JPH0140355B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a video display device that displays a pattern according to data written in a digital memory, and more specifically, when a light pen is placed facing the screen of a video display unit such as a CRT, the screen corresponds to the facing position, that is, the indicated position. The present invention relates to a video display device in which display information data to be displayed at the specified position can be written to an address of a digital memory allocated in this manner. In this type of video display system, color display information is written one after another at the address of the digital memory according to the movement trajectory by moving the light pen indicated position, and the display according to the written content is
This is done on CRT. In order to display a straight line in such a video display device, it is naturally necessary to move the light pen in a straight line, but this is extremely difficult to do manually by an operator, and nearly impossible in a high-resolution device. Therefore, a device has been proposed that has a function called straight line writing, so that a straight line moves in the specified direction while the light pen is outputting the specified information on straight line writing.
According to that proposal, detailed linear writing becomes difficult. The present invention has been made in view of the above circumstances, and aims to provide a video display device that facilitates detailed linear writing by improving existing proposals. This will be explained in detail based on the drawings. FIG. 1 is a block diagram schematically showing the main parts of a video display device according to the present invention, and FIG.
FIG. 4 is a display pattern diagram for explaining various display areas of a CRT screen. If we consider an orthogonal X-Y coordinate system in which the horizontal direction of the CRT12 screen is taken as the X-axis and the vertical direction is taken as the Y-axis, and each pixel is represented by the coordinate values (X, Y) of this coordinate system, then the CRT12
The address system of the memory in which data to be displayed on the screen is written is configured to have a 1:1 correspondence with these coordinate values. That is, the horizontal address of the memory defines the coordinate value X, and the vertical address defines the coordinate value Y. Then 0 on the CRT screen
The area where ≦X≦X6 (total width in the horizontal direction) and 0≦Y≦y ₁ (most of the upper part in the vertical direction) is allocated as a writing area, and the desired color pattern can be displayed in this area. In other words, color display information can be written to the memory address corresponding to this area. x ₁ ≦ on the left side in the area where y ₂ ≦Y≦y ₄ , which is a little further down from the above writing area
The square part where X≦ _x3 is designated as a straight line writing area.
Also, x ₄ ≦ a little distance to the right from the specified area of linear writing
The band-shaped portion where X≦ _x5 is allocated as a color designated area. Color display information to be displayed in the writing area is written in an image memory (RAM) 101 having addresses corresponding to the coordinate values of pixels in the writing area, and a light pen is connected to this memory 101. In a state where no writing is performed using 1, no display is made in the writing area. On the other hand, data related to the display of the color specified area (color specification information) and data related to the display of the linear writing specified area (linear writing specification information) are stored in the read-only memory ( ROM) 102, and predetermined displays are always displayed in these areas regardless of the operation of the light pen. The designated area for linear writing is divided into four equal sections in the shape of a square, and the coordinate range and display of each section, as well as the functions when each section is designated as described later, are as shown in Table 1. In other words, data for displaying four-directional arrows in each section is written in advance in the corresponding address of the ROM 102 as linear writing designation information. Note that the display pattern in these sections is not limited to the illustrated arrow mark, but any appropriate pattern may be used, and any color may be used.

[Table] The color specification area is horizontally divided into eight sections, and each section displays the colors red, green, blue, yellow, cyan, magenta, white, and gray (or black). In other words, it corresponds to each section of the color specified area.
Three-bit data representing each display color is written in advance in each address of the ROM 102 as color designation information. and y ₁ <Y<y ₂ , y ₄ <Y≦y ₅
(lowest edge of the screen) area, other writing areas,
Portions other than the straight line writing designated area and the color designated area are always displayed in a constant color and are not involved in writing with a light pen or straight line writing display. Now, the configuration of the apparatus of the present invention will be explained based on FIG. The light pen 1 emits two types of signals as is well known. One of them is the switch signal SW that reports that the light pen 1 has been pressed against the CRT 12. As shown in C of the timing chart in Figure 3, when this is pressed, the switch signal SW is "1".
