JP2000056748A - On-screen display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-screen display device simple in electric circuit, low in cost and capable of superimposedly displaying a character or graphic signal even in input image signals of personal computers, etc., different in scan frequency standard. SOLUTION: A dot clock frequency dividing between respective horizontal synchronizing signals with a fixed setting value at a clock phase controlled by the number of scanning lines of the input image signal and the horizontal synchronizing signal of the input image signal is generated, and by the number of scanning lines of beforehand fixed scan frequency standard and the character/ graphic memory data that a horizontal direction is made the number of dots of the same setting value, the number of scanning lines of the input image signal is compared/collated with the number of scanning lines read out from a character/graphic memory 11, and expansion/contraction of a vertical direction is controlled by its ratio, and by that the horizontal direction is read out from the character/figure memory 11 by the dot clock of the same numerical value, the size and the display position of the beforehand set character or graphic are superimposed on the input image signal to be image displayed, and the electric circuit is simplified, and cost reduction is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display system corresponding to image signals having various scanning frequencies, and to stably maintain a display size of a character or a figure to be superimposed on an input image signal and outputted. To an on-screen display device that can

[0002]

2. Description of the Related Art A multi-scan monitor is used to display the processing results of a computer such as a personal computer or a workstation. The frequency of horizontal and vertical scanning of an image output signal is not constant depending on the type and mode of the computer, but various standards are used. However, a multi-scan monitor can handle these. Further, there is a computer system which switches and outputs image outputs of various numbers of scanning lines by a large number of computers with a routing switcher or the like, and image signals of different standards with different scanning frequencies are switched and output. By using a monitor or a multi-scan display, each can be handled. By the way, an on-screen display for superimposing and adding an image signal of a figure such as a character or a symbol, a mark, or a picture (hereinafter referred to as a character or a figure) to an image signal of a computer output as described above and displaying it on a screen of a monitor or the like. In a multi-scan monitor or a multi-scan display, brightness, contrast, etc. are used to display a menu for setting the adjustment function of the display device itself such as a monitor on the screen, and the circuit device is Generally, it is often built in a display device such as a monitor.

When superimposing character or graphic data on a computer output image signal and displaying it on a monitor, the number of vertical scanning lines and the number of horizontal scanning pixel dots differ depending on the type of scanning frequency standard of the image signal. When characters or graphics composed of fixed pixel data are simply superimposed and added to image signals having different scanning frequencies, the display size of the characters or graphics with respect to the screen size is different, resulting in a screen that is difficult to see. For example, if the scanning frequency is different, the character display area, which is a collective display portion composed of characters, character groups, or graphics, shown on screen A of the monitor screen of FIG. 2 has a screen B of the monitor screen of FIG. As described above, the screen display such as the adjustment function setting menu of the monitor itself in the multi-scan monitor or the like employs means such as controlling the configuration of character font data so that the character size does not change. There are many, but complicated methods.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the present invention relates to a method of superimposing character or graphic data on an image signal output from a computer and displaying the image signal on a monitor. Even if the number of vertical scanning lines and the number of pixel dots for horizontal scanning differ depending on the size, the screen can be displayed by enlarging or reducing to the same size as a character or figure with respect to the set screen size, and a display device such as a multi-scan monitor To provide a low-cost on-screen display device which can be installed and used in an image input system.

[0005]

Means for Solving the Problems The present inventor has solved this problem by the following means as a result of intensive studies in view of the above. (1) In a display device such as a multi-scan monitor, a superimposing circuit for adding a character or graphic signal stored in an image memory to an input image signal, an output terminal of the superimposing circuit, and reference character or graphic data are stored. A character / graphic memory, a scaling circuit for vertically expanding or reducing the character / graphic memory output signal, the image memory for storing the scaling circuit output data, and a synchronization signal separated from the input image signal by a synchronization separation circuit. A clock generation circuit for controlling the frequency of the number of dots between horizontal synchronization signals to a predetermined set number, and a readout circuit for generating a control signal for reading out image data of an image memory based on a clock output from the clock generation circuit and the synchronization signal A detection circuit for detecting the number of vertical scanning lines based on a vertical synchronization signal input from a synchronization separation circuit, and a detection circuit output Therefore, it is configured to include means for controlling the enlargement / reduction circuit, and a control circuit for controlling the input / output of each memory circuit and the enlargement / reduction circuit, and the data read from the character / graphic memory is the set reference vertical scanning line number, The number of vertical scanning lines of the input image signal is compared and collated, and enlarged or reduced in the vertical direction almost in proportion to the ratio, written into the image memory, read by the clock of the clock generation circuit, and superimposed on the input image signal and output. And an on-screen display device for displaying on a display device such as a multi-scan monitor.

