JPS639382A - Waveform processing circuit for television synchronizing signal - Google Patents

Abstract

PURPOSE:To reproduce and display a stable still picture by outputting cutting pulse for synchronization in vertical synchronizing period in delay period and synthesizing the cutting pulse for synchronization to non-delayed vertical synchronizing signals. CONSTITUTION:A monostable multivibrator 9 operates only in a delay period. When a C.Sync signal becomes H level, and a vertical synchronizing period comes, only one pulse signal is outputted as cutting pulse for synchronization corresponding to horizontal synchronizing signal in a delayed vertical synchronizing period. Such operation is not executed in non-delay period. When reproduction is made by television by such frame signals, reproduction and display are executed as before in the field in non-delay period, and reproduction and display are controlled by a vertical synchronizing signal delayed by 0.25H from a non-delay period in the field of a 0.5H delay period. Even when the image of any kind of pattern is reproduced, the vertical oscillation of the image does not occur, and the stable state of display can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television synchronization signal waveform processing circuit in an electronic still camera reproducing device or the like that reproduces and displays still images using a normal television receiver.

2. Description of the Related Art In recent years, electronic still cameras and the like have been commercially available which magnetically record photographic images taken by a camera on a rotating disk and reproduce and display the photographic images as still images on a television screen. Here, video signals are recorded on a plurality of concentric tracks on a rotating disk in a relationship of one track-one screen, that is, one rotation-one field.

By the way, a 1/2 interlaced scanning (interlaced scanning) scheme is adopted as an ordinary television standard scheme. For example, in the NTSC system, the number of horizontal scanning lines in one field is 262.5H, and the number of striped scanning lines in two fields, that is, one frame, is set to be 525H. When playing back a rotating disk of an electronic still camera on which a video signal of one field (i.e., 262.5H horizontal scanning line) is recorded on one track using such a television, problems arise at the seams of recording. becomes. That is, the video signal on the same track (always the same video signal in each field) is read while the rotating disk is continuously rotated.

Horizontal synchronization is 0 at the recording seam (i.e. start point = end point)
．． Each field is shifted by 5H1, that is, 1/2 of the horizontal synchronization period, and when reproduced on a normal television receiver, the screen becomes distorted and normal still image display becomes impossible.

Therefore, by passing the 1-field repeated playback signal alternately through 0 and 5H delay circuits corresponding to 1/2 horizontal synchronization period for each field from the recording joint on the track, and by synthesizing these, the horizontal synchronization continues. It is necessary to create a playback signal. Figure 8 shows such reproduction signal processing, in which a field reproduction signal by a through signal and a 0.5H
The 0 and 5H delay signals passed through the delay circuit are alternately selected for each field by a switching pulse SWP,
A frame signal (video signal) is obtained by alternately combining these signals. Note that PG is a pulse generator that is generated every rotation of the rotating disk and regulates one field. Note that the pulses indicated by H in the reproduced signal are horizontal synchronizing signals, and the pulses indicated by ■ are vertical synchronizing signals. More specifically, as shown in an enlarged view of a part of the frame signal in FIG. 8, the image signal is placed between the horizontal synchronization signals in the IH row, but near the vertical synchronization, the image signal is 0,
There are a plurality of equivalent pulses arranged in a 5H arrangement, and the vertical synchronization signal V is made up of six of these equivalent pulses, ie, 3H.

By the way, if such a vertical synchronization signal ■ does not always pass through a delay circuit of 0.58 minutes, it will be 1/2 interlaced scanning as the television standard system, but for such reproduced still images, It has the following drawbacks: For example, if one scanning line is a white image and the scanning lines before and after it are black images, or if a certain scanning line forms a boundary between a white image and a black image, the displayed raster is a raster that does not have a delay of 0.5H. The raster delayed by 0.5H vibrates up and down by one scanning line interval for each field.

As a result, the display state of the still image becomes unstable as it vibrates up and down.

