CN115066720A

CN115066720A - Method for driving display device, display device driving apparatus, display device, and display method

Info

Publication number: CN115066720A
Application number: CN202080096179.9A
Authority: CN
Inventors: 寺西康幸; 水桥比呂志
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-02-12
Filing date: 2020-02-12
Publication date: 2022-09-16
Also published as: WO2021159298A1

Abstract

The present invention provides a method of driving a display device (100) that improves the quality of captured images while maintaining the resolution of the OLED. The display device (100) comprises: a storage unit for storing a plurality of frame patterns to be displayed in an object-sensing area in which an object is detected; a light receiving element for detecting the object based on the light from the light emitting element. The method comprises the following steps: scanning the mode image for each of the plurality of frame modes, wherein the scanning comprises: stopping emission of the light emitting elements on a portion of the emission signal lines disposed along the first axis in a frame mode of display; moving a transmission signal line to be inhibited from transmitting along the second axis within the frame mode of the display; by the light receiving element, reflected light from the object is measured from the emission of the light emitting element.

Description

Method for driving display device, display device driving apparatus, display device, and display method

Technical Field

Embodiments of the present disclosure relate to an image sensing function, and in particular, to a method for driving a photon detector, a photon detector driving apparatus, a display method, and a display device.

Background

Currently, a pixel cell driving circuit for a portable terminal OLED includes a 6T1C (6 transistors and 1 capacitor) circuit and a 7T1C (7 transistors and 1 capacitor) circuit for each pixel. As the number of transistors implemented for one pixel increases in this manner, the degree of integration increases and the corresponding resolution decreases.

Further, an image sensor that converts light into an electrical signal is mounted in the portable terminal. In particular, an in-cell (in-cell) image sensor is known in which a part (or all) of an image sensor mechanism (e.g., a CMOS sensor) for converting light into an electrical signal is incorporated in a TFT of an OLED. Typically, image sensors include Active Pixel Sensors (APS) that increase the gain of the signal on a pixel-by-pixel basis to increase the signal-to-noise ratio (S/N ratio). The structure of APS comprises three TFTs for each pixel: a reset transistor for resetting a voltage of a Photodiode (PD) as a light receiving element, an amplifier transistor for amplifying a gain, and a transistor (or a read transistor) for reading a signal. Therefore, when the pixel circuit is configured by implementing both the pixel cell driving circuit such as the 6T1C circuit or the 7T1C circuit and the image sensor for one pixel of the OLED, the circuit integration degree is further improved. Such a complicated circuit configuration adversely affects the corresponding resolution and reduces the space for adding other devices. Therefore, in order to simplify the circuit configuration, referring to fig. 2, it is known to remove the reset transistor and the amplifier transistor from the image sensor to provide a configuration including only the read transistor and the photodiode (1T1 PD). However, a configuration without an amplifier transistor would reduce the S/N ratio.

Disclosure of Invention

It is an object of the invention to improve the quality of the captured image while maintaining the resolution of the OLED.

A first aspect provides a method of driving a display device, wherein the display device comprises: a plurality of emission signal lines disposed along the first axis and respectively providing emission signals to the plurality of light emitting elements; a plurality of data signal lines disposed along a second axis and providing data signals to cause each of the plurality of light emitting elements to emit light; a storage unit that stores a plurality of frame patterns to be displayed in an object sensing area in which an object is detected; a light receiving element that detects the object based on light from the light emitting element, wherein the plurality of frame patterns are designed according to the object, the first axis and the second axis are perpendicular, the method includes, for each of the plurality of frame patterns:

scanning the pattern image, wherein the scanning comprises:

inhibiting emission of light emitting elements disposed along a portion of the emission signal lines in a frame mode of display;

moving a transmission signal line to be inhibited from transmitting along the second axis within the frame mode of the display;

by the light receiving element, reflected light from the object is measured from the emission of the light emitting element.

