JPS62296222A - Coordinate input device - Google Patents

Abstract

PURPOSE:To execute the reading of coordinates with a simple constitution and a high accuracy by reading the coordinates based upon respective terminal voltages at the time of contacting a pair of resistance bodies. CONSTITUTION:When an output port PA1 of a micro-computer 11 is made into an L level, transistors 17 and 18 are turned on and a voltage Vcc is applied to a resistance body 9a of a tablet 1. At this time, since a transistor 20 is OFF state since the output of an inverter 14 is at an H level, and a transistor 21 is OFF state since the output of an inverter 22 is at an L level. Consequently, a resistance body 9b is grounded through a resistance 23, the collector of the transistor 20 is at '0' potential, and therefore, an A/D input terminal ANphi is at '0' volt. At this time, when resistance bodies 9a and 9b are brought into contact, a voltage Vx which makes the collector of the transistor 18 negative and a contacting point P positive is generated, the voltage Vx is proportional to the distance in the X direction of the resistance body 9a and therefore, X coordinates can be detected from the voltage value.

Description

3. Detailed Description of the Invention [Technical Field] The present invention relates to a coordinate input device, and particularly to a coordinate input device configured to detect a coordinate position from a contact position of two resistors.

[Prior art]

Conventionally, in PC tablets, CRT screen input devices, CAD digitizers, operation panels, handwriting input devices for word processors, electronic blackboards, etc., in order to specify the coordinate position within a set coordinate area, A coordinate input device is used.

This type of device includes, for example, a magnetic type and a resistive type. In the magnetic method, narrow metal foils are arranged in a grid pattern at predetermined intervals and insulated from each other, and a predetermined current is passed through each metal foil. When an input pen having a detection coil at its tip is positioned anywhere within this energized grid, the detection coil detects a magnetic field corresponding to that position. By calculating this detected amount using a computer, the coordinate position can be determined.

In addition, the resistance method involves stacking two flexible resistance plates close together, pressing one resistance plate with the tip of a detection pen to contact the other resistance plate, and measuring one resistance at the contact position. This is to detect the coordinate position.

However, in the conventional coordinate input device, the detecting section and the circuit are complicated, resulting in an increase in cost. Furthermore, in the resistance method, the reading speed is slow.

〔the purpose〕

The present invention has been made in view of the above, and an object of the present invention is to provide a coordinate input device that can read coordinate positions with a simple configuration.

〔composition〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 and 2 are a circuit diagram and an external view showing an embodiment of the present invention.

As shown in FIG. 2, the tablet 1 includes a coordinate input board 2 for specifying the portion of the document to be erased during copying, an input pen 3 for setting the coordinate position, and an input for specifying various conditions associated with inputting coordinates. It is configured to include a connection cable 5 connected to a keyboard 4 and a host computer. In addition, 6
is a pen holder.

FIG. 3 shows the internal configuration of the tablet 1. A resistance layer 8 is uniformly formed on the inner surface of the pastes 7a and 7b made of polyester film, etc.
a and 8b to form a resistor 9a.

9b is configured. Dot-shaped spacers 10 made of an elastomer such as rubber are provided at predetermined intervals between the resistors 9a and 9b. Therefore, when the input pen 3 is pressed down on the surface of the resistor 9a at the part desired to be input, the resistive layers 8a and 8b come into contact as shown in FIG. Terminals are provided at the ends of the resistors 9a and 9b, and the resistance value between the contact point and the terminal varies depending on the position of the contact point. By processing this resistance value by a circuit described later, the coordinate position can be determined.

As shown in FIG. 1, a voltage is selectively applied to resistors 9a and 9b by a microcomputer 1). Inverters 12, 13, 14, and 15 are connected in parallel to the boat FAI of the microcomputer 1). An inverter 16 is further connected to the inverter 12, and a transistor 17, which is turned on and off by the inverter 12, is connected to the right end of the resistor 9a. Furthermore, the base of a transistor 18 is connected to the inverter 13, and the transistor 18 makes the left end of the resistor 9a normal or non-conductive with respect to ground. A transistor 18 is connected to the A/D input terminal ANI of the microcomputer 1).
The collector of and the resistor 19 are connected.

A transistor 20 is connected to the upper end of the resistor 9b, and application of voltage VCe to the resistor 9b is controlled by an output signal of an inverter 14. Further, a transistor 21 is connected to the lower end of the resistor 9b, and is controlled by an output signal of an inverter 22 connected to the inverter 15. The A/D input terminal ANφ of the microcomputer 1) and the resistor 23 are connected to the lower end of the resistor 9b.

Further, a pen switch 24 that is turned on when the input pen 3 is operated is connected between the input port PAφ and the ground, and a voltage VCC is applied through a resistor 25 when the pen switch 24 is turned off.

Next, regarding coordinate position detection in the above configuration, the sixth
This will be explained with reference to FIG.

Set the original on the coordinate input plate 2 of the tablet 1 shown in FIG.
Press the desired input key 4. Next, the coordinates of two points on the document are specified using the input bezel 3. for example,"
After pressing the input key for "Trimming", press P+ (X+, 7+) with input pen 3.

When Pt (X!, yt) is specified, p and P,
It is possible to erase the image other than the area surrounded by (the shaded area in Figure 2g5).

