JPH07129117A - Image display device - Google Patents

Abstract

PURPOSE:To provide an image display device by which image data constituted of sacnning line numbers more than horizontal scanning line numbers of a display panel can be diplayed on an image screen natural to look at. CONSTITUTION:When horizontal scanning line numbers M constituting image data DATAIN are more than horizontal scanning line numbers N of a diaplay panel 2, a control part 6 performes operation on P=M/(M-N), and divides horizontal scanning lines into groups of every P pieces. The random sequence of numbers up to P from 1 is created, and respective figures are made to correspond to P-row fields, and numbers of scanning lines to be thinned out are disignated with every group. A first counter 4 and a second counter 5 count horizontal synchronous signals HSYNC, and when it coincides with a scanning line number, they probibit writing operation of a line memory 3 and horizontal scanning of the panel 2. Thereby, positions of the scanning lines to be thinned out are selected in mutually different positions by the P-row fields.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a dot matrix type display panel, and more specifically, it displays an image composed of more horizontal scanning lines than the number of horizontal scanning lines of the panel. The present invention relates to an image display device that is preferably implemented.

[0002]

2. Description of the Related Art As is well known, TV standard systems are classified into three types: NTSC system, PAL system, and SECAM system. One of the main differences between the NTSC system adopted in Japan, the United States, Canada, etc. and other systems is the number of horizontal scanning lines.
The PAL and SECAM methods are both 62 for books.
It is five.

In the NTSC system, the number of horizontal scanning lines is 52.
Of the five lines, 483 horizontal scanning lines excluding the blanking period are used as effective scanning lines. Therefore, in an area where this method is adopted, 480 vertical lines × 640 horizontal lines (aspect ratio 3: The dot matrix type display panel of 4) is widely used by being realized by a liquid crystal element or an EL element.

In an image display device having such a dot matrix type liquid crystal display panel of 480 horizontal scanning lines, the PAL system or SEC having more effective scanning lines than that.
In order to display an AM image, it is necessary to convert the number of scanning lines. A generally used method for conversion is a method of thinning out horizontal scanning lines at appropriate intervals, and the number M of effective scanning lines and the number N of horizontal scanning lines are integers for ease of processing. The number of effective scanning lines is adjusted in advance by overscan or the like so that the ratio can be represented by m: n.

In the case of the PAL system, for example, image data composed of 560 effective scanning lines is input to the image display device. The integer ratio m: n is 560: 480 = 7: 6. Hereinafter, the horizontal scanning line input to the image display device is referred to as an effective scanning line, and image data composed of M effective scanning lines is input.

The number M of effective scanning lines forming one field
Is larger than the number N of horizontal scanning lines of the display panel,
The number of scanning lines to be thinned out is the difference M−N between the two, and if M is divided by M−N, the thinning ratio can be obtained. 560 mentioned above
Books: In the example of 480, 1 in 7 fields per 1
If the scanning lines are sequentially thinned out at the rate of books, the purpose can be achieved with respect to the conversion of the number of scanning lines.

A typical prior art thinning display method is
It is shown in FIG. FIG. 4 shows conversion in the case of 560 effective scanning line pairs and 480 horizontal scanning lines for 7 fields. In FIG. 4 (1), the numbers 1, 2, 3, ..., 11, ..., 15, ... arranged in the vertical columns represent the effective scanning lines in order, and the numbers arranged horizontally in the upper column [ 1], [2], [3], ... represent the order of fields by numbers. Further, the numbers (2), (9), (16), ... Enclosed in parentheses in the column represent scanning lines thinned out at a rate of one in seven lines. In the thinning-out display method according to the conventional technique, the scanning lines to be thinned out and the order thereof are fixed in this way, and the scanning lines having the same number are thinned out in every field. This gives 8 out of 560 effective scan lines.
Zero lines are thinned out, the same as the number of scan lines on the display panel. 4
Eighty scan lines will be obtained.

[0008]

However, the above-described thinning-out display method is a fixed thinning-out method in which the scanning lines to be thinned out are constant in every field, so that in FIG.
As indicated by the double line =, there are 8 points on the display panel where the image is discontinuous at a specific part of the displayed image.
There are 0 places. For example, as shown in FIG. 5 (1),
The image A formed by the effective scanning lines a, b, c, ..., I, j is thinned out in any field of the scanning line f between them, so that the scanning line e as shown in FIG. , G are discontinuous images B and C. This is very noticeable when displaying a tilted image as shown. Since the scanning line f is missing in every field, the screen is displayed with the upper and lower parts left and right deviating from each other at the same position. In addition, since 80 lines are thinned out per field, 80 thin horizontal stripe-shaped patterns always appear at equal intervals on the upper and lower sides of the screen on the display panel, which significantly deteriorates the image quality.

