JPS62200881A - Screen muting method for electronic still picture reproducing device - Google Patents

Abstract

PURPOSE:To insure a picture against being projected while the rotational frequency of a recording medium is unstable by detecting the deviation of a pulse generated by synchronizing with the rotation of a recording medium from an independently set reference signal and outputting a mute signal in a video signal processing circuit. CONSTITUTION:A recording medium rotation synchronizing pulse generator 6 generates a pulse signal synchronizing with the rotation of the recording medium 2, and inputs it as an interruption request pulse to a microcomputer (MC) 8 through a waveform shaping circuit 7 at every rotation of the recording medium 2. After the MC 8 saves the current value of a timer in a memory, it clears the timer, and reactivates it. Thus the saved value of the timer turns out to be the hourly interval between the current and preceding interruptions. Since the hourly interval is equivalent to the rotational frequency of the recording medium 2, it is compared with a preset reference value, and checked to lie within a normal range. If not, the mute signal is outputted to a video signal processing circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electronic still image reproducing device that records different image information for each track on a recording medium such as a floppy disk and reproduces it as needed. This relates to a screen mute method.

BACKGROUND OF THE INVENTION Conventional electronic still image reproducing devices magnetically record images using disk-shaped disks as recording media. The image is played back.

Problems to be Solved by the Invention There is a period when the rotational speed is unstable, such as when a recording medium is installed in a device. During this period, normal reproduction is not possible, so an unsightly image is displayed, causing discomfort to the viewer.

Means for Solving the Problems A deviation between a pulse generated in synchronization with the rotation of a recording medium and a separately set reference signal is detected and a mute signal is output to a video signal processing circuit.

Function: When the rotational speed of the recording medium is unstable, a mute signal is given to the video signal processing circuit, so that an unsightly image is not displayed on the CRT screen. An extremely easy-to-see state can be obtained in the image processing device.

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 to 3. First, a disc-shaped recording medium 2 is detachably attached to a motor 1 and driven, and the rotation of the motor 1 is controlled by a motor drive circuit 3. and,
A head 4 is provided above the recording medium 2 for reading signals recorded on the recording medium 2 by driving in the radial direction thereof. This head 4 is connected to a video signal processing circuit 5, and this video signal processing circuit 5 is connected to a monitor television (not shown).

Further, a recording medium rotation synchronizing pulse generator 6 is arranged above the recording medium 2, and a microcomputer 8 is connected to this recording medium rotation synchronizing pulse generator 6 via a waveform shaping circuit 7. .

The video signal processing circuit 5 is connected to this microcomputer 8 .

In this configuration, the recording medium rotation synchronizing pulse generator 6 generates a pulse signal synchronized with the rotation of the recording medium 2 every time the recording medium 2 rotates, and the waveform and voltage level are adjusted by the action of the waveform shaping circuit 7. And microcomputer 8
The pulse is input as an interrupt request every time the recording medium 2 rotates.

At this time, the program of the microcomputer 8 interrupts the processing currently being performed and moves the processing to the interrupt processing routine shown in FIG.

Therefore, in the interrupt processing routine, first, the current timer value is saved in the memory, the timer is cleared, and the timer is restarted. As a result, the timer value saved in the memory becomes the time interval between the previous interrupt and the current interrupt.

Since this time interval is equivalent to the rotation period of the recording medium 2, it is compared with a preset reference value to check whether it is within the normal range.If it is normal, a mute signal is output, and if it is normal, the mute is released. Output.

Looking at this point with reference to FIG. 3, at point A of the output of the waveform shaping circuit 7, the interrupt processing to the microcomputer 8 starts, and the timer starts. Then, at point B, the next interrupt processing to the microcomputer 8 starts, and the timer stops. At this time, the timer value T is saved in the memory, and the lower value of the timer value is the rotation period of the recording medium 2, and is compared with a reference value.

That is, when the rotational speed of the recording medium 2 is not the specified rotational speed immediately after starting the motor 1, or when the rotational speed is not stable for some reason, the video signal processing circuit 5
to prevent unsightly images from being displayed on the TV monitor.

Next, a second embodiment of the present invention will be described based on FIGS. 4 to 6. The same parts as in the previous embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In this embodiment, a reference phase signal generation circuit 9 is connected to a motor drive circuit 3 and also to an interrupt terminal of a microcomputer 8.

In such a configuration, the reference signal from the reference phase signal generation circuit 9 is applied to the interrupt request terminal of the microcomputer 8. At this time, the program of the microcomputer 8 interrupts the processing currently being performed and shifts the processing to the interrupt routine shown in FIG. In this interrupt processing routine, first, a timer is started at this point in order to set the time point at which the interrupt occurs as the time origin. Then, by monitoring the output of the waveform shaping circuit 7, it waits until a pulse signal synchronized with the rotation of the recording medium 2 comes, and when it comes, it stops the timer and changes the timer value, that is, from the time when the interrupt occurs. The time taken until the recording medium rotation synchronization pulse signal arrives is defined as the difference between the reference phase signal and the actual phase of the recording medium 2. Then, it is determined whether this difference is within the permissible range or not, and if it exceeds the permissible range, a mute signal is output from the 1 output terminal of the microcomputer 8 to the mute signal input terminal of the video signal processing circuit 5. . Further, if the permissible range is not exceeded, a mute release signal is output from the first output terminal of the microcomputer 8 to the mute signal input terminal of the video signal processing circuit 5.

Therefore, the video signal processing circuit 5
to prevent unsightly images from being displayed on the TV monitor.

To explain this state based on the timing chart shown in FIG. Point D of the output β is the point at which the timer stops using a pulse signal synchronized with the rotation.

Then, the phase difference φ, which is the difference between the 0 point of the output α of the reference phase signal generation circuit 9 and the D point of the output β of the waveform shaping circuit 7, is detected and the error with the reference value is determined, and a mute signal is generated. It is used as a standard.

Effects of the Invention The present invention generates a pulse in synchronization with the rotation of a recording medium as described above, uses this pulse as an interrupt request for a microcomputer provided inside the device, and also corrects the deviation of the pulse with respect to a reference signal. Since it detects this and outputs a mute signal to the video signal processing circuit, if the rotation speed of the recording medium does not reach the specified rotation speed immediately after starting playback, or if the rotation speed is unstable for some reason, To prevent an unsightly image from being displayed on a monitor television by generating a mute signal, and thereby only a clear image can be obtained.

[Brief explanation of drawings]

1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a flowchart thereof, FIG. 3 is a timing chart, FIG. 4 is a circuit diagram showing a second embodiment of the present invention, and FIG. The figure is a flowchart, and FIG. 6 is a timing chart. 2... Recording medium, 5... Video signal processing circuit, 8...
・Microcomputer applicant: Tokyo Electric Co., Ltd. 1r""'41-1. Ichiatsu” HoyO7 figure,, i) Must figure J3u mouth

Claims (1)

[Claims] A pulse is generated in synchronization with the rotation of the recording medium, and this pulse is used as an interrupt request for a microcomputer provided inside the device, and a deviation of the pulse from a reference signal is detected and a mute signal is sent to the video signal processing circuit. A screen muting method for an electronic still image reproducing device, characterized in that the screen is output.