JPH05236435A - Display device - Google Patents

Abstract

PURPOSE:To reduce influence on an entire display picture caused by thinning and to realize the more natural display picture by reading video signals only once and executing thinning in the case of reading the video signals of a horizontal scan line selected to be thinned from a line memory. CONSTITUTION:The video signals for one line to be outputted from a video signal generating means 2 are written in line memories 3 and 4. In the case of thinning the written video signals, when video signals are not video signals to be thinned, they are read from the memories 3 and 4 respectively, twice at double speed as high as the writing speed and impressed to a display means 6. When video signals are video signals to be thinned, they are read from the memories 3 and 4 only once at a double speed as high as video signal writing speed and impressed to the display means 6. By repeating this operation, one picture is displayed by video signals for one field. In the case of reading, a line memory write/read control means 5 impresses a read control signal of double speed as high as that of a read control signal respectively twice alternately to the memories 3 and 4, and the same video signal is read twice and impressed to the means 6. Thus, the double speed conversion of video signals is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when converting an interlaced video signal into a non-interlaced video signal for display, displays by thinning out the video signal according to the number of horizontal display lines of the display means. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, an NTSC (National Television System Commi) has been used in a relatively large liquid crystal display device having a display screen of 640 horizontal dots × 480 vertical lines.
ttee) method or PAL (Phase Alternation by L)
In the case of displaying the (ine) system video signal, first, the interlace system video signal is converted into the non-interlace system video signal and then displayed.

FIG. 12 is a diagram showing the structure of an NTSC video signal. Considering non-interlace, an NTSC video signal has 525 horizontal scanning lines within one vertical period, and 483 horizontal scanning lines thereof have video signals as effective data. One horizontal scanning period is 6
3.56 μsec, of which 52.75 μsec
Is the video signal. The ratio of one screen is horizontal: vertical = 4: 3.

FIG. 13 is a diagram showing the structure of a PAL video signal. Considering non-interlace, the PAL system video signal has 625 horizontal scanning lines in one vertical period, and 575 horizontal scanning lines thereof have video signals as effective data. One horizontal scanning period is 64 μs
ec, of which 52 μsec is a video signal.
The ratio of one screen is horizontal: vertical = 4: 3.

A conversion method for converting an interlaced video signal into a non-interlaced video signal will now be described. For example, a video signal for one screen according to the NTSC interlace system is composed of 525 horizontal scanning lines, and a first field (odd field) consisting of 262.5 odd-numbered horizontal scanning lines and an even-numbered horizontal scanning line. It is divided into a second field (even field) consisting of 262.5 scanning lines.

That is, as shown in FIG. 14, 1 / 60s
The first field and the second field are alternately displayed for each ec, and the scanning line of the second field is placed between the scanning lines of the first field to form one complete screen (one frame) in two fields. Constitute. Therefore, 3 per second
The 0 screen is displayed. In order to display such an interlaced video signal on a liquid crystal display device, it is necessary to convert it into a non-interlaced video signal. As such a non-interlaced conversion method, there are a field complement method using a field memory and a line complement method using a line memory.

FIG. 15 is a diagram for explaining a non-interlace conversion method by a field complement method using a field memory. As shown in FIG. 15, the video signals of the first field and the second field are individually supplied to the field memory F1a for the first field and the second field, respectively.
Write to the field memory F2a for field. Then, each field memory F1 is doubled at the writing speed.
The video signals of one horizontal line are alternately read out from a and F2a and given to the liquid crystal display device Da for display.

FIG. 16 is a diagram for explaining a non-interlaced conversion method by a line complement method using a line memory. In the line complement method, a video signal for one line is written in a line memory and read out at a speed twice as fast as writing (double speed conversion) to display two lines of the video signal for one line on the liquid crystal display device Da. I do. Therefore, the first
One screen (one frame) is displayed in the field (odd field), and one screen is displayed in the second field (even field).

