JPH01124101A - Signal track erasure circuit - Google Patents

Abstract

PURPOSE:To rapidly erase only a desired signal track by setting a reproduction mode and an erasure mode at every signal track based on an erasure start command, reproducing the signal track in the reproduction mode, and supplying an erasure signal to a recording and reproducing head in the erasure mode. CONSTITUTION:After the positioning of heads 1 and 2 being completed, an operation is shifted to an erasure operation, simultaneously, a signal reproduction mode is set, and an image is displayed on a CRT22. Waiting the lapse of a prescribed time after an erasure key 17 is turned ON, the erasure mode is set. Next, in case of performing the erasure of a field, only a first head 1 is connected to an erasure gate circuit 11 side by switching a first change-over switch 3, and in case of performing the erasure of a frame, both heads 1 and 2 are connected to the erasure gate circuit 11 side by switching both change-over switches 3 and 4. Afterwards, a video track in reproducing is erased by opening the erasure gate circuit 11 for a constant time. In such a way, it is possible to erase only the track on which an unrequired image is recorded rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a circuit for erasing a video signal written on a video track in a video recording device such as a so-called electronic still camera.

(Prior Art) An electronic still camera rotates a magnetic disk serving as a signal recording medium at high speed, and moves the magnetic head in the radial direction of the disk by the operation of a head transfer means. The specifications of the magnetic disk and the signal recording format have already been standardized (Nikkei Electronics 4, July 2, 1984, issue 80-8, published by Nikkei McGraw-Hill).
(See page 5).

According to electronic still cameras, new images can be recorded by erasing unnecessary video signals recorded on a magnetic disk.

As a method for erasing the magnetic disk, a well-known method (for example, Japanese Patent Laid-Open No. 61-902) of recording an alternating signal having a frequency corresponding to the frequency band of the recorded video signal can be adopted.

(Problem to be solved) However, in conventional electronic still cameras, it is unclear which signal track the image to be erased is recorded on, so it is difficult to erase a large number of images in succession. For each track, an operation is first performed to reproduce the signal, and then the image is reproduced to determine whether or not it is an image that should be erased.Then, based on the result of that determination, an operation for signal deletion is performed. It was tedious to perform complicated operations for each track.

(Means for Solving the Problems) An object of the present invention is to provide a circuit that can quickly erase only a desired signal track by a simple operation in a signal recording/reproducing device such as an electronic still camera. be.

The signal erasing circuit according to the present invention provides a signal erasing circuit for a recording/reproducing head.
A signal reproducing system for reproducing a recorded signal and the erasing signal generating means are switchably connected via a switching means.

A control means is connected to the switching means, which includes an input section for instructing the start and interruption of signal erasure.

The control means sets a playback mode and an erase mode for each signal track based on an erase start command from the input section,
In the reproduction mode, the switching means is switched to the signal reproduction system side to reproduce the signal track, and in the erasure mode following the reproduction mode, the switching means is switched to the erasure signal generation means side to supply the erasure signal to the recording/reproduction head. . Further, when the erasure interruption command is issued by the input section during the reproduction mode, the control means shifts to the reproduction mode of the next signal track without setting the erasure mode.

(Function) When an erasure start command is given to the control means by operating the input section, the signal recording/reproducing head sequentially moves over each signal track, and a reproduction mode and an erasure mode are set for each signal track. . In the reproduction mode, the signal recorded on the signal track is reproduced by the recording/reproducing head and the reproduction system, and in the erasing mode, an erasing signal is supplied to the recording/reproducing head,
The signal recorded on the signal track is erased.

When a signal that is desired to be stored without being erased is reproduced in the above-mentioned reproduction mode, an erasure interruption command is given to the control means by operating the input section. As a result, the erase mode that should follow the playback mode is not set, and the mode shifts to the playback mode for the next track.

Therefore, once the erase start command is issued, signal tracks are erased one after another unless an erase interrupt command is issued. Furthermore, if an erase interruption command is issued during this process, the erase operation will not be performed for the track to be saved.

(Effects of the Invention) According to the erasing circuit according to the present invention, there is no need to perform operations for signal reproduction and signal erasure for each track, and it is preferable to check the contents of the signals that are successively reproduced before storing them. Since it is only necessary to perform an operation to interrupt the erasing operation when the signal is reproduced, the signal can be erased reliably and quickly with a simple operation.

(Embodiment) FIG. 1 shows an example in which the erasing circuit according to the present invention is implemented in a playback device for an electronic still camera.

Recording methods for electronic still cameras include field recording, in which one field of video signals is written in one track round, and frame recording, in which one frame of video signals is written in two track revolutions. Generally, electronic still cameras are equipped with a pair of magnetic heads arranged side by side at an interval that matches the track pitch.Only one magnetic head is used when playing back a field-recorded magnetic disk, but when recording a frame recording When reproducing a magnetic disk, video signals are simultaneously read from two video tracks using both magnetic heads. Therefore, when erasing a frame-recorded video track, it is necessary to erase two tracks consecutively or simultaneously.

