JP5381469B2 - Display device - Google Patents

Description

  The present invention relates to an image forming apparatus such as a digital full-color copying machine and a display device that displays characters and images used in electronic devices such as a car navigation system.

As described above, a display device has been developed in which an optical sensor is arranged in a pixel as a touch sensor and information can be input from a display screen by light.
In a display device having this type of light input function, for example, a photodiode is provided as an optical sensor in a pixel, and a capacitor is connected to the photodiode, and light received from the display screen is received by the photodiode. The amount of charge of the capacitor is changed according to the change in the amount, and the captured image data is generated by generating the data of the captured image by detecting the voltage across the capacitor.

As an application of such a display device, touch panel function to input information by detecting shadows made by objects such as fingers projected on the display screen, and light emitted from light emitting objects such as light pens are detected. There are proposals for inputting information by doing so.
However, an optical sensor type touch sensor uses a shadow created by an object, so that when the surrounding environment is dark, the shadow cannot be accurately identified, and the accuracy of calculating the coordinate position is significantly reduced. Further, when the surrounding environment is bright, a shadow such as a finger is also formed on a non-contact portion, so that the accuracy of contact determination and coordinate position calculation is also lowered.

  As a countermeasure, the touch sensor system described in Patent Document 1 selects the image processing method by acquiring the brightness of external light incident on the panel and comparing it with a predetermined threshold value. . In this case, the shadow of the finger is detected when the external light is brighter than the threshold, and the reflection from the finger by the backlight is detected when the external light is darker than the threshold.

  By selecting the method described in Patent Document 1, the calculation accuracy of the coordinate position is improved regardless of the surrounding environment. However, since the image processing method is selected by comparing the ambient light with the threshold, When the light level is almost the same as the threshold, the contrast between the part with the finger and the part without the finger is lower than when the external light is much brighter or darker than the threshold. It will decline.

The present invention has been made in view of the above, without being affected by the brightness of the intensity of external light, the display means in contact with (panel) (touch) contact object such as a fingertip (touch object) It is intended to be able to detect the position of.

Display device according to the present invention, for achieving the above purposes SL, and it has the characteristics shown in the following (1) or (2).

(1) A display means, a plurality of contact object detection means arranged inside the display means, for detecting the contact of a contact object such as a fingertip, an external light detection means for detecting external light incident on the display means , A light irradiating means for irradiating the display object and the contact object with irradiation light from the back side of the display means ; and a dimming means for detecting the amount of the irradiation light by the light irradiating means and dimming the irradiation light ; based on the detection signals of the plurality of contact object detecting means, it is provided, and control means for identifying the position of the touch object in contact with the display means.

Then, the control means determines the difference between the amount of detected ambient light by the light amount and the external light detection means of the irradiation light by the light irradiating means detected by said light control means, the absolute value of the difference Is less than the preset value,
When the light amount of the external light is larger than the light amount of the irradiation light, the light amount of the irradiation light is lowered with respect to the light control means until the difference from the light amount of the external light becomes equal to or more than the predetermined set value. After controlling, the shadow of the contact object due to the external light is detected, and when the light amount of the external light is not larger than the light amount of the irradiation light, the difference from the light amount of the external light is not less than the predetermined set value. The light control means is controlled so as to increase the amount of the irradiation light until the light is adjusted, and then the reflection from the contact object by the irradiation light is detected.

Further, when the absolute value of the difference between the light amount of the irradiation light and the light amount of the external light is equal to or larger than the set value , the control means, when the light amount of the external light is larger than the light amount of the irradiation light, A shadow of the contact object due to the external light is detected, and when the light amount of the external light is smaller than the light amount of the irradiation light, reflection from the contact object by the irradiation light may be detected .