The point of vertical vibration will be explained with reference to FIG. 9. In this figure, in order to simplify the explanation, it is assumed that one field is composed of 4.5H horizontal scanning lines, and only synchronization pulses are extracted and shown. First, consider the case where the synchronization pulse of the reproduced signal as shown in (a) is delayed by 005H for each field including the vertical synchronization signal (■) as shown in (b). In the case of a synchronization pulse as shown in (b), the vertical scanning waveform is operated by the vertical synchronization pulse ■, and in a normal television receiver, the vertical scanning waveform is as shown by the solid line in (c). was confirmed. In such a state, for example, the number 2 in the horizontal synchronizing pulse H is shifted to an upper position during the 0.5H delay period compared to its upper and lower positions during the non-delay period. On the other hand, for the synchronization pulses like (a), only the vertical synchronization pulse ■ is always non-delayed (d)
Consider the case of synchronized pulses as shown in . In other words, this is standard 1/2 interlaced scanning, and the vertical scanning waveform is as shown by the dashed line in (C). In this case, 0.0 for the non-delay period.
During the 5H delay period, the horizontal scanning position shifts to the lower position.

In the end, if we only delay 0.5H alternately for each field, the displayed image will shift vertically between the non-delay period and the delay period, regardless of whether the vertical synchronization pulse is delayed or not. It's something to put away. As a result, some images may be displayed in a very unsightly manner.

Means to solve the problem To ensure consistency between fields of horizontal synchronization signal,
The basic configuration includes a delay circuit corresponding to a 1/2 horizontal synchronization period to which a 1-field repetitive reproduction signal of a 1/2 interlaced television video signal is input alternately every field repetition period.

As for the vertical synchronizing signal, a through signal that is not delayed by the control signal is output even during the delay period. On the other hand, for such a delay circuit,
A synchronization signal generation circuit is provided that outputs a synchronization cutting pulse corresponding to one horizontal synchronization signal for the vertical synchronization signal during the delay period by the delay circuit. Furthermore, a waveform synthesis circuit is provided which synthesizes the synchronization cutting pulse outputted from the synchronization signal generation circuit with the non-delayed vertical synchronization signal to create a corrected vertical synchronization signal.

Basically, for each field, a through signal which is not delayed and a delayed signal which is delayed by 1/2 horizontal synchronization period by a delay circuit are outputted for each field. However, even during the delay period caused by the delay circuit, a through signal is output as the vertical synchronization signal depending on the control signal. Then, a synchronization cut pulse corresponding to one horizontal synchronization signal is output for the vertical synchronization signal during the delay period, and this pulse is synthesized with the through vertical synchronization signal by the waveform synthesis circuit, so that The vertical synchronization signal of the delay field is substantially delayed in timing. By using the vertical synchronization signal modified in this manner, the raster position of the delayed field is reproduced on the television screen at substantially the same position as the raster position of the non-delayed field.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 6. First, the schematic configuration is shown in the block diagram of FIG. A playback signal of a certain track read by the playback head 1 is input to the head amplifier 2, and after amplification, one side is converted into a non-delayed through signal, and the other side is set to a 0.5H delay circuit 3 corresponding to 1/2 horizontal synchronization period. The signal is input to the demodulation circuit (FM) 4 as a 0.58 delay signal. Here, in the demodulation circuit 4, these through signals and the 0.5H delay signal are alternately switched for each field by a swp(y) signal (Y means a luminance signal). The demodulated signal is then separated into a composite sync (C-Sync) signal by a synchronization signal separation circuit 5, which is then passed through a synchronization signal generation circuit 6 to generate a synchronization signal. A waveform synthesis circuit 7 synthesizes these signals and outputs them to a receiver as a frame signal (video signal). Here, switching pulse SWP
5WP(Y) selects between a through signal and a 0.58 delay signal by switching between H level and L level for each field, but 5WP(Y) selects only the vertical synchronization period during the delay period. is a through signal selection state.

Here, the specific configuration of the synchronization signal generation circuit 6 and the waveform synthesis circuit 7 is shown in the circuit diagram of FIG. First, a signal swp, which is an inversion of the SWP signal, and a C-5ync are input to an A N D gate 8 including diodes D, , D2. These diodes D, , D, are connected to the midpoint of a series circuit of a resistor R1 and a capacitor C1 connected to a power supply.

