JP2011198359A - Display apparatus with touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a malfunction of a touch panel caused by an environmental temperature change in a display apparatus with a touch panel of a capacitance type.SOLUTION: A display apparatus has: a touch panel of a capacitance type; a detector which detects an environment that is at least one of temperature, humidity and pressure; and an adjuster which adjusts the environment based on a result of the detection. The adjuster varies the intensity of adjustment stepwise. For example, as the adjuster, a plurality of fans are provided, an air current for cooling is generated in a space between the touch panel and a liquid crystal panel by using the fans and a rotating speed or the number of rotations of the fans is varied stepwise.

Description

  The present invention relates to a display device provided with a touch panel.

  Currently, there are an increasing number of devices equipped with monitors that employ a touch panel as an interface, such as ATMs at banks and ticket vending machines at stations. Touch panels range from several inches in size to large displays that exceed 50 inches.

  In many cases, a display equipped with a touch panel is installed indoors, but recently, there are increasing examples of installation outdoors or semi-outdoors such as a gas station and a tourist guide bulletin board. Since the touch panel can use the front surface of the monitor as an interface, it has a feature that the user can operate intuitively.

  The touch panel is classified into a resistance film method, a capacitance method, an ultrasonic method, an infrared method, and the like according to the operation principle. Since each method has advantages and disadvantages, an appropriate one is adopted depending on the application. In the case of a large display of 20 inches or more installed outdoors or semi-outdoors, an infrared type or a capacitive type is mainly adopted.

  However, the infrared type has a problem that it easily reacts to rain and that the sensor does not operate when exposed to sunlight. Therefore, when installing outdoors, the installation of the eaves etc. to avoid rain and sunlight is needed. At present, the most widely used touch panels for outdoor displays are those that are less susceptible to the effects of rain and sunlight.

  Capacitive touch panels that are ideal for outdoor use also have weaknesses, which may be affected by the electrical noise generated by the LCD panel due to the effects of temperature, humidity, pressure, etc., which change due to changes in the weather. is there. For this reason, if the device structure is designed so as not to be affected by changes in temperature, humidity, etc. or electrical noise, and the fan or compressor is not optimally softly controlled, the touch panel may malfunction.

Further, since the temperature in the monitor changes rapidly when the power is turned on and enters a standby state, it affects the operation of the touch panel and may lead to a malfunction.
As countermeasures against malfunctions, the touch panel has been devised to cope with changes in the usage environment by periodic initialization processing.

  Further, even in a PC connected with a touch panel, when a malfunction is considered to occur, a device such as ignoring is devised. For example, a method of ignoring the areas other than the effective area is performed, or a method of detecting that the user clicks for a certain period of time.

  When a monitor is installed outdoors or semi-outdoors, it is required to have a dustproof and waterproof performance that is not so necessary indoors. Since the monitor closes the gap in order to ensure dustproof and waterproof performance, the internal temperature is more likely to rise than before. Some monitors installed outdoors are equipped with fans and compressors to adjust temperature and humidity.

  The electrostatic capacity method can be further classified into a surface type and a projection type (or transmission type). The surface type has a sensor on the front side of a protective glass provided on the front side of the liquid crystal panel. As this sensor, a sheet-like transparent conductive film is used. On the other hand, in the projection type, vertical and horizontal (XY) grid-like drive electrodes are mounted on the liquid crystal panel side of the protective glass. In other words, the projection type has a structure in which the sensor is disposed on the liquid crystal panel side, and is relatively resistant to moisture adhesion and wear due to rain and snow, so it is often used outdoors or semi-outdoors.

  Capacitance is generated in a state where two conductors are arranged via a dielectric. The magnitude of the capacitance C is expressed by the following equation (1).

_{C = E 0 × E S ×} S / d ····· (1) equation where, C: capacitance value (F)
E ₀ : Dielectric constant of vacuum = 8.854 × 10 ⁻¹² (F / m)
E _S : relative permittivity of dielectric S: conductor area (m ² )
d: Distance (m) between conductors.

