JP2020118811A - Display device - Google Patents

Abstract

To provide a display device with which the accuracy of abnormality detection is heightened, making it possible to detect a symptom of abnormality.SOLUTION: Provided is a display device comprising: a display unit 110 having a plurality of pixels 111 for image formation; a detection unit 130 provided on the display surface 112 side of the display unit, for detecting the operation state of an operation element according to a change of capacitance based on touch operation on the operation element; and a control unit 140 for controlling a light emission state in the plurality of pixels according to the original pixel data for display and the operation state and controlling image display on the display unit. When there is no touch operation on the operation element, the control unit determines the presence of a symptom of abnormality on the display unit on the basis of the magnitude of capacitance that changes due to high-frequency drive with a short width gate voltage, with its pulse width shorted by a prescribed amount, as compared with a reference gate voltage for driving the pixels.SELECTED DRAWING: Figure 1

Description

The present invention relates to a display device suitable for use in, for example, a vehicle display device that displays various types of vehicle information related to a vehicle.

As a conventional display device, for example, one described in Patent Document 1 is known. The touch panel of the display device (information processing device) of Patent Document 1 includes a touch sensor and a liquid crystal panel. When a liquid crystal panel is driven using a noise driving pattern in which a voltage is applied to a plurality of first sub-pixels and a voltage is not applied to a plurality of second sub-pixels in the liquid crystal panel, in a normal display area, The electromagnetic field emitted from the liquid crystal panel becomes large, and the noise of the electrostatic capacitance detected by the touch sensor becomes large. On the other hand, in the area where the display abnormality occurs, the noise does not increase because the noise drive pattern is not driven even if the drive is performed. In this way, it is possible to identify the area in which the display abnormality of the liquid crystal panel is based on the magnitude of the noise in the touch sensor, and it is not necessary to add dedicated hardware for detecting the display abnormality.

JP, 2017-134179, A

However, in the display device of Patent Document 1, each pixel of the liquid crystal panel can be detected only after an abnormal state such as an inoperable point defect or line defect. In other words, even if an abnormality is detected after the display on the liquid crystal panel becomes impossible, a suitable display cannot be provided to the user already, and the speed display, the warning display, and the peripheral monitoring image cannot be displayed. It is not possible to detect and notify the previous abnormal sign.

In view of the above problems, it is an object of the present invention to provide a display device that improves the detection accuracy of an abnormality and can detect the sign of the abnormality.

The present invention adopts the following technical means in order to achieve the above object.

According to the present invention, a display unit (110) having a plurality of pixels (111) for image formation and a display surface (112) side of the display unit are provided, and a change in electrostatic capacitance based on a touch operation of an operating body is performed. Accordingly, the capacitance type detection unit (130) for detecting the operation state of the operation body, and the light emission state in a plurality of pixels are controlled according to the original image data for display and the operation state, and the display unit of the display unit is controlled. In a display device including a control unit (140) for controlling image display, the control unit shortens a pulse width by a predetermined amount with respect to a reference gate voltage for driving a pixel when there is no touch operation by an operating body. It is characterized in that the presence or absence of an abnormal sign of the display unit is determined based on the magnitude of the electrostatic capacitance that changes by driving at a high frequency with the short gate voltage.

According to the present invention, the transient response characteristic of the display unit (110) is deteriorated when the abnormal sign is generated in the normal state. In the degraded transient response characteristics, the degree of decrease in drain voltage (voltage difference) when a short gate voltage is applied is lower than the degree of drain voltage decrease (voltage difference) when a reference gate voltage is applied. You get bigger. Therefore, when the display unit (110) is driven at a high frequency by the short gate voltage, the voltage difference is large, and therefore the detection unit (130) can improve the detection accuracy of the abnormal sign due to the change in the capacitance based on the noise. Therefore, it is possible to detect the sign of abnormality.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the specific means described in the embodiments described later.