(high level). This switch signal SW is applied to the address determining circuit 2. Another signal is a signal that reports the indicated position on the CRT 12 screen by light pen 1;
The light receiving section of the switch captures the raster line light passing through the indicated position, and the switch signal is emitted.
The signal is input to the address determination circuit 2, which operates only when SW is "1", converted into a signal corresponding to the coordinate values (X ₀ , Y ₀ ) of the light pen indicated position, and input to the address determination circuit 3. . The address determination circuit 3 generates six types of output signals, and which signal to generate is determined by the input signal, that is, the coordinate values (X ₀ , Y ₀ ) of the light pen indicated position. First, the first signal is a color information capture signal a,
This is generated when the light pen 1 indicates a color designated area, and is given to the register 4 as a control signal. The second signal is a 3-bit color signal b,
When the light pen 1 specifies a color specified area, the data content corresponds to the display color of the specified section, and is applied to the 3-bit parallel register 4. The third signal is an address signal c, which is emitted when the light pen 1 indicates a writing area, and the content representing the coordinate values (X ₀ , Y ₀ ) of the indicated position, that is, from the address determination circuit 2. The input contents are as they are, and are inputted to the addition/subtraction circuit 5 and the selection circuit 6. The fourth signal is an addition/subtraction instruction signal d
[Fig. 3 D], which is issued when the light pen 1 indicates a designated area for linear writing, has 2-bit data content corresponding to each of the designated sections, and is sent to the addition/subtraction circuit 5, which will be described later. It is given as a signal instructing four types of addition/subtraction modes.
The fifth signal is a write area designation signal e,
It is generated when (X ₀ , Y ₀ ) is in the write area and is applied to the addition/subtraction circuit 5 and the gate circuit 9 . 6th
The signal f is the straight line designation signal f, which is emitted when the light pen 1 designates the straight line writing designation area, and the third signal is the straight line designation signal f.
As shown in FIG. 2, it becomes "1" when the light pen 1 is instructed to specify a straight line writing area. This straight line designation signal f is applied to the pulse generator 1 shown in FIG.
The other input is an AND gate 7 which receives the signal from the circuit 3 as one input, and the output of the AND gate 7 is given to the addition/subtraction circuit 5. As shown in FIG. 3, the pulse generator 13 generates one pulse each time the switch signal LOW of the light pen 1 is set to positive (SW=1) and the vertical synchronizing signal V shown in FIG. 3 becomes "0" during that period. Output only the preset arbitrary number, and SW=
It is reset to “0” (in the example, any number =
“1”). The linear writing designation signal f is also given to the selection circuit 6 and the gate circuit 9. The register 4 captures the color signal b when the color information capture signal a is input, stores it, and outputs it to the memory 101 as write data. The addition/subtraction circuit 5 takes in the address signal c when the write area designation signal e is input, and also takes in the address signal c according to the contents of the addition/subtraction instruction signal d at the timing when the output signal of the AND gate 7 becomes "1". X ₀ of address (X ₀ , Y ₀ )
Alternatively, add 1 or -1 to the value of Y ₀ and store the result of addition or subtraction internally, and store it at address (X ₁ , Y ₁ ) [i.e. (X ₀ +1, Y ₀ ), (X ₀ -1,
Y ₀ ), (X ₀ , Y ₀ +1) or (X ₀ , Y ₀ -1)] to the selection circuit 6. 8 is a display address counter for reading the contents of the memory 101 and ROM 102 and displaying them on the CRT 12, and the clock A shown in C of the timing chart in FIG. 4 is counted.
The content of the count is changed in response to the beam scanning of the CRT 12, and the content of the count is output to the selection circuit 6 as a read address (X ₂ , Y ₂ ). This counting content, that is, the memory 101,
The read address of ROM102 is X- on the CRT screen.
