JP2000148125A - On-screen display device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control display attributes of fonts of every other character in a simple and inexpensive structure by updating attribute data based on attribute data from a display memory when data fed into a storage means is fixed data. SOLUTION: A display control portion 110 controls display attributes of an outputted signal SC of a shift register 109, and performs on/off control of reverse (I), red(R), green(G), and blue(B). In this case, it exchanges character data from a display memory with preset fixed data according to polarity of a memory data judging signal and outputs them, holds attribute data when the character data is fed into a storage means, and the attribute data is updated based on attribute data from a display memory when fixed data is fed into the storage means. Thus mixing data is separated with signal exchange by the judging signal, and the divided data are respectively used as character data for selecting font data, and as attribute data for controlling font display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-screen display for displaying characters (fonts) and test patterns on a screen by switching or superimposing on an input video signal in order to perform image quality adjustment and screen adjustment of a television or a display. The present invention relates to a display method and a display device.

[0002]

2. Description of the Related Art FIG. 17 shows a conventional on-screen display described in a block diagram of page 931 of, for example, a 1993 edition of Fujitsu Semiconductor Device Data Book "IC for Information / Audio / Video Equipment" (DB52-00931-1). It is the block diagram extracted about the principal part of the apparatus.

In FIG. 1, reference numeral 1 denotes a horizontal synchronizing signal HSYNC.
A dot clock generating unit for generating a dot clock signal CLKD for each horizontal dot of the font by inputting a vertical synchronizing signal VSYNC as an input signal to control the vertical display position of the font on the on-screen display screen A vertical position control unit 3 for controlling a horizontal display position of the font on the on-screen display screen by a signal from the dot clock generation unit 1;
Reference numeral 4 denotes CLKD and RH for adjusting the number of horizontal and vertical dots (character size) of a font formed on the display screen by using output signals RV and RH from the vertical position control unit 2 and the horizontal position control unit 3 as inputs. , And a vertical / horizontal character size control unit that outputs RV1 and RH1 signals.
V1, RH1 as inputs, a timing generator for generating various timing signals of the on-screen display device; 6, a read address counter for generating a memory read address signal for on-screen display of fonts on the screen; Display memory RA for storing coded character data of a font to be displayed on-screen on a screen
M and 8 store font data corresponding to the output character code DD of the display memory RAM 7 and generate a font signal DC.
, A shift register for parallel / serial conversion of the output font signal DC of the character generator ROM 8 and outputting one bit at a time, and 10 a display attribute control for the output signal SC of the shift register 9 for inversion (I ), Red (R), green (G), blue (B) ON / OFF, and the like.

The vertical / horizontal character size control section 4 and read address counter 6 are configured as shown in FIG. Here, 11 is the dot clock generator 1
, A horizontal character size control unit that divides the signal RH from the horizontal position control unit 3 by an integer, and 13 a horizontal character size control unit. And the dot clock CLKD
, A horizontal character dot counter that counts the number of dots in the horizontal direction of the font and generates a pulse for each character,
Reference numeral 14 denotes a horizontal character address counter which counts pulses from the horizontal character dot counter 13 and generates a horizontal address on the screen of the font, and 15 inputs a signal generated by the vertical character size control unit 12 through the timing generation unit 5, A vertical character dot counter for counting the number of vertical dots of the font, and 16 is a vertical character dot counter 1
5 is a vertical character address counter that counts signals from 5 and generates a vertical address of the font.

Next, the operation will be described. In such a conventional on-screen display device, first, a horizontal synchronizing signal HSYNC is input to the dot clock generator 1,
In synchronization with a dot clock for forming horizontal dots of the font, that is, HSYNC of a horizontal synchronization signal,
A dot clock CLK that is an integral multiple of the frequency of the horizontal synchronization signal
Generate D. The horizontal synchronizing signal HSYNC is also input to the horizontal position control unit 3, counts an arbitrary number of dot clocks CLKD generated by the dot clock generation unit 1, and obtains a horizontal reset signal RH whose horizontal phase has been adjusted.
This controls the horizontal display start position of the font on the screen. On the other hand, the vertical synchronizing signal VSYNC is input to the vertical position control unit 2 and counts an arbitrary number of the signals RH from the horizontal position control unit 3 to obtain a vertical reset signal RV whose vertical phase has been adjusted. Controls the top vertical display start position.

The horizontal character size control unit 11 divides the frequency of the dot clock CLKD by an integer to change the number of dots constituting the font in the horizontal direction to an integer multiple. Similarly, in order to change the number of dots constituting the vertical direction of the font to an integral multiple, the vertical character size controller 12 divides the frequency of the signal RH from the horizontal position controller 3 to an integral multiple. By controlling in this manner, for example, as shown in FIG. 19, if only the horizontal character size control unit 11 is set to divide by two, a horizontally long character that is twice as long in the horizontal direction will be divided by two only in the vertical character size control unit 12. When double is set to, double vertically long characters will be displayed on the screen in the vertical direction. Will be displayed.

The timing generator 5 receives the output signals RV1 and RH1 of the vertical / horizontal character size controller 4 and generates various timing pulses for the subsequent on-screen display processing and control. The read address counter 6 receives the clock divided by the horizontal character size control unit 11 and inputs the clock to the horizontal character dot counter 13 through the timing generation unit 5, and counts the number of horizontal dots NH of the font. The output of the horizontal character dot counter 13 is input to a horizontal character address counter 14, which outputs the number M of characters in the horizontal direction on the screen.
H is counted to generate a horizontal display address of the character on the screen.