(2) A display means, a plurality of contact object detection means that are arranged inside the display means and detect contact of a contact object such as a fingertip, and an external light detection means that detects external light incident on the display means , Light irradiation means for irradiating the display means and the contact object with irradiation light from the back side of the display means , and light control means for detecting the amount of the irradiation light by the light irradiation means and dimming the irradiation light If, on the basis of the detection signals of the plurality of contact object detecting means, and control means for identifying the position of the touch object in contact with the display means, the provided
The control means, the ratio of the amount of detected ambient light by the light amount and the external light detection means of the irradiation light by the light irradiating means detected by said light control means, the molecules, darker brighter light amount of If the ratio is less than a preset value,
When the light amount of the external light is larger than the light amount of the irradiation light, the light amount of the irradiation light is decreased with respect to the light control means until the ratio with the light amount of the external light becomes equal to or more than the predetermined set value. When the shadow of the contact object due to the external light is detected and the light amount of the external light is not larger than the light amount of the irradiation light, the ratio with the light amount of the external light is the predetermined set value. The light control means is controlled so as to increase the amount of the irradiation light until it becomes the above, and then the reflection from the contact object by the irradiation light is detected.

In addition, when the ratio between the light amount of the irradiation light and the light amount of the external light is equal to or greater than the set value, the control unit is configured to output the external light when the light amount of the external light is larger than the light amount of the irradiation light. When the shadow of the contact object by light is detected and the light amount of the external light is smaller than the light amount of the irradiation light, the reflection from the contact object by the irradiation light may be detected .

Further, it is preferable to provide means for sampling and averaging the light quantity of the external light and the light quantity of the irradiation light a plurality of times at a predetermined specific period.

Furthermore, a backlight using LED, CCFL, organic EL, or inorganic EL may be used as the light irradiation means of (1) or (2).

According to the display device of the present invention, the control means, the light amount of the outside light detected by the external light detecting means and the illumination light (backlight light) by the light irradiation means which is detected by the light control means of the difference (or Ratio) is performed. That is , the light quantity difference (or ratio) is determined, and if the light quantity difference (or ratio) is less than a set value , the light quantity difference (or ratio) is set to be equal to or greater than the set value. After the illumination unit is dimmed by the dimming unit, the shadow of the contact object due to the external light is detected or reflected from the contact object by the illumination light according to the amount of light between the irradiation light and the external light. Detect light. As a result, the position of a contact object such as a fingertip that is in contact with the display means can be detected without being affected by the brightness of external light.

It is explanatory drawing which shows an example of the positional relationship of each part which comprises the display apparatus which is one Embodiment of this invention. It is a block diagram which shows the structural example of the control system of the display apparatus. It is a flowchart which shows an example of the process sequence until the display apparatus 100 shown in FIG. 1, FIG. 2 detects a finger | toe. It is a flowchart which similarly shows the other example of the process sequence until the display apparatus 100 detects a finger | toe.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
First, the configuration of a display device according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory diagram showing an example of the positional relationship of each part constituting a display device according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a control system of the display device.

The display device (panel device) of this embodiment is described as a liquid crystal display panel in which pixels are arranged in a matrix as display means, but may be a display panel having a pixel arrangement that is not in a matrix. For example, a display panel in which segment-like pixels are arranged may be used. In this case, each finger detection optical sensor, which will be described later, is also arranged in segments. Further, a display panel using a display mechanism other than liquid crystal may be used. For example, an LED display panel or a plasma display panel may be used.

As shown in FIGS. 1 and 2, the display device 100 includes a display panel unit 2 that is a display unit using a liquid crystal display panel in which pixels are arranged in a matrix as described above on a glass substrate, and the display panel unit 2. It includes a plurality of finger detection light sensors 3 arranged in a matrix in the lower (inner), and from the back side of the display panel unit 2 to the finger 1 of 2 and the user display panel unit and a backlight 4 for irradiating light ing. The finger detection optical sensor 3 corresponds to the contact object detection means, and the backlight 4 corresponds to the light irradiation means.