In order to solve such a problem, a thinning-out display method, which should be called a sequential thinning-out method, has been proposed in addition to the fixed thinning-out method. This is a method of shifting the scan lines to be thinned out by one line for each field as shown in FIG. 6 (1). For example, in the field [1], the scan lines from the first scan line (1) to 7 The number of books is reduced to one, and the next field [2]
In the method [2], the scanning lines are sequentially thinned from the second scanning line (2), and in the field [3], the scanning lines are sequentially thinned from the third scanning line (3). Therefore, on the screen displayed by this method, as shown in FIG. 6 (2), discontinuity occurs vertically at the portion marked with double line = Less noticeable.

However, although such a sequential thinning method has a certain effect on a still image, when the moving direction and speed of the image are synchronized with the shift direction and speed in the case of a moving image, the fixed thinning method is used. A phenomenon similar to the thinning method occurs and discontinuity occurs, and in this case, the image is more unnatural because the image is moving. Therefore, when converting image data having a large number of scanning lines into image data composed of a smaller number of scanning lines and displaying the image data, a more natural image display device is desired.

It is an object of the present invention to display an image constituted by a number of horizontal scanning lines larger than the number of horizontal scanning lines on a display means having a predetermined number of horizontal scanning lines as described above. An object of the present invention is to provide an image display device in which the occurrence of discontinuous portions is suppressed as much as possible and images are displayed more naturally.

[0012]

SUMMARY OF THE INVENTION According to the present invention, an image display means for displaying an image based on a predetermined number of horizontal scanning lines and the number of horizontal scanning lines constituting one field of input image data are set. And an image display device including a scanning line converting unit for converting the number of horizontal scanning lines of the image display unit into the number of horizontal scanning lines constituting the input image data. When the number is larger than the number N of horizontal scanning lines of the display means, a quotient P obtained by dividing the number M of the horizontal scanning lines by the difference M−N between the number of the horizontal scanning lines and the number of the horizontal scanning lines is obtained. Seek 1
The M horizontal scanning lines forming a field are divided into groups of P, one scanning line is thinned out for each group, and the positions of the thinned scanning lines are traced for the P fields. The image display device is characterized by selecting different positions.

[0013]

The image display device according to the present invention includes the display means and the scanning line converting means, and constitutes one field of the image data to be inputted, which is more than the number N of horizontal scanning lines which is predetermined in the displaying means. When the number M of horizontal scanning lines is larger, the scanning line conversion means thins out the horizontal scanning lines and converts the number into the number of horizontal scanning lines of the display means.

In the conversion, the scanning line conversion means is
A quotient P obtained by dividing the number M of the horizontal scanning lines by the difference MN between the number of the horizontal scanning lines and the number of the horizontal scanning lines is obtained, and the M horizontal scanning lines forming one field are obtained. ,
It is divided into P groups, and one scan line is thinned out for each group. The positions of the scan lines thinned out in each group are selected at different positions for the P fields.

As a result, the discontinuity that occurs on the screen when the scanning lines are thinned out at successive positions disappears, and an image is displayed in a natural appearance.

[0016]

1 is a block diagram showing the electrical construction of an image display device 1 according to an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the operation of each part of the image display device 1.

Referring to FIG. 1, an image display device 1 includes a display panel 2 which is a display means having a predetermined number of horizontal scanning lines, a line memory 3 forming a scanning line converting means, and a plurality of programmable counters. 4, 5, a control unit 6, a monostable multivibrator circuit 7 and each block of an OR gate 8.

The display panel 2 is realized by, for example, a dot matrix type display panel of 480 vertical by 640 horizontal using a liquid crystal element, and 480 horizontal scanning lines are formed in the vertical direction of the screen. Image data DATAOUT sequentially read from the line memory 3 is displayed on the display panel 2,
Horizontal scanning signal L-H synchronized with horizontal synchronization signal HSYNC
S and the vertical synchronizing signal VSYNC are input. Field scanning is controlled by the vertical synchronization signal VSYNC,
The horizontal scanning lines are sequentially scanned in synchronization with the falling of the horizontal scanning signal L-HS.