According to the implementation, for each of the plurality of frame patterns, emission of light-emitting elements provided along a part of the emission signal lines is inhibited in a frame pattern of display in which emission signal lines to be inhibited are moved along the second axis when the pattern image is scanned. Thus, the combination of the pattern illumination technique and the CDM driving method improves the quality of a captured image while maintaining the resolution of the OLED.

In combination with one possible implementation of the first aspect, the scanning comprises scanning the pattern image only by light emitting elements within the object sensing area.

According to the implementation, since the pattern is only scanned by the light emitting elements within the object sensing area, waste of power consumption is avoided.

With reference to one possible implementation manner of the first aspect, the stopping of emission includes disabling light-emitting elements outside the object sensing region.

According to the implementation, by prohibiting the transmission signal line outside the object sensing region, waste of power consumption is avoided.

With reference to one possible implementation manner of the first aspect, the reading of the light receiving element is controlled according to a reading signal of a scanning signal line, and the stopping of the emission includes disabling the scanning signal line outside the object sensing region.

According to the implementation, the reading of the light receiving element is controlled according to the reading signal of the scanning signal line, and the scanning signal line outside the object sensing region is inhibited while the light emission is stopped, thereby avoiding waste of power consumption.

In combination with one possible implementation manner of the first aspect, the stopping of emission includes simultaneously inhibiting emission of the light emitting elements in the pattern image disposed along at least two adjacent emission signal lines.

According to the implementation, since emission of the light emitting element in the pattern image disposed along at least two adjacent emission signal lines is stopped, the CDM driving method is implemented by moving control to inhibit the optical fiber bundle of the plurality of emission signal lines.

In combination with one possible implementation manner of the first aspect, the light receiving elements are connected to a switch, and the measurement controls the switch so that the plurality of light receiving elements connected to one data signal line are simultaneously connected to a photometric device.

According to the implementation, by removing one TFT from the PD circuit and connecting the PD circuit to an external switch, a simpler configuration can be achieved.

A second aspect provides a display device comprising:

a plurality of emission signal lines disposed along the first axis and respectively providing emission signals to the plurality of light emitting elements;

a plurality of data signal lines disposed along a second axis and providing a data signal to cause each of the plurality of light emitting elements to emit light, wherein the first axis and the second axis are perpendicular;

a storage unit that stores a plurality of frame patterns to be displayed in an object-sensing area in which an object is detected, wherein the plurality of frame patterns are designed according to the object;

a light receiving element that detects the object based on light from the light emitting element;

a controller which displays the plurality of frame modes and displays the mode image for each of the plurality of frame modes, wherein the displaying includes:

stopping emission of light emitting elements disposed along a part of the emission signal lines in a frame mode of display;

a photometric unit that measures reflected light from the object based on the emission of the light emitting element detected by the light receiving element.

In combination with one possible implementation of the second aspect, the controller scans the pattern image only by light emitting elements within the object-sensing area.

In combination with one possible implementation manner of the second aspect, the controller disables the light emitting elements outside the object sensing region.

In one possible implementation manner combined with the second aspect, the controller includes a plurality of Gate On Array (GOAs), and enables only the GOAs that drive the light emitting elements in the object sensing region.

According to the implementation, the controller is made up of a plurality of GOAs, and power consumption can be reduced by enabling only those GOAs that drive the light-emitting elements within the object-sensing area and disabling other GOAs.

With reference to one possible implementation manner of the second aspect, the reading of the light receiving element is read according to a reading signal of a scanning signal line, and the controller disables the scanning signal line outside the object sensing region.

In combination with one possible implementation manner of the second aspect, the controller simultaneously inhibits emission of the light emitting elements in the pattern image disposed along at least two adjacent emission signal lines.

In combination with one possible implementation manner of the second aspect, the light receiving elements are connected to a switch, and the controller controls the switch so that the plurality of light receiving elements connected to one data signal line are simultaneously connected to the photometric device.

