JPH0578102B2 - - Google Patents

Description

[Detailed description of the invention]

Summary of the Invention A disk motor for rotating a magnetic disk in a still image recording/playback device uses a servo control device to generate a synchronization signal of a video signal and a phase detection signal of a phase detector that detects the rotational phase of the magnetic disk. The rotational phase is controlled so that they have a predetermined timing relationship. This device can receive operational input from the front operation panel (first operation), or can receive operational input from an external device such as a computer, wired remote control device, etc. (second operation). In the first operation, in the reproduction mode, the output of the internal oscillation circuit is used as the synchronization signal. In the recording mode, an external synchronization signal separated from the input video signal is used. In the second operation, an external synchronization signal is used in both playback and recording modes. However, when there is no input video signal, the oscillation output of the internal oscillation circuit is automatically switched to be used as the synchronization signal. Table of contents (1) Background of the invention (2) Summary of the invention (2.1) Purpose of the invention (2.2) Structure and effects of the invention (3) Description of embodiments (3.1) Appearance of still image recording and playback device (3.2) Operation mode and its transition (3.3) Electrical configuration and operation of still image recording/playback device (1) Background of the invention The present invention relates to a magnetic disk that has a plurality of recording tracks and on which video signals of still images are recorded. By moving the magnetic head in the radial direction of the disk, it is possible to reproduce signals from any track, and also to record one image of a video signal output from a television camera, television receiver, etc. on the magnetic disk. The present invention relates to a still image recording/playback device. A still image reproducing device reproduces video signals recorded on a magnetic disk by a so-called electronic still camera or video magnetic recording system.
When this reproduction output is applied to a television receiver, a still image is projected on the receiver's cathode ray tube. An electronic still camera is a combination of an imaging device such as a solid-state electronic image sensor and a recording device using a magnetic disk, and is used to electronically photograph a subject and record the still image on a magnetic disk. A video magnetic recording system electronically captures a still image appearing on a visible recording medium such as ordinary film or photographic paper and records it on a magnetic disk. Such still image playback devices are becoming relatively widespread both as consumer products and for business use, but on the other hand, there is a demand for new functions to be added so that they can be used for more purposes. ing. One of them is the recording function. This is one frame (1 frame) of a continuous video shot by a TV camera.
This is a function that records on a magnetic disk a video signal for one frame of a dynamic image displayed on a television receiver at a certain moment. Recording of video signals onto a disk does not have to be done at any arbitrary timing; unless it is done with reference to a certain reference angular position on the magnetic disk, playback will become out of synchronization. A phase detector is provided to detect the reference angular position of the magnetic disk, and recording or reproduction is performed so that the edge of the vertical synchronization signal appears when a period of 7H has elapsed from the phase detection by this phase detector. The standards specify what should be done. The still image reproducing device is provided with an internal synchronization signal oscillation circuit, and the rotation of the magnetic disk is controlled so that the generated synchronization signal and the phase detection signal satisfy the above relationship (internal synchronization). In order to record an input video signal on a magnetic disk, it becomes necessary to maintain the above-mentioned predetermined relationship between the synchronization signal included in the video signal and the rotational phase of the magnetic disk. Therefore, as mentioned above, the synchronization signal from the internal oscillation circuit is used during playback, but during recording, an external synchronization signal separated from the input video signal is used to control the rotation of the magnetic disk (external synchronization). The most standard way of thinking is to use internal synchronization during playback and external synchronization during recording. The still image playback device equipped with the above-mentioned recording function, that is, the still image recording and playback device, uses keys provided on its operation panel to perform playback, recording mode settings, track number designation, forward forwarding, reverse forwarding commands, etc. The standard method is to provide operation inputs.
However, since still image recording and reproducing devices are used for a wide variety of purposes, it is also desirable to have a configuration that allows them to be operated by a computer or remote control device. To this end, it will be necessary to provide terminals and the like for inputting the various operations described above in addition to the operation panel. In operations using such an external device, the device may be used as shown in FIG. 1, for example. A video signal of a dynamic image outputted from a video tape recorder (VTR) 3 or a video signal of a still image outputted from a still image recording/playback device 10 is selected by the changeover switch 2 and the CTR is selected.