(2) In a display device such as a multi-scan monitor, a superimposing circuit for adding a character or graphic signal stored in an image memory to an input image signal, an output terminal of the superimposing circuit, and reference character or graphic data. , A character / graphic memory for storing character / graphic memory output signals, and a sync signal separated from the input image signal by a sync separation circuit to divide the number of dots between each horizontal sync signal to a fixed set number. A clock generation circuit for controlling, a readout circuit for generating a control signal for reading out image data of an image memory by a clock output from the clock generation circuit and the synchronization signal, and a control circuit for controlling input / output of each memory circuit The data read from the character / graphic memory is transferred to the image memory as the set reference pixel number, and A dot clock is generated by dividing the horizontal synchronizing signal between the horizontal synchronizing signals by the same set number as the set reference number of pixels by a horizontal synchronizing signal separated from the signal, and data is read from an image memory by the dot clock to input an image signal. The on-screen display device according to item (1), wherein the output is superimposed on and output on a display device such as a multi-scan monitor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The display density of scanning lines in the vertical direction of a multi-scan monitor screen changes according to the number of scanning lines of an input image signal, and the unit of vertical dots of character or graphic data is the number of scanning lines. Therefore, the display size of the vertical character or graphic changes depending on the number of scanning lines. In the case of the vertical scanning direction, the number of pixel dots, that is, the number of vertical scanning lines is set to a value based on, for example, 480, and character or graphic data is generated. The size of the vertical display of a character or a figure due to the difference in the number of scanning lines depending on the computer model or mode is as follows.
By performing the vertical enlargement or reduction processing substantially in proportion to the ratio of the number of vertical scanning lines of the input image signal to the number of vertical scanning lines based on 80, the display size can be kept substantially constant. The result is as shown in screen D of the monitor screen. Enlargement or reduction processing is generally widely performed as a means of image processing, and there are various methods ranging from simple processing to advanced processing such as interpolation processing. The enlargement or reduction in proportion to the number may be stepwise rather than continuous.

[0008] Font data for forming characters or figures is formed by a fixed pixel structure, and these digital data are output from an image memory and superimposed on an input image signal when displayed on a multi-scan monitor or the like. ,
The horizontal scanning direction is displayed as an analog signal.
If the number of pixels for displaying characters and graphics during the horizontal scanning period of the multi-scan monitor is, for example, a fixed number of 640 dots, it does not matter if the scanning frequency of the multi-scan monitor changes.

That is, regardless of the difference in the scanning frequency of the input image signal from the computer, for example, a character or a figure is generated in the character / graphic memory with the number of dots in which the horizontal scanning period is set to 640 dots in advance, and then the character or figure is stored in the image memory. After being transferred, each horizontal synchronization signal is divided by a fixed number of 640 by a VCO (Voltage Controlled Oscillator) or a PLL (Phase Locked Loop) circuit by phase control of a horizontal synchronization pulse separated from the input image signal. A dot clock whose phase is controlled by a horizontal synchronizing signal at such a frequency is generated, character or graphic data is read from the image memory by the dot clock, and is superimposed on an input image signal as an image signal (analog signal). The display size of characters or graphics in the horizontal direction on the multi-scan monitor is almost constant, So the screen C of the data screen shots. The apparatus according to the present invention can maintain not only the size of the character itself but also the size and display position of the monitor display of the display area, which is a collective display portion of characters or graphics, substantially constant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an on-screen display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an embodiment of the present invention, and FIG. 2 is a monitor screen diagram. In FIG. 1, 1 is an input terminal, 2 is a superimposition circuit, 3 is an output terminal, 4 is a synchronization separation circuit, 5 is a clock generation circuit, 6 is a read circuit, 7 is an image memory, 8 is a detection circuit, and 9 is scaling. A circuit 10, a control circuit, a character / graphic memory 11, a buffer memory 12, and a character / graphic input terminal 13 are shown.

