JP2973915B2 - On-screen display positioning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for generating a second image on a first image.
And an on-screen display position determining device that superimposes and displays the images.

[0002]

2. Description of the Related Art Conventional on-screen display position determining device
Figures for explaining the arrangement are shown in FIGS. Figure 4 is the circuit
FIG. 5 to FIG. 7 are operation procedures or operation diagrams.
It is a figure for explaining the contents of a work.

In this conventional example, for example, the first
When performing on-screen display on the upper left of the
Period pulse (H in the figure) or vertical synchronization pulse (V in the figure)
And the front and back pouches before and after it
Area during the period without image information (the shaded area in the figure)
P) so that the second image (O in the figure) does not overlap
You. For this reason, the start position of the second image (B in the figure) is the same.
A certain period of time from the reference position (A in the figure) of the trailing edge of the period signal
(I, j in the figure).

For example, the "screen display circuit" disclosed in Japanese Patent Application Laid-Open No. 1-254075 is basically composed of the same circuit as the conventional example shown in FIG. This conventional example has a synchronization signal measuring means,
The synchronization period of the main signal is measured, and the ratio of the time until the start of the on-screen display with respect to the synchronization period is calculated by using the timing shown in FIG. 5, that is, i / (horizontal synchronization period), 1 / (vertical synchronization period) ) Is fixed so that the position of the second image with respect to the main image is fixed by determining the on-screen display position.

[0005]

However, in the above conventional example, when performing on-screen display for different signals, a slight shift occurs in the on-screen display position depending on the type of signal. Therefore, for example, when the on-screen display position is set at the end of the display screen, the on-screen display position is set outside the video display period of the first image as shown in FIG. 6C), a part of the second image is not displayed, or the second image is not displayed as shown in FIG.
The display position of the image is no longer set to the extreme end (see FIG. 7).
D) causes a problem.

Although FIGS. 6 and 7 illustrate the position for horizontal synchronization corresponding to the horizontal direction of the screen, the same problem occurs for the position for vertical synchronization. The reason is that the back porch and front porch (a, b, d, and e in FIG. 5) depend on the type of main first image signal,
Alternatively, this is because the times of the synchronization pulse widths (H and V in FIG. 5) are different.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an on-screen display position determining device capable of accurately defining an on-screen display position.

[0008]

In order to achieve the above object, an on-screen display position determining apparatus according to the present invention provides an on-screen display in which a second image is superimposed on a main first image. An on-screen display position determining device for defining a display position of a second image with reference to a display position of a first image, comprising: a synchronization pulse width and a period of a synchronization signal of an image signal of the first image; And storage means for storing information on the time of the back porch, and reading out information on the synchronization pulse width and period of the synchronization signal of the image signal of the first image and the time of the front porch and the back porch stored in the storage means. , The second image signal in the first image signal based on the read information.
Having a display position setting means for defining a display position of the image
You.

[0009]

[0010] Then, the display position setting means sets a predetermined limit on the first image, and displays the synchronous pulse width of the synchronizing signal of the first image and the image display except for the period of the front porch and the back porch. The display position of the second image is set within the period .

The predetermined restriction in the display position setting means is that the horizontal display start position Th × N of the second image starting from the leading edge of the horizontal synchronization pulse is H + a ≦ Th × N and Th × N. ≦ 1 / fh− (b + th) The vertical display start position Tv × M of the second image starting from the leading edge of the vertical synchronization pulse is V + d ≦ Tv × M and Tv × M ≦ 1 / fv− (e + tv) It is good to satisfy. However, each symbol represents the following. H: Horizontal sync pulse width, V: Vertical sync pulse width, a: Period without video information on the horizontal back porch, b: Period without video information on the horizontal front porch, d: Period without video information on the vertical back porch, e: period without video information on the vertical front porch, th: horizontal display period of the second image, tv: vertical display period of the second image, Th: pulse period for horizontal count, Tv: horizontal synchronization period ( 1 / fh: 1 horizontal cycle, 1 / fv: 1 vertical cycle, Sh: horizontal on-screen display start position, Sv: vertical on-screen display start position,

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an on-screen display position determining apparatus according to an embodiment of the present invention; 1 to 3, there is shown an embodiment of an on-screen display position determining apparatus according to the present invention. FIG. 1 is a block diagram showing an example of a circuit configuration of an on-screen display position determining apparatus according to the present embodiment, and FIGS.
FIG. 4 is a conceptual diagram for explaining a display operation.

