JP2010267185A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of detecting the number of fingers which touches therewith. <P>SOLUTION: The display device includes a transparent electrode 2 formed on a main surface on the side facing a display area, of a cover glass 1 having two opposite main surfaces; and a capacitance, varying according to the size of a touched area formed between a finger 7, in contact with the main surface on the other side of the cover glass 1 and the transparent electrode 2 for detecting varied amounts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device that displays an image.

  Conventionally, a technique of a display device that detects the position of a fingertip in contact with a display light emitting surface by an optical method has been disclosed (see Patent Document 1).

  However, there is a problem that the number of touched fingers cannot be detected.

JP 2008-83322 A

  This invention is made | formed in view of the above, and makes it a subject to provide the display apparatus which can detect the number of the fingers which contacted.

  The present invention relates to a transparent electrode formed on one main surface on the side facing the display region in a cover glass having both opposing main surfaces, a finger in contact with one main surface on the other side of the cover glass, and the transparent electrode And a detection unit that detects the amount of change in capacitance that changes according to the size of the contact area.

  ADVANTAGE OF THE INVENTION According to this invention, the display apparatus which can detect the number of the fingers which contacted can be provided.

It is a figure which shows the structure of the display apparatus which concerns on this Embodiment. It is a figure which shows the functional block of a contact position detection part. It is a figure which shows the circuit structure of a contact state detection part. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger. It is explanatory drawing for detecting the number of contact of a finger.

  FIG. 1 is a diagram illustrating a configuration of a display device according to the present embodiment. In this display device, a cover glass 1 having both opposing main surfaces, a transparent electrode 2 formed on one main surface of the cover glass 1 on the side facing the display region 4, and a display region 4 are formed on the surface. An array substrate 3, a capacitance driving substrate 5 connected to the array substrate 3 via the flexible printed circuit board 6, a contact position detection unit 10 formed around the display area 4 in the array substrate 3, and a capacitance And a contact state detection unit 20 formed on the surface of the drive substrate 5. As the transparent electrode 2, for example, ITO (Indium. Tin. Oxide) can be used.

  In the display area 4, a display element is formed near each intersection of the signal line 4b and the scanning line 4a arranged in rows and columns, and the timing at which the TFT 9 of the display element is controlled to be turned on by the scanning signal applied to the scanning line 4a. Then, the image signal applied to the signal line 4b is supplied to the pixel electrode 4d, and the inclination of the liquid crystal molecules in the liquid crystal layer 4d is changed in accordance with the potential difference generated between the pixel electrode 4d and the counter electrode 4f. By doing so, an image can be displayed.

  Each display element is further provided with an image sensor 4g for capturing an image, and each incident light captured by each image sensor 4g is output to the contact position detector 10. Yes. As shown in FIG. 2, the contact position detection unit 10 includes an imaging unit 10a, a charge storage unit 10b, an imaging result storage unit 10c, an output switching unit 10d, and a position coordinate calculation unit 10e.

  First, at least one imaging unit 10a provided corresponding to each display element receives incident light in a specified range and converts it into an electrical signal. Next, the charge storage unit 10b stores a charge corresponding to the electrical signal converted by the imaging unit 10a. Then, the imaging result storage unit 10c temporarily stores a signal corresponding to the charge accumulated in the charge accumulation unit 10b. Thereafter, the output switching unit 10d performs switching control as to whether or not to output the signal stored in the imaging result storage unit 10c according to the logic of the control signal line 8, and the position coordinate calculation unit 10e outputs the output signal. Based on the above, the contact position of the finger 7 that has come into contact with the cover glass 1 is calculated.

  On the other hand, the contact state detection unit 20 is connected to the transparent electrode 2, and when the finger 7 comes into contact with the one main surface of the other side of the cover glass 1, the contact area is between the finger 7 and the transparent electrode 2. Since a capacitance proportional to the size of the capacitor is formed, it has a function of detecting the amount of change in the capacitance. Hereinafter, the configuration and function of the contact state detection unit 20 will be described.

  FIG. 3 is a diagram illustrating a circuit configuration of the contact state detection unit. The contact state detection unit 20 generates an alternating current serving as a reference for grasping a change in the formed electrostatic capacitance in the alternating current signal generation unit 20a and continuously applies the alternating current to the transparent electrode 2. When the finger 7 comes into contact with the cover glass 1 during application of the alternating current, a change occurs in the alternating current flowing through the contact state detection unit 20 due to the influence of the capacitance formed between the transparent electrode 2 and the finger 7. Become. In addition, the comparison capacitor 20b is formed using the same configuration as the configuration of the connection destination of the transparent electrode 2 (20g shown in FIG. 3), and changes due to the influence of the capacitance via the first analog filter 20c1. The AC current noise is removed and the AC current noise output from the comparison capacitor 20b via the second analog filter 20c2 is removed, and then each AC current after noise removal is input to the differential amplifier 20d. As a result, when the finger 7 is not in contact with the cover glass 1, the output of the differential amplifier 20d is 0. When the finger 7 is in contact, only the AC current corresponding to the size of the contact area is amplified. Therefore, it is possible to accurately detect the amount of change in capacitance. Thereafter, the change amount output from the differential amplifier 20d is digitally converted by the A / D converter 20e, and then the contact of the finger 7 is detected by the detection processing unit 20f configured by an FPGA (Field Programmable Gate Array) or the like. It will be.