It is explanatory drawing which shows the whole structure of the display apparatus in 1st Embodiment. It is an explanatory view showing a source voltage and a gate voltage to each pixel for every frame at the time of inversion drive. It is an explanatory view showing the source voltage to each pixel for every frame at the time of inversion drive. It is a flow chart which shows the contents of control in a 1st embodiment. 7 is a graph showing the relationship between the transient response characteristic of the display unit and the gate voltage. It is explanatory drawing which shows a mode that each pixel carries out sweep drive for every column. It is explanatory drawing which shows the point which determines the presence or absence of abnormality of a pixel by noise. It is explanatory drawing which shows the whole structure of the display apparatus in 2nd Embodiment. It is a flow chart which shows the contents of control in a 2nd embodiment. It is explanatory drawing which shows a mode that the next determination is performed from the pixel area with the lowest evaluation of the determination result of the last time. It is explanatory drawing which shows a mode that each pixel carries out sweep drive for every row. It is explanatory drawing which shows a mode that each pixel is sweep-driven for every unit of the arrangement of the diagonal direction.

Hereinafter, a plurality of modes for carrying out the present invention will be described with reference to the drawings. In each form, parts corresponding to the items described in the preceding form may be designated by the same reference numerals, and redundant description may be omitted. In the case where only a part of the configuration is described in each mode, the other mode described above can be applied to the other part of the configuration. Not only the combination of the parts clearly showing that the respective embodiments can be specifically combined, but also the combination of the embodiments is partially combined even if the combination is not particularly specified, unless there is a problem in the combination. It is also possible.

(First embodiment)
The display device 100 according to the first embodiment will be described with reference to FIGS. 1 to 7. The display device 100 of the present embodiment displays various information by images. The display device 100 is mounted on a vehicle, for example, and is used for a predetermined device of the vehicle, that is, a display unit of a car navigation device, a display unit of a car air conditioner, a combination meter unit, or the like. The display device 100 can be touch-operated by a finger (operation body) of an operator (viewer), and as shown in FIG. 1, a display unit 110, a light source 120, a touch panel 130, a control unit 140, and the like. I have it. The control unit 140 is connected to the in-vehicle LAN and displays various kinds of information on the display unit 110.

The display unit 110 has a plurality of pixels 111 arranged in a matrix (mesh) (FIG. 2). By driving the pixels 111, an image is formed on the display surface 112. Has become. As the display unit 110, for example, a TFT (Thin Film Transistor) liquid crystal display using a thin film transistor is used. The plurality of pixels 111 are driven by transistors, and various kinds of information images such as images of various operating states of the vehicle and various operation icons for operating predetermined devices of the vehicle are displayed on the display surface 112. It is supposed to be done.

The light source 120 is a member that is disposed, for example, on the back surface of the display unit 110 and illuminates the display unit 110, that is, a member that emits light for image formation to the display unit 110. For example, an LED is used as the light source 120. The light source 120 has a light emission amount (luminance) adjusted (controlled) by a luminance control signal from a CPU 141 described later.

The touch panel 130 is provided on the display surface 112 side of the display unit 110, and is a capacitance-type detection unit that detects an operation state with a finger according to a change in capacitance based on a touch operation performed by the operator's finger. Has become. According to an operation state (finger operation on various operation icons) with a finger, an operation of inputting operating conditions to various predetermined devices of the vehicle can be performed.

The touch panel 130 has a touch panel sensor (electrode part), a resin cover, and the like. The touch panel sensor is formed, for example, by bonding transparent capacitive electrode portions arranged in a matrix on the back surface of a transparent film member. The resin cover is a transparent thin resin plate material that protects the touch panel sensor, and is provided on the operator side of the touch panel sensor.

The touch panel sensor is configured to form a capacitor between the touch panel sensor and a finger when the operator operates the finger to generate an electrostatic capacitance. As described above, since the touch panel sensor and the resin cover are formed of the transparent member, the images of various information on the display unit 110 are transparent and visible to the operator. The touch panel sensor is an electrostatic charge that is generated according to the position of the operated finger when the operator brings the finger close to any of various operation icons among various kinds of information (for example, about 5 mm) and further touches the finger. The change in the capacitance is output to the control unit 140 (touch panel controller 144) described later as touch operation coordinate information.

Further, the touch panel 130 is configured to detect noise caused by electromagnetic waves radiated by the display unit 110 during high frequency driving using a detection driving pattern described later, and this noise component will be described later as a capacitance value. The output is output to the control unit 140 via the touch panel controller 144.