Here, when an NTSC video signal is displayed on a liquid crystal display device having a display screen of 640 horizontal dots × 480 vertical lines, both the first field and the second field have 241.5 valid data (video). Signal), of which the first and last 1.5 lines in total are made undisplayed areas by overscan, and the remaining 240 video signals are converted into non-interlaced video signals by the field complementing method, that is, 240 x
2 = 480 video signals are converted and displayed.

[0010]

The above-mentioned liquid crystal display device having a display screen of 640 horizontal dots × 480 vertical lines,
When a PAL video signal is displayed, the PAL video signal has 575 valid data (video signals), and it is not possible to display all video signals. Therefore, 575-480 = 95 video signals are thinned out and displayed. In the case of this thinned-out display, since the central part on the screen is normally displayed with priority, the upper and lower parts of the screen are not displayed and data (video signal) is lost.

It is an object of the present invention to provide a display device which can reduce the influence of the thinning on the entire display screen when the video signal is thinned and displayed, thereby realizing a more natural display screen. ..

[0012]

According to the present invention, a video signal for one screen composed of a predetermined number of horizontal scanning lines is provided.
Display device for converting and displaying an interlaced video signal, which is divided into a first field composed of odd-numbered horizontal scanning lines and a second field composed of even-numbered horizontal scanning lines and transmitted, into a non-interlaced video signal In the above, a display means having a number of horizontal display lines smaller than the number of horizontal scanning lines forming a video signal of one screen, a line memory storing a video signal for one horizontal scanning line, and an interlaced video signal are provided. The video signal is written to the line memory in synchronization with the horizontal synchronization signal, and the video signal is continuously and twice read from the line memory in synchronization with the read signal having a frequency twice that of the horizontal synchronization signal and given to the display means. , A video signal to be thinned out is selected for each of a predetermined number of continuous video signal groups, and the video signal to be thinned out is lined only once. A display device which comprises a memory control means for performing decimation by reading from memory.

According to the present invention, a video signal of one screen composed of a predetermined number of horizontal scanning lines is supplied to a first field composed of odd-numbered horizontal scanning lines and a second field composed of even-numbered horizontal scanning lines. In a display device for converting an interlaced video signal to be transmitted after being divided into two and converted to a non-interlaced video signal for display, a display means having a number of horizontal display lines smaller than the number of horizontal scanning lines forming the video signal of one screen A line memory for storing a video signal for one horizontal scanning line, a field memory for storing a video signal for one field, and a field for storing a video signal in synchronization with a horizontal synchronizing signal given together with the interlaced video signal. The video signal is written to the memory and the video signal is read only once in synchronization with the read signal having a frequency twice that of the horizontal synchronizing signal. Read out from the memory to be supplied to the display means and written to the line memory, and the video signal is read once from the line memory in synchronization with the read signal and supplied to the display means. At this time, a continuous predetermined number of video signal groups The display device is characterized in that it includes a memory control unit for selecting a video signal to be thinned out for each time, and performing thinning out by not reading the video signal to be thinned out from the line memory.

[0014]

According to the present invention, among the horizontal scanning lines forming one field, the horizontal scanning lines to be thinned out are selected for each group of a plurality of continuous horizontal scanning lines. The supplied video signal for one horizontal scanning line of the first and second fields is sequentially written in the line memory in synchronization with the horizontal synchronizing signal supplied together with the video signal. When the video signal is read, the same video signal is continuously read twice from the line memory in synchronization with the read signal having a frequency twice that of the horizontal synchronizing signal, and is supplied to the display means for display. That is, the number of lines of the video signal in one field is doubled to display one frame (one screen) in a pseudo manner.

At this time, when the video signal of the selected horizontal scanning line is read, the thinning-out is performed by reading the video signal from the line memory only once. That is,
One line for every N lines is displayed instead of the two line display by so-called double speed conversion. That is, where 2N horizontal display lines are displayed based on N video signals, (2N-1) horizontal display lines are displayed. By repeating this display operation M times, M video signals can be thinned out, and it is possible to prevent only specific video signals such as upper and lower parts from being lost.