Image data DATAIN, which is composed of M effective scanning lines, is stored in the line memory 3 as a horizontal synchronizing signal H.
Image data for one line is sequentially written by a high-level write command WR, which is input in synchronization with SYNC, and data writing is prohibited by a low-level write command WR. The write command WR is given from the second programmable counter 5 described later. The image data written in the line memory 3 is sequentially read line by line in synchronization with the falling edge of the read command RD.
The read command RD is given via an OR gate 8 described later.

The control unit 6 is realized by including a microprocessor and a memory, and receives the vertical synchronizing signal VSYNC and the data MD indicating the number M of effective scanning lines. When the number M of effective scanning lines is larger than the number N of horizontal scanning lines of the display panel 2, the control unit 6 first-programs line data LD that indicates the number of scanning lines to be thinned out for each field. The number LN indicating the number of the scanning line to be thinned out is supplied to the second programmable counter 5 while controlling the thinning operation of the scanning line.
As will be described later, the line data LD is set on the basis of an algorithm for randomly picking out one number from a number in a predetermined range, and the number of scanning lines thinned out for each field. Is data indicating.

The first programmable counter (hereinafter referred to as "first counter") 4 is realized by a preset counter circuit or the like, receives the horizontal synchronizing signal HSYNC and the vertical synchronizing signal VSYNC, and the numerical value of the line data LD. Is preset. The first counter 4 counts the horizontal synchronizing signal HSYNC in synchronism with the falling edge of the vertical synchronizing signal VSYNC, and if the count value and the preset value of the line data LD match, it outputs the first timing signal TS1. Output to the second programmable counter 5.

The second programmable counter (hereinafter referred to as "second counter") 5 is realized by a preset counter circuit or the like, and a numerical value (hereinafter referred to as "thinning number") LN indicating the number of a scanning line to be thinned out is a control unit. Given from 6. The second counter 5 receives the first timing signal TS.
In response to 1, the input horizontal synchronizing signal HSYNC is counted, and if the count value and the preset numerical value LN match, the write command WR is inverted and the line memory 3 and the monostable multivibrator circuit 7 are inverted. And output to.

Monostable multivibrator circuit (hereinafter
The "monostable multi-circuit") 7 is the write command W
In response to the fall of R, the second timing signal TS2 having a time width defined by the resistor R and the capacitor C is input to one terminal of the OR gate 8. The horizontal synchronizing signal HSYNC is input to the other of the OR gates 8, and when the level of the second timing signal TS2 is low, the OR gate 8 outputs the read command RD synchronized with the horizontal synchronizing signal HSYNC and the horizontal scanning signal L-HS. Is output and the second timing signal TS2 is at a high level, the read command RD and the horizontal scanning signal L-HS are not output. Therefore, while the low-level write command WR is being output, both writing and reading of image data in the line memory 3 are prohibited,
No horizontal scanning of the display panel 2 is also performed, and as a result, one horizontal scanning line is thinned out.

The line data LD will be described here. When displaying image data composed of M effective scanning lines on a display panel having N horizontal scanning lines,
The number of scan lines to be thinned out is MN per field. Therefore, the thinning-out ratio is indicated by a quotient P obtained by dividing the number M of effective scanning lines by the difference M−N between the number of effective scanning lines and the number of horizontal scanning lines. The number of scanning lines can be converted by thinning out the lines. It should be noted in the present invention that the line data LD designating the number of the scanning line to be thinned out is randomly generated by the control unit 6 for each field.

The control unit 6 obtains the quotient P by calculation, then randomly picks out one number from the set of integers 1 to P based on a predetermined algorithm, and the P numbers are ordered. A sequence of numbers arranged randomly is generated and stored in a memory in the circuit. At this time, the numbers from 1 to P forming the sequence are P as line data LD indicating the leading line of the scanning line to be thinned out in each field.
Individually assigned to the fields of the column. Since the line data LD makes one round in P fields, if the line data LD is created for each stage with the field of the P column as one stage, the regularity is lost from the thinning pattern of the scanning lines, and the thinning lines to be thinned out. Since the position is different for each field (screen), the inconvenience as seen in the prior art is solved.