Drawings

In order to more clearly describe the technical solutions in the embodiments or the background art of the present invention, the following briefly describes the drawings that need to be used in the description of the embodiments or the background art of the present invention:

fig. 1 is a block diagram of a configuration example of a display device provided by an embodiment;

fig. 2 is a diagram of a configuration example of a pixel circuit used in an OLED;

fig. 3 is a timing chart of an example of drive control of the pixel circuit shown in fig. 2;

FIG. 4 is a perspective view of a combination display and image sensor;

fig. 5 is a diagram of a relationship between an array of OLEDs and PDs and an object;

fig. 6 is a diagram of an example of the patterned light shown in fig. 4 moving in a horizontal direction;

FIG. 7 is a diagram of an example of a frame pattern for pattern illumination;

FIG. 8 is a diagram of an example of pixel driving in fingerprint authentication;

FIG. 9 is a diagram of a cross-sectional structure of a display with a finger placed on the display surface;

fig. 10 is a graph virtually showing the intensity of light received by the PD shown in fig. 9;

FIG. 11 is a diagram of a cross-sectional structure of a display with a finger placed on the display surface, provided by one embodiment;

FIG. 12 is a graph plotting the intensity of light received by the PD of FIG. 11;

FIG. 13 is a diagram of a frame mode provided by one embodiment;

FIG. 14 is a diagram of an example of pixel driving in fingerprint authentication provided by one embodiment;

FIG. 15 is a diagram of an example of pixel driving in fingerprint authentication, as provided by one embodiment;

FIG. 16 is a graph of temporal variations of frame images provided in one embodiment;

fig. 17 is a timing chart of an example of drive control of a pixel circuit provided in one embodiment;

fig. 18 is a diagram of a configuration example of a gate driver circuit;

fig. 19 is a diagram of a configuration example of a gate driver circuit;

fig. 20 is a diagram of a configuration example of a pixel circuit;

FIG. 21 is a timing diagram illustrating drive control of a pixel circuit according to one embodiment;

fig. 22 is a diagram of a relationship between an array of OLEDs and PDs and an object;

fig. 23 is a top view of a PD array in an image sensor, according to an embodiment.

Detailed Description

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments of the present application only and is not intended to be limiting of the present application.

(first embodiment)

The following describes a first embodiment of the present invention. In the present embodiment, a Code Division Multiplexing (CDM) driving method for driving an image sensor is combined with a pattern illumination technique.

Fig. 1 is a block diagram of a configuration example of a display device provided by a first embodiment of the present invention. The display device 100 includes a driving circuit 1. The pixel array 104 included in the drive circuit 1 has a plurality of pixel circuits arranged in a two-dimensional form (matrix form) of N rows × M columns. A vertical scanning circuit 101 that supplies pixel drive signals is provided on one end side (left side in the drawing) of the pixel array 104. The pixel array 104 and the vertical scanning circuit 101 are connected by a signal line 102. Further, a horizontal scanning circuit 107 and a signal converter 106 connected to each column signal line 105 are provided on the lower end side (lower side in the drawing) of the imaging area.

The display device 10 includes a controller 103. From the master clock, the controller 103 generates and outputs the master clock or a clock obtained by dividing the master clock. The vertical scanning circuit 101, the signal converter 106, and the horizontal scanning circuit 107 are controlled in synchronization with the clock output of the controller 103. The controller 103 is connected to the memory 109, and performs control according to data stored in the memory 109.

The vertical scanning circuit 101 sets an address and drives the emission signal line to perform vertical scanning. Emission signal lines are disposed along the x-axis, each of which provides an emission signal to the plurality of OLEDs. The signal converter 106 performs signal conversion processing, for example, converting analog outputs of pixels into digital outputs; and outputs a digital output to the output circuit 108. Further, the horizontal scanning circuit 107 sequentially selects each signal conversion unit of the signal converter 106 in synchronization with the clock output from the controller 103, and controls the signal converter 106 to read a signal from the signal line 105 and output the signal to the output circuit 108. The horizontal scanning circuit 107 drives the data signal lines. The data signal line is disposed along the y-axis and provides a data signal to cause each of the plurality of OLEDs to emit, the plurality of OLEDs being a plurality of emission signal elements. In one embodiment, the signal converter 106 may include an Analog Front End (AFE). The AFE is a photometric device and serves as a detection unit that detects reflected light of an object emitted by the OLED by the PD.

