JPH10340076A - On-screen display generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an on-screen display generator having the function to reverse left and right on-screen displayed characters or symbols on a display screen. SOLUTION: An on-screen display generator consists of a video RAM 309 which stores the code information of characters or symbols to be on-screen- displayed with the position information, a ROM 310 which outputs the bit data of character patterns based on the information outputted form the RAM 309, a left and right reversal control section 317 which reverses the left and the right arrangement order of the bit data in accordance with a left and right reversal control command and outputs the reversed bit data from the ROM 310, a shift register 311 which stores the bit data outputted from the ROM 310 and an output section 312 which outputs the contents of the shift register to realize the left and the right reversal function of the displayed characters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inserting characters or symbols on a display screen of a monitor device for displaying a video signal inputted from a personal computer (hereinafter abbreviated as "PC"). The present invention relates to an on-screen display generator, and more particularly, to an on-screen display generator having a left-right reversing mechanism for a display character or symbol.

[0002]

2. Description of the Related Art In a monitor device for displaying video information from a PC or a television receiver, various kinds of information relating to screen display or audio display are transmitted to a user so as to be superimposed on the video information, and the screen or audio of the audio is displayed by the user. To enable adjustment, an on-screen display technique is used. More specifically, information on screen brightness, color tone, audio volume, and the like are displayed on top of video information from a PC, and can be set and selected by the user.

On the other hand, some monitor devices or television receivers have a function of allowing a user to arbitrarily invert a displayed image horizontally (horizontally).
This function is provided in a liquid crystal projector or a projection type television receiver so as to cope with a difference between the projection types. In such a projector, the arrangement relationship between the device and the screen is 2
There are different types of installation methods. In the front projection system, the device body is placed on the same side as the viewer with respect to the screen. In the rear projection system, the device body is placed on the side opposite to the viewer with respect to the screen.

[0004] In both cases, the same video signal appears to be left and right opposite to each other. To cope with this, many liquid crystal projectors and the like have a function that allows the user to arbitrarily invert the left and right display as described above. For example, in a monitor device having such a left-right inverted display function of an image, when an on-screen character is inserted, a normal monitor device inserts the on-screen character into an analog video signal from a PC, and then inserts the on-screen character. Converts video signals containing characters to digital signals, performs various signal processing including left / right inversion of the video, converts them back to analog signals, and drives a display device such as a liquid crystal panel to display on-screen on the screen The characters are displayed.

FIG. 1 is a block diagram showing a schematic configuration of a conventional liquid crystal display device having such a left-right inverted display function. In the figure, reference numeral 1 denotes a video signal input terminal to which a video signal from a PC is input, and 2 denotes a synchronization signal HD from the PC.
(Horizontal synchronization signal) and a synchronization signal input terminal to which VD (vertical synchronization signal) is input. Note that the video signal referred to here is an analog RGB signal that is currently common in PCs. Therefore, the video signal path generally includes three independent systems of R, G, and B. is there. However, in FIG. 1, for the sake of simplicity, only a minimum required one system is shown.

First, the structure of this apparatus will be briefly described along the flow of a video signal. An on-screen character is inserted into a video signal input from a PC by a character inserter 3 and input to a video amplifier 4. Amplified. The amplified signal is converted from an analog signal to a digital signal by the A / D converter 5 and input to the line memory 6. The line memory 6 typically performs signal processing such as frequency conversion processing and left / right inversion processing.

The signal processed as described above is then input to a D / A converter 7 where it is converted from a digital signal to an analog signal. In addition, processing necessary for driving the liquid crystal panel is performed (this part is not directly related to the present invention, and thus the description is omitted).
Is input to

Next, the synchronization signal processing and the liquid crystal panel transfer system will be described. The synchronization signals HD and VD from the PC
/ F unit 11 performs waveform shaping and
Is input to The microcomputer 12 includes a synchronization determining unit 13 that determines a PC type based on the synchronization polarity and frequency information of the input signal, a setting unit 14 that sets each piece of timing setting information according to the determined PC type, and a key. An input determination unit 15 and a display control unit 16 are provided.