Since this corresponds to the Y coordinate line, when this is given to the memory 101 and ROM 102 via the selection circuit 6, the 3-bit color information written at this address is input to the D/A conversion circuit 11, where it is converted into an analog is converted into a video signal and input to the CRT 12, and a display based on this color information is performed at the coordinates (X ₂ , Y ₂ ) on the screen. As is well known, the vertical synchronizing signal V shown in FIG. 3A and the horizontal synchronizing signal H shown in FIG. This signal D becomes "1" during a period excluding a suitable time period before and after a negative pulse (horizontal synchronizing pulse) of the horizontal synchronizing signal H, and an image is displayed during the period when it is "1". Therefore, the clock A is a signal that appears as many times as the number of pixels in one raster line while D="1". Note that the display period signal D
is applied to the selection circuit 6 and the gate circuit 9. The selection circuit 6 outputs a non-selection signal to the address determination circuit 2, the addition/subtraction circuit 5, and the address counter 8 based on a combination of the write area designation signal e, the straight line designation signal f, and the display period signal D that are input as control signals to the selection circuit 6. Address signals input from each of X ₀ ,
Y ₀ , X ₁ , Y ₁ and X ₂ , Y ₂ are selectively selected and output as addresses X and Y for writing or reading to the memory 101 and ROM 102. It is configured as expressed by the following logical formula. X, Y=X ₀ , Y ₀・e・+X ₁ , Y ₁・f・+
X ₂ , Y ₂ )·D, that is, during the image display period (D=“1”), the outputs X ₂ , Y ₂ of the address counter 8 are selected for displaying the contents of the memory 101 and ROM 102.
Then, specify the writing area with the light pen 1, and while the writing area designation signal e="1", X ₀ ,
Select Y ₀ and specify the straight line writing designation area with the light pen 1, and while the straight line designation signal f = "1", the period other than the image display period (D =
Select X ₁ and Y ₁ at “0”). The gate circuit 9 is a circuit for selectively switching the memory 101 to read or write mode, and its output signal g is configured to be expressed by the following logical formula. g=e.+f. This output signal is given to the memory 101, and when g="1" the memory 101 is put into the write mode, and when g="0" it is put into the read mode.
That is, when X ₀ , Y ₀ or X ₁ , Y ₁ is selected in the selection circuit 6, the memory 101 is in the write mode, and when X ₂ , Y ₂ is selected, the memory 101 is in the read mode. mode. Next, the operation of the device of the present invention will be explained. When displaying a pattern in the writing area of the CRT 12, in order to determine the display color of the pattern, first use the light pen 1 to indicate a section of the color designation area in which a desired color is displayed. Then, the address determination circuit 2 issues an address corresponding to the designated position within this section, and the address determination circuit 3 receives this and outputs a color information acquisition signal a and a color signal b representing the color displayed in the designated section. Output. As a result, the color signal is stored in the register 4. Next, the writing area of the CRT 12 is indicated with the light pen 1. Then, addresses X ₀ and Y ₀ corresponding to the coordinates of the indicated position are output from the address determination circuit 2 and input to the address determination circuit 3.
In this case, the addresses X ₀ , Y ₀ correspond to the coordinates within the write area, so the address determination circuit 2 issues the write area designation signal e and the addresses X 0 , Y ₀ correspond to the coordinates within the write area.
Input Y ₀ to the selection circuit 6. The selection circuit 6 to which the write area designation signal e is input selects these X ₀ and Y ₀ during a period other than the image display period (D="0") and outputs it to the memory 101, and also outputs the write area designation signal e. The gate circuit 9 to which e is input also synchronously receives the write signal g=
Since the memory 101 is set to the write mode by setting it to "1", the color signal stored in the register 4 will be written to these addresses X ₀ and Y ₀ . Then, in the next field, the written data is read out by the read addresses X ₂ and Y ₂ given from the address counter 8 via the selection circuit 6 at the timing of D="1", and the data is read out from the pixel at the position indicated by the light pen. Then, dots of the desired color are displayed. When the light pen 1 is moved within the writing area of the CRT in order to display a desired pattern, writing is performed in the memory 101 following the movement trajectory.