According to the present embodiment, the pixel circuit formed by a combination of the OLED and the APS can be applied to various electronic devices such as, but not limited to, a cellular phone, a smart phone, a Personal Digital Assistant (PDA), and a PC.

Fig. 2 shows a configuration example of a pixel circuit for an OLED. The pixel circuit is configured as a 7T1C +1T + PD circuit, and includes a pixel unit drive circuit 2 and a PD drive circuit 3.

In the pixel array 104, each row includes a plurality of pixel units. The pixel unit driving circuit 2 drives and controls the pixel of each pixel unit in the nth row, and 1 sub-pixel corresponds to a pixel unit in the following description. The pixel cell driving circuit 2 includes 1 OLED, 7 transistors, and 1 capacitor. The 1 OLED corresponds to a sub-pixel of one color of red (R), green (G), and blue (B) constituting the 1 pixel.

The pixel unit driving circuit 2 includes a switching transistor T2 for switching a data writing signal, which is a data signal to be applied to a corresponding data line in response to a writing signal, which is a scanning signal to be applied to the nth writing line. The pixel unit driving circuit 2 further includes a driving transistor T4 and a compensation transistor T3. The driving transistor T4 supplies a charging voltage corresponding to the data signal input to the capacitor C1 via the switching transistor T2 at the gate and supplies a driving current to the organic EL element. The compensation transistor T3 compensates for the threshold voltage of the driving transistor T4. The pixel-unit driving circuit 2 further includes a capacitor C1 and an organic EL element OLED. The capacitor C1 is used to store a data signal having a voltage level applied to the gate of the driving transistor T4, and the organic EL element OLED emits light corresponding to the applied driving current.

The pixel-unit driving circuit 2 further includes a switching transistor T6 and a switching transistor T5. The switching transistor T6 supplies the power supply voltage ELVDD to the driving transistor T4 in response to the emission signal Em, and the switching transistor T5 supplies the driving current from the driving transistor T4 to the OLED in response to the emission signal Em. The pixel-unit driving circuit 2 further includes a reset transistor T1. The reset transistor T1 initializes the data signal stored in the capacitor C1 in response to an Init signal, which is a scan signal as the (n-1) th line. In addition, the pixel unit driving circuit 2 includes a reset transistor T7. The reset transistor T7 has a source connected to a line of the initialization voltage VINI, a gate connected to a line of the write signal, and a drain connected to the OLED. The transistors T1 to T7 are configured as p-type Thin Film Transistors (TFTs).

The switching transistor T2 has a gate, a source, and a drain. The gate electrode is applied with a write signal to be applied to a corresponding scan line, the source electrode is applied with a data write signal (i.e., a data signal) to be applied to a corresponding data line, and the drain electrode is connected to the source electrode of the driving transistor T4.

The driving transistor T4 has a gate and a drain. The gate is connected to one terminal of the capacitor C1, and the drain is connected to one terminal of the OLED via the switching transistor T5. The compensation transistor T3 has a gate, a drain, and a gate. The gate and the drain are connected to the gate and the drain of the driving transistor T4, respectively, and the gate is applied with a write signal. The high-level power supply voltage ELVDD is supplied from the corresponding power supply to the other terminal of the capacitor C1.

A switching transistor T5 gate, source, and drain. The gate electrode is applied with the emission signal Em, the source electrode is connected to the drain electrode of the driving transistor T4, and the drain electrode is connected to one end of the OLED. The other end of the OLED is connected to a power supply of the voltage ELVSS.