The various timing information set by the setting unit 14 in the microcomputer 12 is then transmitted to a timing generator 17, where the processing units 5, 7, and 8 generate necessary timing pulses. The pulse is input to the transfer pulse driver 18 to form a transfer pulse for transferring and displaying a video signal. This transfer pulse is input to the liquid crystal panel 10 and used to display a video signal.

Next, the operation section and the on-screen display system will be described. A key operation from the operation section 19 is detected and judged by a key input discrimination section 15 in the microcomputer 12, and the setting section 14 is appropriately changed and displayed. Display control data is input to the on-screen display generator 20 via the control unit 16. The on-screen display generator 20 generates a character dot pattern using a built-in character pattern ROM based on display control data from the microcomputer 12, that is, display position data and character code data.
This is output to the character inserter 3. The on-screen character generator 20 operates using a signal obtained by shaping the waveforms of the input synchronization signals HD and VD as a clock reference.

[0011]

As described above, in the conventional monitor device, the character inserter 3 is provided at the preceding stage of the line memory 6 and the character dot generated by the on-screen display generator 20 is provided in the character inserter 3. A pattern is input, and on-screen characters are superimposed on the video signal. The inversion processing of the display image is executed by the line memory 6 on the image signal on which the on-screen characters are superimposed as described above. Therefore, as the on-screen display generator 20,
By itself, it does not have a character inversion function.

However, for example, the synchronization signal from the PC is P
Therefore, when the on-screen characters are superimposed on the video signal, it is necessary to appropriately adjust the display start position and the clock frequency of the on-screen characters according to the specific PC. Therefore, in the monitor device shown in FIG. 1 provided with the on-screen display generator 20, the display control unit 16 in the microcomputer 12 calculates the display start position according to the PC and converts the display start position data into the on-screen display generator. 20 and the on-screen display generator itself needs to have a function of changing the clock frequency according to the type of PC. As a result, there is a disadvantage that control of on-screen display in the monitor device becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional on-screen display generator, and an object of the present invention is to provide a built-in left / right display inverting function and control the same when incorporated in a monitor device. To provide a simple on-screen display generator.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. For this reason, the present invention provides a video RAM for storing code information of characters or symbols to be displayed on-screen on an arbitrary display screen together with display position information on the display screen, and the code information output from the video RAM. A character pattern ROM for outputting bit data corresponding to the character or symbol pattern based on the display position information; and a character pattern R corresponding to an arbitrarily input left / right inversion control instruction of the display screen.
A left / right inversion control unit for outputting the bit data from the OM by reversing the arrangement order in the left / right direction of the display screen;
An on-screen display generator includes a shift register for storing bit data output from the character pattern ROM, and an output unit for outputting the contents of the shift register.

In another aspect of the present invention, the video RA
The M, character pattern ROM, left-right reversal control unit, shift register, and output unit constitute an on-screen display generator incorporated on the same substrate. According to still another aspect of the present invention, in a monitor device that displays a video signal from a personal computer, an on-screen character insertion unit is provided at a subsequent stage after the frequency conversion process, and the character insertion unit includes
A monitor device is characterized in that any one of the on-screen display generators is connected.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an on-screen display generating apparatus according to the present invention, first, a configuration of a monitor device configured by applying this apparatus will be described. For simplicity of description, the following description is limited to a monitor device that receives a video signal from a PC, but a projection type television receiver is also included in the category of the monitor device described in this specification. Of course, it is included.

FIG. 2 is a block diagram of a monitor device using a liquid crystal panel as an example of the display device and having a left-right reversal function of an image. In the following drawings, the same or similar components as those in FIG. 1 are denoted by the same reference numerals. The basic difference between the monitor device shown in FIG. 2 using the on-screen display generator of the present invention and the monitor device shown in FIG. 1 using the conventional on-screen display generator is the character inserter in the signal processing path. 3 and the configuration of the on-screen display generator, and the synchronization signal input to the generator. Hereinafter, the configuration and operation of this device will be described with reference to FIG. 2 focusing on this difference.