It is given to the display device 1. The switching of the switch 2, the operation of the VTR 3 and the recording/playback device 10, etc. are controlled by a computer. Since the recording/playback device 10 is used in playback mode, internal synchronization is achieved according to the standard concept described above.
Since the output video signals of the VTR 3 and the recording/playback device 10 each include separate and independent synchronization signals, the switch 2 allows the VTR 3 to output the video signals to the recording/playback device 10.
When switching to or vice versa, the synchronizing signal for the image on the CRT display device 1 is also instantaneously switched, causing disturbances in the screen being displayed at this time. In order to prevent such a situation from occurring, it is necessary to apply the output video signal of the VTR 3 to the recording/playback device 10, as shown by the broken line in FIG. 1, and synchronize its playback operation with the synchronization signal of this input video signal. Is required. For this purpose, the recording/playback device 10
requires external synchronization during playback. On the other hand, there may be cases where the still image recording and reproducing apparatus 10 is used alone without being used together with a VTR, and the still image reproducing operation is controlled by a computer. At this time, there is often no external video signal input for external synchronization. In this case, internal synchronization has to be performed in the playback mode as in the standard mode described above. (2) Summary of the invention (2.1) Purpose of the invention The object of the present invention is to provide a synchronization control device for a still image recording/playback device that can provide a synchronization signal suitable for the mode of use. (2.2) Structure and Effects of the Invention The present invention relates to a motor for rotating a magnetic disk, a phase detector that generates a signal representing the rotational phase of the magnetic disk, and a phase signal and a video signal detected by the phase detector. Still image recording and playback, comprising a motor control device that receives a synchronization signal and controls the motor to rotate at a predetermined number of rotations, and to maintain a predetermined relationship between the input phase signal and the synchronization signal. Applies to equipment. The synchronization control device according to the present invention is controlled by a synchronization separation circuit for extracting a synchronization signal from an input video signal, a synchronization signal oscillation circuit, and a synchronization switching control signal, and selectively outputs the outputs of the two circuits to the motor control device. An operation changeover switch that switches between the first operation that inputs an operation signal from the operation panel and the second operation that inputs an operation signal from an external device, and when in playback mode when the first operation is set. If the second operation is set such that the synchronization selector switch selects the output of the oscillation circuit and the output of the synchronization separation circuit when in recording mode, the switch selects the output of the sync separation circuit in either playback or recording mode. a switching control means for outputting the synchronization switching control signal for controlling the output of the synchronization separation circuit to be selected even when the output of the synchronization separation circuit is selected; a detection circuit for detecting the absence of an input video signal; and a detection circuit for detecting the absence of an input video signal to the detection circuit The present invention is characterized by comprising a circuit for converting the synchronous switching control signal into a signal for controlling the synchronous switching switch to select the oscillation circuit in response to an output representing the oscillation circuit. In a standard usage mode (first operation) in which operation input is provided from an operation panel such as a front operation panel, control is performed by internal synchronization during playback mode operation and external synchronization during recording mode operation. This is the standard synchronous control described above. On the other hand, in a usage mode (second operation) in which an operation input is given from an external device such as a computer or a remote control device, external synchronization control is performed in both playback and recording modes. However, since the system is controlled to automatically switch to internal synchronization when there is no input video signal for external synchronization, it can be adapted to any usage situation. For example, in the example shown in Figure 1, since a video signal is provided from the outside, still image playback is performed in synchronization with the synchronization signal of this video signal, and when no such video signal is input, the still image is automatically played back. Image reproduction is performed with internal synchronization. (3) Description of Embodiments (3.1) Appearance of Still Image Recording and Reproducing Apparatus FIG. 2 shows the external appearance of the still image recording and reproducing apparatus, particularly its front operation panel. Front operation panel 1 of still image recording and playback device 10
A bucket 13 for storing a disk pack 20 and its cover 12 are rotatably supported on the left side of the bucket 1 at their lower ends. By pressing the ejection button (so-called eject button) 16, the closed cover 12 and bucket 13 are mechanically opened as shown in chain lines. By pressing the cover 12, the cover 12 and bucket 13 are closed and locked. Further on the left side of the cover 12, there is a power button 14 and its indicator light 1.