To determine whether the recording unit is a frame or a field, DPSK (differential ph) is used to determine whether the recording unit is a frame or a field.
(aseshift keyiB) This is done by modulating and frequency multiplexing recording, and reading out the identification data at the time of reproduction. The identification data is '00' for field recording, and '00' for frame recording, for outer tracks.
'01', it is standardized to set the inner track at '10°'.

The playback device shown in FIG. 1 includes first and second heads (one
) (2), and both heads are equipped with step motors (14
) with head transfer I! The disk is transported in the radial direction by the mechanism, and can be set on any track by operating the forward key (15) or backward key (16). That is, the activation signal of the forward key (15) or backward key (16) is sent to the system controller (13),
It is converted into a control signal for the step motor (14).

The output signals of both heads are connected to a selection circuit (5) via first and second changeover switches (3) and (4), respectively.

The selection circuit (5) selects only the first head output if the first head output is not a signal from a video track of frame recording, based on a selection control signal to be described later, and selects only the first head output if the first head output is a signal from a frame recording video track. If the signal is from a video track, both head outputs are selected alternately at the field period. The selected playback output is converted to F in the FM demodulation circuit (7).
After being demodulated, the signal is input to the video processing circuit (8).

When the video processing circuit (8) reproduces the video track of frame recording, the video processing circuit (8) outputs the demodulated output to the C which serves as the side monitor device.
When outputting to RT (22) and playing back a field recorded video track, skew distortion is eliminated by alternately selecting delayed output, which is the FM demodulated output delayed by 0.5H, and non-delayed output for each field. It outputs a frame signal created by reinserting the vertical synchronization signal.

The output of the selection circuit (5) is connected to the recording unit detection circuit (9). The detection circuit (9) includes a selection control gate circuit (6).
) selects the first head output, the vertical synchronizing pulse VS and horizontal synchronizing pulse H3 from the video processing circuit (8) are counted, and the 2-bit identification data is determined based on the counted value. A detection signal representing identification data is output to a selection control gate circuit (6), a video processing circuit (8), and a decoder (12) to be described later.

When reproducing a frame-recorded video track, the selection operation of the selection circuit (5) is performed in synchronization with the rotation of the magnetic disk. That is, the PG pulse of the field period obtained as the magnetic disk rotates is sent to the flip-flop (19).
A square wave that is inverted at the field period is created by supplying the square wave to the selection control gate circuit (6). The gate circuit outputs a selection control signal that inverts the level for each field when the first head (1) reproduces a video track outside the frame recording, and otherwise outputs a selection control signal of low level. do.

Therefore, the selection circuit (5) is configured to select the first head output when the selection control signal is at a low level, and select the second head output when it is at a high level. The outputs are selected alternately, and only the first head output is selected as the playback output of the field recorded video track. This allows CRT
A clear still image is displayed at (22).

The output terminal of the erase signal generation circuit (10) is connected to the first and second changeover switches (3) via an erase gate circuit (11) whose opening and closing are controlled by a system controller (13).
) (4).

The detection signal is connected to a system controller (13) via a decoder (12), thereby creating switching control signals for the first and second changeover switches (3) and (4).

System controller (13)/\The input unit that issues various command signals includes a forward key (15) and a backward key (16) for specifying the position of the magnetic head, and an erase key (16) for instructing the start of the erase operation. It consists of a key (17), a stop key (20) for instructing to escape from the erasing range specification routine by key setting described later, and a bus key (21) for instructing to interrupt the erasing operation for each track. Ru.

Command signals from each key are sent to the system controller (13)
The step motor (14), the first and second changeover switches (3) (4), and the erase gate circuit (11)
is converted into a control signal.

The operation of the above circuit will be explained below with reference to FIGS. 2 and 3.

When erasing multiple video tracks, press the forward key (15) or backward key (16) while projecting the image on the CRT.
) to set the magnetic head on the first track to be erased (FIG. 2).

First, it is determined whether the forward key is turned on (23), and when it is turned on, it is determined whether the magnetic head is located at the last track or not based on the reproduced address signal (23).
24) Here, the final track is the 49th track in the case of frame recording, and the 5th track in the case of field recording.
0 tracks. If it is not the last track, the step motor is driven to advance the head (25) and the screen is switched to the next screen. If it is the last track, return to the above judgment (23) 0 Next, judge whether the backward key is turned on (26) L, if turned on, check whether the magnetic head is located on the first track Judgment (27) L,
When not on the first track, move the head to f&3Ji (28)
urge

When it is the first track and the head 113J17, the process returns to the above judgment (23).

After positioning the head in this manner, the erase operation (29) is started (FIG. 3). At this time, the signal reproduction mode is simultaneously set and an image is displayed on the CRT.