The PD drive circuit 3 includes a photodiode PD (i.e., a light receiving element) and a transistor T8. In the PD, a PN junction is constituted by a p-type semiconductor layer on the light receiving side and an n-type semiconductor layer on the substrate side. When a reverse bias is applied to the PN junction, the PN junction with almost no carrier becomes a depletion layer. When light having energy larger than the forbidden band width of the semiconductor is irradiated near the depletion layer, a carrier wave is generated. The PD may be generally configured as a PIN photodiode. The PIN photodiode includes three layers, i.e., p ⁺ -Si, i-Si and n ⁺ Si, and electrodes arranged between the layer structures. In the case of a PIN photodiode, the presence of the i-Si layer widens the width of the depletion layer obtained when a reverse bias is applied, thereby ensuring the use of a photodiode having a high reverse bias voltage. The high reverse bias voltage in the wide depletion layer moves the carrier quickly, increasing the response speed.

The transistor T8 has a gate, a source, and a drain. The gate is connected to a sensing signal (i.e., a scan signal for reading Data), the source is connected to the anode of the PD, and the drain is connected to a read line Data Sense (Data Sense). The transistor T8 is configured as a p-type Thin Film Transistor (TFT).

Next, the operation of the 7T1C +1T + PD circuit shown in fig. 2 is described with reference to an example of the timing chart in fig. 3.

Assume that the 7T1C +1T + PD circuit is driven by the (n-1) th scan signal Init1, the nth scan signal Init2 (i.e., Write1), the emission signal Em1, and the switching signal Sense 1. The period from time t1 to time t2 is an initialization period in which the scan signal Init1 is low, and the scan signal Write1, the emission signal Em1, and the switch signal Sense1 are high.

The reset transistor T1 is turned on by the scan signal Init1, and the other transistors T2 to T7 are turned off by the high-level scan signal Write1 and the emission signal Em 1. Accordingly, the data signal stored in the capacitor C1 is initialized, and the gate voltage of the driving transistor T4 is initialized.

Next, during the precharge period from t3 to t4, the scan signal Init1 is at a high level, the scan signal Write1 is at a low level, and the emission signal Em1 and the switch signal Sense1 are at a high level. The reset transistor T1 is turned off, the compensation transistor T3 and the switching transistor T2 are turned on by the low-level scan signal Write1, and the switching transistors T5 and T6 are turned off by the emission signal Em 1. Accordingly, the voltage level of the data write signal, i.e., the data signal applied to the corresponding data line, is applied to the source of the driving transistor T4, so that the gate voltage of the driving transistor T4 is stabilized to the voltage Vdata of the data write signal plus the threshold voltage Vth of the driving transistor T4 through the compensation transistor T3 and stored in the capacitor C1 completing the precharge operation.

The period after t4 is included is an emission period in which the scan signal Init1 is at a high level, and after the scan signal Write1 becomes a high level, the emission signal Em1 becomes a low level. The switching transistors T5 and T6 are turned on by the low-level emission signal Em1, the reset transistor T1 is turned off by the high-level scan signal Init1, and the compensation transistor T3 and the switching transistor T2 are turned off by the high-level scan signal Write 1. Accordingly, ELVDD is applied to the source of the driving transistor T4, the gate-source voltage Vgs of the driving transistor T4 becomes Vgs which is Vdata + Vth-ELVDD, and the current I flowing through the OLED is Vdata + Vth

I＝k·(Vgs-Vth) ²

＝k(Vdata+Vth-ELVDD-Vth) ²

＝k(Vdata-ELVDD) ²

So that a current independent of the threshold voltage flows through the OLED to emit light.

In a read period from t5 to t6, the scan signals Init1 and Write1 are high, and Em1 and Sense1 are low. Accordingly, the transistor T8 is turned on, so that a signal from the PD is read out by the read line Data Sense (Data Sense).

In the case of a frame of 8 × 8 pixels, the above-described processing is performed on 8 lines. Therefore, 8 scan signals Write1 to Write8 (i.e., Init2 to Init9), 8 emission signals Em1 to Em8, and 8 switch signals Sense1 to Sense8 are applied to the PDs of the 8 lines.

The above combination of OLED and PD has two problems, i.e., signal-to-noise ratio degradation and blur. These problems are described below.