In FIG. 2, a video signal input from a PC to an input terminal 1 is amplified by a video amplifier 4,
The data is digitized by the D converter 5 and input to the line memory 6. The line memory 6 converts the digitized video signal into a signal of a fixed frequency by a frequency conversion process, and performs horizontal reversal processing so that the left and right sides of the video display screen are reversed if necessary. Switches the order of video data. Note that the frequency conversion process is a process for converting various PC video signals having different synchronization frequencies and dot clocks into a signal having a constant frequency optimal for the liquid crystal panel, and optimizing display conditions on the liquid crystal panel. Yes, specifically, by changing the speed of writing to and reading from the line memory 6.

The left-right reversal process is a process for reversing the left and right of a video signal according to the type of the liquid crystal projector. More specifically, the left-right reversal process is performed by changing the direction of write and read data in the line memory 6. ing. The signal processed variously by the line memory 6 is the following D /
The digital-to-analog conversion is performed by the A-converter 7 and the digital-to-analog conversion is performed. Thereafter, in the video signal processing unit 8, processing required for the liquid crystal panel such as amplification, gamma processing, and polarity inversion is performed, and is input to the video panel 10 through the driving unit 9.

Next, the synchronization signal processing and the on-screen display system will be described. In the present embodiment, the on-screen character generator 30 receives a command from the display controller 16 in the microcomputer 12 and, unlike the conventional device shown in FIG. VD 'is input. This reference signal is P
This is a horizontal / vertical synchronization signal serving as a reference for timing generated by the timing generator 17 based on the synchronization signal from C, and is a signal for providing an operation clock of the liquid crystal panel (a reading system of the line memory 6).

As described above, by synchronizing the on-screen character generator 30 with the operation clock of the liquid crystal panel, the on-screen characters can be correctly inserted into the video signal output from the line memory 6 at a constant frequency. it can. Further, this monitor device is characterized in that the on-screen character generating device 30 itself has a function of inverting the on-screen characters horizontally. Therefore, in this monitor device, the line memory 6 inverts only the video signal from the PC.

Hereinafter, the configuration and operation of the on-screen character generator 30 according to one embodiment of the present invention will be described with reference to FIGS. Note that FIG.
FIG. 4 is a block diagram showing a configuration of an on-screen character generation device 30 applied to the liquid crystal projector shown in FIG. In FIG. 3, reference numeral 301 denotes the display control unit 1 of the microcomputer 12.
6 is a control command decoder for decoding what kind of data the input data is, and 303 and 304 are horizontal and vertical directions of a video RAM 309 described later. Horizontal and vertical position counters 304 and 307 for managing positions are horizontal and vertical address counters for counting the number of horizontal and vertical dots of one character in the input character information. Reference numeral 305 denotes a write address counter, and 308 denotes a data selector.
This is for writing to a predetermined position of the AM 309. 3
Reference numeral 09 denotes a video RAM for storing display characters in a required arbitrary position on the screen, and 310 denotes a video RA.
M309 is a character pattern ROM that receives character code data output based on screen position information and outputs bit data of a character pattern, and outputs the character pattern ROM via a shift register 311 and an output circuit 312. Is output to

Reference numeral 313 denotes a display clock oscillating section for generating a display clock, 314 an oscillator for supplying a clock signal to the oscillating section 313, and 315 a timing pulse necessary for each section of the on-screen character generator 30. The timing generator 17 generates a predetermined timing based on the clock signals HD ′ and VD ′ in the reading system of the line memory 6 formed by the timing generator 17 (see FIG. 2) based on the input synchronization signals HD and VD. Is formed. In the display clock oscillator 313, the clock signal generated by the oscillator 314 is reset by these signals so as to be synchronized with the signals HD 'and HV'.

The on-screen character generator 30 of this embodiment further has a left-right reversal control unit 317 for controlling left-right reversal of on-screen characters. This control unit 3
Reference numeral 17 denotes a character pattern RO, which is driven by a signal obtained by decoding a left / right inversion command newly defined in the present invention as control data input from the on-screen display control unit 16 of the microcomputer 12 by the decoder 302, and
The M310 and the shift register 311 are controlled to cause the display characters to be horizontally inverted.