5 is provided. The disk pack 20 consists of a case in which a thin, small-diameter magnetic disk 21 is rotatably housed. A circular opening 22 is formed approximately in the center of the case, and the structure is such that the hub or core at the center of the magnetic disk 21 can be exposed through this opening 22. The disk pack 20 is further provided with a shutter 23 movable in a direction parallel to one side thereof. This shutter 23 has a disk pack 20 and a bucket 1.
3, the magnetic disk 21 is opened so that a regulating plate 53 and a magnetic head 51 (see FIG. 5), which will be described later, can come into contact with the magnetic disk 21 inside.
A claw 24 for preventing erroneous recording is provided on one side of the case of the disk pack 20. A plurality of (for example, 50) tracks (for example, track pitch 100 μm) are provided concentrically on the magnetic disk 21, and each track contains an FM-modulated color video signal (luminance signal) for one image (one frame). , chroma signals, etc.) can be magnetically recorded. FIG. 3 shows the relationship between the tracks provided on the magnetic disk 21 and the home position HP of the magnetic head. The 50 tracks provided concentrically on the magnetic recording surface of the magnetic disk are numbered from No. 1 to No. 50 in order from the outermost track. Home position HP is No.1
outside the track. home position
The HP is not attached to the magnetic disk 21, but is an extreme position assigned on the movement path of the magnetic head. Home position HP is detected by home position switch 84 (see FIG. 5). Referring again to FIG. 2, the right half of the front operation panel 11 is provided with a display 17 and various key switches and indicator lights. Display 1
7 is a liquid crystal display, for example, and a magnetic head 5
The track number of the magnetic disk 21 where 1 is currently located, various warnings (indicated by 17a), and the disk number.
Pack present (17
(indicated by b) is displayed. The key switch includes keys 31, 32, 33, 34, 35 and 3 for instructing various operations.
6, Keys 41, 4 for setting various modes
2, 43 and 44, the key 18 for setting the automatic feed time in the playback mode and operations such as playback and recording using the front operation panel 11 (this is referred to as the first operation) and control signals from external devices; Similar operations performed in the second
There is an operation changeover switch 48 for switching the operation. Indicator lights 45, 46, 47 are key 4
1, 42, and 43, and when these keys are pressed, the corresponding indicator lights are lit. The external devices include a control device called a personal computer including a microprocessor, a wired remote controller, and the like. Connectors for connecting these external devices are provided on the back panel (not shown) of the still image recording/playback device 10. Operation input signals from external devices are also transmitted to the control device 50 (see FIG. 5), which will be described later, of the still image recording and reproducing device 10 through various key switches 31 to 36 on the front panel 11.
It acts in exactly the same way as pressing 41 to 44, 18, etc. Therefore, unless otherwise specified, the operation of the apparatus according to the first operation and the second operation will be collectively described below in relation to the key switch on the front panel 11. (3.2) Operation modes and their transitions The still image recording/playback device is capable of playing back and recording still images. When a video signal is recorded on the above-mentioned magnetic disk 21, it is possible to reproduce the recorded track. Reproduction means reading an FM modulated signal from a predetermined track on a magnetic disk using a magnetic head, demodulating it, and converting it to standard color or NTSC format.
It is to output a television video signal. If the output terminal of this video signal is connected to a television receiver, the reproduced still image will be displayed on the cathode ray tube. Recording is based on the input of standard color television video signals. This video signal may be provided by, for example, a television camera or television receiver. Recording involves FM modulating one frame of a given video signal and writing it onto a predetermined track on a magnetic disk using a magnetic head. When displaying a screen on a television, interlaced scanning is generally performed, so the video signal is created so that two fields constitute one frame.
