JPH0667795A - Input determination method for touch input device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the deterioration of responsiveness and erroneous judgment at the time of input judgment of the touch input device. The touch input device is composed of two transparent films having electrodes, has a touch panel 1 having a plurality of key elements, and is arranged behind the touch panel 1, and displays a key frame and key functions of the touch panel 1. Display unit 2
And an input control unit 3, an A / D conversion unit 4 and a control unit 5, and the input control unit 3 is a threshold value for detecting an input signal for a key element of the touch panel 1 according to an instruction from the control unit 5. Can be set, A / D
The conversion unit 4 can convert an input signal from a key element of the touch panel 1 into a digital value according to an instruction from the control unit 5. Then, when the input signal converted into the digital value decreases with time, it is determined that the input is invalid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input determination method for a touch type input device using a touch panel as an input means.

[0002]

2. Description of the Related Art As a conventional input determination method for a touch input device, a key element of a touch panel having a number of key elements arranged in a matrix is proposed, as proposed in Japanese Patent Laid-Open No. 61-237124. 2 sets of memory arrays corresponding to are provided, the first memory array is checked for the attribute of the key element, the second memory array is checked for the presence or absence of the input of the key element, and the number of times the input is detected is entered, When the number of inputs exceeds a preset threshold value, the attribute written in the first memory array corresponding to the corresponding key element is investigated, and the attribute has the same type (that is, the same key has a predetermined period of time). If it is pressed), it is determined that the input is valid.

[0003]

However, in the above input determination method, in order to investigate which part of the touch panel having a plurality of key elements arranged in a matrix is operated, This is performed while applying a voltage (strobe signal) to each electrode of the matrix. However, each time a voltage is applied to each electrode, a delay characteristic (differential waveform or integrated waveform depending on the configuration of capacitance and impedance) occurs due to the capacitance of the touch panel and the impedance of the circuit system, and the threshold value is set. There is a problem in that a signal exceeding the limit is input, and the input is erroneously determined to be a normal input, although it is not an input by operating the touch panel. Moreover, it is extremely difficult to predict in advance which key element the signal generated by this characteristic will be superimposed on. Further, in the above-mentioned publication, it is specified that electrostatic noise accompanying drive of a display is also randomly generated at a certain frequency, but in a system using a microprocessor today, there is a regularity at a certain period. It is extremely likely that noise with noise will occur continuously. Therefore, similarly to the delay characteristic, such a noise has a problem that a signal exceeding the threshold value is input and is erroneously determined to be a normal input.

The present invention has been made in order to solve such a problem. Based on the input situation when the touch panel is actually operated, each appropriate threshold value is set and the threshold value is used as a basis. Since the input is judged on the input, signals due to the transient phenomenon (physical characteristics, delay characteristics) of the touch panel and signals due to random or regular noise accompanying the drive of the display unit are excluded, and the input signal is accurately determined. Can be determined. Moreover, while the touch panel is being operated, a valid input signal is used as a reference for setting a new threshold value, so the threshold value setting can always be optimized, and erroneous determination can be eliminated as well as the conventional method. To provide an input determination method for a touch-type input device capable of preventing a decrease in operability (responsiveness), which is likely to occur when the input state is determined by increasing the number of surveys (reading number) as described above. With the goal.

[0005]

In order to achieve the above-mentioned object, the present invention provides an input determination method for a touch-type input device, which comprises a touch panel composed of two films having electrodes as input means. An A / D that converts an input signal from an analog value to a digital value in an input device
A converter, threshold value storage means for storing the threshold value of the level of the input signal, level detection means for detecting the level of the input signal, level of the input signal detected by the level detection means, and the threshold value storage means And a level comparison means for comparing the threshold values stored in the threshold value storage means, the level of the input signal from the touch panel detected by the level detection means by the level comparison means is a predetermined threshold value stored in the threshold value storage means. When it is determined that the value exceeds the above, the A / D converter converts the analog value of the input signal into a digital value at a predetermined time interval, and when the input signal converted into the digital value decreases with time,
It is characterized in that the input is determined not to be an input signal due to the touch panel being pressed, but as a signal due to a transient phenomenon that occurs when power is applied to the touch panel.