The operation of the above-described on-screen character generator 30 will be described below with reference to FIG. In order to simplify the description, each control of 1) writing of display characters, 2) output of display characters, 3) display start position control, clock frequency control, and 4) display left / right inverted display of the display characters will be described. 1) Writing characters: First, a procedure for writing characters in the video RAM 309 corresponding to one display screen will be described. In the on-screen display screen, a character pattern is generally assigned to each of the squares of m rows and n columns. In the example of FIG. 3, assuming a square of 6 rows and 8 columns,
The corresponding video RAM 309 is shown. Also, codes are assigned to the ROM 310 storing the character patterns with the number of digits corresponding to the total number of all character types.
A bit pattern of vertical p lines × horizontal q dots is stored for one character. In the conceptual diagram shown in FIG.
As an example, the character code is 8 bits (hexadecimal 2 digits)
The bit pattern of the character is 16 lines in length and 12 lines in width.
The ROM 310 in which data is stored by dots is shown.

To write a character code into the video RAM 309, first, the display control unit 16 of the microcomputer 12 sends horizontal / vertical position designation data (data designating a position on the mxn matrix) to the data input unit 301,
The data is input to the data selector 308 via the write address counter 305. Next, microcomputer 1
When a character code (8 bits) is input from the second display control unit 16, the character code is written to a predetermined position of the video RAM 309 designated by the data selector 308. Note that the control instruction decoder 302 performs identification of what data is input data. That is, several bits for the control command are defined and added before and after the input signal (the description is omitted).
, The input data is identified.
By repeating this operation sequentially, a character array to be displayed on the screen is formed in the video RAM 309. For example, in FIG. 4A, a character string "menu" is stored in the video RAM 309 from the upper left in one line.

2) Character output: Next, the video RAM 30
A procedure for outputting a character array of 9 will be described. First, a timing pulse necessary for each unit is generated by the timing generation unit 315 based on the video synchronization signals HD ′ and VD ′. The clock pulse generated by the display clock oscillator 313 based on the pulse signal supplied from the display clock oscillator 314 is reset by signals HD ′ and VD ′.

The horizontal position counter 303 is a counter for managing the horizontal position of the video RAM in units of 12 clocks because one character has q (12) dots in the horizontal direction. One character has p (16) lines in the vertical direction, so 16 lines (HD '
This is a counter for managing the vertical position of the video RAM in units of (16 periods). The horizontal position counter is 1
The vertical position counter repeats the values of 1 to m.

The horizontal address counter 304 repeats the number of horizontal dots 1 to q (0 to 11) of one character, and the vertical address counter 307 controls the number of vertical lines 1 to p (0 to 0) of one character. This is a counter that repeats the value of 15). For character output, the timing pulse H
The video RAM 3 is determined by the values of m and n based on D 'and VD'.
09 is selected, the character code stored therein is output to the ROM 310, and a character pattern corresponding to the character code is selected. FIG. 4b shows (m,
(n) = (1, 1) shows a state where the character "Me" is selected. The selected character pattern is output to the shift register for each line in synchronization with the clock frequency. The pulse train shown in the forward order in FIG. 4c is the horizontal bit pattern (q = 0) of line p = 6 when the on-screen display generator 30 does not receive the left / right inversion command.
11 to 11) are read at the clock oscillation frequency and input to the shift register 311.

3) Display Start Position Control, Clock Frequency Control A description will be given of a means for controlling where on the screen the character array formed in the video RAM 309 is displayed.
The display start position is an instruction to determine a position on the video screen where the character array is to be arranged.
Defined so that you can specify how many clocks after which the character in the first column is displayed using D 'as a trigger, and in which line the character string in the first line is displayed using the signal VD' in the vertical direction. Have been. The display start position control command input from the microcomputer 12 is decoded by the control command decoder 302 via the data input unit 301 in the same manner as other commands, and controls the horizontal position counter 303 and the vertical position counter 306 to display. Determine the starting position.

