JP4150662B2 - Driving method of input means having electrostatic sensor - Google Patents

Description

  The present invention relates to a driving method of an input unit having an electrostatic sensor, and favorably activates an input unit having an electrostatic sensor that outputs an electric signal when a part of a human body such as a hand or a finger approaches or comes into contact with the input unit. The present invention relates to a driving method of an input means having an electrostatic sensor.

  In general, electrostatic sensors are widely used as input means in various applications. For example, mobile phones that have become widespread in recent years have been adopted as information input means for numbers and characters.

  This electrostatic sensor is provided with an electrode inside a predetermined position, which is an input part of a casing serving as a case of a mobile phone, and when the human body comes in contact with the outer surface of the casing facing the electrode, An output is generated by detecting a change in capacitance of a casing interposed therebetween.

  In such a mobile phone, input means using an electrostatic sensor is intermittently driven in order to reduce power consumption. Specifically, in a standby state in which the mobile phone is not used, a drive pulse (clock signal) for driving the electrostatic sensor is not output, and a drive pulse is generated when use is started.

  However, in the past, when trying to start from a standby state by bringing a finger into contact with the electrostatic sensor, the time required for starting is about 300 msec, the responsiveness of the initial operation is poor, and it is not suitable for intermittent driving. There was a point.

  The present invention has been made in view of these points, and has a very short startup time when starting an electrostatic sensor in a standby state, is responsive and suitable for intermittent driving, and has low power consumption. It is an object of the present invention to provide a driving method of an input means having an electrostatic sensor that can be reliably performed and can obtain a large output by extending a discharge time.

In order to achieve the above object, a driving method of an input means having an electrostatic sensor according to the present invention includes a clock signal generating means for generating a clock signal, and an electrostatic capacity detected when a human body approaches or contacts the electrostatic sensor. A delay means for generating a delay signal by adding a rising delay to the clock signal, an AND means for outputting an output signal using the clock signal and the delay signal as input signals, and smoothing the output of the AND means A method of driving an input means having an electrostatic sensor having a smoothing means for outputting the clock signal generating means when the electrostatic sensor is activated in contact with the electrostatic sensor from a standby state where the clock signal is not output. be characterized by extending the pulse length of the first clock signal generated in length to reach the stroke on the detection voltage of interest of said smoothing means from .

  By forming in this way, the start-up time when starting the electrostatic sensor in the standby state is very short, the response is good, and it is suitable for intermittent drive, and low power consumption can be surely performed.

  Further, the ratio of the pulse length of the clock signal after the first clock signal and the period length of the pulse may be made larger than 1: 3.

  As a result, the discharge time when no pulse is generated is more than twice as long as the charge time between the sensor and the human body corresponding to the pulse length time of the clock signal after the first, thereby reducing the output of the electrostatic sensor. Can be bigger.

  As described above, since the driving method of the input means having the electrostatic sensor according to the present invention is configured and operates, the startup time when starting the electrostatic sensor in the standby state is very short, and the response is good and intermittent. Suitable for driving, low power consumption can be reliably performed, information processing can be performed quickly, and the discharge time can be extended to obtain a large output.

  Embodiments of the present invention will be described below.

  FIG. 1 shows an example of input means having an electrostatic sensor to which the driving method of input means having an electrostatic sensor of the present invention is applied.

  As shown in FIG. 1, a clock signal serving as a drive wave is output as one input signal of an AND circuit 3 serving as AND means from a clock signal generating means 2 of a microcomputer 1 incorporated in a cellular phone. Connected to the input side of the AND circuit 3 is a delay means 6 comprising a resistor 4 and an electrostatic sensor 5 connected in series from the clock signal generating means 2 side. In the delay means 6, a delay signal obtained by adding a rising delay to the clock signal in accordance with the capacitance detected when the human body approaches or contacts the electrostatic sensor 4 is output as another input signal of the AND circuit 3. To do. A resistor 8 and a capacitor 9 are connected to the output side of the AND circuit 3 as smoothing means 7 for smoothing the output. The output of the smoothing means 7 is connected so as to be output to an AD converter 10 provided in the microcomputer 1.

  Next, the case where the input means of FIG. 1 is driven by the driving method of the input means having the electrostatic sensor of the present invention will be described based on FIG. FIG. 2 is a time chart of signals in each part of FIG. 1. FIGS. 2A and 2B show the conventional case, and FIGS. 2C and 2D show the case of the present invention.

  In the present invention, when the electrostatic sensor 5 in the standby state is activated by touching it with a finger, the first first pulse of the clock signal is generated from the clock signal generating means 2 of the microcomputer 1 as shown in FIG. The pulse length (T1) is extended to a length required to obtain the target output of the smoothing means 7, and a regular pulse signal having a predetermined frequency is added after the second pulse (one cycle length is T2, half cycle). A clock signal CK having a long pulse length T3) is output to the AND circuit 3.