Further, the input device measures the period when the level comparison means determines that the level of the input signal from the touch panel exceeds the predetermined threshold value and the period when the level is below the predetermined threshold value. Means is provided, and when the period measured by the measuring means exceeds the threshold for a first predetermined time or more and the period measured below the threshold is less than the second predetermined time, the input signal is It is characterized in that it is determined as valid input, and is determined as invalid input in cases other than this condition.

The predetermined threshold value is set to a value lower than the digital value obtained by A / D converting the input signal when the touch panel is pressed for a few seconds in advance by the A / D converter. It is characterized by doing so.

Further, the predetermined time interval is more than 10 times faster than the delay time (time constant) generated by the capacitance of the touch panel in which the capacitor is formed by the two films and the impedance of the circuit system. The feature is that the time interval is set.

Further, the measurement of the input signal level when the touch panel is pressed in advance is repeated several times for a period in which the input signal level exceeds the threshold value and a period in which the input signal level falls below the threshold value. It is characterized in that the first predetermined period is set shorter than the average value of the values, and the second predetermined period is set longer than the average value.

Further, when it is determined that the input signal is a valid input by the above-mentioned predetermined threshold value serving as a reference for input determination, this input signal is used as a reference signal for setting a new threshold value. It is characterized by

[0011]

In the above structure, when the level of the input signal from the touch panel exceeds the threshold value, the input signal is converted into a digital value by the A / D converter. When this digital value decreases with time, it is determined as an invalid input as a signal due to a transient phenomenon (physical characteristic) that occurs when power is applied to the touch panel. In addition, the input signal when the touch panel is operated is compared with the inspection result of the state of the input signal when the touch panel is operated in advance to determine valid input and invalid input.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of an input determination method for a touch input device according to the present invention. In FIG.
The touch input device is composed of two transparent films having electrodes, and a touch panel 1 having a plurality of key elements.
And a display section 2 arranged behind the touch panel 1 for displaying key frames and key functions of the touch panel 1, an input control section 3, an A / D conversion section 4 and a control section 5. . The input control unit 3 detects a threshold value storage unit (not shown) that stores the threshold value of the level of the input signal, a level detection unit (not shown) that detects the level of the input signal, and the level detection unit. Level comparison unit (not shown) for comparing the level of the input signal with the threshold value stored in the threshold value storage unit
In addition to detecting the level of the input signal by the level detection unit according to an instruction from the control unit 5, the threshold value of the key element of the touch panel 1 is stored and set in the threshold value storage unit. . Then, the A / D conversion unit 4 outputs from the control unit 5 when the level of the input signal from the key element of the touch panel 1 exceeds the threshold value stored in the threshold value storage unit by the level comparison unit. The input signal can be converted into a digital value by an instruction. Further, the display unit 2 displays various information such as the control content of the input device, the operation method, etc.
It can be displayed by instructions from.

FIG. 2 is a principle diagram showing the concept of input on the touch panel in the configuration diagram shown in FIG. The portion indicated by the broken line frame is an equivalent representation of the touch panel 1. FIG. 3 is a transient phenomenon diagram showing the physical characteristics of the touch panel in the principle diagram shown in FIG. First, the physical characteristics of the touch panel 1 will be described. The touch panel 1 is made of a dielectric material such as polyester in the form of a film sheet, and is provided with electrodes for extracting a signal. Two film sheets are made of a minute spacer made of an insulating material so that the electrodes do not come into contact with each other. It has a structure in which is attached as a support base. That is, the touch panel 1 can be equivalently expressed as a capacitor using polyester and air as the dielectric. Due to such a physical structure, when the switch S is closed and the power source E is added to the circuit in FIG. 2, the voltage characteristic V generated in the resistor R by the series circuit including the touch panel 1 and the resistor R is V = E It is represented by the formula of ε ^{-t / CR} (C: capacitance of touch panel 1) and has a differential waveform as shown in FIG.

