JP2615749B2 - Television receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver which displays an image whose effective screen has an aspect ratio different from the aspect ratio (3: 4) of a standard television image. Things.

2. Description of the Related Art In recent years, television receivers (hereinafter, referred to as television receivers) are often used not only for receiving broadcasts but also as display devices for package software such as video tapes and video disks. In recent package software, for example, in a movie or the like, all the images are displayed. Therefore, the aspect ratio (aspect ratio) of the movie is maintained.
The ones with blanking (black band) at the top and bottom are increasing.

By the way, the aspect ratio of a television receiver is 3 to 4,
It is known that, in order to obtain a more powerful image such as a cinemascope or a high-definition television, the image should be more horizontally long.

In a conventional television, the aspect ratio of the receiver is 3: 4, and when playing an image in which the aspect ratio of the effective image is longer, black bands are displayed at the top and bottom, and the aspect ratio of the display unit remains at 4: 3. Therefore, the display unit is not sufficient with the conventional aspect ratio to make a more powerful image. Recently, as high-definition televisions (9:16 aspect ratio) have been put into practical use, proposals have been made to display standard television images on screens having different aspect ratios in order to provide compatibility with standard television broadcasting. ing.

Hereinafter, the above-described conventional television receiver will be described with reference to the drawings.

FIG. 4 is a system diagram of a conventional television receiver for converting an aspect ratio. In FIG. 4, reference numeral 30 denotes a receiving circuit including a tuner to a video detection circuit, from which a high-quality luminance signal Yw or a standard luminance signal Ys is taken out according to a broadcasting form. In the case of high-definition television broadcasting, the luminance signal Yw from the receiving circuit 30 is passed through the high-definition side contact w of the changeover switch 31 and further through the video amplifier 32 to the picture tube 33.
Supplied to The aspect ratio of the picture tube 33 is 9:16 for a high-definition television.

On the other hand, in the case of a standard television broadcast, the standard luminance signal Ys from the receiving circuit 30 is supplied to the memory circuits 34a and 34b including a CCD or the like. The horizontal sync pulses Ph from the horizontal sync separator 35 is supplied to the write read pulse forming circuit 36, to enable the horizontal scanning period of the standard luminance signal Ys, along with the write pulse phi _R of a predetermined distance is formed, Pulse φ
Only the ratio 3/4 interval of the horizontal size of the screen of the high definition level of the screen and the standard television than _R is compressed, and the same number and pulse phi _R, the read pulse phi _P located in the center of the effective horizontal scanning period forms Is done.

These pulses φ _R and φ _P are applied to switch circuits 37 and 38.
And the horizontal synchronization pulse Rh from the horizontal synchronization separation circuit 35 is supplied to the flip-flop circuit 39 to form a rectangular wave signal Sh that is inverted every horizontal period, and controls the switch circuits 37 and 38. As a result, the pulses φ _R and φ _P are alternately supplied to the memory circuits 34a and 34b every horizontal period.
Therefore, in the memory circuits 34a and 34b, the writing and reading of the signal Ys are performed alternately every horizontal period.

In this case, the read pulse phi _P is equal to the number of write pulses phi _R, and because the distance (sync) is compressed to 3/4, the signal Ys read from the memory circuit 34a, 34b is Its time axis is compressed to 3/4. The compressed luminance signal Ys is referred to as a signal Yc. The luminance signal Yc thus read alternately from the memory circuits 34a and 34b
Is supplied to the switch circuit 40, and the signal Sh from the flip-flop circuit 39 is supplied to the switch circuit 40 as a control signal. Therefore, the signal Yc from the memory circuits 34a and 34b is sequentially extracted from the switch circuit 40.

The signal Yc from the switch circuit 40 is supplied to the synthesizing circuit 41, and the horizontal synchronizing pulse Rh from the horizontal synchronizing separation circuit 35 is supplied to the valid signal generating circuit 42. A signal Sb that is inverted between the effective horizontal scanning period and the non-effective horizontal scanning period of the signal Yc is formed and supplied to the synthesizing circuit 41. Thus, the luminance signal Yc in which the non-effective horizontal scanning period is set to the black level is extracted from the synthesizing circuit 41. The luminance signal Yc is supplied to the picture tube 33 through the standard contact s of the switch 31 and further through the amplifier 32.