In FIG. 1, the position determining apparatus for on-screen display according to the present embodiment mainly comprises a horizontal and vertical synchronization measuring circuit 1 for measuring the synchronization frequency of an image signal, and the frequency and synchronization type and polarity of the synchronization signal. A signal type determination circuit 2 for determining the type of signal, a display setting circuit 3 for setting a display position, a nonvolatile memory 4 for storing display timing information,
It comprises a video generation circuit 5, a timing controller 6, a video circuit 7, an addition circuit 8, a display circuit 9, and a synchronization circuit 12.

In each of the above components, the horizontal and vertical synchronization measuring circuit 1 measures the synchronization frequency of the main image signal.

The signal type determination circuit 2 determines the type of the main image signal from the frequency of the synchronization signal measured by the horizontal / vertical synchronization measurement circuit 1 and the type and polarity of the synchronization.

The display setting circuit 3 reads from the nonvolatile memory 4 timing information corresponding to the information on the type of the signal determined by the signal type determining circuit 2, and reads the horizontal and vertical directions of the second image information on the main video. The on-screen display start position is determined, and the count number of the timing controller 6 is set. In addition to making this setting, the range in which the count number of the timing controller 6 can be varied is determined by obtaining the main displayable range on the video.

The timing controller 6 generates a horizontal timing clock having a cycle T synchronized with the horizontal cycle pulse, counts the horizontal timing clock from the leading edge or the trailing edge of the horizontal cycle pulse, and counts the count set by the display setting circuit 3. When the number has been reached, a signal for starting the on-screen display is transmitted to the video generation circuit 5.

Similarly, regarding the on-screen display position in the vertical direction, the horizontal synchronization is counted from the leading edge or the trailing edge of the vertical synchronization pulse, and when the counted number set by the display setting circuit 3 is reached, the on-screen is displayed. A display start signal is transmitted to the video generation circuit 5. When the count number of the display start position is set outside the display range, the maximum value or the minimum value of the variable range is automatically set.

The video generation circuit 5 creates a second image,
In accordance with the on-screen display start signal from the timing controller 6, a second image signal synchronized with the horizontal timing clock and the horizontal synchronization is output.

The addition circuit 8 drives the display circuit 9 by synthesizing the image signal of the video circuit 7 and the image signal of the video generation circuit 5 output at the above timing.

The setting of the display setting circuit 3 is made by combining the signal type discrimination by the signal type discriminating circuit 2 in the portion surrounded by the broken line in FIG. 1 and the timing information of each signal stored in the nonvolatile memory 4. Do. This setting has the features of the present embodiment. The setting operation will be described below.

FIG. 2 is a diagram showing a calculation example regarding a method of defining a variable range of the on-screen start position in the horizontal direction. That is, FIG. 2 illustrates the relationship between one horizontal cycle (1 / fh) period, the first video display period, and the on-screen display start position Sh of the second video. In FIG. 2, each symbol in the figure represents a horizontal synchronization width H, periods a and b without video information of the back porch and front porch, a horizontal display period th of the second image, and a pulse cycle Th for horizontal counting. The symbol l (ell) indicates the end of the video display period,
The symbol Sh indicates the leading edge of the horizontal display period th of the second image. Further, the time point of the count number N of the horizontal counting pulse period Th and the on-screen display start position Sh
Are the same time points.

In the above relationship, the on-screen horizontal display start position Sh is defined by the number N of horizontal count pulses having a period Th from the leading edge k of the horizontal synchronization pulse in the following procedure.

The conditions for preventing the horizontal display time th of the second image from being outside the video display period with the leading edge k of the horizontal synchronization pulse as a base point are as follows.

H + a ≦ Th × N and Th × N ≦ 1 /
fh- (b + th)

The cycle T is determined by the horizontal synchronization width H, the back porch a, the pulse cycle Th for horizontal counting, the horizontal cycle 1 / fh, the front porch b, and the horizontal display time th.
The range of the count number N of the horizontal count pulse of h can be defined.

Further, by clarifying the time from the leading edge k of the horizontal synchronizing pulse in the video display period of the main image signal and the end point l of the video display period, the second time during the video display period is determined. Can be more accurately defined.

FIG. 3 shows a calculation example of a method of defining the variable range of the on-screen start position in the vertical direction.

In FIG. 3, the on-screen vertical display start position Sv is defined by the count number M of the horizontal synchronization pulse having a period Tv from the leading edge m of the vertical synchronization pulse, similarly to the horizontal position determination device.

The conditions for preventing the vertical display time tv of the second image from being outside the video display period with the leading edge m of the vertical synchronization pulse as a base point are as follows.

V + d ≦ Tv × M and Tv × M ≦ 1 /
fv- (e + tv)

The period T is determined by the vertical synchronization width V, the back porch d, the vertical counting pulse period Tv, the vertical period 1 / fv, the front porch e, and the vertical display time tv.
The range of the count number M of the horizontal synchronization pulse of v can be defined.

