JPS5994135A - Light pen input device - Google Patents

Abstract

PURPOSE:To indicate a picture with high precision, by enlarging and displaying a display picture by centering a light pen-indicated point and indicating this enlarged surface with a light pen. CONSTITUTION:When a screen is indicated by a light pen 4 and a display changeover switch 50 is turned on, coordinates X0 and Y0 of this indicated point are latched in latch circuits 7a and 7b. Display coordinates X and Y from counters 5 and 6 for X and Y for display are subtracted by coordinates X0 and Y0 on subtracting circuits 8a and 8b, and subtracted results are divided in dividing circuits 9a and 9b by 2<n>, and division results are inputted as addresses to a display memory 11. As the result, a picture which is enlarged 2<n> times with coordinates X0 and Y0 as the center is displayed on the display screen. When a point to be inputted is indicated on this enlarged display screen, counted values of counters 5 and 6 are latched in circuits 12a and 12b, and latched coordinates are inputted to a CPU30. Hereafter, coordinate points are indicated similarly to input them to the CPU30.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light pen input device for inputting CRT coordinates using a light pen.

Figure 1 shows a conventional coordinate input method using this type of device. In the figure, (1) is the scanning line of CART, (2)
1 indicates the light receiving range of the light pen.

Place the light receiving part of the light pen on any point on the CRT screen,
When you press the switch on the light pen, it emits light for one frame of the CRT. In other words, a run f(1) from the top to the bottom of the screen is performed. From the start of scanning, the light receiving range of the light pen (
2) The coordinates on the CRT can be determined from the time difference until the scanning light passes.

However, with conventional devices, as shown in Figure 1, the light receiving range of the light pen extends over several scanning lines, so the input coordinates vary by several pixels, which directly changes the coordinates of the indicated point in the displayed image. There was a drawback that it resulted in an error.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by enlarging the displayed image around the light pen indication point and pointing on this enlarged display screen with the light pen, the display It is an object of the present invention to provide a light pen input device that can reduce errors in the coordinates of a designated point on an image and can provide accurate image designation.

An embodiment of the present invention will be described below with reference to the drawings.

The second figure is a diagram showing an enlarged screen of the light pen input device according to an embodiment of the present invention. In the figure, +31 is the display screen of CR'r, (41 is the light pen,
+31 is the CRT display screen after enlargement.

FIG. 3 is a block diagram of a light pen input device according to an embodiment of the present invention.
Y display counters (7a) and (7b) indicate the coordinates (xo, y) of the light pen indicated point when the display changeover switch is pressed.
The latch circuits (8a) and (8b) that latch the x and Y display counters (51, +61) are used to latch the two latch circuits (7a) and (8b) from the display coordinates (X and Y), which are the count values of
7b) is a subtraction circuit that subtracts the latch coordinates (Xo, Yo), (9a) and (9b) are both subtraction circuits (8a) and (8
b) 17) A division circuit that divides each output value by the display magnification factor 2. These divide the magnification factor X-Xo) by changing the division connection, and if not, the above-mentioned X display counter (5). a data switching circuit that outputs output X;
(10b) is the above-mentioned display changeover switch (when sol is pressed, the above-mentioned division data changeover circuit; 圓 is a display memory that stores image information to be displayed on the CLT; the above-mentioned components (7a) to ( 10a), (7b) to (10b) Grinning, respectively, when the display changeover switch - is pressed, the display memo vani is displayed for enlarging the coordinates of the point indicated by the light pen (4). X,
X, Y enlarged display circuit (20a) that creates a Y address signal
), (20b) are configured. Also (12a).

(12b) is an X, Y coordinate latch that latches the count value of the X, Y display counter t5+ +61 when light is received by the light pen (4) when pointing on the CRT screen with the light pen (4). circuit, (to) the corresponding X,
This is a central processing unit (hereinafter referred to as CPLI) into which the latch coordinates of the Y-seat ridge latch circuits (12a) and (12b) are input.

Next, the operation will be explained.

When the display changeover switch is off, the count values X and Y of the X and Y display counters (5) and (6) are addressed to the display memory 0υ via the data changeover circuits (10a) and (10b). is input. Therefore, display memory tin
The image information stored in is displayed on the CRT in a normal size as shown in the display screen (3) in FIG.

In this state, use the light pen (4) to instruct the screen and turn on the display changeover switch, and the coordinates of the indicated point (X
6 * Y6) are latch circuits (7a), (7b)
icte 5 times. X, Y image display counter (51,
Display coordinates (x, y) from +61 are subtracted circuit (8λ),
(8b), the latch coordinates (x., yo) are subtracted, and the subtraction results X-X0 and Y-Yo are obtained by the division circuit (9a).

Display memo U through circuit (10a) and (Job)
(The address is manually entered in Ill. As a result, the display screen in Figure 2 (3; as shown in Figure 2, the instructions ACXo, Yo of the light pen (4)) and its vicinity are enlarged to 2. A display is made.

Next, when you indicate the point you want to input on this enlarged display screen (31, The count value (Xl.

Yl″3″’5’/ Chil,, Kono 5 fjMIM
! (Xl, Y, ) is input to LLCPU (to).

Similarly, the points (X, , Y2), (x3.y,
)..., the coordinates of the contact point can be input to the CPU (31) in the same way as above.

In the device of this embodiment, the display screen is enlarged twice in both the X and Y directions for the latch coordinates, so if the input coordinates are divided by 2n after input, the light pen (4) The input error ε is as small as /n when specifying the position of the displayed image.

In the above embodiment, the l[iIi image was enlarged by the circuit, but this may also be done by using a digital converter.

As described above, according to the present invention, when inputting coordinates on the display screen, the coordinates are input while being enlarged and displayed centered on a certain indicated point, which makes it possible to input coordinates with high accuracy. Enlarged display requires only the address history of the display counter in the X, Y enlarged display circuit, which is an address counter for the display memory, so that the device can be made inexpensive and the CRT can be relatively small.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a coordinate input method using a conventional light ben input device, the second figure is a diagram showing an enlarged display of the screen of a light ben input device according to an embodiment of the present invention, and FIG. 1 is a diagram illustrating a block configuration of a light ben input device according to an embodiment of the invention. i31, (31-C'''A Show 1111 II
, [41=U()hen, (111...display memory,
151, (61...X, Y display counter, i
O+...Display changeover switch, (20a), (20b
)-X, Y Enlarged display circuit, (12a), (12b
) -X, Y am 5"/f circuit, side...
CPU0 Note that the same reference numerals in the drawings indicate the same or equivalent parts. Agent Shin Kuzuno - Figure 1

Claims (1)

[Claims] (11CIL T) A light pen for inputting the coordinates of a desired point on the screen, a display memory storing image information to be displayed on the CRT, and an address counter for displaying the screen on the CRT. X/YH indicating counter for performing the above operations, and X for creating an address signal for the display memory for enlarging the display centering on the FM building at the point indicated by the light pen in response to the operation of the display changeover switch.
, Y enlarged display circuit and the above CRTil with the above light pen.
Latch the count value of the X, Y display counter when the light pen receives light when pointing on the i side.
, a Y coordinate latch circuit, and a central processing unit into which the latch coordinates of the X and Y coordinate latch circuits are input.