Referring to FIG. 1, with respect to the vertical screen enlargement / reduction operation, an image signal from a computer or the like input from an input terminal 1 is separated by a sync separation circuit 4 into sync signals, and horizontal and vertical sync pulses are converted. The generated signal is connected to the clock generation circuit 5, the detection circuit 8, and the readout circuit 6. The clock generating circuit 5 is a VCO or a PLL circuit or the like that controls the phase of the horizontal synchronization pulse. A clock is generated and input to the read circuit 6. The readout circuit 6 controls the image memory 7 by generating a control signal for reading out image data from the image memory 7 based on the dot clock and the horizontal synchronization pulse. The data output read from the image memory 7 is image data of an on-screen character or graphic, which will be described later, and is connected to the superimposition circuit 2 to be superimposed on an input image signal and output to the output terminal 3.

The detection circuit 8 detects the number of horizontal scanning lines per screen based on the horizontal and vertical synchronization pulses from the synchronization separation circuit 4, and is connected to the enlargement / reduction circuit 9. The character / graphic memory 11 stores characters or graphics to be displayed on the screen, and can store character or graphic data designated in advance, or a character / graphic input terminal 13.
It is also possible to input the data and write the data from the outside through the buffer memory 12. Character / graphic memory 11
The setting or writing of character or graphic data in, related to the size when this data is displayed on screen,
For example, the number of vertical scanning lines is 480, and the number of dots in the horizontal direction is 6
This is performed with a dot configuration based on a reference numerical value set in advance to 40 or the like. The above enlargement / reduction circuit 9, character / graphic memory 11, and buffer memory 12 are provided by a CPU (Central Processing Unit).
nit) and the like.

The character or graphic read data from the character / graphic memory 11 depends on the scanning frequency of the input image signal.
If the number of vertical scanning lines differs from the number of vertical scanning lines set as the reference, the scaling circuit 9 compares and compares the number of vertical scanning lines of the input image signal detected by the detection circuit 8 with the number of vertical scanning lines set as the reference. The image data is written into the image memory 7 after the enlargement or reduction processing in the vertical direction which is substantially proportional is performed. For example, if the reference number of vertical scanning lines is set to 480 and the number of vertical scanning lines of the input image signal is set to 1024, the size of the vertical display of the screen is reduced to about half, and the enlargement process is performed by about twice. Characters or graphics of a predetermined size set or written in the graphic memory 11 are reproduced. The respective functional operations of the detection circuit 8 and the scaling circuit 9 are CP
Software processing using U or the like may be used.
The memory capacity of the character / graphic memory 11 and the image memory 7 is as follows.
It may be a frame unit or a character or graphic display area unit. In the case of a character or graphic display area unit, it is possible to perform processing to control the display position of this area on the monitor screen It is.

Regarding the horizontal screen enlargement / reduction operation, as described above, the clock generation circuit 5 generates a clock from a VCO or a PLL circuit based on a horizontal synchronization pulse generated by the synchronization separation circuit 4 from the input image signal,
A dot clock whose phase is controlled by the horizontal synchronizing signal to a frequency that divides the number of dots between each horizontal synchronizing signal by, for example, a fixed set value of 640 is generated and input to the readout circuit 6. On the other hand, the character / graphics memory 11 stores character / graphics to be displayed on-screen as described above, and can set character or graphic data designated in advance, or can be input from the character / graphics input terminal 13 and stored in the buffer memory. The data can be written from the outside through the line 12. For example, the number of dots in the horizontal direction is 640, and the number of vertical scanning lines is set in a dot configuration based on reference numerical values set to 480 or the like. The data in the character / graphic memory 11 is transferred to the image memory 7, the data in the image memory 7 is read out by the dot clock of the readout circuit 6, superimposed on the input image signal by the superimposition circuit 2, and output to the output terminal 3. Since the data stored in the image memory 7 and the dot clock of the output of the readout circuit 6 always have the same number of dots in the horizontal direction, even if the scanning frequency of the input image signal changes, the data can be set in the character / graphic memory 11 or A screen similar to the size and display position of the character or graphic input from the input terminal 13 is obtained at the output terminal 3.