The on-screen display position determining apparatus according to the above-described embodiment determines the type of the main image signal, and uses the information read from the storage device in which the timing information corresponding to the signal can be registered in advance. The second image is set at an accurate position in the video display period of the image.

Therefore, in the present embodiment, in contrast to the conventional on-screen display position determination device, the timing of the main image signal specified by determining the signal type is used to determine the timing of the pre-registered storage device. By selecting an appropriate one, the on-screen display position can be more accurately defined. Further, even when the on-screen display position is arbitrarily changed, the variable range of the position can be defined so that the on-screen display position is always displayed during the video display period of the main image.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.

[0036]

As is apparent from the above description, the on-screen display position determining apparatus of the present invention stores information relating to the synchronization width and period of the image signal of the first image and the time of the front porch and the back porch. Then, the display position of the second image is defined in the image signal of the first image based on the stored information. In the definition of the display position of the second image, a period during which the image signal of the first image does not include a video does not overlap. Thus, the main first
Since the display position of the on-screen second image is determined based on the data on the signal form of the image, the on-screen display position can be more accurately specified on the display device. Also, by accurately defining the variable range of the on-screen display position, the on-screen image can be reliably displayed without missing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of an on-screen display position determining apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of a procedure for determining a horizontal on-screen display position range.

FIG. 3 is a diagram illustrating an example of a procedure for determining a vertical on-screen display position range.

FIG. 4 is a block diagram showing a circuit configuration example of a conventional on-screen display position determination device.

FIG. 5 is a diagram for explaining an example of a conventional procedure for determining the position of an on-screen display.

FIG. 6 is a diagram for explaining a problem caused by a conventional on-screen display position determining device.

FIG. 7 is a diagram for explaining a problem caused by a conventional on-screen display position determination device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Horizontal and vertical synchronous measuring circuit 2 Signal type discriminating circuit 3 Display setting circuit 4 Non-volatile memory 5 Video generating circuit 6 Timing controller 7 Video circuit 8 Addition circuit 9 Display circuit 10 Video signal 11 Synchronizing signal 12 Synchronizing circuit H, V Horizontal, vertical Synchronization width a, b, d, e, P Period without video information on back porch and front porch th, tv Horizontal and vertical display periods of second image Th Horizontal pulse period Tv Horizontal synchronization period (vertical count 1 / fh 1 horizontal cycle 1 / fv 1 vertical cycle Sh, Sv On-screen display start position O 2nd image A Reference position of trailing edge of sync signal B On-screen display start position C, D On-screen display Example that cannot be set at the screen display end i, j Time from the reference position of the trailing edge of the synchronization signal k, m Horizontal and vertical synchronization pulses The leading edge l (el), n horizontal, the end of the vertical image period

Claims (2)

(57) [Claims] 1. A display position of the second image is defined on the basis of a display position of the first image in order to superimpose a second image on a main first image and to perform on-screen display. In the position determination device for on-screen display, a storage means for storing information relating to a synchronization pulse width and a period of a synchronization signal of an image signal of the first image and time of a front porch and a back porch; The information on the synchronization pulse width and period of the synchronization signal of the image signal of the first image and the time of the front porch and the back porch are read out, and the image signal of the first image is read out based on the read information. Display position setting means for defining a display position of the second image, wherein the display position setting means has a predetermined position with respect to the first image.
And a synchronization pulse of the synchronization signal of the first image is provided.
Excluding width and front porch and back porch period
The display position of the second image within the video display period
An on-screen display position determining device, comprising: 2. The method according to claim 1, wherein the predetermined position is determined by the display position setting means.
Water restrictions and, said second image as a base point the leading edge of horizontal sync pulse
The horizontal display start position Th × N is defined as H + a ≦ Th × N and Th × N ≦ 1 / fh− (b + th), which is the vertical direction of the second image starting from the leading edge of the vertical synchronization pulse.
2. The on-screen display according to claim 1, wherein the vertical display start position Tv × M satisfies V + d ≦ Tv × M and Tv × M ≦ 1 / fv− (e + tv).
Positioning device for on-screen display. However, each symbol represents the following. H: Horizontal sync pulse width, V: Vertical sync pulse width, a: Period without video information on the horizontal back porch, b: Period without video information on the horizontal front porch, d: Period without video information on the vertical back porch, e: period without video information on the vertical front porch, th: horizontal display period of the second image , tv: vertical display period of the second image, Th: pulse period for horizontal count, Tv: horizontal synchronization period ( Pulse count for vertical counting
Period), 1 / fh: 1 horizontal period, 1 / fv: 1 vertical period, Sh: horizontal on-screen display start position, Sv: vertical on-screen display start position.