However, in still image recording devices such as the above-mentioned electronic still cameras, in order to save the recording surface of the magnetic disk for recording video signals, and for other purposes, one field is recorded on the magnetic disk so that one frame (one image) is recorded. Video signals are often recorded. This is called field recording. Furthermore, the manner in which one frame of image is obtained using the two fields described above is called frame recording. In this embodiment, field recording is performed, but it goes without saying that the present invention can also be applied to frame recording. There are three recording modes: single-frame recording, recording review, and continuous shooting. In the recording mode (more specifically, the recording standby mode to be described later), the magnetic head must be kept on standby on an unrecorded track of the magnetic disk. When one frame recording is selected, a video signal for one frame (one field) is recorded on that track, and immediately thereafter the magnetic head moves to the next (inner) track and waits. Recording review/
In this mode, after one frame of video signal is recorded on a track, the video signal recorded on that track is immediately played back and output for a certain period of time (for example, 2 seconds), and then the magnetic head moves to the next track and waits. do. In the continuous shooting mode, the above-described one-frame recording operation is performed continuously (for example, about 6 to 8 times per second). In relation to the various keys shown in FIG.
Each of the above-mentioned recording operations and other operations will be explained with reference to the drawings. In stop mode, when the single-frame key 43, review key 42, or continuous shooting key 41 is pressed, the corresponding indicator light 47, 46, or 45 lights up, the pressed key is memorized, and the device enters recording standby.・Go to mode. Then press record key 3
When 3 is pressed, if there is a memory that the 1-frame key 43 was pressed, a 1-frame recording operation is performed, and a review/recording operation is performed.
If there is a memory that the key 42 has been pressed, a recording review operation is performed. After these operations, the device returns to recording standby mode again. If the record key 33 is pressed while there is a memory that the continuous shooting key 41 has been pressed, continuous shooting will continue while the recording key 33 is pressed, and when the recording key 33 stops being pressed, the recording standby mode will be activated. Return to In order to prevent double recording on one track, if any signal has already been recorded on the track where the magnetic head is located, the various recording operations described above are prohibited, and the corresponding indicators 45 to 47 are disabled. Things that do flicker. Whether or not a signal is recorded on a track is determined based on the envelope detection output, which will be described later. In such a case, the forward key 32 or reverse key 31 can be pressed to move the magnetic head to the adjacent inner or outer track.
This is the track feed mode. Each press of these keys 31, 32 advances the magnetic head one track at a time, and then returns to the recording standby mode. However, in each recording operation, the next unrecorded track may be searched after recording the video signal. If you want to delete the recorded track signal,
All you have to do is press the 1-frame key 43 and the erase key 44 from the stop mode. When the erasing process for that track is completed, the recording standby mode is returned to. When the stop key 34 is pressed from the recording standby mode, the magnetic head is moved outward (in the opposite direction) by one track and returns to the stop mode, unless erasing is performed. This is because in the three recording modes described above, the magnetic head is moved inward (forward direction) by one track after recording. When the forward key 32 or reverse key 31 is pressed from the stop mode, the mode shifts to the playback mode, and the video signal recorded on the track where the magnetic head is located is played back. If the forward key 32 or reverse key 31 is pressed again, the magnetic head is sent to the next inner or outer track, and the signal of that track is reproduced. When the automatic feed key 35 is pressed and the automatic feed time is set using the key group 18, the magnetic head is sequentially fed in the forward direction at each set time, and each track is played back. . Also, when the track number display key 36 is pressed, the track on which the magnetic head is located is displayed.
Since the signal for displaying the number is superimposed on the reproduced video signal and output, the track number is displayed at the upper right of the screen of a cathode ray tube, for example.