A signal from the vertical character size control unit 12 is input to the vertical character dot counter 15 through the timing generation unit 5, and counts the number of vertical dots NV of the character. The output of the vertical character dot counter 15 is input to a vertical character address counter 16, and the vertical character address counter 16 counts the number of vertical characters MV on the screen and generates a vertical display address of the character on the screen. With the above configuration, as shown in FIG. 20, a character area of an MH character can be constituted by NH dots per character in the horizontal direction and an MV character by NV dots per character in the vertical direction.

In the display memory RAM 7, on-screen display character code data DD is written on a display memory map corresponding to a screen by a display memory write address signal WA from a microcomputer bus or the like. Further, the display memory RAM is used by the memory read address signal RA generated by the read address counter 6.
The character code data DD written in 7 is read.

Here, for example, the display memory RAM
7 can be represented as shown in FIG. In the figure, Nd-bit character codes are written in a memory map horizontal NH character × vertical NV character area corresponding to a display area of a screen, and are read out in parallel as output data DD according to a memory read address.

In this case, the character code signal is generally well known as an ASCII code, but in this case, the 1993 edition of the Fujitsu Semiconductor Device Data Book "IC for Information / Audio / Video Equipment". (DB52-0093
The character code described on page 961 of 1-1) is assumed. Then, this character code signal DD
Accordingly, the font data DC written in the character generator ROM 8 is read.

Nd-bit font data DC output in parallel in the horizontal direction of the character generator ROM 8
Are converted from parallel / serial by the shift register 9 to become a time-series font signal SC. The font signal SC is input to the display control unit 10, and the on-screen display signals RO, GO, BO, which are attribute-controlled independently for RGB.
Is output as

The display controller 10 has a circuit configuration as shown in FIG. 22, for example. Here, 17 is an exclusive OR gate for inverting and displaying the input font signal SC, and 18, 19 and 20 are AND gates for distributing and switching the font signals inverted and controlled by the exclusive OR gate 17, respectively. The gate. In the display control unit 10 having such a configuration, the font signal SC
, Non-inversion / inversion control is performed by one input control signal SI of the exclusive OR gate 17, and one input control signal SR, SG, one of the AND gates 18, 19, 20
The signals are output as on-screen outputs RO, GO, and BO that are ON / OFF controlled independently by RGB by the SB.

In such a conventional on-screen display device, the characters displayed on the screen are SI, SR,
Its attributes can be changed by SG and SB signals.
However, these SI, SR, SG, and SB signals are generally controlled by control signals stored in a memory or the like external to the on-screen display device. In many cases, different attributes cannot be set for each font displayed in one screen, and for example, control can often be performed only on a screen basis.

In order to more effectively perform on-screen display of a television, a display having a wide variety of adjustment items in recent years, which has a wide variety of adjustment items, and a large number of menu screens to be displayed for screen adjustment, a single screen is required. Among them, there is a need for an on-screen device capable of switching attributes for an arbitrary font.

Therefore, there is a case where an on-screen display device which performs a display control in units of characters by adopting a circuit configuration as shown in FIG. In the figure, reference numerals 1 to 10 are the same as those of the above-described conventional apparatus, and the description thereof is omitted. Reference numeral 21 denotes an attribute control memory RAM, which receives the same address signal and control signal as those of the display memory RAM 7.
Writing and reading are performed.

In the on-screen display device having such a configuration, the attribute control memory RAM 21 is represented as shown in FIG. 24, similarly to FIG. 21 showing the configuration of the display memory RAM 7. Therefore, when character code data for on-screen display is read from the display memory RAM 7, a display control signal (hereinafter, referred to as an "attribute data signal") relating to the character can be read at the same time. The signals are converted to the non-inversion / inversion control signals SI and R, G, B, ON / O in the display control unit 10.
By connecting as FF control signals SR, SG, and SB, it is possible to realize an on-screen display device that can change the attribute of a character in units of one character.

In the conventional on-screen display device, a test pattern signal having a gradation such as a staircase wave or a window signal is displayed together with or instead of the above-described attribute display of the character. Some have a test pattern generation circuit function.

FIG. 25 is a main block diagram of an on-screen display device to which the function of such a test pattern generation circuit is added.

In the drawing, reference numerals 1 to 10 are the same as those in the above-described conventional example, and the description thereof is omitted. Reference numeral 22 denotes a test pattern generation unit which receives a timing signal synchronized with the display screen generated by the timing generation unit 5 and generates a test signal having a gradation such as a staircase wave or a window signal.
Reference numeral 3 denotes a digital / analog converter connected with the output digital signal of the test pattern generator 22 as a data input. Reference numerals 24, 25 and 26 denote R, G and B on-screen signals RO, GO and BO of the display controller 10. These are R, G, and B adders for adding the outputs RT, GT, and BT of the digital / analog converter 23, respectively.

In the on-screen display device thus configured, for example, a test pattern generator 22 for generating a test pattern signal for adjusting a screen is provided independently, so that a digital test signal output therefrom can be digitally output. / Analog converter 23 converts the signals into analog signals, and the converted RT, GT, and BT signals are R,
The output signals RS, GS, and BS are obtained by adding the font signals RO, GO, and BO, which are display-controlled in the G and B adders 24, 25, and 26, respectively.

