JP3519977B2 - Estimation method of resistive film pressure sensitive digitizer circuit constant - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating a resistive film pressure-sensitive digitizer, and more particularly to a method for estimating a circuit constant of a resistive film pressure-sensitive digitizer.

[0002]

2. Description of the Related Art As shown in FIG. 1, a resistive film pressure-sensitive digitizer 100 comprises a base 101 made of glass or film, and a conductive film 10 provided on the base 101.
2 and the insulating film 103 provided on the conductive film 102.
In some cases, a main resistance film 104 provided on the upper layer of the insulating film 103 for coordinate detection and electrodes 105 and 106 arranged at both ends of the main resistance film 104 are laminated and formed.
This structure is excellent in electrical characteristics and optical characteristics (translucency).

Generally, as an index showing the characteristics of the resistance film pressure-sensitive digitizer, there are linearity of the resistance film, resistance value between electrodes, insulation resistance value between resistance films, capacitance value between resistance films, and the like. Resistive film pressure-sensitive digitizers currently on the market perform operation confirmation using a so-called static characteristic measuring method that detects a place where measured values are sufficiently stable by applying a pen load for a long time,
The measurement results are announced. Therefore, when designing a system using a digitizer, the design value is designed with reference to the published values measured by the static characteristic measuring method.

When a system design that does not require high-speed operation such as the sampling speed of the digitizer is used, it is sufficient to use a digitizer whose operation has been confirmed only by the static characteristic measuring method described above. When it is necessary to increase the speed or the operation speed, in the two-layer structure digitizer 100, the capacitor component between the main resistance film 104 which is the first resistance film and the conductive film 102 which is the second resistance film is generated. Therefore, when the digitizer is operated at high speed, the response of the output to the input is slow and there are some that cannot obtain accurate coordinate values.

Therefore, when designing a system using a digitizer, it is necessary to know whether or not the digitizer is a digitizer that can support high-speed operation. Therefore, an index showing a so-called dynamic characteristic for detecting a response speed at the time of high speed operation such as a case where the pen load is applied only for a moment is required.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for obtaining an index representing a dynamic characteristic of a resistance film pressure sensitive digitizer having a two-layer structure.

[0007]

According to the present invention, the first aspect of the present invention is provided.
Is a circuit constant estimation method for a two-layer resistance film pressure-sensitive digitizer having a second resistance film below the main resistance film with an insulating film interposed between two electrodes arranged at both ends of the main resistance film. 2
A resistor that is regarded as a terminal circuit element and corresponds to the second resistance film.
The inter-film capacitance between the element and the main resistance film and the second resistance film.
Connect the corresponding capacitor element in series and parallel it
, Before connecting the resistance elements corresponding to the main resistance film in parallel.
Equivalent circuit of resistance film pressure sensitive digitizer
Then, the circuit constant of the two-layer structure resistive film pressure-sensitive digitizer is estimated based on the equivalent circuit.

According to a second aspect of the present invention, the electrode according to the first aspect is provided.
Step input and measure the output step response
Compare the calculated value with the calculated step response value.
It is characterized in that the inter-film capacitance value of the equivalent circuit and the resistance value of the second resistance film are estimated.

A third aspect of the present invention is the same as the first aspect of the present invention.
Standard 2-layer resistive film pressure-sensitive digitizer and the above-mentioned standard
Construct a Wheatstone bridge by facing the equivalent circuit
Then, by adjusting the circuit constant of the equivalent circuit,
The balance point is detected, and the inter-film capacitance value of the equivalent circuit and the resistance value of the second resistance film are estimated.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an equivalent circuit in which the electrodes 105 and 106 of the two-layer resistance film pressure-sensitive digitizer shown in FIG. 1 are regarded as two-terminal circuit elements.

In FIG. 2, reference numeral 204 represents a main resistance R1 corresponding to the main resistance film 104 which is the first resistance film in FIG. 1, and 202 is a conductive film which is the second resistance film in FIG. 102
Represents the second resistor R2, and 205 and 206 are
Electrodes 105 and 10 arranged at both ends of the main resistance film 104 of FIG.
Equivalent to 6. The resistance is the main resistance film 104 (main resistance R1 (2
04)) alone may be treated as pure resistance, but in the case of a two-layer structure, the conductive film 10 is formed through the inter-film capacitance.
2 (second resistor R2 (202)) is assumed to have a path through which an alternating current flows, so that the main resistance film 104 (main resistance R1 (204)) and the conductive film 102 (second resistance R2 (2) are formed.
02)) between capacitors C1 (211) and C2
(212) occurs. When the resistance film pressure-sensitive digitizer having the two-layer structure is strictly expressed, it is necessary to form a distributed constant circuit in which infinitely small capacitors are arranged innumerably and infinitely small resistance elements are arranged innumerably. When a normal electrode operation is performed as a digitizer, it can be accurately represented by an equivalent circuit composed of simple lumped circuit constants in FIG.

When coordinate detection is performed using such a digitizer, a potential difference is applied to the electrodes 205 and 206, and a state in which a potential difference is applied between the electrodes 205 and 206 and a state in which no potential is applied are alternated. Repeat.

Next, a method of estimating the lumped circuit constant of the resistance film pressure-sensitive digitizer having the two-layer structure will be described.

First, the first method is to estimate the circuit constant by observing the step response of a two-layer resistive film pressure-sensitive digitizer and comparing it with a logically calculated value.