According to the invention, the horizontal scanning lines to be thinned out are selected for each of a plurality of consecutive horizontal scanning line groups among the horizontal scanning lines forming one field. First given
Alternatively, the video signal of the second field is once written in the field memory in synchronization with the horizontal synchronizing signal given together with the video signal. A video signal for one line is read once from the field memory in synchronization with a read signal having a frequency twice that of the horizontal synchronizing signal, supplied to the display means, and written in the line memory. Then, the video signal is read once from the line memory in synchronization with the read signal and given to the display means. That is, the same video signal is applied to two continuous horizontal display lines of the display means, and the number of lines of the video signal of one field is doubled to display one frame (one screen) in a pseudo manner. ing.

At this time, when the video signal is read from the line memory of the selected horizontal scanning line, thinning is performed by not reading the video signal. That is, N
One line is displayed for each line instead of two-line display by so-called double speed conversion. That is, where 2N horizontal display lines are displayed based on N video signals, (2N-1) horizontal display lines are displayed. By repeating this display operation M times, M video signals can be thinned out, and it is possible to prevent only specific video signals such as upper and lower parts from being lost.

[0018]

1 is a block diagram showing the basic construction of a display device 1 according to a first embodiment of the present invention. Display device 1
Displays an interlaced video signal from the video signal generator 2 realized by, for example, a video tape recorder by converting it into a non-interlaced video signal.

The display device 1 includes line memories 3 and 4 for storing video signals for one line, and a line memory write / read control means 5 for controlling writing and reading of video signals to and from the line memories 3 and 4, Width 640
The display unit 6 is realized by a liquid crystal display device or the like having a display screen of dots × vertical 480 lines.

The video signal from the video signal generating means 2 is output as a digital signal. However, in the case of an analog signal, an A / D (analog / digital) converter (not shown) is connected between the video signal generating means 2 and the line memories 3 and 4 and digitized. The display means 6 is a display means such as a liquid crystal display device that can be driven by a digital signal. However, in the case of the display means driven by an analog signal, a D / A (digital / digital / not shown) is provided between the line memories 3 and 4 and the display means 6.
(Analog) converter is connected.

The display device 1 converts the interlaced video signal into a non-interlaced video signal by so-called double speed conversion and displays it on the display means 6. For example, when a video signal of the NTSC system is given from the video signal generating means 2, there are 241.5 video signals in the first field and the second field, and a total of 1.5 video signals at the beginning and end of them. Is set as a non-display area by overscan, and the remaining 240 video signals are sequentially written into the line memories 3 and 4 alternately.

After the video signals have been written in the line memories 3 and 4, the video signals of one horizontal scanning line from the line memories 4 and 3 are continuously transmitted twice at the time of reading the video signals. It is read out and given to the display means 6. As a result, 240 × 2 = 480 video signals are given to the display means 6, and the video signal of the first field is displayed as one screen on the display screen of the display means 6. When the video signal of the second field is sequentially written in the line memories 3 and 4, the same operation as described above is performed, and the video signal of the second field is displayed as one screen on the display screen of the display means 6.

In this embodiment, a case where a video signal having a number of horizontal scanning lines larger than the number of horizontal display lines of the display means 6 is displayed on the display device 1 will be described. Here, the case where a PAL video signal is displayed will be described.

The video signal of the PAL system has 625/2 = 312.5 horizontal scanning lines per field, of which 575/2 = 287.5 horizontal scanning lines have a video signal as effective data. .. Here, 25.5 video signals are set as a non-display area by overscan,
It is assumed that the remaining 262 video signals are displayed.

The 262 video signals are converted into 5 by double speed conversion.
If there are 24 video signals, the number of horizontal display lines of the display means 6 is 480, so it is necessary to thin out 524-480 = 44 video signals. That is, the 44 video signals are not double-speed converted, and the remaining 262-44 = 218 video signals are double-speed converted into 436 video signals, so that a total of 480 video signals are obtained.
It can be displayed on the display means 6.

At this time, 262/44 = 5.95 ... ≈6
During the double speed conversion of the video signal of the book, the video signal is thinned out at a rate of one. Further, considering the linearity of the display screen in the vertical direction, it is better to thin out evenly in each of the first and second fields. Therefore, here, a set of six video signals in each field is considered, and six video signals in the first field are considered. Of the video signals of the book, for example, the first video signal is thinned out, and in the second field, the video signal corresponding to the video signal thinned out in the first field is thinned out. That is, the video signals displayed on the same horizontal display line are thinned out.