Accordingly, an image based on the luminance signal Yc is reproduced in the picture tube 33. In this case, the signal Yc is compressed to 3/4 of the original luminance signal Ys at every horizontal period, and the picture tube is reproduced. The screen 33 has an aspect ratio of 9:16, and the horizontal size is 4/3 times that of the standard screen (aspect ratio 3: 4). An aspect ratio of 3/4 is reproduced in a 3/4 portion, that is, the standard luminance signal Ys is reproduced with a correct aspect ratio. (JP-A-53-51922).

Problems to be Solved by the Invention However, in the above configuration, the aspect ratio of the effective screen takes into account only two types, that is, standard television broadcasting and high-definition television. However, in the case of the package software in which the information is inserted, there is a problem that necessary information is lost or the video is compressed more than necessary, so that the image is less powerful.

In view of the above problems, the present invention provides a compression ratio of several types (at least two types) of images, and selects an optimal compression ratio when playing video software having various aspect ratios. An object of the present invention is to provide a television receiver which displays a powerful image without losing necessary information.

Means for Solving the Problems To solve the above problems, the television receiver of the present invention is
A display unit having an aspect ratio different from that of a standard television receiver,
A memory circuit for storing a video signal, a generator for generating a write clock for writing to the memory circuit, and n (n) having a higher frequency than the write clock
A read clock generating unit for generating a clock of ≧ 2) and a switching circuit therefor, and a vertical amplitude switching circuit for switching the vertical amplitude by (n + 1) steps, and by switching the read clock and the vertical amplitude in conjunction with each other, the display unit , An n-stage compressed image is displayed.

Function The present invention provides a powerful image without distortion without losing necessary information by selecting an optimal compression ratio when reproducing video software having various aspect ratios by the above configuration. It can be displayed.

Embodiment Hereinafter, a television receiver according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of a television receiver according to an embodiment of the present invention.

In FIG. 1, a composite video signal is supplied to a terminal 1, a luminance signal and a chrominance signal are separated and demodulated by a Y / C separation / color demodulation circuit 2 and converted into a digital signal by an A / D converter 3. Are stored in the memory 4. Reference numeral 5 denotes a D / A converter for converting a digital video signal read from the memory 4 into an analog signal. The analog video signal is amplified by an amplifier 6 and supplied to a terminal 1 of a picture tube 7. Composite video signal is displayed. Here, the picture tube 7
It is wider than standard TV receivers to display powerful images, and its aspect ratio is 9:16, which is often used for movies as a Vista size, and is being standardized as a high-definition TV.

The composite video signal supplied from the terminal 1 forms a horizontal synchronization signal in a horizontal synchronization separation circuit 8 and is supplied to a write clock generator 15 and a read clock generator 16. The deflection coil 27 is driven through the horizontal output unit 19. The write clock generated by the write clock generator 15 is also supplied to a switch 25 for determining a write cycle for the memory 4 and for switching a read clock for the memory 4. The read clock generator 16 generates clocks of two different frequencies, and supplies the clocks to the memory 4 via the switches 25 as read clocks. The vertical sync separation circuit 20 forms a vertical sync signal from the composite video signal from the terminal 1, and the vertical oscillation circuit 21 generates a sawtooth wave synchronized with the composite video signal. The switch 26 is a switch for switching the vertical amplitude, and is adjusted to the required vertical amplitude by the variable resistors 22a, 22b, 22c, and the vertical drive circuit 23, the vertical output circuit 24
The deflection coil 27 is driven via.

The operation of the television receiver configured as described above will be described below with reference to FIGS. 1 and 2.