When the stop key 34 is pressed, the system returns to the stop mode. In any of the above modes, the track number on which the magnetic head is currently located is displayed on the display 17. In the initial state when the power is turned on by the power switch 14, the magnetic head is temporarily returned to the home position HP, and then moved inward by a predetermined distance and positioned on the No. 1 track. In the recording mode, the transport of the magnetic head takes place in a so-called absolute track order manner. That is, although the magnetic head is transferred in the radial direction of the magnetic disk, the position of each track on which the magnetic head should be positioned is always determined based on the distance from the home position HP, with the position of the home position HP as a reference. It will be done. In the playback mode, the approximate position of the magnetic head is determined using the above-mentioned absolute track number formula, and then the center of the magnetic head is located at the center of the recorded signal based on envelope detection, which will be described later. As such, minute position control is performed. (3.3) Electrical configuration and operation of still image recording/playback device Figure 5 shows the electrical configuration of the still image recording/playback device. The overall operation of this still image recording and reproducing apparatus is supervised by a control device 50. This control device 5
0 is composed of a central processing unit, preferably a microprocessor (hereinafter referred to as CPU), a memory for storing its programs and necessary data, and interfaces with peripheral elements, circuits, devices, etc. When the disk pack 20 is placed in the bucket 13 and the bucket 13 is closed, the magnetic disks 21 in the disk pack 20 are mounted on the spindle of the disk motor 54. When the magnetic disk 21 is rotated, the magnetic head 51
Since recording or reproducing is performed by the magnetic disk 21, a regulating plate 53 is provided inside the cover 12 in order to maintain good contact between the magnetic head 51 and the magnetic disk 21 at all times. This regulation plate 53
has a groove along the moving path of the magnetic head 51, and is in contact with or close to the magnetic disk 21 at a portion other than the groove, so that the magnetic disk 21 is sandwiched between the magnetic head 51 and the magnetic disk 21. magnetic head 51
As described above, is disposed so as to be movable in the radial direction of the magnetic disk 21 and is in contact with the magnetic recording surface of the magnetic disk 21. In addition, a magnetic material is provided at one location of the core of the magnetic disk 21 to leak a part of the magnetic flux of the permanent magnet for chuck provided in the core, and this leakage magnetic flux is detected and the magnetic disk 21 rotates once. One phase detection pulse per
A phase detector 52 that generates PG is close to the core. The phase detection pulse PG of the phase detector 52 is input to the servo control circuit 56 and the control device 50. Frequency generator 5 provided on disk motor 54
5 outputs a signal with a frequency proportional to the number of rotations of the motor 54, and is applied to the servo control circuit 56. Furthermore, a vertical synchronization reference signal refV is input to this servo control circuit 56. Based on such input signals, the servo control circuit 56 controls the disk motor 54 at a constant rotation speed, for example, 3600 r.p.
m., and the rotational phase of the motor 54 is controlled so that the phase pulse PG advances 7H from the rise of the reference signal refV as shown in FIG. period).
Further, the servo control circuit 56 starts and stops the motor 54 in response to commands from the control device 50. The phase control of the motor 54 by the servo control circuit 56 has the following meaning. For example, in the first operation, the magnetic head 51 drives the magnetic disk 2.
Consider the case where an FM-modulated video signal is recorded on one predetermined track. A standard format color video signal applied to the input terminal 60 from a television camera, television receiver, etc. is processed by a recording processing circuit 61 in which its luminance signal component and chroma signal component are
The FM modulated signals are combined and given to the amplifier circuit 63. This amplified FM modulation signal is applied to the magnetic head 51 via a recording control switch 64 and a recording/reproduction changeover switch 65. On the other hand, horizontal and vertical synchronization signals of the input video signal are extracted by a synchronization separation circuit 61a and provided to a waveform shaping circuit 66. The waveform shaping circuit 66
As shown in the figure, a reference signal refV having a leading edge synchronized with the leading edge of the input vertical synchronizing signal Vsync and a duty ratio of approximately 1/2 is generated and output. This reference signal refV is given to the servo control circuit 56 via the synchronization changeover switch 68 (this is called external synchronization). Therefore, on the magnetic disk 21,
Recording of the video signal is performed by starting recording of the vertical synchronization signal from a reference position that is shifted by a rotation angle corresponding to a period of 7H from the position of the above-mentioned magnetic body that generates the phase pulse PG. It turns out. In the case of reproduction in the first operation, the oscillation circuit 6
7, a similar vertical synchronization reference signal refV is applied to the servo control circuit 56 via a switch 68 (this is called internal synchronization). By controlling the phase of the motor 54 using the reference signal refV and the phase pulse PG by the servo control circuit 56, the magnetic head 51 reads out a video signal in which the vertical synchronization signal always starts 7H behind the PG. It turns out. The phase pulse PG is given to the control device 50, and the video signal is synchronized with this pulse PG with a certain delay during both recording and reproduction, so the control device 50 controls timing in various processes. This pulse PG can now be used as a reference. This is the significance of phase control of the motor 54. The modulated video signal read out from the magnetic head 51 is input to an amplifier circuit 73 via a changeover switch 65, and further sent to a reproduction processing circuit 71 and an envelope detection circuit 72. The reproduction processing circuit 71 is
The input modulated luminance signal and chroma signal are respectively demodulated and combined and outputted to the output terminal 70 as a standard color video signal. When this video signal is applied to a television receiver, a still image for one frame is displayed on a cathode ray tube. The erase signal generation circuit 62 generates an erase signal, for example, for a certain period of time (about 1 second) in the erase mode.
