JP3226532B2 - Search device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a search device suitable for application to, for example, a VTR or the like.

[Summary of the Invention]

The present invention relates to a search device suitable for application to, for example, a VTR, etc., and relates to an envelope detection circuit for performing envelope detection on a reproduced signal, a waveform shaping circuit for shaping a waveform of an output signal from the envelope detection circuit, and a waveform shaping circuit. Counting means for counting the number of signals, and a method of detecting the running speed and address information of the tape based on the calculation result of the counting result from the counting means or the address information from the reproducing system and the desired external address information. And step-by-step control means for searching for a track corresponding to the desired address information from the outside, thereby ensuring a track corresponding to the desired address information on the tape, and It is designed to be able to search at high speed.

[Conventional technology]

Conventionally, for example, a search for a track at a desired address on a tape in a VTR that searches for an arbitrary track using a capstan motor is performed by playing back an address recorded on a track on a magnetic tape and a running speed of the tape ( PB) speed, read at any time, and compare it with the desired, ie, target, address at any time. Cue (Cue: 9 times the playback speed, for example) or review (Rev: At a speed of, for example, seven times the playback speed), the address recorded on the track of the magnetic tape is read once every nine tracks or seven tracks, and a reel pulse or the like is used for an address that cannot be read. Calculate the distance between the target address and the current address (address), and calculate the tape speed using the fast forward (FF) or rewind (R) EW) (in this case, the address recorded on the tape track cannot be read), and for example, every time a reel pulse or the like is detected, “1” is subtracted from the distance (address) by one. Until the result becomes “0”, measurement is performed by microcomputer processing using the method of repeating this, the tape winding diameter on the reel,
A method of searching for a target address by obtaining a current address based on the measured value has been considered.

[Problems to be solved by the invention]

However, in the above-mentioned method of searching for a target address by setting the running speed of the tape to the speed of playback (PB),
Since the tape is run at the playback speed, it takes a very long time to reach the target address, which is very inconvenient for both business and consumer use.

In the above-described method of searching for a target address by setting the tape traveling speed to the speed of a cue or a review (Rev), an address can be read only once every 9 or 7 tracks. The address from the address to the next address must be calculated by using the reel pulse and the like, and the circuit configuration becomes complicated.
If the correspondence is not one-to-one, there is a problem that an address other than the target address is searched.

In the above-described method of searching for a target address by setting the running speed of the tape to the speed of fast forward (FF) or rewind (RWD), it is necessary to use a reel pulse or the like and to calculate the tape deflection. If the track and reel pulses do not correspond one-to-one due to various causes, for example, there is a problem that an address other than the target address is searched.

Further, the above-described method using the tape winding diameter has a disadvantage that an error occurs in the current address due to various causes such as expansion and contraction of the tape, and an address other than the target address is searched.

The present invention has been made in view of such a point, and an object of the present invention is to propose a search device capable of reliably and quickly searching for a track corresponding to desired address information on a tape.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a search device including the following means. That is, an envelope detection circuit for envelope detection of the reproduced signal, a waveform shaping means for waveform shaping the output signal from the envelope detection circuit, a counting means for counting signals from the waveform shaping means, and a tape running speed, A tape speed control means for changing to an A mode running at a high speed in the forward and reverse directions, a B mode running at a medium speed in the forward and reverse directions, a C mode running at a normal speed, and a D mode running at a step feed. When traveling in the A mode, the address information detection method detects the difference between the current address given by the counting result of the counting means and a target address specified from the outside. Detecting the difference between the current address obtained from the reproducing system and the target address at a rate of once each time, and determining the current address given by the counting result of the counting means. When running in the C and D modes, an address information detecting method for detecting a difference between a current address and a target address obtained from a playback system is used to detect a plurality of tapes. The traveling speed and a plurality of address information detection methods are selected in a stepwise manner, a track corresponding to the target address information is searched, and finally the tape is stepped and stopped at the target address. A search device is provided.

[Operation] According to the present invention, the control means (11) calculates the calculation result of the counting result from the counting means (10) or the address information from the reproducing system (6) and the desired address information from the outside. The method for detecting the traveling speed and the address information of the tape (1) is selected step by step based on the above, and a track corresponding to the desired external address information is searched. Tracks corresponding to the desired address information of
In addition, a high-speed search can be performed.

〔Example〕

Hereinafter, an example in which the search device of the present invention is applied to a VTR will be described in detail with reference to FIG. The illustration and description of the audio signal processing system and the video signal recording system are omitted.

In FIG. 1, (1) is a magnetic tape, and a modulated video signal recorded on the magnetic tape (1) is reproduced by heads (2a) and (2b), and an amplifier circuit (3
a) and (3b).

Reference numeral (4) denotes a switch. One fixed contact (4a) of the switch (4) is connected to the output side of one amplifier circuit (3a), and the other fixed contact (4b) of the switch (4) is connected to the other. And the movable contact (4c) of this switch (4) is connected to the input side of a reproduction system comprising a demodulation circuit (6a) and a reproduction signal processing system (6b).