  In other words, the contact position detection unit 10 can detect the position coordinates where the finger 7 is in contact from the captured image of the light reflected from the finger 7 by the shadow of the finger 7 or the backlight (not shown) light. At the same time, the contact state detection unit 20 detects the amount of change in capacitance that changes in accordance with the size of the contact area, so a display device having a touch panel function that can detect the number of fingers 7 that have touched is provided. Can be provided.

  Subsequently, the detection processing of the number of contacts of the finger 7 in the detection processing unit 20f of the contact state detection unit 20 will be specifically described. As described above, since the amount of change in capacitance due to contact with the finger 7 is proportional to the contact area, the detection processing unit 20f associates a plurality of threshold values corresponding to the amount of change in capacitance with the number of fingers 7. If it is stored in advance and the detected change amount exceeds any threshold value, it is detected that the number of fingers associated with the exceeded threshold value are in contact. For example, as shown in FIG. 4, a first threshold value associated with one finger and a second threshold value associated with two fingers are stored in advance. Then, the detection processing unit 20f assumes that one finger is in contact when the detected amount of change exceeds the first threshold, and two more when the second threshold is exceeded. The detection result is output assuming that the finger is in contact.

  Further, in order to reliably detect the number of touched fingers even when the contact area is increased by pressing solidly with one finger, the detection processing unit 20f has a short first as shown in FIG. 1 grace period is further memorized, and when the detected amount of change exceeds the first threshold and further exceeds the second threshold within the first grace period, one finger touches. Detect as being. This utilizes the fact that the displacement of the detected amount of change fluctuates sharply when the solid is pressed. As a result, even if the finger is pressed with one finger, it is possible to prevent an erroneous detection result from being output, assuming that the number of touched fingers is two.

  Furthermore, in order to reliably detect the number of touched fingers even when the contact area is increased by gradually pressing with one finger, the detection processing unit 20f, as shown in FIG. A predetermined first inclination threshold value is further stored, and the inclination of the locus of change in electrostatic capacitance is monitored after exceeding the first threshold value, and the inclination of the locus of change of the monitored change amount in the time axis direction is monitored. On the other hand, when the slope of the amount of change from the first threshold value to the second threshold value is greater than or equal to the first tilt threshold value, the finger of one finger touches Detect as being. This makes it possible to prevent an erroneous detection result from being output when the number of touched fingers is two even if the finger is pressed with a single finger.

  Furthermore, in order to reliably detect the number of touched fingers even when the second finger is further touched with a single finger pressed, the detection processing unit 20f is shown in FIG. As described above, the second grace period is further stored, and the amount of change detected after exceeding the second threshold within the first grace period is substantially constant within the second grace period (that is, to some extent). The second threshold value is set so as to be associated with the changed amount when the amount of change further changes due to the second finger contact. This makes it possible to reliably detect the number of touched fingers even when the original second finger comes into contact with the solid pressed state.

  Further, the detection processing unit 20f can detect a period from the moment when the finger 7 contacts the cover glass 1 until it exceeds any threshold as a contact determination period. For example, as shown in FIG. 8, the contact determination period A is a period from when the finger 7 contacts the cover glass 1 without contact and the amount of change in capacitance starts to change and exceeds the first threshold value. Yes. Here, since the amount of change gradually varies depending on how the finger is touched, it takes time until the contact determination is established. Therefore, the detection processing unit 20f stores a certain second inclination threshold value, and when the inclination of the detected change trajectory exceeds the second inclination threshold value with respect to the time axis direction, Determine that they are touching. That is, since it is determined that the finger is in contact with the cover glass when the second inclination threshold is exceeded, it is possible to shorten the period until the contact determination is established (the contact determination shown in FIG. 8). (Corresponding to period B), it is possible to give a quick response to the user who is operating the touch panel and to improve the practicality of the display device.

  Furthermore, in order to accurately perform contact determination even when the reason why the second inclination threshold is exceeded is due to the influence of noise, the detection processing unit 20f has a larger value than the second inclination threshold, as shown in FIG. The inclination threshold value 3 is further stored, and it is determined that the finger is not in contact when the inclination of the detected change amount trajectory exceeds the third inclination threshold value with respect to the time axis direction. In other words, even if the second tilt threshold is exceeded, if the third tilt threshold is also exceeded, erroneous input due to noise is prevented by invalidating the finger contact determination. It becomes possible to do.