Generates a signal whose frequency is continuously swept over a range of about 4.5 to 20 MHz. The magnetic head 51 is controlled by its transfer drive control device 57.
The magnetic disk 21 is supported movably in the radial direction of the magnetic disk 21 and is controlled to be moved in the same direction. The control device 50 provides instructions to the device 57 regarding the direction and amount of transfer of the magnetic head 51. The device 57 includes a step motor, and the magnetic head 51 is moved in proportion to the rotation angle of the step motor. For example, each drive pulse of the step motor causes the motor to rotate approximately 15 degrees, thereby moving the magnetic head 51 approximately 8.33 .mu.m (1 pitch). Therefore, the magnetic head 51 is transported very precisely. The envelope detection circuit 72 is connected to the magnetic head 51.
This is a detection circuit that detects the envelope of the read signal, that is, the FM modulated video signal recorded on the track of the magnetic disk 21, and outputs a voltage signal corresponding to the envelope. The voltage signal representing the envelope is converted by an analog/digital converter (A/D converter) built into the circuit 72 into an 8-bit digital signal representing, for example, 256 quantization levels, and then sent to the control device 50. Enter. The envelope detection signal is used to search for unrecorded tracks on the magnetic disk 21 and to detect the center position of recorded tracks (in playback and erase modes). If the level of the detected signal does not reach a predetermined threshold level when the magnetic head 51 is moved across a track, that track is unrecorded. When reproducing a video signal, after the magnetic head 51 is positioned using the above-mentioned absolute address method, the position where the detected signal shows a peak is searched for by moving the magnetic head 51 inward or outward one pitch at a time. The position showing the peak is determined to be the center of the track where the video signal is recorded,
The video signal is reproduced with the magnetic head 51 positioned at this center. This peak search is similarly performed for erasing the video signal, and areas within a certain range on both sides of the peak position are targeted for erasure. The recording control switch 64, the recording/playback switch 65, the synchronization switch 68, and the video output control switch 69 are shown as contact switches, but of course they are generally non-contact switches made of semiconductor elements or the like. Realized. These switches are turned on and off by the control device 50 in the following manner. First, control of the synchronization changeover switch 68 will be explained. This switch 68 is a synchronous switching control signal.
Controlled by SYCH. This signal SYCH is H
When the switch 68 is at the level, the waveform shaping circuit 66
This signal is connected to the side (i.e. external sync)
When SYCH becomes L level, switch 68 is connected to the oscillation circuit 67 side (ie, internal synchronization). The following table summarizes the level of the control signal SYCH output from the control device 50 for the first operation and the second operation.