The control unit 140 controls the image display on the display unit 110 by adjusting the light emission state (color, brightness, etc.) in the plurality of pixels 111 according to the original image data for display and the operation state with a finger. Has become. The control unit 140 has a CPU 141, a video processing unit 142, a liquid crystal drive unit 143, a touch panel controller 144, a failure determination unit 145, and the like.

The CPU 141 forms (draws) an internal video signal (an image to be displayed on the display unit 110) and outputs it to the video processing unit 142, and at the same time, based on the failure determination result determined by the failure determination unit 145, the user It is the part that issues a failure notification to.

The image processing unit 142 performs a predetermined image process on an internal image signal output from the CPU 141 or an external image signal output from an external camera, video, or the like, and outputs it to the liquid crystal drive unit 143. Has become. The internal video signal and the external video signal correspond to the original image data.

The liquid crystal drive unit 143 applies a normal reference gate voltage to each pixel 111 in order to display (form) an image based on the internal video signal (original image data) or the external video signal (original image data) on the display unit 110. In addition, it serves as a part for controlling driving (adjusting the light emitting state) of the plurality of pixels 111.

In addition, the liquid crystal driving unit 143 sets a short-width gate voltage, which will be described later, to each pixel 111 with respect to the reference gate voltage when determining whether there is an abnormality sign of the display unit 110 at the time of shipping the product, at the time of regular inspection, or the like. In addition, it is designed to be driven at high frequency (details will be described later).

The touch panel controller 144 is a part that receives a noise signal detected by the touch panel 130 and outputs a capacitance value to the failure determination unit 145 when determining whether there is an abnormality sign of the display unit 110. There is.

The failure determination unit 145 is a unit that determines whether or not there is an abnormality sign of the display unit 110 based on the capacitance based on the noise signal output from the touch panel controller 144. The failure determination unit 145 outputs the failure determination result to the CPU 141.

The display device 100 of the present embodiment has the above-described configuration, and hereinafter, the operation and operational effects will be described with reference to FIGS. 2 to 7.

When controlling the image display of the display unit 110, the control unit 140 (liquid crystal drive unit 143) adds a normal reference gate voltage (voltage of the reference width pulse) to each pixel 111, as shown in FIGS. 2 and 3. Then, each pixel 111 is driven. In the present embodiment, for example, the column line inversion driving method is adopted. That is, in the column line inversion drive, the positive and negative potentials of the source voltage applied to the pixel 111 in the column direction are opposite to each other next to the column, and each frame (current frame and next frame) This is a driving method that inverts positive and negative potentials. By driving each pixel 111 in this manner, various images on the display unit 110 are displayed.

Here, in the display device 100 of the present embodiment, it is possible to perform the inspection determination of the presence or absence of an abnormal sign of the display unit 110, for example, at the time of shipping the product, at the time of regular inspection, or the like. The procedure for determining the presence/absence of an abnormal sign will be described below with reference to the flowchart of FIG. 4 and FIGS.

First, in FIG. 4, the control unit 140 turns off the light source 120 in step S100, drives the display unit 110 in step S102, and in step S104, a noise removal filter for removing noise in the display unit 110. Turn off the.

Then, in step S106, the control unit 140 sets normal driving to high frequency driving as a condition for driving the display unit 110 (pixel 111). Here, the high frequency driving refers to driving the pixel 111 with a short width gate voltage obtained by shortening the pulse width by a predetermined amount with respect to the normal reference gate voltage, as shown in FIG. The short-width gate voltage has a shorter pulse width than the reference gate voltage, and therefore has a higher frequency and is driven by a high-frequency voltage.

Next, in step S108, the control unit 140 selects an area for determining the presence/absence of an abnormality on the display unit 110, and in step S110, drives each pixel 111 with a predetermined sweep detection drive pattern. Here, as shown in FIG. 6, the sweep detection drive pattern is a unit of the pixels 111 arranged in a predetermined direction among the plurality of pixels 111 for each frame in the inversion drive described in FIG. Of the positive and negative electric potentials of the source voltage in 111, only one electric potential (here, a positive electric potential) is added and driven while sequentially sweeping. In the present embodiment, the sweep detection drive pattern uses the pixels 111 arranged in the predetermined direction as units of columns (column line sweep).

Next, the control unit 140 (fault determination unit 145) acquires the capacitance value of the touch panel 130 from the touch panel controller 144 in step S112, and starts determination of whether there is an abnormality sign on the display unit 110.