Next, the operation of each section in one field will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and description will be given with reference to FIG. It is assumed that the control unit 6 gives "3" as the line data LD of the field and "7" as the thinning-out number LN to the first counter 4 and the second counter 5, respectively.

FIG. 2A shows the image data DATAIN input to the line memory 3, and the image data D1 for one line is synchronized with the horizontal synchronizing signal HSYNC shown in FIG. 2B. D2, D3, ... Are sequentially input.
FIG. 2C shows the vertical synchronization signal VSYNC at time t.
At the falling edge of the vertical synchronizing signal VSYNC at 0, the first counter 4 counts the horizontal synchronizing signal HSYNC at each falling edge, and the time when it coincides with the preset value of the line data LD (here, LD = 3). At t1, as shown in FIG.
As shown in (4), the first timing signal TS
1 is output to the second counter 5. In other words, in this case, the count value 3 of the horizontal synchronizing signal HSYNC of the first counter 4 in the period T1 from time t0 to t1 indicates the leading number of the thinned horizontal scanning line.

At time t1, the second counter 5 has the first counter
In response to the timing signal TS1, the level of the write command WR is inverted from high to low as shown in FIG. 2 (5). This low level write command WR prohibits writing of the image data D3. In order to ensure the thinning operation, the time width T2 in which the write command WR is at the low level is set to be slightly longer than the cycle B of the horizontal scanning period HSYNC. The second counter 5 responds to the first timing signal TS1 and outputs the horizontal synchronization signal HSYNC.
And the thinning-out number LN given by the control unit 6
The period T3 until the numerical value (here, LN = 7) matches
Keeps the level of the write command WR high. Therefore, in the line memory 3, the image data D4 to D9 for 6 lines after the image data D3 are written, and the writing of the image data D10 of the 7th line is prohibited. Similarly, the writing of the input image data DATAIN is prohibited at a rate of one in seven horizontal scanning lines.

The write command WR is input to the monostable multi-circuit 7 as a trigger signal, and the monostable multi-circuit 7 has the second timing signal T of the time width T4 shown in FIG. 2 (6).
S2 is input to one terminal of the OR gate 8. Time width T
4 is set in advance by the time constant of the resistor R and the capacitor C so as not to exceed the period T5 of the horizontal synchronizing signal HSYNC.

FIG. 2 (7) shows the waveforms of the read command RD and the horizontal scanning signal L-HS output from the OR gate 8. The horizontal synchronizing signal H is applied to the other terminal of the OR gate 8.
SYNC is input, and the second timing signal TS2
Is low, the read command RD and the horizontal scanning signal L-HS are output in synchronization with the horizontal synchronization signal HSYNC, but when the second timing signal TS2 is input at a high level, the read command RD and Horizontal scanning signal L-
The HS level remains high and does not change. For this reason,
As indicated by the broken line S in (7), the levels of the read command RD and the horizontal scanning signal L-HS are not inverted. Therefore, the reading of data from the line memory 3 and the horizontal scanning of the display panel 2 are stopped immediately after the second timing signal TS2 is output. This ensures that the horizontal scanning lines are thinned out, and the thinning out of the horizontal scanning lines does not cause blanking of the scanning lines.

FIG. 3 is a diagram showing an example of thinning patterns of scanning lines obtained in this embodiment. FIG. 3 shows an example in which 560 effective scanning lines are converted to 480, and the number strings 1, 2, 3, ..., 11, ..., 15, ... Arranged in vertical columns are shown.
Represents the effective scanning lines in order, and the numbers [1], [2], [3], ... arranged side by side in the upper column represent the field order by number. Is forming. Also, the numbers in parentheses (2), (9),
(16), ... Represent the number of effective scanning lines thinned out at a ratio of one to seven lines in each field. Therefore, 80 scanning lines are thinned out in one field. FIG. 3 is similar to FIGS. 6A and 6B showing a conventional example, but is characterized in that the thinning pattern of scanning lines is irregular.

In FIG. 3, forming the stage 1 [1]-
Referring to the [7] field, the numbers (2), (7), (4), (1), (6), (3), which indicate the leading numbers of the scanning lines thinned in each field,
(5) can be seen. This is the line data LD set for each stage, and as described above, it is generated by the control unit 6 randomly picking up one by one from the set of numbers 1 to 7. Next [8]-[14]
For the stage 2 formed in the field, (4), (6), (2),
(5), (1), (3) and (7) are given. Similarly, the line data LD that differs for each stage
Is given. The probability that regularity appears in the array of line data LD is extremely small, and it is easy to bring this probability close to 0 by an algorithm.