FIG. 2 is a flow chart for explaining the operation of the display device 1. At step a1, the video signal for one line given from the video signal generating means 2 is written in the line memory 3 (4). At step a2, it is judged whether the video signal written in the line memory 3 (4) is a video signal when thinning out.

If the video signal is not to be thinned out, the process proceeds to step a3, and the line memory 3 (4) reads out from the line memory 3 (4) twice at twice the speed of writing the video signal and gives it to the display means 6.

If it is a video signal to be thinned out, the process proceeds to step a4, where it is read from the line memory 3 (4) only once at a speed twice as high as that at the time of writing the video signal and given to the display means 6. By repeating such an operation, one screen is displayed by the video signal of one field.

FIG. 3 is a timing chart for explaining the operation of the display device 1, and FIG. 4 is a diagram for explaining the operation of the display device 1. From the video signal generating means 2, FIG.
In synchronization with the composite sync signal CSYNC shown in (1), FIG.
As shown in (2), a video signal is applied line by line. The line memory writing / reading control means 5 synchronizes with the composite synchronizing signal CSYNC, and the line memory writing / reading controlling means 5 shown in FIG.
As shown in (4), high level write control signals are alternately applied to the line memories 3 and 4. This high level period is selected to be equal to the video signal transmission period. The video signals are written in the line memories 3 and 4 only while the high level write control signal is being applied. That is, all the video signals of one field are sequentially written in the line memories 3 and 4.

Subsequently, at the time of reading, the line memory writing / reading control means 5 operates as shown in FIG.
As shown in (6), a read control signal having a speed twice that of the write control signal is alternately applied to the line memories 3 and 4 twice, and the same video signal is supplied twice as shown in FIG. 3 (7). It is read out one by one and given to the display means 6. Thereby, the double speed conversion of the video signal is performed.

Here, at the time of reading, for example, an n-line video signal selected to be thinned out in advance, the line memory write / read control means 5 gives the read control signal to the line memory only once, and the video signal only once. Read out 1
The line is displayed. When reading other video signals, the video signals are read twice, so-called 2-line display is performed.

Thus, as shown in FIG. 4, the two-line display by the double speed conversion is stopped once every N times and the one-line display is performed. That is, 2N-1 lines are displayed where N lines of data should be originally displayed by the line complement method. By repeating this M times, M video signals can be omitted.

For example, in the PAL system, there are 287.5 lines of data in both the odd and even fields, of which 25.5 lines in total at the beginning and the end are over-scanned as undisplayed regions, and N = 6 for the remaining 262 lines. , M = 44, and non-interlace conversion is performed by the line complement method, 2N-1 = 11 lines are displayed where 2N = 12 lines are displayed, and 480 video signals are displayed by repeating 44 times. As a result, 262 × 2 = 524 lines of data excluding overscan are displayed on 480 lines, data loss in the upper and lower parts of the conventional technique is minimized, and a natural and comfortable screen is displayed. can do. Also, the N, M
The rate of overscan can be changed by selecting the value of. By executing such a line complement method, a PAL video signal can be displayed on an NTSC liquid crystal display device.

Here, write / write as the line memories 3 and 4.
If you use a dual port type line memory that can read independently, you can operate with one line memory,
A block diagram in this case is shown in FIG. In FIG. 5, a dual port type line memory 31 is used instead of the line memories 3 and 4, and the basic operation is the same as that shown in FIG.

FIG. 6 is a timing chart for explaining the operation of FIG. In this case, since writing to and reading from the line memory can be performed simultaneously, the line memory write control signal in FIG. 6C and the line memory read control signal in FIG. 6D are continuous.

FIG. 7 is a block diagram showing the basic structure of the display device 11 according to the second embodiment of the present invention. The display device 11 converts the interlaced video signal from the video signal generation means 12 realized by a video tape recorder or the like into a non-interlaced video signal and displays it.