FIG. 4 is an input characteristic diagram showing an input situation when the touch panel is operated. FIG. 5 is a noise characteristic diagram showing how noise is generated when the display unit is driven. Prior to the description of FIG. 4 and FIG. 5 described above, setting of a threshold value that is a criterion for valid input will be described. First, the display section 2 of the touch-type input device displays an instruction “Please continue to press the part marked with a circle”, and it is initially stored and set in the threshold value storage section of the input control section 3. The input signal of the touch panel 1 is monitored by the threshold value. Touch panel 1
When the level of the input signal exceeds the threshold value by the level comparison unit, the control unit 5 causes A /
Instruct the D conversion unit 4 to start conversion. The input signal converted into a digital value by the A / D conversion unit 4 is stored in the control unit 5, and the conversion is continued by the A / D conversion unit 4 until the change of the digital value becomes stable. When the digital value becomes stable, the control unit 5 sets 90% of the stored digital value to
A new threshold value VTH is stored and set in the input control unit 3, the A / D conversion unit 4 is instructed to end the conversion, and the display unit 2 is instructed to display "a threshold value has been set. Please release your finger." When the setting of the threshold value is completed, the display section 2 displays an instruction of "please press the part marked with ●". The specified portion of the touch panel 1 is pressed and the level of the input signal is set to the threshold value VT newly set in the input control unit 3.
When H is exceeded, the measurement unit is caused to start measurement, and a period in which the threshold VTH is exceeded and a period in which the threshold VTH is dropped are measured and stored in the control unit 5. Then repeat this operation several times. The control unit 5 takes an average of the measured times, and 90% of the average value is 90% of the average value for the period exceeding the threshold value VTH, and 110% of the average value for the period of being less than the threshold value VTH. Is stored as the threshold value tL, and the display unit 2 is instructed to display “Measurement is completed”.

Next, how the judgment is made when the touch panel 1 is actually operated with the threshold value stored and set by the above method will be described with reference to FIG. The control unit 5 applies a voltage (hereinafter referred to as a strobe signal) to each key element via the input control unit 3 in order to investigate the input state of each key element of the touch panel 1. The input control unit 3 sets the threshold value VT
With H, the level of the input signal from the touch panel 1 is monitored. When the level of the input signal does not exceed the threshold value VTH, it is determined that there is no input, and the strobe signal is continuously added to the next key element. Threshold V at this point
Signals less than TH, such as unstable signals and noise, can be eliminated. Input signal level is threshold VTH
If it exceeds, it is determined that there is an input, and the control unit 5 receives the input presence signal from the input control unit 3 and instructs the A / D conversion unit 4 to start conversion. When the A / D conversion unit 4 A / D converts the input signal from the touch panel 1, the converted data (digital value) is sent to the control unit 5. The control unit 5 stores the conversion data, and based on the time constant obtained from the capacitance C of the touch panel 1 and the impedance of the circuit system, the A / D conversion unit 4 has a time interval about 10 times faster than this time. I am trying to instruct the conversion. When the input signal level converted into a digital value at a predetermined time interval tends to decrease with time, it is due to a transient phenomenon that occurs when a strobe signal is applied to the key elements of the touch panel 1 as shown in FIG. Since the differential waveform has been input, it is determined to be an invalid input. The input control unit 3 continues to monitor the level of the input signal from the touch panel 1 with the set threshold value VTH. The control unit 5 determines the period when the level of the input signal exceeds the threshold value and falls below the threshold value,
The signal from the input control unit 3 is a timing signal (when the threshold value VTH is exceeded, an H period timing start signal and an L period timing end signal, and when it is lower than the H period timing end signal and an L period timing end signal.
It is used as a period clocking start signal) to compare the clocked result with the respective threshold values stored in the control unit 5. When the H period is equal to or more than the threshold value tH (H ≧ tH) and the L period is less than the threshold value tL (L <tL), it is determined that the input is valid, and in other cases, the input is invalid. Judge that there is.