The display device 100 also dims the input unit 12 to which input conditions for the operation of the display device 100 are input, the control unit 11 that controls the operation of the display device 100 and performs image processing, and the backlight 4. A backlight dimming unit 10 that is a dimming unit, a backlight drive circuit unit 9 that drives the backlight 4, and an external light sensor 7 that is an external light detection unit that detects external light 5 incident on the display panel unit 2. And a light sensing unit 8 for detecting the amount of light detected by the external light sensor 7 and each finger detection light sensor 3, and a flash memory 15 for storing and holding data. In place of the flash memory 15, other nonvolatile memory (nonvolatile storage means) can be used.

The backlight 4 is a lamp for irradiating the display panel unit 2 and the like from the back side. In this embodiment, a CCFL (Cold Cathode Fluorescent Lamp), which is a general backlight device, is used. However, when it is environmentally friendly without mercury, an LED backlight is used, an organic EL backlight, or an inorganic EL backlight. For example, a flexible and thin material may be used.
The backlight dimming unit 10 dimmes the backlight 4 by using the backlight light 6 that is the irradiation light of the backlight 4 and the amount of light (also referred to as “brightness”, “intensity”, “luminance”, etc.). It has a function to detect. In addition, you may provide the sensor which detects the backlight light 6, and the optical sensing part which detects the light quantity separately.

The optical sensing unit 8 is a circuit that detects (senses) the magnitude of leakage current of each of the plurality of finger detection optical sensors 3 arranged in a matrix. The sensing may be performed for each finger detection optical sensor 3 or may be performed collectively.
The light sensing unit 8 also detects the amount of the external light 5 detected by the external light sensor 7 (also referred to as “brightness” or “intensity”), or detects the magnitude of the leakage current of the external light sensor 7. To do. The output of the light sensing unit 8 is input to the control unit 11. The external light sensor 7 may also have a function of detecting the amount of external light.

The control unit 11 has a function of controlling each element of the display device (liquid crystal display panel device) 100 as a whole, and can be specifically configured by a microprocessor or the like. The control unit 11 executes a program in a ROM or RAM (not shown) and controls the apparatus to perform image processing on detection signals of the plurality of finger detection photosensors 3 and touch a finger touching the display panel unit 2. It is possible to fulfill the function as a control means for specifying the position of. That is, it has a function of specifying the position of a contact object such as the fingertip 16 that has touched the display panel unit 2 regardless of the brightness of the external light 5. Further, it receives data from the optical sensing unit 8 and has a coordinate detection function. Furthermore, it has a function of performing a process of selecting an image processing method suitable for finger detection according to the brightness of the external light 5 and the brightness of the backlight 4.

Each embodiment of the control related to the present invention in the display device configured as described above will be specifically described with reference to FIGS.
[First embodiment]
First, a first embodiment will be described with reference to FIG.
3 shows an example of a processing procedure until the display device 100 shown in FIGS. 1 and 2 detects a finger.

When the control unit 11 of the display device 100 starts processing in step S11, it first determines whether or not the fingertip 16 has touched (touched) the display panel unit 2 in step S12. This procedure is realized by the function of the optical sensor 3 for finger detection . Since the fingertip 16 is a part of the human body, specific infrared rays are emitted based on the body temperature and blood flow. The detection of a specific wavelength can be detected by the finger detection optical sensor 3 by matching the wavelength characteristic of the finger detection optical sensor 3 to the specific wavelength. Alternatively, a special sensor may be provided.

Next, the brightness (light quantity) of the external light 5 and the backlight light 6 is acquired in step S13. These can be acquired from the external light sensor 7, the light sensing unit 8, and the backlight dimming unit 10.
In step S14, the absolute value of the difference in brightness (light quantity) between the acquired external light 5 and the backlight light 6 is compared with a set value stored in advance in the flash memory 15, and Determine whether the absolute value is greater than or equal to the set value. The set value is provided to determine whether there is a difference between the brightness of the external light 5 and the brightness of the backlight light 6.

When the brightness of the external light 5 and the brightness of the backlight light 6 are at the same level, even if an image processing method for detecting the shadow of the finger 1 by the external light 5 is selected, the reflection from the finger 1 by the backlight light 6 Even if the image processing method for detecting the light is used, compared with the case where there is a difference in brightness between the backlight light 6 and the external light 5, the shadowed portion of the finger 1 on the display panel unit 2 and the portion that does not Since the contrast is low, there is a possibility of error detection.