A composite video signal supplied from a terminal 1 is separated and demodulated by a Y / C separation / color demodulation circuit 2 into a luminance signal and a chrominance signal.
The signal is converted into a digital signal by the converter 3 and written into the memory 4, and the writing cycle is determined by the write clock Cw generated by the write clock generator 15. The write clock generator 15 includes a phase comparator (PD) 11
Voltage controlled oscillator (CV
_O ) A PLL oscillator composed of 9 and a 1 / i frequency divider for dividing the clock from the voltage controlled oscillator 9 into 1 / i,
The phase comparator 11 generates a voltage and controls the frequency of the voltage-controlled oscillator 9 so that the phase of the clock formed from 0 and the phase of the horizontal synchronization signal supplied from the horizontal synchronization separation circuit 8 match. Therefore, in the steady state, the voltage controlled oscillator 9 oscillates at a frequency _H × i which is i times the horizontal scanning frequency _H.
The read clock generator 16 includes a phase comparator 14a, a voltage controlled oscillator 12a, a PLL oscillator including a 1 / j1 frequency divider 13a, a phase comparator 14b, a voltage controlled oscillator 12b, and a 1 / j2 frequency divider 13b. It is composed of a PLL oscillator.
2a oscillates at a frequency of _H × j1, and the voltage controlled oscillator 12b oscillates at a frequency of _H × j2.

By the way, since the aspect ratio of the picture tube 7 is set to 9:16, the vertical direction is 3/4 compared to the aspect ratio of 3: 4 of a standard television receiver.
It has become. The composite video signal supplied from terminal 1 is
Normally, a picture tube having an aspect ratio of 3 to 4 is targeted, and when an image without distortion is projected without changing the horizontal amplitude, the image 27 indicated by a dotted line in FIG. 2A is lost. The vertical amplitude must be reduced to 3/4 in order to eliminate video loss.
To further reduce image distortion, the horizontal direction should be 3/4
Must be compressed.

Therefore, if the frequency division value j2 of the 1 / j2 frequency divider 13b is j2 = 4 / 3i, the oscillation frequency of the voltage controlled oscillator 12b becomes 4/3 times the oscillation frequency of the voltage controlled oscillator 9, and the read clock switching switch If 25 is set to the door c, the read clock Cr of the memory 4 becomes 4/3 times the write clock Cw, and the time axis of the digital video signal read from the memory 4 is compressed to 3/4. The digital video signal thus compressed is projected on a picture tube 7 via a D / A converter 5 and an amplifier 6. The vertical amplitude changeover switch 26 is linked with the read clock changeover switch 25,
Similarly, it is set at the position of c. Therefore, if the vertical amplitude adjustment volume 22c is adjusted so that the vertical amplitude becomes 3/4, as shown in FIG. 2b, an image without distortion and without distortion can be projected. Can be.

On the other hand, when a video such as a movie having a different aspect ratio from a standard TV receiver is converted into a TV video signal while maintaining the different aspect ratio, and the TV video signal is projected on a standard TV receiver, the second A black portion 28 as shown in FIG. C appears, and the image lacks power. When the composite video signal having such a horizontally long aspect ratio is supplied to the terminal 1, even if the vertical amplitude is not reduced and displayed on the 9 to 16 picture tube 7, there is no image loss. Therefore, there is no need to compress the image in the horizontal direction.

When a horizontally long image is projected in this manner, the frequency of the write clock Cw and the frequency of the read clock Cr of the memory 4 are made equal by setting the linked read clock switch 25 and vertical amplitude switch 26 to the position a. And the image is not compressed. The vertical amplitude is adjusted to the same size as that of a standard television receiver by the vertical amplitude adjusting volume 22a.

Also, depending on the video software, the aspect ratio is 3: 4 and 9:
Some of the movies in the middle of 16 and foreign movies have subtitles 29 below the video as shown in Fig. 2e. Second
FIG. E shows a screen on which a video including subtitles is projected on a standard television receiver. In the screen of FIG. 2e, there is no image loss, but the image lacks power. FIG. 2f shows a screen in which the contact point of the read clock changeover switch 25 and the vertical amplitude changeover switch 26 is set to the position a and the image is not compressed, as in d, but the aspect ratio of the screen is 9:16. Therefore, the figure shows that a part of the subtitle supermarket 29 is missing.

Therefore, in the embodiment of the present invention, the image compression ratio is increased in two stages (the first is a compression ratio of 3/4 determined by the aspect ratio of the display unit).
9:16 like a foreign movie with subtitles superimposed
Reproduction of a vertically long image displays the image at the second compression ratio. FIG. 2g shows the projected screen.