As described above, in this embodiment, the input determination method has been described for the transparent touch panel arranged on the front surface of the display unit. However, the input means having a similar physical structure, for example, a membrane. Switch (A structure in which multiple key elements are arranged in a matrix, and the conductor mounted on the elastic film and the conductor mounted on the hard film that is the base make contact by being pressed. (Generally, the attributes are printed.)
Or an analog touch panel (two films on which a material having a resistance value has been vapor-deposited are displaced by 90 °, and a fine spacer made of an insulating material is used as a support to interpose them, and the information of the pressed portion is displayed. The input determination method of the present invention can also be applied to the above). Moreover, it is needless to say that the input determination method of the present invention can be applied to the conventional mechanical key (switch) only by not causing the transient phenomenon shown in FIG.

[0017]

Since the input determination method for the touch input device of the present invention is configured as described above, the input situation when the touch panel is actually operated is
Since an appropriate threshold value is set for each and input is judged based on this threshold value, the signal due to the physical characteristics of the touch panel and the signal due to random or regular noise are eliminated, and the input signal is accurately determined. Can be determined. Moreover, while the touch panel is being operated, a valid input signal is used as a reference for setting a new threshold.
The threshold setting can always be optimized and erroneous judgments can be eliminated, and the operability (responsiveness) that often occurs when the input status is judged by increasing the number of investigations (reading times) as in the past ) Can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an input determination method for a touch input device according to the present invention.

FIG. 2 is a principle diagram showing a concept of input on a touch panel in the configuration diagram shown in FIG.

FIG. 3 is a transient phenomenon diagram showing physical characteristics of the touch panel in the principle diagram shown in FIG.

FIG. 4 is an input characteristic diagram showing an input situation when a touch panel is operated.

FIG. 5 is a noise characteristic diagram showing how external noise is generated when a display or the like is driven.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Touch panel 2 ... Display part 3 ... Input control part 4 ... A / D conversion part 5 ... Control part

Claims (6)

[Claims] 1. A method for determining an input of a touch input device, comprising a touch panel composed of two films having electrodes as input means, wherein the input device converts an input signal from an analog value to a digital value. A / D converter, threshold value storage means for storing the threshold value of the level of the input signal, level detection means for detecting the level of the input signal, level of the input signal detected by the level detection means, and Level comparison means for comparing the threshold values stored in the threshold value storage means is provided, and the level of the input signal from the touch panel detected by the level detection means is stored in the threshold value storage means by the level comparison means. When it is determined that the value exceeds the predetermined threshold value, the analog value of the input signal is calculated by the A / D converter at a predetermined time interval. When the input signal converted to a digital value and converted to a digital value decreases with time, the invalid input is not the input signal due to pressing the touch panel, but the transient phenomenon that occurs when power is applied to the touch panel. An input determination method for a touch-type input device, characterized in that 2. A measurement for measuring, in the input device, a period in which the level comparison means determines that the level of an input signal from the touch panel exceeds the predetermined threshold value and a period in which the level is below the predetermined threshold value. Means is provided, and when the period measured by the measuring device exceeds the threshold value is equal to or longer than a first predetermined time period and the time period below the threshold value is less than a second predetermined time period, the input signal is The input determination method for a touch input device according to claim 1, wherein the input determination is made as valid input, and invalid input is made in other cases than this condition. 3. The predetermined threshold value is an input signal when the touch panel is kept pressed for a few seconds in advance, the A / D
2. The input determination method for a touch input device according to claim 1, wherein the input value is set to a value lower than a digital value obtained by A / D conversion by a converter. 4. The predetermined time interval is 10 times or more faster than the delay time (time constant) generated by the capacitance of the touch panel in which a capacitor is formed by the two films and the impedance of the circuit system. The input determination method for a touch-type input device according to claim 1, wherein the input interval is set to a time interval. 5. The measurement of the period in which the level of the input signal when the touch panel is pressed in advance exceeds the threshold value and the period in which it falls below the threshold value is repeated several times,
The first predetermined period is set to a shorter time and the second predetermined period is set to a longer time than the average value of the respective measured values obtained. The input determination method of the touch input device according to 2 or 3. 6. When the input signal is determined to be a valid input by the predetermined threshold value serving as a reference for input determination,
The input determination method for a touch type input device according to claim 1 or 2, wherein the input signal is used as a reference signal for setting a new threshold value.