[Table] That is, in the first operation, external synchronization is used in recording mode, and internal synchronization is used in playback mode. In addition, in the second operation, external synchronization is basically used in any mode. However, in the second operation, the video signal may not be provided to the input terminal 60 in the playback mode. At this time, internal synchronization must be used. In order to detect when there is no video signal input and forcibly convert the control signal SYCH given to the changeover switch 68 to the L level to connect the changeover switch 68 to the oscillation circuit 67, a low - A pass filter 77 and a switching transistor 68 are provided. The above-mentioned synchronization separation circuit 61a outputs vertical and horizontal synchronization signals extracted from the input video signal when it exists. This synchronization signal is low
Since the synchronizing signal applied to pass filter 77 mainly consists of high frequency components, the output of filter 77 is at L level, and transistor 78 is kept off. Therefore, the H level control signal SYCH output from the control device 50 is applied to the changeover switch 68 as is. When no video signal is applied to the input terminal 60, the synchronization separation circuit 61a outputs an H level signal. Therefore, this H level signal passes through the filter 77 and is applied to the base of the transistor 78, which turns on the transistor 78 and forcibly pulls the control signal SYCH line to the ground side. As a result, the control signal SYCH applied to the changeover switch 68 becomes L level, the switch 68 is connected to the oscillation circuit 67, and internal synchronization is established. In the first operation, the signal is
Since SYCH is at L level, even if no video signal is input at this time and transistor 78 is turned on, this signal SYCH remains at L level.
No problems arise. Next, control of the other switches 64, 65, and 69 will be explained. Since these switches are controlled in exactly the same way in both the first and second operations, only the operations in the first operation will be described. In the recording mode, the switch 64 is turned on at a certain timing, with exceptions to be described later, the switch 65 is connected to the recording processing circuit 61 side, and the switch 68 is connected to the waveform shaping circuit 66 side as described above. , the switch 69 is turned on. That is, when the recording standby mode is entered, the changeover switches 65 and 68 are respectively switched as described above by the recording/playback switching signal REC/PB and the synchronization switching signal SYCH from the control device. The switch 69 also outputs a video output control signal.
Turned on by VIDCH. Then, when the recording key 33 is pressed, as shown in FIG.
The switch 64 is turned on by the recording control signal REC only between two consecutive pulses PG.
Therefore, the FM modulated video signal is sent to the magnetic head 51 during this time, and one field is recorded in one rotation of the magnetic disk 21. At this time, since the switch 69 is on, the video signal input to the input terminal 60 is output to the output terminal 70 as is. When the recording review 42 is stored (recording review mode), playback is performed after recording as described above. Therefore, the magnetic head 51
When the recording is completed, the switch 65 is switched to the reproduction processing circuit 71 side in synchronization with the PG signal, and the switch 69 is turned off. Therefore, the video signal read by the magnetic head 51 is sent to the output terminal 70.
It will be output as playback output. After a certain period of time, these switches 65, 6
9 returns to the above state again. Even during the above-described playback in the recording review mode, the changeover switch 68 is connected to the waveform shaping circuit 66.
external synchronization. That is, since a video signal is input to the input terminal 60, servo control is performed based on the synchronization signal. As mentioned above, in the playback mode, the changeover switch 68 is connected to the oscillation circuit 67 side and internal synchronization is achieved, but during playback in the recording review mode, switching from external synchronization to internal synchronization is not performed, and external synchronization is not consistent. I can continue. This is because when switching from external synchronization to internal synchronization, the rotational phase of the disk motor 54 is temporarily shifted, which causes distortion in the video signal output from the output terminal 70, causing distortion in the image displayed on the cathode ray tube. This is because disturbances occur. Even in erase mode, switches 64, 65, 6
The states of 8 and 69 are the same as in the recording mode. In playback mode, switches 64 and 6
9 is kept off, switch 65 is switched to the reproduction processing circuit 71 side, and switch 68 is switched to the oscillation circuit 67 side as described above. Determination of the first operation and second operation, switching of operation modes, and various operations are all performed based on inputs from various switches and various keys. The various switches include a load end switch 81 that detects when the bucket 13 is closed to a position where the magnetic disk 21 therein will be securely attached to the spindle of the disk motor 54; A pack switch 8 detects that a disk pack 20 is stored in the bucket 13.