The display device 11 has a field memory 13 for storing a video signal for one field, a field memory writing control means 14 for controlling writing of the video signal to the field memory 13, and a field memory 13.
Field memory read control means 15 for controlling the reading of the video signal to the line memory, line memory 16 for storing the video signal for one line, and line memory write / read control means for controlling the writing and reading of the video signal to and from the line memory 16. 17, a selector 18 for switching and outputting each output of the field memory 13 and the line memory 16, and a display means 1 realized by a liquid crystal display device having a display screen of 640 horizontal dots × 480 vertical lines.
9 and 9.

The video signal from the video signal generating means 12 is output as a digital signal. However, in the case of an analog signal, an A / D converter (not shown) is connected between the video signal generating means 12 and the field memory 13 and digitized. The display means 19 is a display means such as a liquid crystal display device that can be driven by a digital signal. However, in the case of display means driven by an analog signal, a D / A converter (not shown) is connected between the selector 18 and the display means 19.

The display device 11 converts the interlaced video signal into an interlaced video signal by so-called double speed conversion and displays it on the display means 19. For example, when a video signal of the NTSC system is given from the video signal generating means 12, there are 241.5 video signals in both the first field and the second field, and a total of 1.5 video signals at the beginning and the end. Is set as a non-display area by overscan, and the remaining 240 video signals are collectively written in the field memory 13. After the video signal for one field is written in the field memory 13,
At the time of reading the video signal, the video signal of one horizontal scanning line is read once from the field memory 13 at a speed twice that at the time of writing and is given to the display means 19 via the selector 18. At this time, at the same time, the read video signal of one horizontal scanning line is written in the line memory 16.

After that, the video signal is read from the line memory 16 at double speed (the same speed as when writing) and given to the display means 19 via the selector 18. By this, 2
40 × 2 = 480 video signals are given to the display means 19, and the video signal of the first field is displayed as one screen on the display screen of the display means 19. Even when the video signal of the second field is given, the same operation as described above is performed, and the video signal of the second field is displayed as one screen on the display screen of the display means 19.

In this embodiment, the display means 11 is provided on the display device 11.
A case where a video signal having a number of horizontal scanning lines larger than the number of horizontal display lines of 9 is displayed will be described. Here, the case where a PAL video signal is displayed will be described.

The video signal of the PAL system has 625/2 = 312.5 horizontal scanning lines per field, of which 575/2 = 287.5 horizontal scanning lines have a video signal as effective data. .. Here, it is assumed that a total of 25.5 lines at the beginning and the end are made undisplayed areas by overscan, and the remaining 262 image signals are displayed.

262 video signals are converted to 5 by double speed conversion.
If there are 24 video signals, the number of horizontal display lines of the display means 19 is 480, so it is necessary to thin out 524-480 = 44 video signals. That is, the 44 video signals are not double-speed converted and the remaining 262−44 = 218.
By converting the video signal of the book into a video signal of 436 by double speed conversion, and making a total of 480 video signals,
It can be displayed on the display means 19.

At this time, the video signals are thinned out at a rate of one while 262 ÷ 44 = 5.9 ... ≈6 video signals are converted at double speed. Further, considering the linearity of the display screen in the vertical direction, it is better to thin out evenly in each of the first and second fields. Therefore, here, a set of six video signals in each field is considered, and six video signals in the first field are considered. Of the video signals of the book, for example, the first video signal is thinned out, and in the second field, the video signal corresponding to the video signal thinned out in the first field is thinned out. That is, the video signals displayed on the same horizontal display line are thinned out.

FIG. 8 is a flowchart explaining the operation of the display device 11, and FIGS. 9 and 10 are the display device 11.
11 is a timing chart for explaining the operation of FIG. 11, and FIG. 11 is a diagram for explaining the operation of the display device 11.
In this embodiment, one of the six video signals is thinned out and displayed in one field. Therefore,
Eleven horizontal display lines are displayed by six video signals.