The configuration of the test pattern generator 22 is, for example, the same as that of the attribute control memory RAM 21 described with reference to FIG. The use of the "gradation memory RAM" enables highly accurate signal generation. The test pattern signal generated thereby includes a color bar, a staircase wave, a window signal, and the like. In addition to the test pattern, various features can be added as color gradation signals that can be displayed simultaneously during on-screen display.

[0023]

Since the conventional on-screen display device is configured as described above, it has the following problems. That is, in the conventional on-screen display device, as shown in FIG. 23, in order to control the attributes of individual fonts, it is necessary to newly add an attribute control memory RAM 21 for display control unit control bits. In the case of this conventional example, SI, SR, SG, SB
And a 4-bit configuration, but if another attribute is required, it is necessary to add additional bits for the required attribute.
There is also the problem of increasing costs.

Further, the gradation memory RAM as the test pattern generation section 22 also needs to add, for example, 6 to 8 bits in order to obtain the gradation characteristics required as a test signal, which leads to an increase in cost. .

The present invention has been made in order to solve the above-mentioned problems, and has an on-screen system capable of controlling the display attribute of every other character with a minimum memory for one bit and a simple and inexpensive configuration. It is an object to obtain a display device / display method.

It is another object of the present invention to provide an on-screen display device / display method to which a function of a test pattern generation circuit is added by means equivalent to the above object.

[0027]

According to a first aspect of the present invention, there is provided an on-screen display device for displaying a font on a screen together with an image or by switching to an image. A display memory for storing attribute data for determining the attributes of fonts to be displayed, storage means for storing font data corresponding to character data output from the display memory, and a memory read from the storage means. Display control means for controlling display of font data based on the attribute data; providing a memory data determination signal having a polarity different from that of a part of the character data and the attribute data of the display memory; Switch between character data from the display memory and preset fixed data according to the polarity of the signal Output to the storage means and hold the attribute data when the input to the storage means is character data, and store the attribute data from the display memory when the input to the storage means is fixed data. It is characterized by updating with attribute data.

According to a second aspect of the present invention, there is provided an on-screen display device, comprising: a display memory for storing coded character data and test pattern data of a font to be displayed on-screen on a screen; and an output from the display memory. Storage means for storing font data corresponding to the character data to be displayed, display control means for controlling display of the font data read from the storage means, and a part of the character data and test pattern data of the display memory. On the other hand, a memory data discrimination signal provided with different polarities, and an output from the display memory and first fixed data set in advance based on the memory data discrimination signal are output to the storage means. 1 switching means and the first switching means having a polarity different from that of the first switching means. The first is set in advance with the force 2
A second switching means for switching and outputting the fixed data, and an adding means for adding an output signal of the second switching means to an output of the display control means.

According to a third aspect of the present invention, there is provided an on-screen display method for displaying a font on a screen together with an image or by switching to an image, wherein a part of character data and attribute data stored in a display memory is displayed. Are provided with memory data discrimination signals having different polarities, and the character data from the display memory and the preset fixed data are switched and output according to the polarity of the memory data discrimination signal. Display font data, hold the attribute data when the data output from the display memory is character data, and display the attribute data from the display memory when the output data is fixed data. Updating with the data, and controlling the attribute of the font data based on the attribute data. To.

According to a fourth aspect of the present invention, in the on-screen display method, a part of the character data and the test pattern data stored in the display memory are provided with memory data determination signals having different polarities, respectively. By switching and outputting the output from the display memory and the first fixed data set in advance according to the polarity of the determination signal, font data corresponding to the output is selectively displayed, and the polarity of the memory data determination signal is displayed. The output signal from the display memory is switched between the output from the display memory and the second fixed data set in advance, and the output signal is added to the selected and output font data.

[0031]

According to the on-screen display device and the on-screen display method of the present invention, character data for selecting font data and attribute data for controlling font display are stored in the display memory. The discrimination signals having different polarities are added to each type of data and mixed, and during reproduction, the mixed data is separated by signal switching based on the discrimination signals, and character data for selecting font data and font display control are respectively used. It can be used as attribute data.

According to the on-screen display device according to the second aspect of the present invention and the on-screen display method according to the fourth aspect, the display memory stores two types of data of character data for selecting font data and test pattern data. Add discrimination signals with different polarities and mix them,
At the time of reproduction, mixed data is separated by signal switching based on the discrimination signal, and can be used as character data for selecting font data and test pattern data for controlling test pattern display, respectively.

[0033]

[Embodiment 1] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the on-screen display device according to the first embodiment of the present invention.

In the figure, reference numeral 101 denotes a horizontal synchronizing signal HSY.
A dot clock generation unit for generating a dot clock signal CLKD for each horizontal dot of a font by using NC as an input, and a vertical synchronization signal VSYNC as an input signal for controlling a vertical display position of the font on an on-screen display screen. A vertical position control unit 103 for controlling the horizontal display position of the font on the on-screen display screen based on a signal from the dot clock generation unit 101; 104 a vertical position control unit 102 and a horizontal position control unit In order to adjust the number of horizontal and vertical dots (character size) of the font formed on the display screen with the output signals RV and RH from the input 103 as input, the frequency division control of CLKD and RH is performed and the RV1 and RH1 signals are output. The vertical / horizontal character size control unit 105 receives the above RV1 and RH1 as inputs and A timing generator for generating various timing signals of the display device; 106, a read address counter for generating a memory read address signal for displaying a font on-screen on a screen; 107, encoding of a font for on-screen display on a screen Display memory RAM 108 for storing the extracted character data
a is a character generator ROM corresponding to the output character code DD of the display memory RAM 107 as shown in FIG. 2 and storing a large number of font data provided with a vertical dot number adjustment blank portion below the character data; 109
Is a shift register that converts the output font signal DC of the character generator ROM 108a from parallel to serial and outputs one bit at a time.
9 is subjected to display attribute control on the output signal SC, and inversion (I),
A display control unit that performs ON / OFF control of red (R), green (G), and blue (B).