When the line data LD is determined, the number of scanning lines thinned out in each field is a series 7 with a tolerance of 7 with the number a (a = 1 to 7) of the line data LD as the first term, and the number of terms 80. Specified by a sequence of numbers. For example, the scanning line numbers thinned out in the field [1] are 2, starting with 2, 9,
16, ..., 548, 555. Similarly, for example, the scanning line numbers thinned out in the field [2] are 14, 21, ..., 553, 560, starting with 7. A number corresponding to the tolerance 7 is given from the control unit 6 to the first counter 4 as a thinning-out number LN, and the first counter 4 counts the horizontal synchronizing signal HSYNC seven times and then outputs the second number.
The timing signal TS is output, and reading of data for one line and horizontal scanning are stopped.

As described above, according to this embodiment, the scanning lines to be thinned out are not ordered by the line data LD as described above, and further, they are selected at different positions for each field. Therefore, it is possible to prevent the occurrence of discontinuity in the displayed image without being continuous, and to obtain a visually natural screen.

In the above-mentioned embodiment, the head number of the effective scanning line to be thinned out is designated for each field by the line data LD, and thereafter the scanning line is thinned out with a certain tolerance. The data map for one stage may be created by creating 80 stages and the thinning-out number LN may be read from the data map. For example, the sequence of numbers from 1 to 7 is 7! =
Since there are 5040 patterns, if you select 80 sequences from these and create a data map for one stage, the positions of the thinned scanning lines become more irregular, and different data maps should be used for each stage. By doing so, it is possible to make the discontinuous portion occurring in the image less noticeable.

[0036]

As described above, in the image display device according to the present invention, the horizontal scanning lines constituting one field of the input image data are more than the number N of the horizontal scanning lines predetermined in the image display means. When the number M is larger, the scanning line conversion means thins out the horizontal scanning lines and converts them into the number of horizontal scanning lines. Moreover, in the conversion, the quotient P obtained by dividing the number M of the horizontal scanning lines by the difference M−N between the number of the horizontal scanning lines and the number of the horizontal scanning lines is obtained to form one field. The M horizontal scanning lines are divided into P groups, and one scanning line for each group is selected and thinned out at different positions for P fields. For this reason, the discontinuous portions that occur on the screen when the scanning lines are thinned out at continuous positions disappear, and an image is displayed in a natural appearance. Therefore, for example, it is used in Japan, the US, Canada, etc. where the NTSC system is adopted.
This is a great effect that a natural image can be displayed even when displaying an image of a larger number of scanning lines, for example, a PAL system or a SECAM system on a display device of 80 lines.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image display device that is an embodiment of the present invention.

FIG. 2 is a waveform chart showing the operation of each part of the image display device shown in FIG.

3 is a diagram showing a thinning pattern of scanning lines obtained by the image display device shown in FIG.

FIG. 4 is a diagram showing a thinning pattern of scanning lines by a conventional image display device.

5 is a diagram showing an example of an image displayed by the image display device shown in FIG.

FIG. 6 is a diagram showing thinning patterns of scanning lines by another conventional image display device.

[Explanation of symbols]

 1 Image Display Device 2 Display Panel 3 Line Memory 4 First Programmable Counter 5 Second Programmable Counter 6 Control Circuit DATAIN Image Data HSYNC Horizontal Sync Signal LD Line Data LN Thinning Number RD Read Command L-HS Horizontal Scan Signal TS1 First Timing Signal TS2 Second timing signal VSYNC Vertical sync signal WR Write command

Claims (1)

[Claims] 1. A display means for displaying an image on the basis of a predetermined number of horizontal scanning lines, and the number of horizontal scanning lines constituting one field of input image data is defined as the horizontal scanning line of the display means. In the image display device, the number of horizontal scanning lines constituting the input image data is greater than the number N of horizontal scanning lines of the display unit. When there are many, the number M of the horizontal scanning lines
Is divided by the difference M−N between the number of horizontal scanning lines and the number of horizontal scanning lines to obtain a quotient P, and the M horizontal scanning lines forming one field are grouped into P groups. An image display device, characterized in that it is divided and one scanning line is thinned out for each group, and the positions of the scanning lines thinned out in each group are selected at different positions for P fields.