As for the step response, as shown in FIG. 3, a resistor r (303) is connected in series to one electrode 105 of the resistance film pressure-sensitive digitizer 100 having a two-layer structure, and a step input is applied from the input terminal 301, The other electrode 106 applies a ground level potential (0 V). When observing the step response, the output from the terminal 302 is observed as the step response. It is to be noted that the resistance r (303) is usually about 1 KΩ.

On the other hand, when the step response in the circuit shown in FIG. 2 is calculated,

[0018]

[Equation 1] Becomes

Therefore, comparing the step response observed in FIG. 3 with the result of the step response obtained by the calculation of the equation (1), the second resistor R2 in FIG.
Approximate values for (202) and capacitors C (211, 212) can be estimated.

The second method is to estimate the circuit constant by forming a Wheatstone bridge by making a two-layer resistive film pressure-sensitive digitizer and an equivalent circuit face each other.

FIG. 4 shows an example of the Wheatstone bridge structure.

One electrode 106 of the resistance film pressure-sensitive digitizer 100 having a two-layer structure as a measurement sample is connected to the terminal 409, and the other electrode 105 is connected to the terminal A of the resistor 408. Reference numeral 405 denotes an equivalent circuit of the resistance film pressure-sensitive digitizer 100, which includes a main resistance 401, a second resistance film 402, and an inter-film capacitance (capacitor C4) 403 between the main resistance 401 and the second resistance film (R4) 402. Is connected to the terminal 409, and the other end is connected to the terminal B of the resistor 408.

[0023]

[Equation 2] Note that the inter-membrane capacitances are considered to be the same for simplification and are summarized as one. 406 to 408 are resistance groups for forming a Wheatstone bridge, and are about 1 KΩ.
It is formed by a resistance of a certain degree. The resistors 406 and 407 are connected to the terminal 410.

A ground level potential (0
V) is applied, and an AC waveform or a step waveform (continuous rectangular wave) is applied to the terminal 410. In this state, the values of the capacitor C4 (403) and the second resistance film R4 (402) are adjusted, and the value at which the potential difference between both ends (between A and B) of the resistor 408 becomes 0 is detected, thereby forming a two-layer structure. The approximate value of the second resistor R2 (202) and the capacitor C (211 and 212) of the resistive film pressure-sensitive digitizer 100 can be estimated.

[0025]

According to the present invention, it is possible to detect the dynamic characteristics of the resistance film pressure-sensitive digitizer having a two-layer structure.

Further, assuming a usage state as a resistive film pressure-sensitive digitizer, it can be expressed by a simple lumped parameter equivalent, which is effective for application to circuit simulation and the like.

Further, the dynamic characteristics of the resistance film pressure-sensitive digitizer having a two-layer structure can be expressed by two parameters,
Simplifies quality control during manufacturing of a two-layer resistive film pressure-sensitive digitizer.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the structure of a resistance film pressure-sensitive digitizer having a two-layer structure.

FIG. 2 is a schematic diagram showing an embodiment of a configuration of an equivalent circuit of a resistance film pressure-sensitive digitizer having a two-layer structure.

FIG. 3 is a schematic diagram showing an embodiment of a circuit of a first constant estimation method of the present invention.

FIG. 4 is a schematic diagram showing an embodiment of a circuit of a second constant estimation method of the present invention.

[Explanation of symbols]

100 Two-layer resistance film pressure-sensitive digitizer 101 Base 102 Conductive film 103 Insulating film 104 Main resistance film 105, 106 Electrode 202 Second resistance R2 204 Main resistance R1 205, 206 Electrode 211 Inter-membrane capacitance capacitor C1 212 Inter-membrane capacitance capacitor C2 303 Resistor r 405 Two-layer resistance film pressure-sensitive digitizer equivalent circuit 401 Equivalent circuit main resistor 402 Second equivalent circuit resistor R4 403 Equivalent circuit inter-membrane capacitance capacitor C4

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Baba 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (56) Reference JP-A-9-305303 (JP, A) JP JP-A-9-81301 (JP, A) JP-A-8-255050 (JP, A) JP-A-4-102114 (JP, A) JP-A-6-332605 (JP, A) JP-A-8-328742 (JP , A) JP-A-11-161429 (JP, A) JP-A-4-6478 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 3/03-3/037

Claims (3)

(57) [Claims] 1. In a method for estimating a circuit constant of a two-layer structure resistive film pressure-sensitive digitizer having a second resistive film below a main resistive film with an insulating film interposed therebetween, the resistive element is provided at both ends of the main resistive film. Two-terminal circuit between two electrodes
And a resistance element corresponding to the second resistance film,
It corresponds to the inter-film capacitance between the main resistance film and the second resistance film.
A capacitor element is connected in series, and in parallel with this, the main
The two-layer structure in which resistance elements corresponding to resistance films are connected in parallel
A method for estimating a circuit constant of a resistive film pressure-sensitive digitizer , comprising forming an equivalent circuit of a resistive film pressure-sensitive digitizer and estimating a circuit constant of the two-layer structure resistive film pressure-sensitive digitizer based on the equivalent circuit . 2. The step of forming the electrode according to claim 1.
Input the value and measure the output step response,
Comparing the calculated step response value with the equivalent circuit
And a resistance value of a second resistance film of the resistance film pressure-sensitive digitizer circuit constant estimation method. 3. The two-layer structure for measurement according to claim 1.
Resistive film pressure sensitive digitizer and the equivalent circuit as a reference
To form a Wheatstone bridge,
Balance point is detected by adjusting the circuit constant of the value circuit
Then, the inter-film capacitance value of the equivalent circuit and the resistance value of the second resistance film are estimated, and the resistance film pressure-sensitive digitizer circuit constant estimation method is characterized.