The horizontal size of the character array on the display screen is changed by changing the clock frequency. In this apparatus, as described above, the timing generator 17 is used.
Therefore, the timing generator 315 and the display clock oscillator 313 need only generate a fixed pulse signal. 4) Left / Right Inversion Display As control data input from the on-screen display control unit 16 of the microcomputer 12, a newly defined left / right inversion command is controlled via the data input unit 301 in the same manner as other control data. It is decoded by the instruction decoder 302 and input to the left / right inversion control unit 317. With this input, the left / right inversion control unit 17 performs control to invert the reading order of the character pattern ROM 310, and outputs the bit patterns to the shift register 311 in the reverse order. The pulse train shown as the reverse order in FIG. 4C illustrates the bit pattern in the shift register 311 read in response to the left / right inversion command. This bit pattern is then output as a pulse train to the character inserter 12 via the output circuit 312.

In the embodiment shown in FIG. 3, only the function of switching the left / right display direction of each character pattern is realized as hardware.
In the process of writing a character code to the video RAM 309, it is necessary to change the arrangement order of the characters. This is to prevent “menu” from being displayed as “menu”, for example. This exchange is performed in the microcomputer 12. That is, the operation unit 19
Is input from the user, the microcomputer 12 detects this command,
A process for automatically inverting the character array to be written to the video RAM in the horizontal direction (horizontal direction) is performed. Therefore, the character data input to the on-screen display generation device 30 has already been reversed in the arrangement order.

As described above, the on-screen display generation device 30 of the present embodiment has the function of inverting the display characters to the left and right by itself. Therefore, when incorporated in a monitor device, this device should be connected to the latter stage of the frequency conversion process. Can be. Therefore, the clock generator 313 and the timing generator 31
In 5, it is only necessary to generate a clock signal and a timing pulse having a fixed frequency, and the configuration of the device is simplified. Furthermore, in the microcomputer 12, the generation of the display start position control data, which conventionally had to be set for each PC type, need only generate a constant value in the present embodiment, so that the control in the microcomputer 12 becomes easy. .

For reference, the configuration and operation of the on-screen display generator 20 used in the monitor device shown in FIG. 1 will be described with reference to FIGS. The effect of the on-screen display generator in the embodiment will be clarified. In the apparatus shown in FIG. 5, constituent members that are the same as or similar to those of the components of the embodiment of the present invention shown in FIG. 3 are denoted by reference numerals of the 200s instead of reference numerals of the 300s. Therefore, description of the same or similar parts will be omitted. 6a, b, c
Correspond to a, b, and c in FIG. 4, and a detailed description thereof will be omitted.

In the on-screen display generation device shown in FIG. 5, unlike the device of the present invention shown in FIG. 3, the control data input from the microcomputer 12 does not include a left-right inversion command. Instead, different display start position data is included depending on the PC type. In the apparatus of the present invention, the display start position data is a fixed value as described above. Further, in the apparatus shown in FIG.
Has a function of generating a pulse signal of a different frequency according to the PC type, and the oscillation unit 214 also generates a clock signal of a frequency according to the PC type in response to a control signal from the clock frequency control unit 216. Has a function.

The clock frequency control unit 216 changes the horizontal size (stretch / shrink) of the character array on the display screen.
It is considered that the frequency is changed discretely or continuously. In the example of FIG. 5, it is assumed that the frequency is changed continuously. Therefore, the oscillation frequency is varied by using a variable capacitance diode in the oscillation unit 214. In the clock frequency control unit 216, P
Since there is an appropriate control input according to the determination of the C type, the clock frequency is changed according to this control input, and the size of the character on the display screen in the horizontal direction is changed.