Display will be performed on the CRT 12. On the other hand, the write area designation signal e is also given to the adder/subtraction circuit 5, and while this is being input, the address signal c is taken in, and when the write area designation signal e disappears, the address signal taken in, that is, X ₀ , Y ₀ are held as initial values for straight line writing, which will be described later. In other words, if you specify only one point in the writing area with the light pen, the address X ₀ ,
Capture and hold Y ₀ . Now, straight line writing, which is a feature of the device of the present invention, is performed as follows. That is, when a straight line designation area is designated with the light pen 1, the address determination circuit 3 outputs an addition/subtraction designation signal d and a straight line designation signal f. The content of the addition/subtraction instruction signal d differs depending on the designated section in the designated area of the straight line, and when a section is designated, the addition/subtraction circuit 5 takes in the initial value as described above. address
Vertical address of X ₀ , Y ₀ If a partition is specified in the mode of subtracting 1 from Y ₀ , the horizontal address
In the mode of adding 1 to X ₀ , if a partition is specified, in the mode of adding 1 to the vertical address Y ₀ , and if the partition is specified, in the mode of subtracting 1 from the horizontal address X ₀ . Each of them works. These additions and subtractions are performed using the straight line designation signal f
and an AND gate 7 whose two inputs are the output B of the pulse generator 13 that appears in synchronization with the vertical synchronization signal V.
This is done at the timing of the output signal. The addition or subtraction results are then output to the selection circuit 6 as address signals X ₁ , Y ₁ . In this case, since the straight line instruction signal f=“1”, the address signal
X ₁ and Y ₁ are periods other than the image display period (D = “0”)
is selected by the selection circuit 6, and at the same timing, the write signal g becomes “1” and the memory 101 enters the write mode, so the data stored in the register 4 is written to addresses X ₁ and Y ₁ . , D="1"
The display is performed during the image display period. As described above, according to the existing CRT display device of this type, as long as the light pen continues to indicate the designated area for straight line writing, the number of fields is added or subtracted during that period, and the straight line advances by that number of dots. For example, since the straight line advances only by a preset number, it has become easier to draw detailed straight lines. In addition, a new linear writing mode switching signal is created and the pulse generator is set to the "1" level, and even if you continue to point out the designated straight writing area with a light pen, it will only generate the set number of pulses and then set to the "0" level. Controlling the generation of pulses without limit will greatly contribute to improving the convenience of using this type of video display device and expanding its uses.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the device of the present invention, FIG. 2 is a display pattern diagram to explain the configuration of a CRT screen, FIG. 3 is a timing chart to explain the operation of the device of the present invention, and FIG. FIG. 4 is a timing chart showing the relationship among the horizontal synchronization signal, display period signal, and clock A. 1...Light pen, 2...Address determination circuit,
3...Address judgment circuit, 4...Register, 5...
... Addition/subtraction circuit, 6... Selection circuit, 9... Gate circuit, 12... CRT, 13... Pulse generation circuit,
101...image memory, 102...ROM.

Claims (1)

[Claims] 1. A video display device comprising a video display section, a writable image memory, and a light pen, and capable of displaying the contents of the image memory in a writing area allocated to a predetermined portion of the video display section, Color specification information and straight line specification information are written.
ROM, means for displaying the contents of the ROM in predetermined areas of the video display section, and storing color specification information in a register when an area where display based on color specification information is performed is indicated with a light pen. means for writing the contents of the register to an address in the image memory corresponding to the specified position when the light pen indicates an arbitrary position in the writing area; and a light pen instruction in the writing area. Addition/subtraction means for adding or subtracting the address value of the image memory determined corresponding to the position one by one, means for performing this addition/subtraction a preset number of times, and an area where display is performed based on the linear writing designation information. When the light pen specifies, the value of the address of the image memory corresponding to the light pen specified position in the writing area is added or subtracted by the specified number of times in the writing area according to the linear writing specification information. A video display device comprising: means for sequentially writing the contents of the register to an address of an image memory corresponding to a value obtained as a result of subtraction.