  In the case of the surface type, one electrode is a transparent electrode such as ITO (Indium Tin Oxide, a compound obtained by adding tin to indium oxide), and the other electrode is a finger. In the case of the projection type, an operation input is detected by utilizing the fact that the capacitance between two transparent electrode films such as ITO or the sensor wire changes when touched with a finger.

  By the way, in the air, the dielectric constant has a characteristic that it is inversely proportional to the temperature when the pressure is constant. In addition, the relative dielectric constant of air is 1.00058, whereas the relative dielectric constant of water is 81. Therefore, the capacitance changes even when the humidity changes. Thus, the capacitive touch panel is affected by temperature, humidity, pressure, and the like.

  FIG. 9 shows the principle of position detection of a projected capacitive touch panel. XY electrodes represented by X1 to X5 and Y1 to Y5 are mounted on the glass liquid crystal panel side. When a finger touches the vicinity of the dotted line ○ portion (100), a change in voltage or frequency due to the capacitance of the touched finger occurs, and the touched position is determined by integrating data in the CPU of the controller portion.

  The controller of the touch panel monitors changes in the capacitance of the entire screen in order to respond to changes in the installation environment. In order to obtain an average value of the sensor value on the screen based on the monitoring result, the initialization process is periodically performed with a period of about 10 to several seconds. By performing the initialization process, it is possible to cancel not only the temperature and humidity but also the influence of dust and the like on the touch panel surface and prevent malfunction.

JP 2009-258903 A JP 2009-296105 A

  As described above, since the capacitive touch panel is affected by temperature, humidity, atmospheric pressure, etc., there may be a problem under the location conditions where conditions change, such as outdoors. In addition, since the temperature in the display changes abruptly after the power is turned on or when a standby state is entered, the operation of the touch panel is affected and a malfunction of the touch panel may occur. In order to deal with these problems, the initialization process described above is effective, but if the degree of temperature change is large, the initialization process alone may not be sufficient.

  In view of the above-described problems, an object of the present invention is to further reduce malfunctions of a capacitive touch panel.

  A display device according to an aspect of the present invention includes a capacitive touch panel, a detection unit that detects an environment that is at least one of temperature, humidity, and pressure, and adjusts the environment based on a result of the detection. An environment adjustment unit that changes the intensity of the adjustment stepwise.

  A display device according to another aspect of the present invention includes a liquid crystal panel, a light transmissive member disposed in front of the liquid crystal panel, a touch panel disposed in front of the light transmissive member, and an air flow in a space between the liquid crystal panel and the light transmissive member. The generator is driven so as to change the strength of the air flow stepwise.

  According to the display device of the present invention, malfunction of the capacitive touch panel can be reduced.

It is a figure which shows the system configuration | structure of the display system of this embodiment. It is the figure which looked at the monitor part (1) from the upper part. It is the figure which looked at the monitor part (1) from the side. It is a block diagram of a monitor part (1). It is a graph showing the internal temperature change by a prior art. It is an example of control when three fans for intake and three fans for exhaust are attached as in the monitor section (1) of FIG. It is an example at the time of further improving the control of FIG. It is a flowchart which concerns on the malfunction prevention control of a touch panel. It is a figure explaining the position detection principle of a projection capacitive touch panel.

  Embodiments of the present invention will be described below.

  FIG. 1 is a diagram showing a system configuration of a display system according to the present embodiment. This display system has a configuration in which a monitor unit (1) and a PC (personal computer) unit 2 are connected by a cable (3). The monitor unit (1) is a liquid crystal display. The PC (2) controls the monitor unit (1) and stores video / audio contents to be displayed on the monitor unit (1).