Reference numeral 111 denotes a horizontal character size control unit that divides the dot clock CLKD from the dot clock generation unit 101 by an integer multiple, and 112 denotes a vertical character size control that divides the signal RH from the horizontal position control unit 103 by an integer multiple. Part, 11
Reference numeral 3 denotes a horizontal character size control unit 111 which controls the dot clock CL.
A signal obtained by dividing KD by an integral multiple is used as a timing generation unit 105
The horizontal character dot counter 114 counts the number of horizontal dots of the font and generates a pulse for each character, and 114 counts the pulses from the horizontal character dot counter 113 to generate the horizontal address of the font. The address counter 115a outputs a signal generated by the vertical character size controller 112 to the timing generator 1
The vertical character dot counter 116 is input through the vertical character dot counter 105 and the count number NV is controlled according to the change in the number of scanning lines of the input signal.
A vertical character address counter 117 which counts the signal from a to generate a vertical address of the font 117 is a scanning line number detecting unit which detects the number of scanning lines of the input signal from the input synchronization signals HSYNC and VSYNC, and 118 is a scanning line The vertical character dot counter control unit generates a control signal of the count value NV of the vertical character dot counter 115a according to the number of scanning lines detected by the line number detection unit 117.

In the on-screen display device according to this embodiment, the detection signal detected by the scanning line number detection unit 117 is converted by the vertical character dot counter control unit 118, and a vertical character dot counter control signal is output. The count value NV of the vertical character dot counter 115a is controlled by the vertical character dot counter control signal.

The character generator ROM 108a stores a plurality of fonts each provided with a blank portion for adjusting the number of vertical character dots below the character data. The vertical character dot counter control unit 118 controls the set value of the vertical character dot counter 115a. By controlling the NV to increase or decrease the number of dots read from the blank portion, the number of vertical dots NV per character is controlled. Further, even when the number of vertical dots NV exceeds the maximum number of vertical dots NV (MAX) constituting the font data, the vertical character size counter 112 controls the vertical character dot counter by the detection signal from the scanning line number detector 117. By controlling the reading of the character 115a a plurality of times, the number of characters displayed on the screen can be kept constant, and the character display position on the screen can be kept constant.

For example, at a certain point in time, if the number of vertical characters on the screen is an MV character and the number of scanning lines of the input signal is SV, the number of vertical dots N per character is N
V is expressed as NV = INT (SV / MV) (1). Here, the function INT (X) is a function that takes an integer part of X. At this time, the character generator ROM
If the maximum number of vertical dots of the font data stored in the font data 108a is NV (MAX), NV ≦ NV (M
In the case of AX), the vertical character dot counter 115a is set to read once by the setting of the vertical character size control unit 112, and the counter value NVc of the vertical character dot counter is set.
Is set as NVc = NV (2).

Also, NV (MAX) <NV ≦ 2N
If V (MAX), the vertical character size control unit 112 reads the vertical character dot counter 115a twice (divides by two) and sets the count value NVc of the vertical character dot counter 115a to NVc = INT (SV / 2MV).・ ・ (3)

Similarly, 2 NV (MAX) <NV
If (n-1) × NV (MAX) <NV ≦ n × NV (MAX) (4) (where n is an integer of 3 or more), the vertical character size control unit 112 Vertical character dot counter 11
5a is read n times (divide by n), and the count value NVc of the vertical character dot counter 115a is set as follows: NVc = INT (SV / (n × MV)) (5)

As described above, the vertical character dot counter 115a controls the reading of the vertical character dot counter 115a a plurality of times in accordance with the setting of the vertical character size control unit 112 in accordance with the number of scanning lines of the input signal. The number of displayed characters in the vertical direction above can be kept constant. Also,
At this time, the character display position on the screen can be kept constant by setting the vertical dot number NV of the character.

Table 1 shows an example of the setting value NVc of the vertical character dot counter 118 corresponding to the number of scanning lines SV of the input signal, and the setting of n-degree reading by the vertical character size control unit 112.

[0043]

[Table 1]

In Table 1, for example, the setting when the number of scanning lines of the input signal is 252 will be specifically described. Assuming that the number of vertical display characters in one screen is 14, the number of vertical dots NV per character in one screen when the number of scanning lines is 252 is obtained from the above equation (1): NV = INT (252 / 14) = 18 (6) Here, if NV ≦ NV (MAX),
The count value NVc of the vertical character dot counter 115a is set to "18", and the vertical character size control unit 112 causes the vertical character dot counter 115a to read characters once. The display characters on the screen at this time are as shown in FIG.