  Furthermore, in order to accurately perform contact determination even when the fluctuation width (baseline) of the calculated value of inclination changes due to the influence of surrounding electromagnetic waves or the like, the detection processing unit 20f, as shown in FIG. The second inclination threshold value is changed in accordance with the increase / decrease of the inclination of the detected change amount locus, and the third inclination threshold value is changed so as to follow the change of the second inclination threshold value. Specifically, when the baseline changes from time A to time B when the baseline is high, the second slope threshold and the third slope threshold are increased in response to an increase in the slope value. Further, when the B time is changed to the baseline C time which is lower than the B time but higher than the A time, the second inclination threshold and the third inclination threshold corresponding to the decrease in the inclination value. Decrease. However, in time B, when the slope temporarily exceeds the second slope threshold and is less than the third slope threshold (D shown in FIG. 10), the second slope threshold and the third slope threshold are Do not change. Similarly, even when the slope temporarily exceeds the third slope threshold during time C (E shown in FIG. 10), the second slope threshold and the third slope threshold are not changed. That is, since the second slope threshold and the third slope threshold are updated in real time according to the increase / decrease of the baseline, it is possible to prevent an increase in the false recognition rate and a reduction in the recognition rate due to environmental changes.

  According to the present embodiment, in the cover glass 1 having both opposing main surfaces, the transparent electrode 2 formed on one main surface on the side facing the display region and the other main surface on the other side of the cover glass 1 are in contact with each other. Provided is a display device that can detect the number of touched fingers because it detects the amount of change in electrostatic capacitance that is formed between the finger 7 and the transparent electrode 2 and changes according to the size of the contact area. Can do.

DESCRIPTION OF SYMBOLS 1 ... Cover glass 2 ... Transparent electrode 4 ... Display area 7 ... Finger 8 ... Control signal line 10 ... Contact position detection part 10a ... Imaging part 10b ... Charge storage part 10c ... Imaging result storage part 10d ... Output control part 10e ... Position coordinate Arithmetic unit 20 ... contact state detection unit

Claims (5)

A transparent electrode formed on one principal surface on the side facing the display region in the cover glass having both opposing principal surfaces;
A contact state detection unit that is formed between a finger that is in contact with one principal surface of the other side of the cover glass and the transparent electrode, and detects a change amount of capacitance that changes according to the size of the contact area;
A display device comprising: The contact state detector is
A plurality of threshold values corresponding to the change amount of the capacitance are stored in association with the number of fingers, and when the detected change amount exceeds any threshold value, the number of the threshold values corresponding to the threshold value is stored. Detect that your finger is touching,
The plurality of threshold values are a first threshold value associated with one finger and a second threshold value associated with two fingers,
A first grace period is further stored, and when the detected amount of change exceeds the first threshold and further exceeds the second threshold within the first grace period, one change is made. Detected as touching, and
A first inclination threshold value is further stored, and the inclination of the detected locus of the change amount is not less than the first inclination threshold value with respect to the time axis direction and exceeds the first threshold value before the change. 2. The display device according to claim 1, wherein when the inclination of the change amount until the second threshold is exceeded is substantially constant, it is detected that one finger is touching. The contact state detector is
A second grace period is further stored, and the amount of change detected after exceeding the second threshold within the first grace period is substantially constant within the second grace period; 3. The display device according to claim 2, wherein when the amount of change further changes due to contact of a second finger, the second threshold is associated with the amount of change after the change. The contact state detector is
A second inclination threshold value is stored, and it is determined that the finger is in contact since the inclination of the detected locus of the change amount exceeds the second inclination threshold value in the time axis direction,
A third inclination threshold value that is larger than the second inclination threshold value is further stored, and the inclination of the detected locus of the change amount exceeds the third inclination threshold value with respect to the time axis direction. Determines that the finger is not touching,
The second inclination threshold value is changed in accordance with the increase or decrease of the inclination of the detected locus of the change amount, and the third inclination threshold value is changed to follow the change of the second inclination threshold value. The display device according to claim 1, wherein the display device is a display device. Display elements formed in the vicinity of the intersections of signal lines and scanning lines arranged in rows and columns in the display region;
An image pickup unit provided at least one for each of the display elements, each receiving incident light in a specified range and converting it into an electrical signal;
A charge accumulating unit that accumulates electric charges according to the electric signal converted by the imaging unit;
An imaging result storage unit that temporarily stores a signal corresponding to the charge stored in the charge storage unit;
An output switching unit that controls whether to output the signal stored in the imaging result storage unit according to the logic of the control signal line;
The contact state detector is
The display device according to claim 1, wherein an amount of change in the capacitance is detected by applying an alternating current to the transparent electrode.

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