Also, two diodes DI' are connected to this connection midpoint.
ID, is connected to the diode D, and the base of the transistor Tr is connected to the diode D. A resistor Ra and a resistor Rh are connected to the collector and emitter of the transistor Tr, respectively. The midpoint between Rb and the emitter is the resistor R2 and capacitor C connected to the power supply.
It is connected to the midpoint of the series circuit with 2. The purpose of using such a resistor Rb is to eliminate the influence of temperature, but if the influence of temperature can be ignored, a diode may be used instead of the resistor Rb (diode D is used in the modification shown in FIG. 6).

). Moreover, this transistor Tr1
The collector of is connected to the B terminal of a monostable multivibrator 9 having a CMO3 configuration. The A terminal of this monostable multivibrator 9 is grounded, and the output terminal Q is output to the waveform synthesis circuit 7. That is, it is input to the base of the switching transistor Tr via the resistor R3. A capacitor C3 is connected to the emitter side of the transistor Tr, and the midpoint between the two is connected to the resistor R1 of the resistors R4, R,, R, connected to the power supply. Further, the collector of the transistor Tr is connected to the signal line of the demodulated reproduction signal, that is, the resistor R? It is connected to the midpoint of IRl. Further, the reset terminal CD of the monostable multivibrator 9 is connected to the midpoint between a resistor R3 and a capacitor C4 connected to the power supply. A resistor R1° is connected via a diode D between this midpoint and the collector of the transistor Tr.

In such a configuration, the monostable multivibrator 9 of this circuit operates only during the delay period.

In other words, when SWP is at H level, AND gate 8
That is, input of C-3 sync is allowed only during one period of 0.58 days. When this C-8ynC signal becomes H level, it is charged with the time constant of resistor R1 and capacitor CI, but as shown in Fig. 3, during the horizontal synchronization period, C-8ynC
Since the H level period of Tr is short, the transistor Tr does not turn on. However, during the vertical synchronization period, C
Since the H level period of -3ynC becomes longer, the time constant due to resistor R1 and capacitor C1 (currently 10-15
(on the order of μs). This turns on the transistor Tr. This transistor Tr.

The monostable multivibrator 9 is triggered by the falling edge caused by turning on, and outputs a pulse output from the output terminal Q as shown by the signal E in FIG. At this time, the reset terminal CD of the monostable multivibrator 9 is initially maintained at the H level by the time constant of the resistor R3 and the capacitor C4 and is not reset, but the input terminal B is L level (0,4■
)fall into. Therefore, the waveform at point D is the resistance R,,R,. and drops to L level (1.4V) by capacitor C4. When this point D falls to the L level, the monostable multivibrator 9 enters the reset state.

Therefore, the monostable multivibrator 9 outputs only one pulse signal indicated by the signal E as a synchronization cutting pulse corresponding to the horizontal synchronization signal during the delayed vertical synchronization period.

More specifically, as shown in FIG.
is turned on at a timing delayed by the charging operation of capacitor C8, and monostable multivibrator 9 also operates at this timing. As a result, the synchronization cutting pulse output from the monostable multivibrator 9 is output at a timing delayed by 0.25H from the vertical synchronization start timing.

Such a synchronizing cutting pulse is generated by a transistor Tr,
By being output to the signal line through the signal line and being synthesized, the timing of the vertical synchronization signal is outputted as a vertical synchronization signal delayed by 0.25H in one period with a delay of 0.58H compared to that in the through period. . In other words, the period during which the monostable multivibrator 9 is reset is 5WP (
Y) Corresponds to the period in which the signal is in a through state only during the vertical synchronization period during one period of 0°5 delay, and 0.
The vertical synchronization signal during the 5H delay period is corrected to a signal delayed by 0.258. Such operations are not performed at all during the non-delay period. Therefore, one synchronizing cutting pulse is inserted for every two vertical synchronizations, that is, one per frame, only for the 0.5H delay field.

Such an operation is shown in FIG. 5, which compares it with the conventional example shown in FIG. The timing chart of this reproduction signal processing shows that even if swp(y) is in a 0.5H delay period, it is inverted and in a non-delayed state (through state) during the vertical synchronization period. , it is shown that the frame signal corresponds to this period, and the synchronization cut pulse is synthesized with the through vertical synchronization signal. If the frame signal as shown in FIG. 5 is played back on a television, the field in the non-delay period will be played back and displayed as before, and 0.5)! In the delay period field, reproduction and display is controlled by a vertical synchronizing signal delayed by 0.25H from the non-delay period. According to the reproduction display of the field in such a non-delay period, 0. Even during the 5H delay period, the raster position is always the same, and no matter what picture image is reproduced, the image does not vibrate up and down, resulting in a stable display state.