[0015]

According to the present invention, the following effects are exhibited. 1. According to the first aspect of the present invention, by automatically controlling the scanning frequency of an input image signal of various scanning frequency standards and character or graphic data created in advance with a fixed scanning frequency standard, a character or a graphic is automatically controlled. The graphics and their display areas are scaled and superimposed on the input image signal, and can be displayed on the screen in a predetermined size. By installing the on-screen display device of the present invention in front of an image input system of a multi-scan monitor or a multi-scan display, the horizontal and vertical scanning frequencies are not constant depending on the model and mode. Superimposed on the image signal of the processing result of the computer, etc., so that characters or graphics of a predetermined size can be displayed on the screen. Therefore, conventionally, when superimposing a character or graphic signal on a display screen, character or graphic data created by a device based on each model or standard was required. Simplification and cost reduction can be achieved.

2. According to the second aspect of the present invention, the screen display such as the adjustment function setting menu of the monitor itself in the multi-scan monitor or the like includes means for controlling the configuration of the font data of the character so that the size of the character does not change. Some have been taken, but many are based on complex methods.
According to the present invention, a dot clock is generated by dividing the number of dots between each horizontal synchronizing signal by a fixed set value with a clock whose phase is controlled by a horizontal synchronizing signal separated from the input image signal, and the same number of dots is generated by the dot clock. By reading out the character or graphic data set in step 4 and superimposing it on the input image signal, even if the scanning frequency of the input image signal changes, the size and display of the character or graphic set in advance are automatically performed even if the scanning frequency of the input image signal changes. Since the position can be obtained, the circuit can be simplified and the price can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a monitor screen diagram.

[Explanation of symbols]

1: input terminal 2: superposition circuit 3: output terminal 4: synchronization separation circuit 5: clock generation circuit 6: readout circuit 7: image memory 8: detection circuit 9: enlargement / reduction circuit 10: control circuit 11: character / graphic memory 12: Buffer memory 13: Character / graphic input terminal

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/445 H04N 5/445 Z

Claims (2)

[Claims] A display device such as a multi-scan monitor includes a superimposing circuit for adding a character or graphic signal stored in an image memory to an input image signal, an output terminal of the superimposing circuit, and a reference character or graphic data. A character / graphic memory for storing, a scaling circuit for vertically expanding or reducing a character / graphic memory output signal, the image memory for storing output data of a scaling circuit, and a synchronization signal separated from an input image signal by a synchronization separation circuit A clock generating circuit for controlling the frequency of the dots between the horizontal synchronizing signals to a predetermined set number, and a control signal for reading out image data from an image memory based on a clock output from the clock generating circuit and the synchronizing signal. A readout circuit, a detection circuit for detecting the number of vertical scanning lines based on a vertical synchronization signal input from a synchronization separation circuit, and a detection circuit. It comprises means for controlling the enlargement / reduction circuit by output, and a control circuit for controlling the input / output of each memory circuit and the enlargement / reduction circuit, and the data read from the character / graphic memory is set to the set reference number of vertical scanning lines. The number of vertical scanning lines of the input image signal is compared and collated, and enlarged or reduced in the vertical direction substantially in proportion to the ratio, written in the image memory, read out by the clock of the clock generation circuit, and superimposed on the input image signal. An on-screen display device which outputs the data and displays it on a display device such as a multi-scan monitor. 2. A display device such as a multi-scan monitor, comprising: a superimposition circuit for adding a character or graphic signal stored in an image memory to an input image signal; an output terminal of the superimposition circuit; A character / graphic memory for storing, an image memory for storing a character / graphic memory output signal, and frequency division control of the number of dots between each horizontal synchronization signal to a fixed set number by a synchronization signal separated from the input image signal by a synchronization separation circuit. A clock generation circuit, a readout circuit for generating a control signal for reading out image data of an image memory by a clock output from the clock generation circuit and the synchronization signal, and a control circuit for controlling input / output of each memory circuit. The data read from the character / graphic memory is transferred to the image memory as a set reference pixel number, and the input image signal A dot clock is generated by dividing the horizontal synchronization signal between the horizontal synchronization signals by the same set number as the set reference number of pixels by the separated horizontal synchronization signal, and data is read out from the image memory by the dot clock to generate an input image signal. 2. The on-screen display device according to claim 1, wherein the output is superimposed and displayed on a display device such as a multi-scan monitor.