  FIG. 2 is a view of the monitor unit (1) as viewed from above. The housing of the monitor unit (1) includes a front cabinet (24) on the screen side and a back cabinet (25) on the back side. A liquid crystal panel (23) is attached inside. In addition to the general monitor configuration, this monitor unit (1) has a capacitive touch panel (22) on the front side of the liquid crystal panel (23), and a fan ( 20) (21) is attached. These fans are configured to allow intake from outside the monitor and exhaust from outside the monitor. Moreover, a filter is attached to the fans (20) and (21) in order to ensure the dustproof and waterproof performance.

  FIG. 3 is a side view of the monitor unit (1). In FIG. 2, only two fans, ie, the fans (20) and (21) are shown, but in reality, each of the fans (20) and (21) is composed of three fans. That is, there are three intake fans and three exhaust fans. The number of fans is not limited to three. The fans (20) and (21) blow air to the space between the liquid crystal panel (23) and the touch panel (22). Thereby, cooling of a liquid crystal panel (23) or a touch panel (22) can be aimed at.

  FIG. 4 is a block diagram of the monitor unit (1). Input 1 (41), input 2 (42), and input 3 (43) are input terminals. For example, the terminal (41) is a UHF / VHF terminal to which a broadcast signal received by an outdoor antenna is input, the terminal (42) is an RGB input terminal to which an RGB signal from an external device such as the PC unit (2) is input, The terminal (43) is a component input terminal to which a component signal from an external device such as the PC unit (2) is input. In addition, the input terminals (41) to (43) may be HDMI terminals, DVI terminals, USB terminals, or Ethernet (registered trademark) terminals for receiving video signals transmitted over the Internet. The SW (45) selects any one of the input terminals (41) to (43) based on the user's selection.

  The video signal selected by the SW (45) is passed from the video output circuit (50) to the panel section (52) through the video processing circuit (46) and the OSD / scaler (48). Thereby, an image is displayed. In the following description, it is assumed that a liquid crystal module is used for the panel.

  The audio signal selected by the SW (45) passes through the audio processing circuit (47) and the audio output circuit (49) and passes to the speaker (51). Thereby, a sound is output.

  The key signal of the remote control transmitter (53) is received by the remote control light receiving unit (54) and input to the CPU (56). The key signal is analyzed by the CPU (56) and the control is changed.

  The CPU (56) controls the entire video signal processing unit (44). A program for determining the control contents of the CPU (56) is stored in the memory (55). The memory (55) stores input information selected by the user, image quality and sound quality setting information, and the like.

  The signals exchanged between the video output circuit (50) and the liquid crystal module (52) include the power supply and control signals for the liquid crystal module (52) in addition to the video signals. The liquid crystal module (52) is configured to be easily turned on / off by controlling the video output circuit (50) according to an instruction from the CPU (56).

  A temperature sensor (58) and a humidity sensor (59) are also connected to the CPU (56), and the temperature and humidity can be measured in real time. The fan (61) is also controlled by the CPU (56).

  Further, a communication cable (RS232C, USB, etc.) in the cable (3) connected to the PC (2) in FIG. 1 is connected to the serial communication unit (57) for communication.

  The touch panel mounted on the monitor (1) in FIG. 1 is controlled by the CPU in the PC (2).

  As mentioned above, the touch panel initialization process can cope with changes in temperature, humidity, and atmospheric pressure to some extent, but the touch panel initialization process may not be able to follow when sudden changes occur. A malfunction may occur. Therefore, in the present embodiment, the fan control is performed as described below so that the temperature, humidity, atmospheric pressure and the like do not change abruptly.

  Hereinafter, control of the fans (20) and (21) of the monitor unit (1) of the present invention will be described.

  First, temperature information is measured with a temperature sensor (58) of FIG. 4 at a cycle of about several seconds. As the measurement value of the temperature sensor (58), a value obtained by a moving average is adopted in consideration of an error. Similarly, the humidity is measured with a period of several seconds from the humidity sensor (59), and a value is obtained by a moving average.