At step b1, the video signal generating means 12
The video signal for one field given from is written in the field memory 13. That is, as shown in FIG. 9, from the video signal generating means 12, in synchronization with the composite sync signal CSYNC shown in FIG. 9 (1), for example, a video signal of the first field as shown in FIG. 9 (2) is generated. It is given one line at a time. The field memory write control means 14 synchronizes with the composite sync signal CSYNC and controls the field memory 1
The write control signal shown in FIG. This high level period is selected to be equal to the video signal transmission period. The video signal is written in the field memory 13 only while the high level write control signal is being applied. Here, since all the video signals of the first field are sequentially written in the field memory 13 line by line, all the write control signals are at the high level during the sending period of the video signals.

At step b2, the field memory 13
It is determined whether or not the video signal read out from the video signal is a video signal to be thinned out, and if it is a video signal to be thinned out, step b3.
Go to step b4 if it is not a video signal to be thinned out.
Proceed to.

At step b4, the field memory 13
The video signal of one line is read out from the above and given to the display means 19 through the selector 18 and at the same time the field memory 1
The video signal of one line read from 3 is stored in the line memory 1
Write to 6. That is, as shown in FIG. 10 (2), the field memory read control means 15 causes the sync signal H having a frequency twice that of the composite sync signal CSYNC shown in FIG. 9 (1).
In synchronization with SYNC (see FIG. 10 (1)), a field memory read control signal is applied to the field memory 13 to read a video signal of one line (see FIG. 10 (3)). In FIGS. 9 and 10, “n” is used as the data before the double speed conversion, and “m” is used as the data after the double speed conversion.

The video signal read from the field memory 13 is given to the line memory 16 and the selector 18. The line memory 16 is supplied with the line memory write control signal shown in FIG. 10 (4) from the line memory write / read controller 17, and the read video signal of one line is written. Further, a low level selector signal SEL (see FIG. 10 (7)) is given to the selector 18 from the line memory write / read control means 17,
The input A is given as the output Y to the display means 19.

If it is not a video signal to be thinned out, the process proceeds to step b3 to read the video signal of one line from the field memory 13 and give it to the display means 19 via the selector 18.

At step b6, it is judged whether or not the reading of the video signal of one field is completed, and if not completed, the process returns to step b2 to read the next video signal.

When the reading of the video signals of all one field is completed in step b6, the process returns to step b1, the video signals of the next one field are written in the field memory 13, and the above-mentioned reading operation is repeated. ..

Thus, as shown in FIG. 11, by not reading the video signal to be thinned out from the line memory 16, the video signal is displayed on only one line of the display means 19. Video signals are thinned out by repeating this thinning-out operation for each of a plurality of predetermined video signal groups. This embodiment also has the same effect as the above-mentioned embodiment.

Further, in the present embodiment, as shown in FIG. 3 of the above-mentioned embodiment, the occurrence of the blank time of the data at the time of displaying one line is prevented, and the display timing of the video signal can be made the same. .. That is, as shown in FIG. 10, the video signal can be displayed on the display unit 19 at the same timing in both the two-line display and the one-line display. Therefore, the PAL video signal is
When displaying on the display device 11 compatible with the TSC system, the PAL signal and the NTSC signal are apparently the same signal for the display means 19.

[0056]

As described above, according to the present invention, among the horizontal scanning lines forming one field, the horizontal scanning line to be thinned out is selected for each of a plurality of horizontal scanning line groups, and the selected horizontal scanning line is selected. When a video signal of a line is read from the line memory, the video signal is thinned out by reading the video signal only once. In other words, one line is displayed for every N lines instead of displaying two lines by so-called double speed conversion. That is, the display of 2N horizontal display lines based on the N video signals is (2N-1)
Perform the display of the horizontal display line of the book. By repeating this display operation M times, M video signals can be thinned out, and it is possible to prevent only a specific video signal such as the upper and lower portions of the screen from being lost.