  At the same time that the human body comes into contact with the electrostatic sensor 5, the first pulse of the clock signal CK is input to the delay means 6, and the time constant CR determined by the resistance value R of the resistor 4 and the capacitance C of the electrostatic sensor 5. The analog output is input to the AND circuit 3 based on the above.

  In the AND circuit 3, since the first pulse of the clock signal is in the ON state after the output of the delay means 6 exceeds the threshold value between the H level and the L level, the AND circuit 3 is a logical product output of the AND circuit 3. The product pulse is output to the smoothing means 7. The AND pulse of the AND circuit 3 is a pulse having a long pulse length that is the same as the first pulse of the clock signal.

  Thereafter, the output composed of the AND pulse of the AND circuit 3 is smoothed based on the time constant C1 · R1 determined by the resistance value R1 of the resistor 8 and the capacitance C1 of the capacitor 9 in the smoothing means 7. As shown in FIG. 2D, the voltage rises to a predetermined detection voltage during the first pulse length of the clock signal, and is output to the AD converter 10, and then the digital value corresponding to the detection voltage by the AD converter 10, for example, d0 to Converted to d7 digital value.

  In the present embodiment, the first pulse length of the clock signal is set to a length (for example, 4 msec) that reaches the target detection voltage of the smoothing means 7 at a stroke (for example, 4 msec). Detecting in time, subsequent information manipulation can be performed immediately. The output of the smoothing means 7 after the second pulse of the clock signal is constant. Specifically, the detection voltage differs depending on the configuration of the electrostatic sensor size and the like, but once the child sex is determined, it becomes constant. Therefore, if the detection voltage, R1, C1, and multiplier are determined, the optimum time of the pulse length T1 of the first pulse of the clock signal can be calculated. Therefore, the shortest time until detection can be obtained, and intermittent drive is performed. This can be executed to reliably reduce power consumption. Thereby, information can be input quickly.

  On the other hand, in the conventional driving method, as shown in FIG. 2 (a), a regular pulse signal (one cycle length is T4, having a short frequency) from the clock signal generating means 2 of the microcomputer 1 is short. A clock signal CK having a half-cycle length pulse length T5) is output to the AND circuit 3. Therefore, it takes a long time of 300 msec for the output of the smoothing means 7 to reach the detection voltage. Therefore, depending on the conventional driving method, intermittent driving cannot be performed, and power consumption cannot be reduced.

  FIGS. 3A and 3B are time charts showing signals based on another driving method according to the present invention. In this embodiment, as shown in FIG. 3 (a), the ratio of the pulse length T5 of the clock signal after the first clock signal with the pulse length T1 to the one cycle length T4 of the pulse is from 1: 3. Largely formed. Specifically, the ratio between the charging time T5 and the discharging time T6 is greater than 1: 2.

  As a result, the discharge time T6 when no pulse is generated is more than twice the charge time between the sensor and the human body corresponding to the time T5 of the pulse length of the clock signal after the first, so that the electrostatic sensor The output can be increased (see FIG. 3B).

  On the other hand, in the conventional method, since T5 = T6 is formed, since the discharge time is short, the charge formed between the sensor and the human body cannot be completely discharged. The output of the electric sensor could not be taken large.

  According to this drive method, the start-up time when starting the electrostatic sensor in the standby state is very short, the response is good and suitable for intermittent drive, and low power consumption can be reliably performed, Furthermore, a long output can be obtained by extending the discharge time.

  Further, it is needless to say that the driving method shown in FIG. 3 may be performed separately from the driving method shown in FIG.

  In addition, this invention is not limited to the said embodiment, It can change as needed.

The circuit diagram which shows an example of the input means which has an electrostatic sensor which adapts the drive method of the input means which has an electrostatic sensor of this invention FIG. 1 is a time chart showing signals in various parts of the circuit of FIG. 1 is a time chart showing signals based on other driving methods in each part of the circuit of FIG.

Explanation of symbols

2 Clock signal generating means 3 AND means (AND circuit)
5 Electrostatic sensor 6 Delay means 7 Smoothing means

Claims (2)

A clock signal generating means for generating a clock signal; and a delay means for generating a delay signal by adding a rising delay to the clock signal in accordance with a capacitance detected when a human body approaches or contacts the electrostatic sensor. A driving method of an input means having an electrostatic sensor having AND means for outputting an output signal using the clock signal and the delay signal as input signals, and smoothing means for smoothing and outputting the output of the AND means, When a human body comes into contact with the electrostatic sensor from a standby state where no clock signal is output, the pulse length of the first clock signal generated from the clock signal generation unit is set to the target detection voltage of the smoothing unit. A method for driving an input means having an electrostatic sensor, wherein the input means is extended to a length that reaches at once .   2. The input means having an electrostatic sensor according to claim 1, wherein a ratio of a pulse length of a clock signal after the first clock signal and a cycle length of the pulse is made larger than 1: 3. Driving method.