  In some existing monitors, the fan may be controlled by the value of the temperature sensor, but in this embodiment, in addition to the temperature and humidity, the initialization cycle of the touch panel is considered. When the initialization period of the adopted touch panel is about 10 seconds or more, the number of data samples is set so as to average at a period of about 3 to 5 times the initialization period. This is because if the fan control period is shorter than the initialization period of the touch panel, the accuracy of the initialization process of the touch panel is lowered.

  The humidity sensor (59) is used to detect dew condensation inside the monitor, but the characteristics of dew generation vary with temperature, so the values of the temperature sensor (58) and the humidity sensor (59) are measured. Control the fan.

The measured values of temperature and humidity are compared with predetermined threshold values, and if the threshold value for turning on fan control is exceeded, the fan is turned. Similarly, if it is lower than the threshold value, the fan is stopped. FIG. 5 is a graph showing a change in the internal temperature of the monitor according to the prior art. The dotted line represents the temperature change in the monitor without fan control. The solid line represents the change in the internal temperature of the monitor that is performing fan control.

  The temperature in the monitor varies depending on internal and external factors such as the temperature of the installation location and the heat generated by the liquid crystal monitor. For example, when the outside air temperature changes abruptly, when the power of the monitor itself changes from the OFF state to the ON state, or when the liquid crystal panel changes from the OFF state (non-display state) to the ON state (display state). is there. Even if the outside air temperature is high, the temperature rises only to about 40 degrees, but the temperature of the liquid crystal panel may rise to about 60 degrees. Since the low temperature of the outside air may drop to about 0 degrees, the temperature change range in the monitor is wide. When the temperature rises, the liquid crystal panel deteriorates in operating characteristics or may be damaged in some cases.

  Therefore, in this example of the existing monitor, the internal temperature of the monitor is controlled by turning on the fan at the timing (A) and turning off the fan at the timing (B). Thereby, prevention of malfunction and protection of the liquid crystal panel and the like are achieved.

  FIG. 6 shows an example of control when three intake fans and three exhaust fans are attached as in the monitor section (1) of FIG. In (C), turn on two sets of intake and exhaust fans (one set), in (D) turn on one set of intake and exhaust fans, and in (E) turn on the remaining one set of fans. . When turning off, one set of fans is turned off in (F), and another set of fans is turned off in (G). (H) turns off the last set of fans.

  FIG. 7 shows an example in which the control of FIG. 6 is further improved. In the control of FIG. 7, the timing for turning on each fan is optimized. In other words, the threshold temperature for turning on each fan is optimized. That is, in the example of FIG. 6, the timing (C) for turning on the first set of fans is the same as the fan activation timing (A) in FIG. On the other hand, in the example of FIG. 7, the timing (I) for turning on the first set of fans is set earlier than in the case of (A) or (C). Thereby, compared with the case of FIG. 5, temperature control can be performed gently and the malfunction of a touch panel can be prevented.

  Supplementally, for the purpose of preventing or protecting the malfunction of the liquid crystal panel, it is only necessary to control the liquid crystal panel so that it does not exceed a predetermined temperature. Therefore, temperature control as shown in FIG. 5 is sufficient. That is, it is sufficient to perform fan control only at the timing shown in FIG.

  However, the operation characteristics of the touch panel change depending on the temperature even at a relatively low temperature. In the touch panel, the offset initialization process is performed to cope with the temperature change. However, if the change is abrupt, it is not sufficient. When the monitor unit (1) is permanently installed outdoors for digital signage, the user needs to be able to use the touch panel at all times. Therefore, it is necessary that the touch panel does not malfunction even in an environment where there is a temperature change. Therefore, in order to control the temperature change in the monitor to be gradual even if the environmental temperature changes suddenly, in the example of FIG. 7, the drive number of fans is changed stepwise and the drive timing is also optimized. (For example, it is driven earlier than before).

  The situation where the fan is turned off is, for example, when the sky has changed to cloudy, before or after sunset, or when the power of the liquid crystal panel is turned off.

  Further, by adopting a fan that can change the rotation speed by PWM control instead of using three sets of fans, the same effect can be realized by adjusting the amount of wind intake and exhaust.

