JP2533114B2 - Image playback device - Google Patents

Description

The present invention relates to an image reproducing device such as a video disc player or a video tape recorder, and more particularly to a device for reproducing a still image thereof.

(Prior Art) As is well known, in image reproducing devices such as video disc players and video tape recorders, for example, a television signal read from a disc or tape is converted into digitized data, and this digital television signal is converted into digital data. A digital image processing technique has been introduced in which various special image processes are performed by writing and reading to and from a memory.

Among such digital image processing, for still image reproduction, one field of the interlaced digital television signal (263 horizontal synchronization period) is stored in the memory,
This stored data is read out for 263 horizontal synchronization periods by even field scanning and an image is displayed, and by odd field scanning.
By reading out 262 horizontal synchronization periods for image display, a still image of a television signal for one frame (525 horizontal synchronization periods) is displayed.

By the way, as described above, in order to alternately read the television signal for the 263 horizontal synchronizing period and the television signal for the 262 horizontal synchronizing period to display an image, the position of the vertical synchronizing signal is changed each time. It is necessary to let Therefore, in the conventional art, as shown in FIG. 6, a pseudo vertical synchronization signal generated by alternating 263 horizontal synchronization periods and 262 horizontal synchronization periods is generated, and this pseudo vertical synchronization signal is generated in the vertical synchronization in the television signal. By inserting in a portion, the vertical sync signal is maintained in a uniform continuity, and a high-quality image free from skew is obtained.

However, in the conventional still image reproducing means as described above, since it is necessary to separately provide a circuit for generating the pseudo vertical synchronizing signal, the configuration becomes complicated and large, and
There is a problem that it is not suitable for practical use.

(Problems to be Solved by the Invention) As described above, the still image reproducing means provided in the conventional image reproducing device has a problem that the configuration is complicated and large.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an extremely good image reproducing apparatus which can perform high quality still image reproduction with a simple configuration and is suitable for practical use.

[Structure of the Invention] (Means for Solving the Problems) That is, the image reproducing device according to the present invention stores the one-field period of the interlaced digital television signal in the memory and then reads it out to read the original television. It is intended for playback of still images by converting to John signals. Then, when reading a digitized television signal from the memory, 0.5 horizontal synchronization is performed in the equalization period provided before and after every other vertical synchronization portion in the continuous vertical synchronization portion in the television signal. A hold time in which an integer number of color subcarriers intervenes by adding a correction time to the period is inserted by holding a read address for the memory. In this case, the hold time is set so that the total of four times corresponds to two horizontal synchronization periods.

(Operation) According to the above configuration, the 262
When reading a digital television signal for the horizontal synchronization period, in the equalization period provided before and after every other vertical synchronization portion in the continuous vertical synchronization portion in the television signal, in the 0.5 horizontal synchronization period. By inserting a corresponding hold time, the period of the vertical synchronizing portion, that is, one field is set to 262.5 horizontal synchronizing period, and one frame (525 horizontal synchronizing period) of a television signal is displayed as a still image by scanning two fields. By doing so, it becomes possible to obtain a good-quality still image without skew.

Also, the insertion of the hold time can be easily realized by holding the read address of the memory, and it is not necessary to generate the pseudo vertical synchronization signal as in the conventional case, and the configuration is simplified and the miniaturization is promoted. Is something that can be done.

In addition, the correction time is added to the hold time of 0.5 horizontal synchronization period to set the integer number of color subcarriers, so that the continuity of the color subcarriers can be maintained and, in this case, the hold time for four times. By setting so that the total of 2 corresponds to 2 horizontal synchronization periods, it is possible to cancel the time axis error due to the addition of the correction time.

(Embodiment) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 11 is an input terminal to which an analog television signal reproduced from a recording medium such as a disk or tape is supplied. The analog television signal supplied to the input terminal 11 is converted into a digital television signal by the A / D (analog / digital) conversion circuit 12 and then supplied to the field memory 13.

Here, the field memory 13 has a capacity capable of storing 262 horizontal synchronizing periods (one field) of the digital television signal, and is controlled by the control circuit 14 into a writing mode and a reading mode. And
The field memory 13 stores a digital television signal based on the write address output from the write address counter 15 controlled by the control circuit 14.

Further, the field memory 13 reads the stored digital television signal based on the read address output from the read address counter 16 controlled by the control circuit 14.