Here, as shown in FIG. 7, when the pixel 111 of the display unit 110 is normal, a large change in capacitance due to noise when driven at a high frequency with the sweep detection drive pattern occurs, but an abnormal sign. If so, the change in capacitance due to noise will be small (not detected).

Therefore, the failure determination unit 145 compares the generated noise for each pixel 111 with a predetermined threshold value (obtains a difference from the threshold value) in step S114, and determines whether the generated noise is equal to or greater than the threshold value in step S116. Determine whether or not. The threshold value is a determination value for determining the presence/absence of an abnormality sign of the pixel 111 (for detecting display abnormality), and is stored in the failure determination unit 145 in advance.

When the failure determination unit 145 determines that the generated noise is smaller than the threshold value (No determination) in step S116, the failure determination unit 145 determines that there is a display abnormality symptom for the pixel 111 in step S118. Then, in step S120, it is determined whether the determination is completed for all the pixels 111, and if the determination is negative (No), steps S108 to S118 are repeated. Then, if an affirmative determination (Yes) is made in step S120, the control unit 140 (CPU 141) outputs the display abnormal region (the region of the pixel 111 having the display abnormal sign) to the user in step S122.

On the other hand, when the failure determination unit 145 determines in step S116 that the generated noise is equal to or greater than the threshold value (Yes determination), the process proceeds to step S124, and the acquired capacitance causes the operator to perform a normal finger operation. It is determined whether or not the contact detection threshold is less than or equal to the contact detection threshold.

When the determination in step S124 is affirmative (Yes), the failure determination unit 145 determines in step S126 that there is no finger operation by the operator and there is no sign of display abnormality of the pixel 111, and the process proceeds to step S120. If the failure determination unit 145 makes a negative determination (No) in step S124, there is a finger operation by the operator in step S128, and the obtained capacitance is due to the finger operation. Cancels the presence/absence of a display abnormality sign.

Then, the control unit 140 turns on the operation of the noise removal filter in step S130 after step S122 and step S128, and ends the present control.

As described above, in the present embodiment, when there is no touch operation with a finger, the control unit 140 uses the short gate voltage obtained by shortening the pulse width by a predetermined amount with respect to the reference gate voltage for driving the pixel 111, The presence/absence of an abnormality sign of the pixel 111 in the display unit 110 is determined based on the magnitude of the electrostatic capacitance that changes by driving at high frequency.

As a result, when the abnormal sign is generated compared to the normal state, as shown in FIG. 5, the transient response characteristic τ in the display unit 110 is lowered (solid line characteristic→dotted line characteristic). In the reduced transient response characteristic τ, the degree of decrease in the drain voltage when the reference gate voltage is applied (voltage difference ΔV1) to the degree of decrease in the drain voltage when the short width gate voltage is applied (voltage difference ΔV1) ΔV2) is obtained larger. Therefore, when the display unit 110 is driven at a high frequency by the short width gate voltage, the voltage difference is large, and therefore, in the touch panel 130, it is possible to improve the detection accuracy of the abnormality sign due to the change in the electrostatic capacitance due to the noise. It becomes possible to detect signs.

The transient response characteristic τ is represented by the following mathematical formula 1.

(Equation 1)
τ = {- μ · W / L · Ci / Cpx · (V G -Vth-V D)} -1
Where μ=transistor mobility,
W = transistor channel width,
L = transistor channel length,
Ci=capacitance per unit area of the gate insulating film,
Cpx=capacity of liquid crystal cell,
V _G =gate-source voltage,
Vth=threshold voltage,
V _D =drain-source voltage.

In addition, the control unit 140, in a unit of pixels arranged in a predetermined direction among the plurality of pixels 111, for each frame in the inversion drive that inverts the positive and negative potentials (positive electrode and negative electrode) during high frequency driving. A detection drive pattern for driving while sweeping in order is used. Here, in the detection drive pattern, the unit of pixels arranged in the predetermined direction is the unit of column (column line sweep).

Accordingly, the presence/absence of an abnormality sign can be detected in units of pixels 111 arranged in a predetermined direction, so that it is possible to determine the presence/absence of an abnormality sign in a short time as compared with the case of corresponding to each pixel 111.