Therefore, the set value may be set as a value of a difference in brightness (light quantity) between the backlight light 6 and the outside light 5 that is obtained by an experimental value and does not cause erroneous detection .

If the result of determination in step S14 is that the absolute value of the brightness difference is greater than or equal to the set value, the process proceeds to step S15.
In step S15, the brightness of the external light 5 and the brightness of the backlight light 6 are compared to determine which of the external light 5 and the backlight light 6 is brighter.
Then, an image processing method is selected according to the determination result. That is, when it is determined that the external light 5 is brighter than the backlight light 6, the processes of steps S16, S17, and S18 are sequentially performed. When it is determined that the external light 5 is darker than the backlight light 6 (the backlight light 6 is brighter than the external light 5), the processes of steps S19, S20, and S21 are sequentially performed.

The processing procedures of steps S16, S17, and S18 are processing procedures when the external light 5 is dominant. Here, detection data such as leakage current of each finger detection photosensor 3 arranged in a matrix is obtained from the optical sensing unit 8, converted into brightness, and further, the position on the plane of the display panel unit 2. Are converted into data such as a two-dimensional brightness map.
Based on the data such as the two-dimensional brightness map, the processes in steps S16 to S18 are sequentially performed.

First, in step S16, the shadow of the finger 1 due to external light is detected. At this time, the brightest background portion and the darkest shadow portion are distinguished.
In the next step S17, the fingertip 16 is detected in the shadow of the finger 1. Here, among the shadow portions of the finger 1, the portion touched by the fingertip 16 is brighter than the portion other than the fingertip 16 due to the influence of reflection from the backlight light 6. This distinguishes between the darkest shaded part and the relatively bright part touched by the fingertip 16.

As described above, in steps S16 and S17, the fingertip 16 is detected by distinguishing three levels of brightness.
In step S18, the finger coordinates (the position of the fingertip 16) can be obtained in the process of the control unit 11.

The processing procedures of steps S19, S20, and S21 are processing procedures when the backlight light 6 is dominant. This process is executed by the functions of the light sensing unit 8 and the control unit 11 as described above.
First, in step S19, reflection from the finger 1 by the backlight 6 is detected. At this time, the darkest background portion is distinguished from the next dark finger shape portion.
In the next step S20, the fingertip 16 is detected in the reflection from the finger 1.
Thereafter, in step S21, the finger coordinates can be obtained in the process of the control unit 11.

On the other hand, if the result of determination in step 14 is that the absolute value of the brightness difference is less than the set value, the process proceeds to step S22.
In step S22, the brightness of the external light 5 and the brightness of the backlight light 6 are compared to determine which of the external light 5 and the backlight light 6 is brighter.

Then, the image processing method is selected according to the determination result, and the difference between the brightness of the external light 5 and the brightness of the backlight light 6 is set to a set value or more in order to reduce the occurrence of false detection of the fingertip 16. To dimm. That is, if it is determined that the external light 5 is brighter than the backlight light 6, the processes of steps S23, S24, S25, and S26 are sequentially performed. When it is determined that the external light 5 is not brighter than the backlight light 6 (the backlight light 6 is brighter than the external light 5 or the same brightness ), the processes of steps S27, S28, S29, and S30 are sequentially performed. . These processes are performed by the light sensing unit 8, the control unit 11, and the backlight dimming unit 10.

  In step S23, a control signal for reducing the light amount is sent to the backlight dimming unit 10 so that the difference between the brightness (light amount) of the external light 5 and the brightness of the backlight light 6 is equal to or greater than a set value. Then, after confirming that the difference between the brightness of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value, the processes of steps S24, S25, and S26 are sequentially executed. Each process is the same as each process of steps S16, S17, and S18 described above.

