Electric.

Claims (1)

[Claims] (1) In a servo circuit used in a capstan motor or reel motor control device to perform a high-speed search on a tape, there is an integrator circuit that takes in the high-speed search control signal, and the output signal of the integrator circuit is digitized and output as a count. A/ to do
A D converter, a multiplexer whose output is sequentially switched according to the count output, and a frequency signal from the capstan motor or reel motor is divided to create several types of frequencies, and each frequency is output in parallel to the multiplexer. A high-speed search servo circuit comprising a counter and an FV converter that takes out a voltage output inversely proportional to frequency from the multiplexer.