The setting when the number of scanning lines of the input signal is 784 will be described. Similarly to the above-described example, the number of vertical dots NV per character on one screen can be calculated from the following equation (1): NV = INT (784/14) = 56 (7) where NV (MAX) <NV ≤ 2 NV (MA
If X), the vertical character size control unit 112 reads the vertical character dot counter 115a twice, and the count value NVc of the vertical character dot counter 115a is NVc = INT (784 / (2 × 14)) = 28 ·・ ・ (8) Therefore, the vertical character size control unit 112
If the character is read twice in the vertical character dot counter 115a and the count value NVc of the vertical character dot counter 115a is set to "28", the characters displayed on the screen are as shown in FIG. Thus, according to the present embodiment, as can be seen by comparing FIGS. 3 and 4, even if the number of scanning lines of the input signal changes, the number of vertical characters displayed on the screen is kept constant. Also, the display position of the character on the screen can be kept constant.

Embodiment 2 FIG. Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, 101 to 107, 1
Reference numerals 09 to 114 and 116 to 118 have the same configurations as those in the first embodiment, and a description thereof will be omitted.
Reference numeral 108b denotes a character generator RO storing a plurality of types of font data having different numbers of vertical dots constituting a character.
M and 119 correspond to the number of scanning lines of the input signal detected by the number-of-scanning-lines detecting unit 117 and correspond to the character generator RO.
A font selection control unit configured to be able to select an arbitrary font from a plurality of types of fonts having different numbers of vertical dots in the character configuration stored in M108b.

In the thus constructed on-screen display device, the number of scanning lines detecting section 117 detects the number of scanning lines of the input signal, and the vertical character dot counter control section 118 responds to the detected number of scanning lines. Control the count value NVc of the vertical character dot counter 115a,
The vertical character size control unit 112 controls the reading of the vertical character dot counter 115a a plurality of times, and switches the vertical size of the character to keep the character display position on the screen constant. In accordance with the detected number of scanning lines, the font selection control unit 119 selects a font having the optimum number of vertical dots per character at that time from the data stored in the character generator ROM 108b, and The size can be kept almost constant.

[0048]

[Table 2]

Table 2 shows the set value NVc of the vertical character dot counter control unit 118 and the n-degree reading by the vertical character size control unit 112 corresponding to the number of scanning lines of the input signal detected by the scanning line number detection unit 117. FIG. 6 shows an example of setting of the font type and selection of a font type having a different number of vertical dots in the character configuration by the font selection control unit 119. Here, the number of vertical dots constituting a character indicates the number of vertical dots that actually constitute a character in the character data as shown in FIG.

For example, the number of scanning lines of the input signal is SV, the number of vertical characters on the screen is MV, and the maximum number of vertical dots of font data stored in the character generator ROM 108b is NV (MAX). Assuming that the number of dots in the direction is NV, the set value NV of the vertical character dot counter 115a corresponds to the number of scanning lines of the input signal.
By setting c and the vertical character size control in the same manner as in the first embodiment, the number of characters displayed on the screen can be always kept constant, and the position of the characters displayed on the screen can be kept constant.

The vertical character dot counter control unit 11
8 is set by the vertical character dot counter 115a.
By selecting a plurality of fonts having different numbers of vertical dots constituting the character stored in the character generator ROM 108b as shown in Table 2 corresponding to the count value NVc, the size of the character displayed on the screen is substantially constant. Can be kept.

Here, as an example, for example, when the number of scanning lines of the input signal is 252, the vertical character dot counter control unit 118 has described the count value NVc of the vertical character dot counter 115a in the first embodiment. And the set value is “18”. Then, the vertical character size control unit 112 is read once, and the character generator ROM 10 is read by a control signal from the font selection control unit 119.
As the font type 8b, the font 1 in which the number of vertical dots constituting the character is 11 dots is selected. Then, the characters displayed on the screen in this case are as shown in FIG.

Next, consider the case where the number of scanning lines changes and 784 signals are input. The vertical character dot counter control unit 118 calculates the count value NVc of the vertical character dot counter 115a in the same manner as in the first embodiment, and sets the set value to “28”.
, The vertical character size control unit 112 is read twice, and the font type of the character generator ROM 118b is selected by the control signal from the font selection control unit 119 to be the font 3 whose character configuration dot number is 16 dots. In this case, the characters displayed on the screen are as shown in FIG. 7, and the number of characters displayed on the screen can be maintained at a constant value as in the case where the number of scanning lines is 252. It is possible to keep the display character position on the screen constant. Furthermore, in the present embodiment, the size of the characters displayed on the screen can be kept constant because the font type is selected from the fonts having the optimal number of vertical dots constituting the character according to the scanning line. it can.

As described above, the vertical character dot counter control unit 118 controls the setting value NVc of the vertical character dot counter 115a and the n-th reading of the vertical character size control unit 112 according to the number of scanning lines of the input signal. By selecting a font suitable for the number of scanning lines from the character generator ROM 108b in which a plurality of types of fonts having different numbers of vertical dots constituting the character are stored in advance, the display character position on the screen and the number of characters that can be displayed on the screen are fixed. At the same time, the size of the characters on the screen can be kept almost constant.

Embodiment 3 FIG. Further, by storing more types of fonts having different numbers of vertical dots constituting the character in the character generator ROM 108c, the vertical / horizontal character size control unit 104 can be omitted from the configuration of the second embodiment as shown in FIG. Thus, the same effect as in the second embodiment can be obtained.