(Second embodiment)
A display device 100A according to the second embodiment is shown in FIGS. The display device 100A of the second embodiment has a storage unit 146 (FIG. 8) added to the display device 100 of the first embodiment, and a procedure for determining whether or not an abnormal symptom has occurred on the display unit 110 (FIG. 9). It has been changed.

The storage unit 146 is connected to the CPU 141 and serves as a unit for storing the determination result of the presence or absence of an abnormality sign. The storage unit 146 is configured to store data based on changes in noise in the plurality of pixels 111 as a determination result for each inspection.

Further, the flowchart for determining the presence or absence of an abnormal sign shown in FIG. 9 is obtained by adding step S107 and changing step S122 to step S123 with respect to the flowchart of the first embodiment described in FIG.

In FIG. 9, after a step S100 to a step S106, the control unit 140 selects a start region of the present abnormality symptom presence/absence determination in a step S107 based on the previous determination result. Specifically, as shown in FIG. 10, the control unit 140 starts the determination of this time (corresponding to the next time of the present invention) from the region of the pixel 111 having the lowest evaluation of the previous determination result. ing.

Then, after step S120 and step S128, the control unit 140 (storage unit 146) outputs the display abnormal region (the region of the pixel 111 having the display abnormal sign) to the user in step S123, and at the same time, this time. The determination result of is stored.

As a result, the region of the pixel 111, which has the lowest determination result of the previous time, is estimated to have the largest degree of deterioration. Therefore, by performing determination from this pixel region this time, the presence/absence of an abnormality sign is determined. can do.

(Third Embodiment)
In the first and second embodiments, as the sweep detection drive pattern, the plurality of pixels 111 are driven while sequentially sweeping in the unit of column line, but the present invention is not limited to this and, for example, FIG. Alternatively, another pattern as shown in FIG. 12 may be used.

In FIG. 11, the unit of the pixels 111 arranged in a predetermined direction at the time of sweep is set as a unit of row (row line sweep). Further, in FIG. 12, the unit of the pixels 111 arranged in a predetermined direction at the time of sweep is set as a unit of oblique arrangement (oblique line sweep).

As described above, even when the sweep pattern is changed, the same effect as that of the first and second embodiments can be obtained.

(Other embodiments)
In each of the above-described embodiments, the liquid crystal display is used as the display unit 110, but the display unit 110 is not limited thereto. For example, a self-luminous organic EL display having an organic EL element using an organic compound or the like. Other types may also be used. Since the organic EL display is a self-luminous type, the light source 120 provided in the case of a liquid crystal display is unnecessary.

100, 100A display device 110 display unit 111 pixel 112 display surface 130 touch panel (detection unit)
140 control unit 146 storage unit

Claims (6)

A display unit (110) having a plurality of pixels (111) for image formation;
A capacitance type detection unit (130), which is provided on the display surface (112) side of the display unit and detects the operating state of the operating body in response to a change in electrostatic capacitance based on a touch operation of the operating body. When,
A control unit (140) for controlling the image display of the display unit by controlling the light emitting states of the plurality of pixels according to the original image data for display and the operation state;
When the touch operation by the operating body is not performed, the control unit performs high-frequency driving with a short gate voltage with a pulse width shortened by a predetermined amount with respect to a reference gate voltage for driving the plurality of pixels. A display device for determining the presence/absence of an abnormality sign of the display unit based on the magnitude of the changing capacitance. The control unit, when performing the high-frequency drive, a detection drive in which a plurality of pixels arranged in a predetermined direction are sequentially swept and driven for each frame in the inversion drive in which the positive electrode and the negative electrode are inverted. The display device according to claim 1, wherein a pattern is used. The display device according to claim 2, wherein the detection drive pattern has pixels arranged in the predetermined direction as columns. The display device according to claim 2, wherein in the detection drive pattern, a unit of pixels arranged in the predetermined direction is a unit of a row. The display device according to claim 2, wherein in the detection drive pattern, pixels arranged in the predetermined direction are arranged in a diagonal direction. A storage unit (146) for storing the determination result of the presence or absence of the abnormal sign,
The display device according to claim 1, wherein the control unit performs the next determination from the pixel region having the lowest evaluation result of the determination result of the previous time.

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