  Next, the effect of the above embodiment on electrical noise will be described.

  Capacitive touch panels have a weak point that they are vulnerable not only to temperature and humidity but also to electrical noise. Therefore, it cannot be extremely close to a liquid crystal panel that emits a lot of noise. If it is too far away from the liquid crystal panel, a parallax occurs between the liquid crystal monitor and the touch panel, so that a malfunction is likely to occur due to a shift in the image displayed on the touch panel and the liquid crystal. When the size of the monitor is about 40 inches, the touch panel and the liquid crystal module are generally separated by a distance of about 1 to 2 cm.

  Regarding the noise of the liquid crystal panel, it is possible to cancel the noise to some extent after several tens of seconds by the initialization process of the controller, but it is particularly unstable for several tens of seconds after the liquid crystal panel is turned on and off. It becomes a state and malfunction is likely to occur.

  Therefore, in the system of the present embodiment, communication can be performed between the monitor unit (1) and the PC (2) in FIG.

  Further, since the signal exchanged between the video output circuit (50) and the liquid crystal module (52) in FIG. 4 includes the power supply and control signal of the liquid crystal module (52) in addition to the video signal, the CPU (56). The liquid crystal module (52) can be easily turned on / off by controlling the video output circuit (50) according to the instruction. Since it has such a configuration, the following control is possible, and it is possible to perform control so that a malfunction by the touch panel does not easily occur.

Specifically, referring to the flowchart of FIG. 8, if the power is on, the monitor is first turned on (except for the liquid crystal module) (step 70). Next, before the liquid crystal module is turned on, the control waits until the control of temperature, humidity, etc. is stabilized (step 71). next,
It is confirmed whether the PC side permits the lighting of the liquid crystal panel (step 72). Then, the liquid crystal module is turned on (step 73).

  The PC (2) can instruct the lighting timing of the liquid crystal panel at any time by an RC-232S command or the like, and information such as whether the touch panel operation is stable to the monitor unit (1) or the temperature change status of the monitor unit (1). Similarly, since it is possible to make an inquiry at any time using an RC-232S command or the like, it is possible to predict a time zone where a malfunction is likely to occur on the PC side. Since it can be determined whether the malfunction is likely to occur, the information on the touch panel can be easily ignored. For example, when the liquid crystal panel is turned from OFF to ON, it can be predicted that the temperature rise as shown in the graph of FIG. Also, the timing at which the temperature change becomes zero can be roughly predicted. Therefore, it is also effective to use the prediction information and perform control such as prohibiting the input operation to the touch panel until, for example, the temperature change becomes zero.

  At this time, since the monitor unit has been activated, the time required to turn on the liquid crystal is about 1 second, but the timing for turning on the liquid crystal panel is delayed as compared with the conventional case. However, the controlling PC is in a known state and there is no major problem. Further, by blinking the LED (60) in FIG. 4 so that it can be determined without looking at the PC, the user can be relieved to understand at a glance why the liquid crystal panel is lit late. Similarly, when the monitor unit is set to the standby state, the timing can be controlled on the PC side, so that malfunctions can be avoided by ignoring the information on the touch panel on the PC side during a period when the change in noise is large.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the gist of the present invention.

Claims (3)

Capacitive touch panel,
A detector that detects an environment that is at least one of temperature, humidity, and pressure;
An environment adjusting unit for adjusting the environment based on the detection result;
The display device according to claim 1, wherein the adjusting unit changes the strength of the adjustment stepwise. LCD panel,
A light transmitting member disposed on the front surface of the liquid crystal panel;
A touch panel arranged in front of the light transmissive member,
A generator for generating an air flow in a space between the liquid crystal panel and the light transmitting member
The display device is characterized in that the generator is driven to change the strength of the airflow in a stepwise manner. In a display device having a capacitive touch panel with an offset initialization function to cope with temperature changes,
A display device comprising a temperature adjusting unit that suppresses the degree of temperature change of the touch panel.