In the on-screen display device according to the third embodiment configured as shown in FIG. 8, in response to a change in the number of scanning lines of the input signal detected by the number-of-scanning-lines detecting unit 117,
The vertical character dot counter control unit 118 controls the count value NVc of the vertical character dot counter 115a, and also controls the count value NV of the vertical character dot counter 115a.
The font selection control unit 119 switches the font type according to the set value of c. The character generator ROM 108c stores a plurality of different fonts having different numbers of vertical dots constituting the character, and by selecting an optimal font corresponding to the count value of the vertical character dot counter 115a, the vertical / horizontal characters can be selected. As in the second embodiment, the display position of characters and the number of characters that can be displayed on the screen can be kept constant, and the size of the characters displayed on the screen can be maintained without the need for the size control unit 104. It can be kept constant.

[0057]

[Table 3]

Table 3 corresponds to the number of scanning lines of the input signal detected by the number-of-scanning-lines detecting section 117. The vertical character dot counter 1
15 shows an example of the setting of the count value NVc of 15a and the font selection by the font selection control unit 119.

For example, if the number of scanning lines of the input signal is SV and the number of vertical characters on the screen is MV characters, the number of vertical dots NV per character is NV = INT (SV / MV) (9) Becomes Further, the set value NVc of the vertical character dot counter 115a is set as NVc = NV (10).
In accordance with the setting value NVc of a, the font selection control unit 119 selects an optimum font from a plurality of types of fonts having different numbers of vertical dots in the character configuration as shown in Table 3.

Here, as an example, consider the case where the number of scanning lines of the input signal is 252, for example. In this case, the count value NVc of the vertical character dot counter 115a is set to 1 by the vertical character dot counter control unit 118 as in the first embodiment.
If the number of vertical display characters on the screen is 14, "1"
8 ", and the font 1 of the character generator ROM 108c having the vertical character dot number of 11 is selected by the control signal from the font selection control unit 119. The characters displayed on the screen in this case are as shown in FIG.

Next, when the number of scanning lines changes and 784 signals are input, the vertical character dot counter control unit 1
18, the count value NVc of the vertical character dot counter 115a is set to "56".
At 19, the font 7 in which the number of vertical dots constituting the character is 32 is selected. In this case, the characters to be displayed on the screen are as shown in FIG. 10. As in the second embodiment, the positions of the characters to be displayed on the screen and the number of characters that can be displayed on the screen can be kept constant. It can be kept constant.

Embodiment 4 FIG. Next, a fourth embodiment of the present invention will be described with reference to the drawings. In the on-screen display device of the present invention according to each of the above-described embodiments, the number, position, size, etc. of fonts displayed on the screen can be kept substantially constant regardless of how the number of scanning lines of the input signal changes. It is possible. However, in this embodiment, the attributes of the displayed fonts can be basically changed only for each screen. In view of this point, the present embodiment provides an on-screen display device that can change the attribute for each character on the display screen with a simple configuration.

FIG. 11 is a block diagram showing a schematic configuration of an on-screen display device according to this embodiment. In the figure, 101 to 110 are the same as those described in each of the above embodiments, and the description thereof will be omitted. 12
0 is a memory data changeover switch, and the display memory RA
Output data DD from M107 and built-in fixed data DE
Is switched by the discrimination bit signal DP inserted in the data DD. Numeral 121 denotes a data hold circuit, which is a discrimination bit signal inserted into the data DD of the display memory RAM 107.
In the data 07, the display control unit 110 holds data only for the required attribute control bits, and controls the display control unit 110 with the output.

The operation of the thus configured on-screen display device will be described below. FIG. 12 shows a data configuration of the display memory RAM 107, and corresponds to FIG. 21 described in the conventional example. Also in this configuration, as in FIG. 21, N is added to the horizontal NH character × vertical NV area of the memory map corresponding to the display area of the screen.
A d-bit character code signal is written. For example, in addition to the Nd-bit character code signal, a memory area of at least 1 bit is reserved for a memory data discrimination signal. For example, in a character code memory area of Nd bits, when the polarity of the discrimination bit signal DP is 0, the character code signal and the discrimination signal have the same polarity as the conventional one.
In this case, it is assumed that the data is written as an attribute data signal for font display control.

Therefore, in the embodiment shown in FIG. 11, the switching operation of the memory data switch 120 is performed by using the discrimination bit signal in which the discrimination code is written as the switching signal. The memory data switch 120 is
Display memory RAM 107 when display memory discrimination signal is 0
On the data side, when it is 1, the data is switched to the fixed data DE set in the memory data changeover switch, and this fixed data DE is, for example, a font code that is all black, that is, a code that does not display characters. .

According to such a configuration, as the input signal to the character generator ROM 108, when the discrimination bit signal is 0, the output signal DD of the display memory 107 is 1, and when the discrimination bit signal is 1, the fixed data DE is input. The data hold circuit 121 is configured to hold previous data when the data discrimination signal is 0, and to update the data content when the data discrimination signal is 1.

Next, a specific operation example of this embodiment will be described with reference to FIG. For example, FIG. 13A shows a screen to be displayed. A blank area (nothing is displayed) is displayed in the Q area, and various characters are displayed in the S area. For example, on the first line of the S area, white “A” is six, and on the second line, three “B” is red and blank for one character, and then two green “C” are set. On the third line, three inverted characters [D] are displayed in blue and one character is blanked, and then two inverted characters [E] are displayed in purple.