  In step S27, a control signal for increasing the amount of light is sent to the backlight dimming unit 10 so that the difference between the brightness of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value. Then, after confirming that the difference between the brightness of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value, the processes of steps S28, S29, and S30 are sequentially executed. Each process is the same as each process of steps S19, S20, and S21 described above.

  In this way, instead of selecting an image processing method based on a threshold value, processing is performed according to the difference in brightness between the backlight light detected by the backlight dimmer and the external light detected by the external light sensor. In other words, that is, whether the difference in brightness is greater than or less than the set value, and if the difference in brightness is greater than or equal to the set value as a result of the determination, the brightness of the backlight and the outside Select the image processing method for finger detection by comparing with the brightness of the light, and if the brightness difference is less than the set value, turn on the backlight so that the brightness difference is greater than the set value. Dimmed by the backlight dimming unit (therefore, the part with the finger on the panel and the part without the finger have a higher contrast than the prior art), and then the backlight light detected by the backlight dimming unit Brightness By comparing the brightness of the ambient light detected by the ambient light sensor and selecting an image processing method for finger detection, the fingertip touching the panel is not affected by the intensity of the brightness of the ambient light. The position can be detected.

  If the difference in brightness is greater than or equal to a set value and the backlight light is brighter than the external light, the touch is detected by detecting reflection from the touch object by the backlight light. By selecting an image processing method for detecting an object by detecting the shadow of the touch object by the external light when the external light is brighter than the backlight light, respectively. The position of the fingertip touching the panel can be detected more reliably.

Further, as a result of the determination, if the difference in brightness is less than the set value, the backlight light is compared with the external light. If the external light is brighter than the backlight light, the backlight is compared. By reducing the brightness of the backlight light (surface brightness of the backlight) by a light dimming unit and increasing the brightness of the backlight light when the outside light is not brighter than the backlight light, Therefore, it is possible to select the one that requires less dimming light, and it is possible to reduce the amount of change in the brightness of the panel and improve the visibility.
Furthermore, by using various types of backlight such as LED, CCFL, organic EL, or inorganic EL as the backlight, the above configuration can be used in a wide range of display devices.

[Second Embodiment]
First, a second embodiment will be described with reference to FIG.
The flowchart in FIG. 4 shows another example of the processing procedure until the display device 100 shown in FIGS. 1 and 2 detects a finger.
In the flowchart shown in FIG. 4, the processes of steps other than steps S33, S34, S35, S36, and S37 are the same as those in the first embodiment (the flowchart in FIG. 3).

In steps S33 and S34 in FIG. 4, the brightness (light quantity) of the external light 5 and the backlight light 6 is sampled a plurality of times (predetermined number of times) at a predetermined specific period, and an average value is calculated (acquired). . In calculating the average value, the brightest value and the darkest value may be cut off. In each subsequent step, the average value of the brightness of each sampled external light 5 is simply used as the brightness of the external light 5, and the average value of the brightness of each sampled backlight light 6 is simply used as the backlight light 6. Use each as brightness. Such averaging of the external light 5 and the backlight light 6 may be performed according to the flow of FIG.

In step S35, the ratio between the brightness of the external light 5 and the brightness of the backlight light 6 is compared with a set value stored in advance in the flash memory 15, and it is determined whether the brightness ratio is equal to or greater than the set value. The set value is provided to determine whether or not the ratio between the brightness of the backlight light 6 and the brightness of the external light 5 is sufficient. The ratio between the brightness of the external light 5 and the brightness of the backlight light 6 is a ratio when the brighter one of the external light 5 and the backlight light 6 is the numerator and the darker is the denominator.

  In step S36, a control signal for reducing the light amount is sent to the backlight dimming unit 10 so that the ratio between the brightness (light amount) of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value. Then, after confirming that the ratio between the light amount of the external light 5 and the light amount of the backlight light 6 is equal to or greater than the set value, the processes of steps S24, S25, and S26 are sequentially executed.