(5) is an input terminal to which a switching pulse is supplied from, for example, a system controller (not shown). The switching pulse is supplied to the switch (4) through the input terminal (5). As a result, the modulated video signal from the head (2a) and the modulated video signal from the head (2b) are alternately supplied to the demodulation circuit (6a) of the reproduction system (6) and the envelope detection circuit (8) described later. .

The demodulation circuit (6a) demodulates the reproduced modulated video signal supplied from the amplifier circuit (3a) or (3b) via the switch (4), and converts the demodulated reproduced video signal into a reproduced signal processing system (6b). To supply. The reproduction signal processing system (6b) performs various signal processing such as time axis correction on the reproduction video signal from the demodulation circuit (6a), and supplies the resulting video signal to the output terminal (7). . Also, the address information (frame number) written during the vertical blanking period of the video signal is read and supplied to the CPU (11) through a bus (data address control bus).

The envelope detection circuit (8) performs envelope detection on the reproduced and modulated video signal alternately supplied from the amplifier circuits (3a) and (3b) via the switch (4), and converts the envelope signal into a waveform shaping circuit (9). To supply.

The waveform shaping circuit (8) is an envelope detection circuit (8)
The envelope signal from is shaped into a pulse waveform. The pulse from the waveform shaping circuit (9) is supplied to a counter (10) and counted by the counter (10).

The counter (10) counts the pulses from the waveform shaping circuit (9) and outputs the count result to the CPU via the bus (12).
Supply to (11).

The CPU (11) reads programs and data from the ROM (14) via the bus (12), and stores calculation results and the like in the RAM (13). From the input terminal (15), for example,
Target address information from the outside is transferred to the CPU (1) via the bus (12).
Supplied to 1). The CPU (11) outputs the target address information,
Based on the address information from the reproducing system, the distance between the current position of the head on the magnetic tape and the target position (that is, the difference in the address) is calculated, and the tape reel and the capstan are driven through the drive circuit (16). To control the rotation speed of the capstan motor (17) that drives the motor. Further, according to the rotation speed, the track on which the target address information is recorded is determined by the counting result from the counter (10) or the distance between the address information and the target address information from the reproduction system (address = frame). As shown in FIG. 2, four traveling types are selected in stages and searched.

That is, when the number of frames is 6000 or more,
Run at forward (FF) or rewind (RWD) speed, run at cue or review (Rev) speeds from 600 to 5999 frames, and run at speeds from 20 to 599 frames Forward (FWD)
Speed, and if the number of frames is less than 20, 1
Run with automatic step feed that plays back frame by frame. When traveling at the speed of cue, review (Rev) or forward (FWD), for example, whether or not a video signal is output from the video signal output terminal (7) (see FIG. 1) is output. good.

When the tape is run at the speed of first forward (FF) or rewind (RWD), when the target address is input, the current address supplied from the reproducing system (6) and the target address are compared. Distance (address = number of frames)
, The count result of the counter (10) is subtracted from time to time to search for the track where the target address is recorded, and when running the tape at the speed of cue or review, The track on which the target address is recorded is searched based on the current address supplied from the reproduction system (6) once every approximately nine or seven tracks and the count result of the counter (10).

Next, the operation of the search device of the present invention will be described with reference to the flowchart of FIG.

It is assumed that a target address is externally input to the control device.

First, in step (100), the running of the tape (1) is stopped in the still mode, that is, through the drive circuit (16). Then, while reading the current address from the reproduction system (6), the current address is compared with the already input target address, and the distance (address = frame) is calculated (note that the calculated distance is calculated as follows).
AD). Then, control goes to the next step (101).

In step (101), it is determined whether the mode is A. That is, in the mode A, as shown in FIG. 2, when the number of frames (distance between the target address and the current address) is 6000 or more, the first forward (FF) or rewind (RWD)
This is a mode in which the tape runs at the speed of. And
If YES, the process proceeds to step (105). If NO, the process proceeds to step (102).

In step (102), it is determined whether the mode is B. That is, as shown in FIG. 2, when the number of frames is between 600 and 5999, the mode B is a mode in which the tape is run at a cue (Cue) or review (Rev) speed. If YES, the process proceeds to step (112) and NO
If so, the process proceeds to step (103).

In step (103), it is determined whether the mode is C. That is, as shown in FIG. 2, the mode C is a mode in which the tape is run at a forward (FWD) speed when the number of frames is between 20 and 599. If YES, the process proceeds to step (117), and if NO, step (10)
Go to 4).

In step (104), it is determined whether the mode is D. That is, in this mode D, as shown in FIG.
When the number is less than 20, the tape is run in a so-called frame-feed running mode. If YES, the process proceeds to step (120), and if NO, the process proceeds to step (101).