In this case, as shown in FIG.
', A, B, C, D, and E display memory RAM 107
Is set to 0, and the display memory RAM1
A character code corresponding to the screen is written in the Nd bit 07 character code memory area. Character A to write
Areas a, b, c, d, and e one character before B, C, D, and E
In this case, the discrimination bit signal is set to 1, and for example, attribute data as shown in Table 4 is written in order from the upper bits of the Nd-bit character code memory area.

[0069]

[Table 4]

The data hold circuit 121 inputs and holds a signal of each bit corresponding to the attribute data assigned from the upper bit, and outputs the signal. Then, the SI, SR, SG, S of the data hold circuit 121
By connecting a signal corresponding to the control of B to each control terminal of the display control unit 110, an on-screen display screen shown in FIG. 13A can be obtained.

Embodiment 5 FIG. Next, a fifth embodiment will be described. FIG. 14 is a block diagram schematically showing an on-screen display device according to the fifth embodiment. In the figure, 1
Reference numerals 01 to 110 and 121 have the same configurations as those described in the above embodiments, and a description thereof will be omitted. 122 is a second memory data changeover switch,
The determination bit signal D
The polarity is opposite to that of P, and the display memory RAM 10
7 is switched between the output data DD and the fixed data DF according to the discrimination bit signal inserted into the output data DD of the display memory RAM 107.

In the thus constructed on-screen display device, the second memory data changeover switch 122
Is the output data D of the display memory RAM 107 when the memory data determination bit signal is 1 in accordance with the memory data determination bit signal input from the display memory RAM 107.
When D and 0, the operation is switched to the fixed data DF. Here, DF is, for example, data 0 for outputting a level 0 in the digital / analog converter 123. The signals RT, GT, and BT output from the digital / analog converter 123 are added to R, G, B adders 124,
At 125 and 126, the output signals RS and GO are added to the font signals RO, GO and BO whose display is controlled, respectively.
GS and BS are obtained.

An operation example of the fifth embodiment thus configured will be described with reference to FIGS. For example, FIG.
FIG. 16A shows an example of a screen to be displayed.
F, g, h, i, as shown by the signal level of (b)
It is assumed that the staircase test pattern signal at the j level and the character display as shown in the figure are performed in the area indicated by S.

In this case as well, as in the case of the fourth embodiment, the display memory RAM1 in the S area for displaying characters is displayed.
07 is set to 0, and the discrimination bit signal D of the display memory RAM 107 in the P region for displaying the staircase wave is set to 0.
P writes 1 in advance. Display memory R in S area
In the character code memory area of the AM 107, as shown in FIG. 15, character data corresponding to the screen is written.
Also, for the data in the P region, staircase wave test pattern data is written as shown in FIG. 15 so that the output of the digital / analog converter 123 has the level shown in FIG. 16B. If the data in the display memory RAM 107 is written as described above, FIG.
An on-screen display screen as shown in FIG.

[0075]

According to the on-screen display device and the on-screen display method of the present invention, character data for selecting font data and attribute data for controlling font display are stored in the display memory. A discrimination signal for discriminating both data is added to and mixed with the two types of data, and at the time of reproduction, the mixed data is separated by signal switching based on the discrimination signal, and character data for font data selection, Since it can be used as attribute data for font display control, the attribute of the font displayed on the screen can be controlled in units of one character by only slightly increasing the number of bits of the display memory.

According to the on-screen display device according to the second aspect of the present invention and the on-screen display method according to the fourth aspect, the display memory stores two types of data of character data for selecting font data and test pattern data. A discrimination signal for discriminating both data is added and mixed, and at the time of reproduction, mixed data is separated by signal switching based on the discrimination signal, and character data for selecting font data and test data for controlling test pattern display are respectively provided. Since it can be used as test pattern data, a conventional on-screen display device should have a test pattern generation function to generate test patterns such as gray scale and window patterns with only a slight increase in the number of bits in the display memory. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of an on-screen display device according to a first embodiment of the present invention.

FIG. 2 shows a character generator R according to the first embodiment.
FIG. 4 is a diagram illustrating an example of a font stored in the OM.

FIG. 3 shows a case where the number of scanning lines of an input signal is 25 in the first embodiment.
It is a figure showing an example of a character display screen at the time of two.

FIG. 4 shows that the number of scanning lines of an input signal is 78 in the first embodiment.
It is a figure showing an example of a character display screen at the time of four.

FIG. 5 is a block diagram illustrating a main configuration of an on-screen display device according to a second embodiment of the present invention.

FIG. 6 shows that the number of scanning lines of an input signal is 25 in the second embodiment.
It is a figure showing an example of a character display screen at the time of two.

FIG. 7 shows that the number of scanning lines of an input signal is 78 in the second embodiment.
It is a figure showing an example of a character display screen at the time of four.

FIG. 8 is a block diagram illustrating a main configuration of an on-screen display device according to a third embodiment of the present invention.

FIG. 9 shows that the number of scanning lines of an input signal is 25 in the third embodiment.
It is a figure showing an example of a character display screen at the time of two.

FIG. 10 shows that the number of scanning lines of an input signal is 7 in the third embodiment.
It is a figure showing an example of a character display screen at the time of 84 lines.

FIG. 11 is a block diagram illustrating a main configuration of an on-screen display device according to a fourth embodiment of the present invention.

FIG. 12 is a diagram illustrating a data configuration of a display memory RAM according to a fourth embodiment.