In order to realize the second compression ratio in this manner, in FIG.
The contact between the switch 25 and the vertical amplitude switch 26 is set to the position b. Here, the division value j1 of the 1 / j1 divider 13a is 1 / i divider
A value larger than i of 10 and smaller than j2 of the 1 / j2 frequency divider 13b is selected. For example, if a value of j1 = 8 / 7i is selected, the voltage controlled oscillator 12a generates a clock having a frequency of 8/7 times the write clock Cw, and the vertical amplitude adjustment volume 22b
If the vertical amplitude is adjusted to be 7/8, an image compressed to 7/8 can be obtained. FIG. 2g shows the compressed video.

As described above, according to the present embodiment, two read clock generators and a three-stage vertical amplitude switching circuit are provided, and by switching them in conjunction, a two-stage compressed image can be obtained. It is possible to provide a television receiver that displays a powerful image without losing necessary information such as a subtitle supermarket.

FIG. 3 shows a clock generator (write clock generator and read clock generator) in one embodiment of the present invention.
FIG.

In FIG. 3, a horizontal sync separation circuit 8, a voltage controlled oscillator 9, and a 1 / i frequency divider 10 are the same as those in FIG. The variable frequency divider 13 sets the frequency division value to 1 / j by the control (CONT) signal.
Variable frequency divider that switches between 1,1 / j2 and voltage controlled oscillator
The clock generated from 12 is frequency-divided, and the phase is compared with the horizontal synchronization signal supplied from the horizontal synchronization separator 8 by the phase comparator 14. In the steady state, the oscillation frequency of the voltage controlled oscillator 12 is
_The two frequencies _H × j1 and _H × j2 are switched by the CONT signal.

As described above, by using the frequency divider of the read clock generator 16 as a variable frequency divider, a read clock having two frequencies can be obtained with one set of the phase comparator and the voltage controlled oscillator.

In the first embodiment, the read clock generation unit 16
Is composed of two sets of PLL oscillators. However, if the read clock generator 16 is composed of two or more sets of PLL oscillators, the image compression ratio is increased, and it is possible to cope with a wider variety of video software.

Further, in the second embodiment, the frequency dividing value of the variable frequency divider 13 is switched to two. However, by setting the frequency dividing value to a larger value, the same effect as described above can be obtained.

Effect of the Invention As described above, according to the present invention, there are provided a generator for generating n (n ≧ 2) read clocks, a switching circuit therefor, and a vertical amplitude switching circuit for switching the vertical amplitude in (n + 1) steps. By switching the read clock and the vertical amplitude in conjunction with each other, an image compressed in n stages can be obtained, and a powerful image can be obtained without losing the image.

[Brief description of the drawings]

FIG. 1 is a block diagram of a television receiver in a first embodiment of the present invention, FIG. 2 is a front view showing an example of a screen in the embodiment, and FIG. 3 is a front view of a second embodiment of the present invention. FIG. 4 is a block diagram of a read clock generator of the television receiver, and FIG. 4 is a block diagram of a conventional television receiver. 4 memory, 7 display unit, 15 write clock generator, 16 read clock generator, 22a, 22b, 22c
…… Vertical amplitude adjustment volume, 25 …… Read clock switch, 26 …… Vertical amplitude switch.

Claims (2)

(57) [Claims] A display unit having an aspect ratio different from that of a standard television screen; a memory circuit for storing a video signal; a write clock generation unit for generating a write clock for writing a video signal in the memory circuit; A read clock generator for generating n (n ≧ 2) read clocks having a higher frequency than the write clock and a switching circuit thereof; and a vertical amplitude switching circuit for switching the vertical amplitude to (n + 1) or more steps, By interlocking and switching the read clock and vertical amplitude, n
A television receiver characterized in that an image compressed in stages is displayed on the display unit. 2. A read clock generating section comprising a PLL oscillator for comparing the phase of a frequency-divided signal of a read clock and the horizontal synchronizing signal of a video signal, wherein the read clock generator generates n read clocks by dividing the read clock by a dividing ratio. The television receiver according to claim 1, wherein the television receiver is generated by switching.