In step S37, a control signal for increasing the amount of light is sent to the backlight dimmer 10 so that the ratio between the brightness of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value. Then, after confirming that the ratio between the brightness of the external light 5 and the brightness of the backlight light 6 is equal to or greater than the set value, the processes of steps S28, S29, and S30 are sequentially executed.

When the brightness of the external light 5 and the brightness of the backlight light 6 are at the same level, even if an image processing method for detecting the shadow of the finger 1 by the external light 5 is selected, the reflection from the finger 1 by the backlight light 6 Even when the image processing method for detecting the light is used, the shadowed portion of the finger 1 on the display panel unit 2 and the portion that is not the same are compared with the case where the brightness ratio between the backlight light 6 and the external light 5 is large. Since the contrast is low, there is a possibility of error detection.
Therefore, it may be set as a value of the ratio between the backlight light 6 and the external light 5 that does not cause erroneous detection, and may be set to 2 or more .

  In this way, instead of selecting an image processing method based on a threshold value, processing is performed in accordance with the brightness ratio between the backlight light detected by the backlight dimmer and the external light detected by the external light sensor. In other words, that is, whether the brightness ratio is greater than or less than the set value, and if the brightness ratio is greater than or equal to the set value, the brightness of the backlight Select the image processing method for finger detection by comparing with the brightness of the light, and if the brightness ratio is less than the set value, turn on the backlight so that the brightness ratio is greater than the set value. Dimmed by the backlight dimming unit (therefore, the part with the finger on the panel and the part without the finger have a higher contrast than the prior art), and then the backlight light detected by the backlight dimming unit Brightness By comparing the brightness of the ambient light detected by the ambient light sensor and selecting an image processing method for finger detection, the fingertip touching the panel is not affected by the intensity of the brightness of the ambient light. The position can be detected.

  In addition, if the backlight ratio is brighter than the external light when the brightness ratio is greater than or equal to a set value as a result of the determination, the touch is detected by detecting reflection from the touch object by the backlight light. By selecting an image processing method for detecting an object by detecting the shadow of the touch object by the external light when the external light is brighter than the backlight light, respectively. The position of the fingertip touching the panel can be detected more reliably.

Further, as a result of the determination, when the brightness ratio is less than the set value, the backlight light is compared with the external light. When the external light is brighter than the backlight light, the backlight is compared with the backlight light. By reducing the brightness of the backlight light (surface brightness of the backlight) by a light dimming unit and increasing the brightness of the backlight light when the outside light is not brighter than the backlight light, Therefore, it is possible to select the one that requires less dimming light, and it is possible to reduce the amount of change in the brightness of the panel and improve the visibility.

Furthermore, when comparing the brightness of the external light and the backlight light, if the number of times of sampling is one, it is impossible to cope with noise and sudden environmental changes. By sampling and averaging the external light and the backlight light a plurality of times at a predetermined specific period, noise resistance and environmental resistance can be enhanced.
Further, by using various types of backlights such as LEDs, CCFLs, organic ELs, and inorganic ELs as backlights, the above configuration can be used in a wide range of display devices.

  Note that the processing according to the brightness difference or ratio between the backlight light detected by the backlight dimming unit and the external light detected by the external light sensor is not limited to that described with reference to FIG. 3 or FIG. . For example, the processing in steps S14 to S18 in FIG. 3 is omitted and the processing in step S13 is performed after the processing in step S13, or the processing in steps S35 and S15 to S18 in FIG. After performing the process of S34, the process after step S22 is performed so that the backlight is dimmed by the backlight dimming unit so that the brightness difference or ratio is greater than or equal to the set value (the brightness difference or If the ratio is already greater than or equal to the set value, nothing is done.) Then, the brightness of the backlight detected by the backlight dimmer is compared with the brightness of the ambient light detected by the ambient light sensor. An image processing method for detection may be selected.

  As mentioned above, although embodiment which applied this invention to the display apparatus which has a function which detects the position of a fingertip was described, this invention is not restricted to this, The display apparatus which has a function which detects the position of touch objects, such as a touch pen, is explained. Is also applicable.