FIG. 13 is a diagram illustrating an example of a screen displayed by the on-screen display device according to the fourth embodiment.

FIG. 14 is a block diagram illustrating a main configuration of an on-screen display device according to a fifth embodiment of the present invention.

FIG. 15 is a diagram illustrating a data configuration of a display memory RAM according to the second embodiment.

FIG. 16 is a diagram illustrating an example of a screen displayed by the on-screen display device according to the second embodiment.

FIG. 17 is a block diagram illustrating a main configuration of a conventional on-screen display device.

FIG. 18 is a block diagram showing a main part configuration of a conventional on-screen display device.

FIG. 19 is a diagram illustrating characters displayed on a screen when a vertical / horizontal character size control unit is operated in a conventional on-screen display device.

FIG. 20 is a diagram showing a screen configuration in a conventional on-screen display control device.

FIG. 21 is a diagram showing a data configuration of a display memory RAM in a conventional on-screen display device.

FIG. 22 is a block circuit diagram illustrating an example of a configuration of a display control unit of a conventional on-screen display device.

FIG. 23 is a block diagram showing a main configuration of a conventional on-screen display device.

FIG. 24 is a diagram showing a data configuration of a display memory RAM in a conventional on-screen display device.

FIG. 25 is a block diagram showing a main configuration of a conventional on-screen display device.

FIG. 26 is a diagram showing an example of characters displayed on a screen when an input signal is an NTSC signal in a conventional on-screen display device.

FIG. 27 is a diagram showing an example of characters displayed on a screen when an input signal is an EDTV signal of a double scan of an NTSC signal in a conventional on-screen display device.

[Explanation of symbols]

1: dot clock generation unit 2: vertical position control unit 3:
Horizontal position controller, 4: vertical / horizontal character size controller,
5: timing generator, 6: read address counter, 7: display memory RAM, 8: character generator ROM, 9: shift register, 10: display controller,
11: horizontal character size control unit, 12: vertical character size control unit, 13: horizontal character dot counter, 14: horizontal character address counter, 15: vertical character dot counter, 1
6: vertical character address counter, 17: exclusive OR gate, 18, 19, 20: AND gate, 2
1: attribute control memory RAM, 22: test pattern generator, 23: digital / analog converter, 24, 2
5, 26: adder for R, G, B, 101: dot clock generator, 102: vertical position controller, 103: horizontal position controller, 104: vertical / horizontal character size controller, 10
5: timing generator, 106: read address counter, 107: display memory RAM, 108a, 108
b, 108c: character generator ROM, 10
9: shift register, 110: display control unit, 111: horizontal character size control unit, 112: vertical character size control unit,
113: horizontal character dot counter, 114: horizontal character address counter, 115: vertical character dot counter, 1
16: vertical character address counter, 117: scanning line number detector, 118: vertical character dot counter controller, 11
9: font selection control unit, 120: memory data changeover switch, 121: data hold circuit, 122: second memory data changeover switch, 123: digital / analog converter, 124, 125, 126: R, G, B Adder

Claims (4)

[Claims] 1. An on-screen display device for displaying a font on a screen together with a video or by switching between the video and an image, wherein character data coded for the font and attribute data for determining the attribute of the font to be displayed are stored. A display memory, storage means for storing font data corresponding to character data output from the display memory, and display control means for controlling display of the font data read from the storage means based on the attribute data. A memory data discrimination signal having a different polarity for each of the character data and the attribute data of the display memory,
In accordance with the polarity of the memory data discrimination signal, character data from the display memory and preset fixed data are switched and output to the storage means, and the attribute is set when the input to the storage means is character data. An on-screen display device wherein data is held, and when the input to the storage means is fixed data, the attribute data is updated with the attribute data from the display memory. 2. A display memory for storing coded character data and test pattern data of a font to be displayed on a screen on a screen, and font data corresponding to character data output from the display memory. Storage means, display control means for controlling display of font data read from the storage means, and memory data provided with different polarities for a part of the character data and test pattern data of the display memory, respectively. A first switching unit that switches between the output from the display memory and first preset fixed data based on the determination signal, the memory data determination signal, and outputs the fixed data to the storage unit; and the first switching unit. And the polarity is different, and the output from the display memory and the second preset
An on-screen display device, comprising: a second switching means for switching and outputting the fixed data of the second switching means; and an adding means for adding an output signal of the second switching means to an output of the display control means. . 3. An on-screen display method for displaying a font on a screen together with or switching to a video, wherein the character data and the attribute data stored in the display memory have different polarities from each other. A determination signal is provided, and font data corresponding to the output is displayed by switching and outputting character data from the display memory and preset fixed data in accordance with the polarity of the memory data determination signal. When the data output from the memory is character data, the attribute data is held, and when the output data is fixed data, the attribute data is updated with the attribute data from the display memory. And controlling an attribute of the font data based on the font data. 4. A memory data discrimination signal having a different polarity is provided for a part of the character data and test pattern data stored in the display memory, and the memory data discrimination signal is outputted from the display memory in accordance with the polarity of the memory data discrimination signal. The font data corresponding to the output is selectively displayed by switching between the output of the display data and the first fixed data set in advance, and the output from the display memory and the output from the display memory are determined in advance according to the polarity of the memory data determination signal. Set second
An on-screen display method characterized by adding an output signal output by switching between the fixed data and the selected font data to the selected and output font data.