In other words, it is clearer from FIG. 6, which is shown in contrast to FIG. 9, that such raster positions are always constant. In this Figure 6, the timing of the vertical synchronization signal in the 0.5H delay period is delayed by the timing of 0.25H with respect to the vertical synchronization signal in the non-delay period by the synchronization cutting pulse, and the timing is corrected as shown in 2. This shows that even if the horizontal scanning lines based on the vertical synchronizing signal are in a non-delay period, they are located on the same line and there is no vertical shift.

Note that this embodiment is not limited to magnetic recording, as long as it is a one-field recording method, optical recording, uneven recording, and rotating disks may be used; however, instead of these, E-
In the case of E optical input, since the original 1/2 interlaced television video signal is input, it is necessary to avoid inserting a synchronization cutting pulse as in this embodiment in place of the vertical synchronization signal. . In this case, the RFC signal may be input to the A terminal of the monostable multivibrator 9 to disconnect this circuit.

FIG. 7 shows a modification. Basically, it is the same as the case shown in FIG. 1, but only C-5ync is input to the input side of the transistor Tr. Moreover, instead of the monostable multivibrator 9, a circuit configuration including two transistors Tr, Tr, a plurality of resistors R, . This is what I did. Here, diode D
, ~D constitute the OR gate 10, the output from the collector side of the transistor Tr3 is input to the diode D, and the output from the collector side of the transistor Tr3 is input to the diode D.
, the output from the collector of diode D is input.

is the color signal switching pulse 5WP(C)(S
(corresponding to WP(Y)) is input. Even with this configuration, one synchronization cutting pulse is output to the transistor Tr2 during the vertical synchronization period in the field of the 0.5H delay period.

Used for waveform synthesis.

Effects of the Invention As described above, the present invention includes a synchronization signal generation circuit that outputs a synchronization cutting pulse corresponding to one horizontal synchronization signal to a vertical synchronization signal during the vertical synchronization period during the delay period. Since a waveform synthesis circuit is provided that synthesizes this same JtJJ notch pulse with the non-delayed vertical synchronization signal, the vertical synchronization signal of the field to be delayed can be combined with the vertical synchronization signal of the non-delayed period into the synchronization notch pulse. The timing is corrected to a slightly delayed timing due to the pulse, and by performing synchronization control using such a vertical synchronization signal, the raster position of the delayed field becomes substantially the same as the raster position of the non-delayed field. Since there is no raster position shift, stable still images can be reproduced and displayed without vertical vibration, no matter what kind of picture the picture is.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a schematic block diagram, FIG. 3 is an operation waveform diagram of the circuit in FIG. 1, and FIG.
The figure is an operation waveform diagram showing an enlarged part of Fig. 3, Fig. 5 is a timing chart of reproduction signal processing, Fig. 6 is a timing chart showing a state in which vertical vibration does not occur, and Fig. 7 is a timing chart showing a state in which vertical vibration does not occur.
FIG. 8 is a circuit diagram showing a modified example, FIG. 8 is a timing chart of reproduction signal processing showing a conventional example, and FIG. 9 is a timing chart showing a state in which the vertical vibration state occurs.

Claims (1)

[Claims] In a television synchronization signal waveform processing circuit equipped with a delay circuit corresponding to 1/2 horizontal synchronization period, a one-field repetitive playback signal of a television video signal by 1/2 interlacing is input alternately every field repetition period. A synchronization signal generation circuit generates a control signal that does not always delay only the timing of the synchronization period, and outputs a synchronization cutting pulse corresponding to one horizontal synchronization signal with respect to the vertical synchronization signal timing during the delay period by the delay circuit. A television synchronization signal waveform processing circuit comprising: a waveform synthesis circuit for synthesizing the synchronization cutting pulse with the non-delayed vertical synchronization signal to create a corrected vertical synchronization signal.