JPS6366628A - Method for correcting parallax of touch screen - Google Patents

Abstract

PURPOSE:To obtain a correct detecting position with an infrared touch screen by correcting as prescribed the deviation between the detecting position set based on a visual point position and a display position when a display screen is spherical. CONSTITUTION:When a display surface 22 is separate from a detecting surface 21 in a CRT display device, the coordinates X and Y of the normal detecting positions on the surface 21 are corrected by equations and according to the distance Z between both surfaces 22 and 21, the distance L between a visual point position V and the surface 21, and the coordinate X' and Y' of the actual detecting positions on the surface 21. In such a way, the deviation caused by the position V between a detecting position and a display position is corrected and a correct detecting position is obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is used by being attached to the front of the display screen of a CRT display device, and the display screen is directly touched instead of operating a switch or keyboard. The present invention relates to a parallax correction method for a touch screen that performs data input operations.

(Prior Art) In recent years, amid calls for improvements in man-machine interfaces, devices have appeared that allow data input operations to be performed by directly touching the display screen of a CRT display device. A familiar example of this type of device is the Captain System terminal on a street corner.

There are cash dispensers in banks, etc., but here we will explain a touch screen applied to a color CRT display device used in industrial control systems to operate and monitor plants.

First, a touch screen is used by attaching it to the front of the display screen of a CRT display device, and instead of operating a push button switch located above to select the corresponding function during normal operation, the touch screen Pictures of pushbutton switches are displayed on the display screen of the HH, and data input operations are performed by directly touching the pictures and selecting the respective functions.

When realizing such a touch screen, there are a resistive film type, a capacitive type, a surface elastic type, an infrared type, and the like. Each of these methods has its own advantages and disadvantages, but infrared touch screens are often used in industrial control systems due to their high reliability, environmental resistance, longevity, and screen transparency. ing.

Next, the principle of this type of infrared type touch screen will be explained using an example shown in FIG.

In FIG. 2, inside the frame of a touch screen attached to the front of the display screen of a CRT display device (not shown), a light emitting diode 11, a phototransistor 12, etc. are placed bare and facing each other as shown in the figure, facing toward the display screen. A light emitting diode 71 is arranged on the right side and the lower side, and a phototransistor 12 is arranged on the left side and the upper side. As a result, the infrared beams run vertically and horizontally in a grid pattern. Therefore, if you directly touch the display screen of a CRT display device with your finger, the infrared beam will be cut off by your finger, so it is possible to detect the number in the horizontal direction and the number in the vertical direction of this cut-off infrared beam. By this, it is possible to know which position on the CRT display screen is touched.

However, the above-mentioned infrared type touch screen has the following problems. That is,
Since infrared rays are light and have a straight propagation property, the detection surface on which the above-mentioned infrared beams run is a flat surface. On the other hand, the display screen of a CRT display device, that is, the front surface of the display tube, is a part of a spherical surface, and the periphery of the screen is much more recessed than the center of the screen. Therefore, in the peripheral area of the display screen of a CRT display device, even if an operator touches a point displayed on the screen with a finger, the position where the infrared beam is cut off by the finger, that is, the detection position and the display position are different. In the meantime, a discrepancy will actually occur. This deviation will be explained using FIG. 3. That is, S displayed on the display screen 22 from the viewpoint position v in FIG.
When a finger touches a point, the detection surface 21 cuts off the infrared beam at the point T, resulting in a deviation of α. This deviation α becomes larger as the curvature of the spherical surface of the display surface 22 becomes larger and as the distance between the display surface 22 and the detection surface 21 becomes greater.

Therefore, in order to reduce such deviations, a method of arranging the vertical infrared beam and the horizontal infrared beam in a cylindrical shape has been considered, but even in such a method, the spherical surface of the display surface 22 This occurs only on the center line of the screen, and if the screen is square, the display surface 22 and the detection surface 21 will be separated, and the above-mentioned deviation cannot be eliminated.

(Problems to be Solved by the Invention) As described above, in the conventional touch screen that is attached to the front of the display screen of a CRT display device, there is a difference between the detection position and the display position depending on the position of the operator's viewpoint. There was a problem in that misalignment occurred.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide a touch screen that can correct the deviation between the detected position and the display position due to the viewpoint position and find the correct detected position. The object of the present invention is to provide a parallax correction method.

[Structure of the Invention (Means and Effects for Solving the Problems)] In order to achieve the above object, the present invention is used by being attached to the front of a spherical display screen of a CRT display device, In a touch screen that has a flat detection surface that detects a touched position when touched, and that performs data input operations by directly touching the display screen, the display screen of the CRT display device and the detection surface are connected to each other. If the distance between the display screen and the detection surface is 2
．． Using the distance IML from the viewpoint position to the detection plane and the coordinates X-, Y' of the actual detection position on the detection plane, calculate the coordinates X, Y of the normal detection position on the detection plane as X=Z. /L X”+X-.

Y-Z/L Y-+Y= This is calculated by correcting the following.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining a touch screen parallax correction method according to the present invention, and the same parts as in FIG. 3 described above are designated by the same reference numerals. The touch screen parallax correction according to this embodiment is performed as follows.

That is, as shown in FIG. 1, assuming that the screen has a y-axis in the horizontal direction, a y-axis in the vertical direction, and two axes in the depth direction, the position C is a perpendicular line drawn from the display position S to the detection surface 21. The coordinates (X, Y) of are the correct detection position. In this case, the distance Z between the display position S and the correct detection position C can be determined as follows. 2 from display position 'aS
If the position of the perpendicular line on the axis is U, then this display position S
The distance between and position U is expressed as:

0bi]ko0...(1) Also, the distance between the center position P of the spherical surface of the display surface 22 and the position U is 4R2---...(2) expressed. Here, the display position S on the display surface 22 is
Since the distance wiZ between the detection position U of detection @21 is equal to the distance between the position O and the position U, Z=D+R−J
R2-X2-Y2 (3).