As is apparent from the above description, according to the present invention, the position of the contact object in contact with the display means can be detected without being affected by the intensity of the brightness of external light. Therefore, it is possible to provide a display device that does not cause erroneous detection of a contact object.

1: user 's finger 2: display panel unit 3: finger detection light sensor 4: backlight 5: outside light 6: backlight light 7: outside light sensor 8: light sensing unit 9: backlight driving circuit unit 10: back Light dimming unit 11: Control unit 12: Input unit 15 : Flash memory
100: Display device

JP 2007-183706 A

Claims (6)

Display means;
A plurality of contact object detection means arranged inside the display means for detecting contact of a contact object such as a fingertip ;
External light detection means for detecting external light incident on the display means ;
Light irradiation means for irradiating the display means and the contact object with irradiation light from the back side of the display means ;
A light dimming means regulating the 該照Shako detects the light amount of the illumination light by the light irradiating means,
Control means for identifying the position of the contact object that has contacted the display means based on detection signals of the plurality of contact object detection means ; and
The control means includes
The difference between the amount of light emitted by the light irradiating unit detected by the light adjusting unit and the amount of external light detected by the outside light detecting unit is determined, and the absolute value of the difference is less than a predetermined set value. in case of,
When the light amount of the external light is larger than the light amount of the irradiation light, the light amount of the irradiation light is lowered with respect to the light control means until the difference from the light amount of the external light becomes equal to or greater than the predetermined set value. To detect a shadow of the contact object due to the external light,
When the amount of the external light is not larger than the amount of the irradiated light, the amount of the irradiated light is increased with respect to the light control means until the difference from the amount of the external light is equal to or greater than the predetermined set value. After the control is performed, the display device detects reflection from the contact object due to the irradiation light . The control means includes
When the absolute value of the difference between the light amount of the irradiation light and the light amount of the external light is not less than the set value,
When the light amount of the external light is larger than the light amount of the irradiation light, the shadow of the contact object due to the external light is detected,
The display device according to claim 1, wherein when the light amount of the external light is smaller than the light amount of the irradiation light, reflection from the contact object by the irradiation light is detected. Display means;
A plurality of contact object detection means arranged inside the display means for detecting the contact of a contact object such as a fingertip ;
External light detection means for detecting external light incident on the display means ;
Light irradiation means for irradiating the display means and the contact object with irradiation light from the back side of the display means ;
A light dimming means regulating the 該照Shako detects the light amount of the illumination light by the light irradiating means,
Based on the detection signal of the plurality of contact object detecting means, and control means for identifying the position of the touch object in contact with the display means is provided,
The control means includes
The ratio between the amount of light emitted by the light irradiating means detected by the light adjusting means and the amount of external light detected by the external light detecting means is a numerator of the brighter light amount and a denominator of the darker light amount. If the ratio is less than the preset value,
When the amount of the external light is larger than the amount of the irradiated light, the amount of the irradiated light is decreased with respect to the light control means until the ratio to the amount of the external light is equal to or greater than the predetermined set value. To detect a shadow of the contact object due to the external light,
When the amount of the external light is not larger than the amount of the irradiated light, the amount of the irradiated light is increased with respect to the light control means until the ratio with the amount of the external light is equal to or greater than the predetermined setting value. After the control is performed, the display device detects reflection from the contact object due to the irradiation light . The control means includes
When the absolute value of the ratio of the light amount of the irradiation light and the light amount of the external light is not less than the set value,
When the light amount of the external light is larger than the light amount of the irradiation light, the shadow of the contact object due to the external light is detected,
The display device according to claim 3, wherein when the light amount of the external light is smaller than the light amount of the irradiation light, reflection from the contact object by the irradiation light is detected. The display device according to claim 3 or 4 ,
A display device comprising means for sampling and averaging the light quantity of the external light and the light quantity of the irradiation light a plurality of times at a predetermined specific period. The light irradiation means, LED, CCFL, a display device according to any one of claims 1 to 5, characterized in that a backlight using an organic EL, an inorganic EL.

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