First, it is determined whether or not the erase key is turned on (30), and if it is turned off, the process returns to determination (23) in FIG. 2.

After the erase key is turned on, a predetermined period of time (for example, 1 second)
Wait for the elapse of (31), and then judge whether the erase key is still pressed (32). If it is OFF, return to judgment (23) in Figure 2, and if it is ON, erase. mode is set. First, it is determined whether the output of the decoder (12) represents frame erasure or field erasure (33).L, in the case of field erasure, switch the first changeover switch (3);
Connect only the first head (1) to the erase gate circuit side (34
), or if you want to erase the frame, press both selector switches (
3) Switch (4) and connect both heads (1) and (2) to the erase gate circuit side (35).

Thereafter, the gate circuit is opened for a certain period of time (36) to erase the video track being reproduced.

After that, determine whether the erase key is still ON (
37) When L and ON, it is determined whether the track where the magnetic head is located is the final track (38), and if it is not the final track, the magnetic head is further advanced (38).
39) Then, return to the process of waiting for the above-mentioned time (31). If it is found in the above judgments (37) and (38) that the erase key is OFF or that it is the last track, the process returns to judgment (23) in FIG.

Therefore, the operator can continue to press the erase key (17) while looking at the CRT playback screen, and when an image that does not need to be erased is displayed, release the erase key (17) to delete the unnecessary image. Only recorded tracks can be quickly erased.

Furthermore, as shown by the chain line in FIG. 1, a keypad device (18) equipped with a numeric keypad is connected to the system controller (13), and the last track to be erased can be set in advance by operating the keypad device (18). By specifying it, it is also possible to define the track range to be erased. The circuit operation in this case will be explained based on FIG.

First, after the head positioning operation (FIG. 2) is performed, it is determined whether the erase key has been turned ON (40) L
, if OFF, judgment (23) in Figure 2/\Return, ON
In this case, the system waits for operation of the numeric keypad (41).

If there is a key input, the numerical value indicated by the input signal is set in the memory as the final track number (42).

Also, at the same time, the playback mode is set.

Next, it is determined whether the stop key has been operated (43),
If the passkey is ON, the process returns to the judgment (23) in FIG.
If it is OFF, determine whether a predetermined time (for example, 1 second) has elapsed since the transition to playback mode (45) L, No
In the case of YES, the process returns to the above-mentioned judgment (43), and in the case of YES, the process shifts to the erase mode.

In the erase mode, first, the contents of the decoder output are determined (46
) to the opening of the erase gate circuit (49), the same processing as shown in FIG. 3 (33) to (36) is performed.

Next, check the number of the track that the magnetic head is currently facing (
A comparison (50) is made between the current track number) and the value set on the numeric keypad (end track number), and if the current track number is greater than or equal to the end track number, it is determined whether the current track is the last track on the magnetic disk. Judging (51)
L: If it is not the last track, the head is advanced by one screen and then returns to the above-mentioned judgment (43). Judgment (50) (51
), if the current track number is smaller than the ending track number or if it is the last track, the judgment in Figure 2 (2
Return to 3).

Therefore, the operator selects the key T! from the track where the erase key (17) was operated. (18) Unnecessary images are recorded by operating the passkey when images that do not need to be erased are being played back while images are being played back sequentially across the tracks set in (18). Only tracks can be quickly erased.

Note that the configuration of each part of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the claims.For example, the signal to be erased may be not only a video signal, but also a video signal.
Of course, it may be an audio signal, a data signal, etc., for example.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an erasing circuit according to the present invention, and FIGS. 2 to 4 are flowcharts showing the circuit operations, respectively.

Claims (2)

[Claims] (1) Signal recording that includes a recording/reproducing head that sequentially scans a large number of signal tracks formed on a signal recording medium, and erases the signal tracks over the recording range of the erase signal by supplying an erase signal to the head. In the reproducing device, the signal reproducing system for reproducing the recorded signal and the means for generating the erasing signal are connected to the head via a switching means so as to be switchable, and the switching means has a signal erasing system for erasing the signal. A control means having an input section for commanding start and interruption is connected, and the control means sets a playback mode and an erase mode for each signal track based on the erase start command from the input section, and sets the playback mode to the playback mode. The switching means is switched to the signal reproduction system side to reproduce the signal track, and in the erase mode following the reproduction mode, the switching means is switched to the erase signal generation means side to supply the erase signal to the recording/reproducing head, and the reproduction mode A signal track erasing circuit characterized in that when an erasing interruption command is issued by an input section during the signal track erasing circuit, the signal track erasing circuit shifts to a reproduction mode of the next signal track without setting an erasing mode. (2) The erasing signal generating means includes an erasing signal generating circuit (10)
2. The signal track erasing circuit according to claim 1, wherein the output terminal of the circuit is connected to the input terminal of the switching means via a gate circuit (11) whose opening and closing are controlled by the control means.