2. An erroneous recording prevention switch 83 that detects that the erroneous recording prevention claw 24 of the disk pack 20 housed in the bucket 13 has been removed and does not exist (that is, recording is prohibited), the above-mentioned home position switch 84, etc. be. Various keys include the key groups 31 to 3 provided on the front operation panel 11 described above.
6, 41 to 44, 18 and 48, and switches 3 provided corresponding to these key groups (excluding key 48) for operation by external devices.
There are 1A to 36A, 41A to 44A, and 18A. These switches 31A to 36A, 41A
~44A and 18A will of course be constructed by non-contact switches. When an external device is connected to the connector on the back panel of the still image recording/playback device 10, an operation control signal for this external device is given to the interface 88. The interface 88 includes a decoder that converts the operational control signal provided in the code data into a corresponding switch on/off control signal. As a result, switches 31A~
36A, 41A to 44A, 18A are turned on and off. The control device 50 performs a key scan routine at regular intervals (for example, 1/60 seconds), and in this key scan routine, the control device 50
sends a key scan pulse to the above-mentioned switch group, key group, and switch group, and detects and stores the on/off state of the switch or key depending on whether or not this pulse returns. Regarding the switch 48, processing may be performed based on an interrupt caused by switching the key scan routine. When the operation selector switch 48 indicates the first operation, the key groups 31-36, 41-44, and 18 on the front panel 11 are scanned. Further, when the switch 48 is set to the second operation, the switch groups 31A to 36A, 41A to 44 controlled by an external device
A, 18A is scanned. The control device 50 is
Key groups 31-36, 41-44, 18 and 31A-
36A, 41A to 44A, 18A are evaluated to be completely equivalent, so in both the first operation and the second operation, the above-mentioned synchronization changeover switch 6
Exactly the same operation is performed with some exceptions such as the control of No. 8. Further, the control device 50 includes the above-mentioned key scan
display control of indicator lights 45 to 47 based on routine;
It also controls the display of the display 17 based on routines for various operations.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the use of a still image recording and reproducing apparatus. FIG. 2 is a perspective view showing the appearance of the still image recording and reproducing device. FIG. 3 shows the track numbers and home positions on the magnetic disk. FIG. 4 shows various operating modes and how the operating modes change in response to inputs from various keys. FIG. 5 is a block diagram showing the electrical configuration of the still image recording and reproducing apparatus. FIG. 6 is a time chart showing the synchronous control of the disk motor by the servo control circuit and the recording timing. 21...Magnetic disk, 50...Control device, 5
1... Magnetic head, 52... Phase detector, 54...
...disk motor, 56...servo control circuit,
61a...Synchronization separation circuit, 66...Waveform shaping circuit, 67...Oscillation circuit, 68...Synchronization changeover switch, 77...Low pass filter, 78...Switching transistor.

Claims (1)

[Claims] 1. A motor for rotating a magnetic disk, a phase detector that generates a signal representing the rotational phase of the magnetic disk, and input of the phase signal detected by the phase detector and a synchronization signal related to a video signal. And the above motor is
A still image recording/playback device comprising: a motor control device that controls the motor to rotate at a predetermined number of rotations and to maintain a predetermined relationship between the input phase signal and the synchronization signal; a synchronization separation circuit for extracting the output, an oscillation circuit for the synchronization signal, a synchronization changeover switch that is controlled by the synchronization switching control signal and selectively applies the outputs of both of the circuits to the motor control device, and a first operation and a second operation. an operation changeover switch for switching, a first operation so that when the first operation is set, the synchronization changeover switch selects the output of the oscillation circuit in the playback mode, and selects the output of the synchronization separation circuit in the recording mode; 2 operation is set, a switching control means for outputting the synchronization switching control signal that controls the output of the synchronization separation circuit to be selected in either playback or recording mode; and a video signal to be input. a detection circuit that detects that there is no input video signal, and in response to an output of the detection circuit indicating that there is no input video signal, controls the synchronization switching control signal such that the synchronization switching switch selects the oscillation circuit. A synchronous control device in a still image recording/playback device, comprising: a circuit for converting into a signal.