In step (105), the tape travel is temporarily stopped. Then, control goes to a step (106).

In step (106), it is determined whether or not the target address is larger than the current address. If YES, the process proceeds to step (107), and if NO, the process proceeds to step (108).

In the step (107), the FF, that is, the tape is caused to run at the fast forward speed. Then, control goes to a step (109).

In step (108), the RWD, that is, the tape is caused to run at the rewind speed. Then, control goes to a step (109).

In step (109), the detection, that is, the count value from the counter (10) is subtracted from the distance (number of frames) AD of the target address and the current address calculated in step (100) to obtain a constant distance AD. . Then, control goes to a step (110).

In step (110), it is determined whether or not the distance AD is 6000, and Y
If ES, the process proceeds to step (111), and if NO, the process proceeds to step (106).

In step (111), the tape running is temporarily stopped. Then, control goes to a step (112).

In step (112), it is determined whether the target address is larger than the current address. If YES, the process proceeds to step (113), and if NO, the process proceeds to step (114).

In step (113), Cue, that is, the tape is caused to run at the cue speed (for example, 9 times speed). Then, control goes to a step (115).

In step (114), Rev, that is, the tape is caused to run at the review speed (for example, 7 times speed). Then, control goes to a step (115).

In step (115), detection is performed, that is, the present address from the reproduction system is read once every 9 tracks or 7 tracks,
The distance AD to the target address is calculated, and in the period when the current address is not supplied from the reproduction system (6), the counter (10)
, For example, the lowest count value is subtracted from the above-described distance AD. Then, control goes to the next step (116).

In step (116), it is determined whether or not the distance (the number of frames) is 600. If YES, the process proceeds to step (117), and NO
If so, the process proceeds to step (112).

In step (117), FWD, that is, forward (playback: P
Run the tape at the speed of (B speed). Then, control goes to the next step (118).

In step (118), the detection, that is, the distance AD between the target address and the current address constantly supplied from the reproduction system (6) is calculated. Then, control goes to a step (119).

In step (119), it is determined whether or not the distance AD is 20 and YES
If so, the process proceeds to step (120), and if NO, the process proceeds to step (117).

In step (120), continuous step feed, ie, 1
A so-called frame advance for reproducing every frame is performed. Then, control goes to the next step (121).

In step (121), the detection, that is, the distance AD between the target address and the current address from the reproduction system (6) is calculated. Then, control goes to a step (122).

In step (122), it is determined whether or not the distance AD is "0". If YES, the process proceeds to step (123). If NO, the process proceeds to step (120).

In step (123), when the distance AD is determined to be "0" in the frame still mode, that is, in step (122), the running of the tape is stopped, and the reproduction of only that frame is performed. And it ends.

As is apparent from the above, when the target address of the desired track is input, after calculating the distance AD from the current address,
While running the tape based on the value of the distance AD,
The current address is obtained from the information recorded on the tape according to the traveling, and the distance AD is detected based on the obtained current address. Therefore, the current capstan motor or the current capstan motor and the reel are used. Even in a simple system with one motor, so-called overrun does not occur, and high-speed and reliable search can be performed.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various other configurations can be adopted without departing from the gist of the invention.

〔The invention's effect〕

According to the present invention, the control means determines the running speed of the tape and the operation mode (that is, the operation mode (ie, (Type of traveling) is selected step by step, and a track corresponding to the desired address information from the outside is searched. Therefore, a track corresponding to the desired address information on the tape is surely and at high speed. There are benefits that can be searched.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the control device of the present invention, FIG. 2 is an explanatory diagram for explaining the control device of the present invention, and FIG.
4 is a flowchart for explaining the operation of the control device of the present invention. (1) is a tape, (8) is an envelope detection circuit,
(9) is a waveform shaping circuit, (10) is counting means, and (11) is control means.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 27/00

Claims (1)

(57) [Claims] An envelope detection circuit for envelope-detecting a reproduced signal; a waveform shaping means for waveform-shaping an output signal from the envelope detection circuit; a counting means for counting signals from the waveform shaping means; Is changed to A mode, which runs at high speed in the forward and reverse directions, B mode, which runs at medium speed in the forward and reverse directions, C mode, which runs at normal speed, and D mode, which runs at step feed. Control means;
When traveling in the A mode, the address information detection method detects the difference between the current address given by the counting result of the counting means and a target address specified from the outside. Address information by both detecting the difference between the current address obtained from the reproducing system and the target address at a rate of one time and detecting the difference between the current address and the target address given by the counting result of the counting means. According to the detection method, in the above C and D mode running, a plurality of tape traveling speeds and a plurality of address information detecting methods are stepwisely changed by an address information detecting method for detecting a difference between a current address and a target address obtained from a reproducing system. A search device for selecting and searching for a track corresponding to the target address information, and finally stepping the tape to stop at the target address.