On the other hand, if the coordinates of the actual detection position T are (X-, Y''), then L:Z=X=:(X-X') ...--... (4
)-Y'+<Y-Yl There is the relationship (5), and from this the coordinates (X, Y) of the correct detection position C
can be obtained as follows.

X-Z/L X-+X -・・・・・・ (6)Y
-Z/L Y"+Y' ・・・・・・ (
7) Here, since Z includes the coordinates (X, Y), it becomes a two-dimensional simultaneous formula, but for simplicity, 2 is replaced by the distance Z' between the display surface 22 and the detection surface 21 at the outermost side. Even if you replace it with , there is almost no error.

X = Z ′/ L X −+ X −−−−−−
・(8)Y-Z'/L Y-+Y-...(9
) In this way, using the coordinates of the actual detection position T on the detection surface 21 of the touch screen <X'', Y'), (8
), the correct detection position @ C position 1 m (X.

Y) can be obtained.

Incidentally, in each of the above-mentioned formulas, a point on the display screen of a CRT display device is expressed by coordinates with the center of the screen as the origin. On the other hand, in the touch screen shown in FIG. 2, there are 96 pairs of light emitting diodes 11 and phototransistors 12 in the horizontal direction (y-axis) from 0 to 95, and 42 pairs from 0 to 41 in the vertical direction (y-axis). The origin is at the upper left in the figure. Therefore, for example, the coordinates of the actual detection position T are expressed as (M-, Nl) (
M-=0-95. N-=0 to 41, both integers). In order to obtain the above-mentioned X' and Y'' from M' and N-, let the interval between the infrared beams in the horizontal direction be ΔX and the interval between the infrared beams in the vertical direction be ΔY, and the equation can be expressed as follows.

x==<M--4,s>ΔX+1/2 ΔX...
...(10) Y--<21-N') ΔY-1/2 ΔY...
・(11) Find X- and Y- from these formulas (10) and (11),
Next, calculate X and Y using equations (8) and (9). However, here too, X and Y are coordinates with the center of the screen as the origin, so
The coordinates of the infrared beam are converted as follows: 11=, N')
seek.

~1-X/△X-! -48-L・/2 ・・・・・・(12) N=21-Y/ΔY+1. '2 ・・・・・・(13) Note that since M and N are integers, (12).

Find the right side of equation (13) by rounding it to the nearest whole number.

As described above, this embodiment is used by being attached to the screen of the spherical display surface 22 of a CRT display device.
When a finger or the like touches 2, the touched position is displayed on the light emitting diode 11. In an infrared type touch screen that has a planar detection surface 21 that is detected by a phototransistor 12, and in which data is input by directly touching the display surface 22, the display surface 22 of the CRT display device and the detection surface are connected to each other. 21, the display surface 22 and the detection surface 21 are located at the outermost part of the screen.
The distance Z-1 is the distance from the viewpoint position V to the detection surface 21, and the distance between the infrared beams in the horizontal and vertical directions ΔX,
Since the coordinates M and N of the correct detection position on the detection surface 21 are corrected and determined by (8) to (13) using ΔY, etc., the difference between the detection position and the display position based on the viewpoint positions a and V is calculated. It becomes possible to correct the deviation between the two and find the correct detection position.

It should be noted that the present invention is not limited to the above-mentioned example, but can be implemented with various modifications without changing the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, there is a flat surface that is attached to the front surface of a spherical display screen of a CRT display device, and that detects the touched position when the display screen is touched. It also has a detection surface of.

In a touch screen where data is input by directly touching the display screen, when the display screen of the CRT display device and the detection surface are separated, the distance between the display screen and the detection surface is Using the distance mz, the distance L from the viewpoint position to the detection plane, and the coordinates X-, Y- of the actual detection position on the detection plane, the coordinates X, Y of the normal detection position on the detection plane are expressed as X= Z/L X-+X-.

Y=Z/L Y-+Y", so the touch screen parallax correction makes it possible to correct the deviation between the detected position and the display position due to the viewpoint position and find the correct detected position. method can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment of the touch screen parallax correction method according to the present invention, FIG. 2 is a diagram for explaining an example of the principle of an infrared type touch screen, and FIG. FIG. 3 is a diagram for explaining a problem. DESCRIPTION OF SYMBOLS 11... Light emitting diode, 12... Phototransistor, 21... Detection surface, 22... Display surface. Applicant's agent Patent attorney Takehiko Suzue Figure 1 12 2 years old) ■-7 Synsta Figure 2 Figure 3

Claims (1)

[Scope of Claims] Used by being attached to the front of a spherical display screen of a CRT display device, the display screen has a flat detection surface that detects a touched position when the display screen is touched; In a touch screen where data input operations are performed by directly touching, when the display screen of the CRT display device and the detection surface are separated, the distance Z between the display screen and the detection surface; Using the distance L from the viewpoint position to the detection plane and the coordinates X', Y' of the actual detection position on the detection plane, calculate the coordinates X, Y of the normal detection position on the detection plane as X=Z/LX A parallax correction method for a touch screen, characterized in that the parallax correction method for a touch screen is obtained by correcting as follows: '+X', Y=Z/LY'+Y'.