Further, according to the present invention, of the horizontal scanning lines forming one field, the horizontal scanning line to be thinned out is selected for each group of a plurality of continuous horizontal scanning lines, and the image of the selected horizontal scanning line is selected. At the time of reading a signal, the thinning-out is performed by reading the video signal from the field memory only once, that is, by not reading from the line memory. In other words, one line is displayed for every N lines instead of displaying two lines by so-called double speed conversion. That is, the display of 2N horizontal display lines based on N video signals is performed by (2N-
1) Display the horizontal display line of the book. By repeating this display operation M times, M video signals can be thinned out, and it is possible to prevent only specific video signals such as upper and lower parts from being lost.

Further, after the video signal for one field is once written in the field memory, the video signal can be read out for displaying two lines via the line memory, if necessary. Therefore, the read-out timing of the video signal can be made the same in the two-line display and the one-line display, and no timing deviation occurs. Therefore, even if the number of horizontal scanning lines constituting one screen is different, the display means can display the same signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a display device 1 which is a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the display device 1.

FIG. 3 is a timing chart showing the operation of the display device 1.

FIG. 4 is a diagram for explaining the operation of the display device 1.

5 is a block diagram showing another configuration example of the display device 1. FIG.

FIG. 6 is a timing chart showing the operation of the configuration shown in FIG.

FIG. 7 is a block diagram showing a configuration of a display device 11 which is a second embodiment of the present invention.

FIG. 8 is a flowchart for explaining the operation of the display device 11.

FIG. 9 is a timing chart illustrating an operation of the display device 11 when writing a video signal.

FIG. 10 is a timing chart explaining an operation at the time of reading a video signal in the display device 11.

FIG. 11 is a diagram for explaining double speed conversion of a video signal in the display device 11.

FIG. 12 is a diagram showing a configuration of an NTSC video signal.

FIG. 13 is a diagram showing a structure of a PAL video signal.

FIG. 14 is a diagram showing interlaced scanning in the NTSC system.

FIG. 15 is a diagram for explaining a field complementing method using a field memory.

FIG. 16 is a diagram for explaining a line complement method using a line memory.

[Explanation of symbols]

 1, 11 Display device 2, 12 Video signal generating means 3, 4, 16, 31 Line memory 5, 17 Line memory write / read control means 6, 19 Display means 13 Field memory 14 Field memory write control means 15 Field memory read control Means 18 Selector

Claims (2)

[Claims] 1. A video signal of one screen composed of a predetermined number of horizontal scanning lines is divided into a first field consisting of odd-numbered horizontal scanning lines and a second field consisting of even-numbered horizontal scanning lines. In a display device for converting an interlaced video signal to be transmitted by transmission into a non-interlaced video signal and displaying the display signal, a display means having a number of horizontal display lines smaller than the number of horizontal scanning lines forming the video signal of one screen; A line memory for storing a video signal of a horizontal scanning line, a video signal written in the line memory in synchronization with a horizontal synchronizing signal given together with the interlaced video signal, and a read signal having a frequency twice that of the horizontal synchronizing signal. The video signal is read from the line memory two times in succession in synchronism with the above, and given to the display means, and a predetermined number of continuous video images are read. A display device, comprising: a memory control unit for selecting a video signal to be thinned out for each image signal group and reading out the video signal to be thinned out from the line memory only once. 2. A video signal of one screen composed of a predetermined number of horizontal scanning lines is divided into a first field composed of odd-numbered horizontal scanning lines and a second field composed of even-numbered horizontal scanning lines. In a display device for converting an interlaced video signal to be transmitted by transmission into a non-interlaced video signal and displaying the display signal, a display means having a number of horizontal display lines smaller than the number of horizontal scanning lines forming the video signal of one screen; A line memory for storing a video signal for a horizontal scanning line, a field memory for storing a video signal for one field, and a video signal written in the field memory in synchronization with a horizontal synchronizing signal given together with the interlaced video signal. , The video signal is read from the field memory only once in synchronization with the read signal having a frequency twice that of the horizontal synchronizing signal. Then, the video signal is supplied to the display means, written in the line memory, and the video signal is read once from the line memory in synchronization with the read signal and applied to the display means. At this time, for each of a continuous predetermined number of video signal groups. A display device, comprising: a memory control unit that selects a video signal to be thinned out and does not read out the video signal to be thinned out from a line memory.