Now, the output of the microcomputer 1) FAI is 1
When the level is set to L, transistors 17 and 18 are turned on, and Kt pressure VCC is applied to the resistor 9a of the tablet 1. At this time, the transistor 20 is in an off state because the output of the inverter 14 is at the t Ha level, and the transistor 21 is in the VC off state, female, because the output of the inverter 22 is 1L level. Therefore, the resistor 9b is grounded via the resistor 23, and since the collector of the transistor 20 is at 0 potential, the A/D input terminal ANφ is at O volts.

Under this condition, when the resistors 9a and 9b come into contact,
As shown in FIG. 6, a voltage Vx is generated which makes the collector of the transistor 18 negative and the contact point P positive. This voltage Vx
is proportional to the distance of the resistor 9a in the X direction, so the X coordinate can be detected from this voltage value.

On the other hand, when the output port FAI of the microcomputer 1) is set to 1H level, transistors 17 and 18 are turned off and transistors 20 and 21 are turned on. In this state, when the resistors 9a and 9b come into contact, the circuit shown in FIG. 7 is formed in the tablet 1, and the voltage vy generated at the contact point P with respect to the resistor 9b is applied to the input terminal ANI.

This voltage Vy is proportional to the distance of the resistor 9b in the Y direction, so the X coordinate can be detected from the voltage 7.

As is clear from FIGS. 6 and 7, the voltage generated at the contact point P is generated by dividing the resistor 9a or 9b, so care must be taken to ensure that this voltage is not affected by external circuits. , it is necessary to make the values of the resistors 19 and 23 sufficiently large (eg, ioo times or more for each of the resistors 9a and 9b).

Note that if the resistor 7a is pressed at several locations at the same time in response to coordinate position input, the coordinates cannot be read accurately. Therefore, a switch 24 is provided at the tip of the input pen 3, and when this switch 24 is on, only the input terminal ANφ
The star is validating the voltage to ANI.

For example, the microcomputer 1) is a 78 manufactured by NEC Corporation.
1) When using G, the built-in A/D converter has a resolution of 8 pits, so the tablet size is A3 (4
20ga x 297 *ri), then X@ is 1.6
4fl (420/28), Y axis is 1, ・l 6tg (2
97728)? It can be read with lf ur=.

Next, the processing by the microcomputer 1) will be explained based on the time chart of FIG. 8 and the flowcharts of FIG. 9 and FIG. 1O.

As shown in FIG. 8, the A/D conversion time (for example, 57.
An interval timer set to K is run for a sufficiently longer time than 6u3) (for example, several m8), and the output level of PAI is inverted every time the interval timer interrupts.

The X coordinate of ANφ is read when the FAI output is 1L level, and the X coordinate of ANI is read when the FAI output is at 'H' level. The read information is stored in a buffer within the microcomputer 1).

FIG. 9 shows a flowchart of the main routine. P.A.
φ is set as an input, FAI is set as an output for switching between X and Y (step 91), and a timer built in the microcomputer 1) is started (step 92). Next, the RAM that stores the A/D conversion results is cleared (step 93), and the A/D converter is placed in select mode (AN
φ and ANI (software selection mode). (Step 94). Next, the level of PAφ is determined (step 95), and if PAφ is O, PAφ is checked again after the chattering time has elapsed (soft timer 96) (step 97). If it is confirmed to be 0 again, set the VALiD (switch 24 is ON) flag (step 98), and if +1), step 9
Return to 5.

Among the processes in step 9B, the copying machine control routine is processed, and then the process returns to step 95.

After starting the timer setting in step 92, at the time of setting 1
A timer interrupt is generated every 'tJJ according to the flowchart in FIG. 10).

101), Calculate the average value of the A/D conversion data saved in an A/D conversion result register (not shown) (step 1o2), and set the VALiD flag (step 103). Next, if PAL is 10' (step 104), the coordinate data is stored in the X buffer (step 105), and if it is ``1'', it is stored in the Y buffer (step 1o6).

Next, invert the PA1 output (step 107), select the ANφ channel of the A/D converter in Solverker '0' (step 109), and set the level to '0'.
1), select ANI channel 1) (step 1)
to) t,, Start A/D conversion. When the interrupt is accepted, the interrupt is automatically disabled, the interrupt is enabled (step 1), and the process returns to the main routine.

〔effect〕

As explained above, according to the present invention, layer images can be read with high reliability through simple mixing.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an external appearance 1 showing an embodiment of the invention, Fig. 3 is a sectional view showing a tablet 1 according to the invention, and Fig. 4 is a diagram of the tablet 1. 5 is an explanatory diagram of the coordinate area setting of the tablet shown in FIG. 2, FIGS. 6 and 7 are a clear diagram of the resistor connection when using the input pen, and FIG. 9 and 10 are flowcharts showing a main routine and timer interrupt processing as an example of processing according to the invention. 1... Tablet, 2... Coordinate input board, 3... Input pen, 7a, 71)...
Pace, 8a, 8b... Resistance layer, c+a,
91)... Resistor, 10... Sube?
,1)...Microcomputer, 17,18
20.21...Transistor, 24...
・Pen switch. Figure 1 Figure 20 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 VCC ■ Figure 8

Claims (1)

[Claims] (1) 1 that is arranged face-to-face so that it can be contacted at any position
comprising a pair of sheet-like resistors, and a voltage applying means for alternately forming a state in which one of the pair of resistors is energized and the other is open, and each of the resistors when the pair of resistors is in contact A coordinate input device characterized by reading coordinates based on terminal voltage of.