On the other hand, in the apparatus of the present invention shown in FIG. 3, since the clock frequency is fixed irrespective of the type of PC, a clock frequency control unit is not required. Also, the clock signal oscillating unit and the timing pulse generating unit need only generate a fixed value signal, so that the configuration is simplified as compared with the device of FIG. When the device of the present invention is applied to a liquid crystal display device, the following secondary effects occur. In general, a monitor device requires an on-screen display so that a user can operate the device even when there is no video signal from a PC. For LCD timing generators,
In order to prevent the deterioration of the liquid crystal, even when there is no input of the video signal and the synchronization signal from the PC, the timing pulse is free-run oscillated by some method during the energization to refresh the liquid crystal. In the monitor device shown in FIG. 2, since the on-screen character inserter 3 is connected to the subsequent stage of the line memory converted to a constant frequency, the timing of the constant frequency is always constant regardless of the presence or absence of the video signal input from the PC. A pulse is obtained. Therefore, even when a video signal is not input, on-screen display on a liquid crystal panel can be easily performed by using this timing pulse. In addition, in order to enable on-screen display when no video signal is input in the conventional device, there is a disadvantage that a new timing generating means for that purpose is required.

As another embodiment of the present invention, the device shown in FIG. 3 can be integrated on the same substrate to constitute one IC. Further, in the embodiment of the present invention shown in FIG. 3, the character array is inverted left and right in the microcomputer 12,
As in the case of the character pattern ROM, a configuration in which hardware for reversing the character array from side to side is added may be adopted. More specifically, this can be achieved by associating the squares of the video RAM with the count value of the horizontal position counter of the video RAM in the normal and reverse order. In this case, even when the left / right inversion command is input from the operation unit 19, the microcomputer inputs the character arrangement data in the normal order to the on-screen display generator 30.

[0039]

As described above in detail, in the on-screen display generation device of the present invention, since the device itself has a built-in left-right (horizontal direction) inversion mechanism of the on-screen character or symbol, the on-screen display generation device can receive the data from the PC. In a monitor device or a television receiver that displays video information, it is possible to insert on-screen characters into a video signal that has been converted to a constant frequency. As a result, it becomes unnecessary to use a conventional on-screen display generator without a built-in left-right reversing mechanism, and it becomes unnecessary to adjust the display start position for each PC type by microcomputer control. In this case, the control mechanism when the device is incorporated into the device is simplified. On the display screen, the on-screen display position is PC
Regardless of the type, the position is always the same, giving the user a stable impression. Furthermore, since the clock signal and the timing pulse required for the on-screen display generator may be of a fixed frequency, a mechanism for generating a clock signal and a timing pulse having a different frequency for each PC type, which is conventionally required, becomes unnecessary. In addition, the configuration of the device itself is simplified, and the product cost is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a general monitor device.

FIG. 2 is a block diagram showing a configuration of a monitor device to which the device of the present invention is applied.

FIG. 3 is a block diagram showing a configuration of an on-screen display generation device according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of the device shown in FIG. 3;

FIG. 5 is a block diagram showing a configuration of a conventional on-screen display generation device.

FIG. 6 is a diagram for explaining the operation of the device shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Video signal input terminal 2 ... Synchronization signal input terminal 3 ... Character inserter 5 ... Line memory 10 ... Liquid crystal display panel 12 ... Microcomputer 17 ... Timing generator 19 ... Operation part 30 ... On-screen display generator 309 ... Video RAM 310: character pattern ROM 311: shift register 317: left / right reversal control unit

Claims (3)

[Claims] 1. A video RAM for storing code information of characters or symbols to be displayed on-screen on an arbitrary display screen together with display position information on the display screen, and the code information and display output from the video RAM A character pattern ROM that outputs bit data corresponding to the character or symbol pattern based on position information.
A left / right inversion control unit for outputting the bit data from the character pattern ROM in an inverted arrangement order in the left / right direction of the display screen in response to a left / right inversion control command of the display screen arbitrarily input; An on-screen display generation device, comprising: a shift register that stores bit data output from the character pattern ROM; and an output unit that outputs the contents of the shift register. 2. The video RAM and a character pattern RO.
The on-screen display generation device according to claim 1, wherein the M, the left / right inversion control unit, the shift register, and the output unit are integrated on the same substrate to form one integrated circuit. 3. A monitor device for displaying a video signal from a personal computer, wherein an on-screen character insertion unit is provided at a stage subsequent to the frequency conversion processing, and the character insertion unit
A monitor device, comprising the on-screen display generator according to claim 1 or 2 connected thereto.