On the other hand, the digital television signal read from the field memory 13 is D / A (digital / analog).
It is converted into the original analog television signal by the conversion circuit 17 and is used for image reproduction through the output terminal 18. Then, when a new digital television signal is not written in the field memory 13, the still image is reproduced by reading the same digital television signal for one field.

Here, when reading a digital television signal from the field memory 13, as shown in FIG.
The hold time of the horizontal sync period is inserted. However, as shown in FIG. 3, the insertion of the hold time is specified in the equalization period before and after every other vertical synchronizing signal with respect to the continuous vertical synchronizing signal.

In this way, by inserting a hold time of 0.5 horizontal synchronization periods in the equalization period before and after every other vertical synchronization signal, the intervals of each vertical synchronization signal can be unified to 262.5 horizontal synchronization periods. High-quality image display can be performed without generating a pseudo vertical synchronizing signal as in the conventional case.

Next, a means for inserting a hold time of 0.5 horizontal synchronization period in the equalization period before and after the vertical synchronization signal will be described. First, as shown in FIG. 4A, when the digital television signal stored at the read address output from the read address counter 16 is output from the field memory 13, at time T1 immediately after the equalization pulse. , 0.5 The operation of the read address counter 16 is stopped only during the horizontal synchronization period. Then, as shown in FIG. 4 (b), the digital television signal output from the field memory 13 is held in the data at time T1 for 0.5 horizontal synchronization period,
A hold time of 0.5 horizontal synchronization period is inserted here.

By the way, since an integer number of color subcarriers cannot be included in the 0.5 horizontal synchronization period of the hold time described above, in order to maintain the continuity of the color subcarriers, the correction time α is added to the hold time of the 0.5 horizontal synchronization period. , It is possible to add an integer number of color subcarriers. For example, if the total hold time including the correction time α is T HOLD, then T HOLD = (1/2) H + α = (1/2) (455/2) T SC + (1/4) T sc = 114T sc Become. However, H is the cycle of the horizontal synchronizing signal, and Tsc is the cycle of the color subcarrier.

In this case, assuming that the hold time is 0.5 horizontal synchronization period plus the correction time α, a time axis error occurs for the correction time α from the reference time base. Therefore, as shown in FIG. 5, the correction time α is (1/4) T s
Since it is c, if the fourth correction time α is set to − (3/4) T sc, the correction time α is canceled and the time axis error can be eliminated. In other words, it is only necessary to set the total hold time for four times to be two horizontal synchronization periods.

The present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the invention.

[Effects of the Invention] Therefore, according to the present invention as described in detail above,
A still image of high quality can be reproduced with a simple structure, and an extremely good image reproducing apparatus suitable for practical use can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image reproducing apparatus according to the present invention, FIGS. 2 and 3 are timing charts showing hold time insertion positions in the embodiment, and FIG. FIG. 5 is a timing chart showing a holding time inserting means in the example, FIG. 5 is a timing chart showing a modification of the embodiment, and FIG. 6 is a timing chart showing a conventional still image reproducing means. 11 …… input terminal, 12 …… A / D converter, 13 …… field memory, 14 …… control circuit, 15 …… write address counter, 16 …… read address counter, 17 …… D / A
Conversion circuit, 18 ... Output terminal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Abe 8 Shinshinsita-cho, Isogo-ku, Yokohama-shi Toshiba Audio Video Engineering Co., Ltd. (56) Reference JP-A-61-65583 (JP, A) JP-A-63-50292 (JP, A) JP-B-55-39945 (JP, B2)

Claims (2)

(57) [Claims] 1. An image reproducing apparatus for reproducing a still image by storing one field period of an interlaced digital television signal in a memory, reading it out, and converting it into an original television signal. When reading the converted television signal, with respect to the continuous vertical synchronization portion in the television signal,
Hold the read address to the memory for a hold time in which an integer number of color subcarriers are interposed by adding a correction time to the 0.5 horizontal synchronization period in the equalization period provided before and after every other vertical synchronization portion. An image reproducing apparatus characterized in that it is configured to be inserted in. 2. A total of 4 hold times is 2 hold times.
The image reproducing apparatus according to claim 1, wherein the image reproducing apparatus is set so as to correspond to a horizontal synchronization period.