First, signal-to-noise ratio degradation is described. The integration level of the 7T1C +1T + PD circuit is lower than that of the 7T1C + APS circuit, and the corresponding reduction of the resolution is also alleviated. However, since the 7T1C +1T + PD circuit has no amplifier transistor, the signal-to-noise ratio decreases. For example, when authentication (e.g., fingerprint authentication) is performed from a captured image, a very small difference in reflected light of an object must be detected for each frame, which requires a high signal-to-noise ratio. When the signal-to-noise ratio is low, a full-noise fingerprint image is given, which adversely affects authentication.

Among methods of improving the signal-to-noise ratio, it is known to apply a CDM driving method to an image sensor driving method. Since the CDM driving method simultaneously opens a plurality of gate lines, a large amount of data should be collected at the same time. This complicates the circuit configuration driven by CDM. In this respect, the CDM driving method in the present embodiment is implemented with a simple configuration.

The ambiguity problem is described below. In the case of a display including an image sensor, it is necessary to mount an optical device for the image sensor. The optical means for the image sensor are arranged on a pixel cell comprised in the display. In the case where the optical device is a lens, for example, a microlens for collecting more light on the light receiving element is provided on the pixel unit, and a focusing lens is provided on the microlens. However, for a display, in order to secure a wide viewing angle, it is necessary to diffuse light. Since the optical device of the image sensor adversely affects the diffusion of light, the quality of the acquired display image is degraded, resulting in blurring.

As a method of eliminating blur, a lens-less camera technique is known in which a lattice of an encoding mask is disposed on a surface of an image sensor without using a focusing lens. Light reflected from the object passes through the lattice to reach the image sensor in slightly different combinations. The image captured by the image sensor becomes an image of the subject after synthesis and analysis. However, the encoding mask should prepare a complicated pattern. In addition, it is difficult to prepare a code mask that does not degrade display quality.

To improve blur, the present embodiment uses a pattern illumination technique. Specifically, in order to avoid crosstalk of received light, patterned light that varies with time is output from the display, and light reflected from an object is detected.

Next, a pattern illumination technique is described with reference to fig. 4 to 6.

Fig. 4 is a perspective view of a combination of a display and an image sensor. As shown in fig. 4, when the image sensor is mounted on the display, a structure is adopted in which the display 1102 shown in fig. 4 (a) is overlaid on the image sensor 1104 shown in fig. 4 (b). Fig. 5 is a diagram showing a relationship between a combined array of OLEDs and PDs and an object in the apparatus. As shown in fig. 5, the image sensor 1104 has an array of PDs 1204 and the display 1102 includes an array of OLEDs 1202. For example, when light is emitted from a column of red (R) subpixels according to light patterned on the display 1102, red light hits the object 1203, as shown in (a) of fig. 5. Light reflected from the object 1203 is diffused and hits each of the plurality of PDs 1204. Light emitted from the OLED1202 is reflected in different directions depending on a position on the object 1203, and one PD1204 receives light reflected from different positions. Thus, the PD1204 detects the object 1203 from the light from the OLED 1202.

As shown in fig. 4, a light array 1106 perpendicular to the x-axis is an example of patterned light, and various patterns may be applied to the patterned light. For example, for patterned light, a light array horizontal to the x-axis, a grid pattern of light arrays, a plurality of columns having a predetermined angle with the x-axis, a dot grid pattern, a checkerboard pattern, and the like may be used.

In pattern illumination, the patterned light array 1106 varies over time. Fig. 6 illustrates an example in which the patterned light illustrated in fig. 4 moves in a horizontal direction (i.e., an x-axis direction). In the example shown in fig. 6, the OLED1202 located directly below the object 1203 emits light, and the reflected light of the object 1203 is less diffused than the light in fig. 5. Therefore, the PD1204 located in the vicinity of the OLED1202 right under the object 1203 receives stronger reflected light. Therefore, according to the intensity of reflected light received by each PD, the shape of the object 1203 can be obtained by the AFE connected to the PD.

Fig. 7 shows an example of a frame pattern for pattern illumination. The frame mode is a mode image displayed in an object sensing area in which an object approaching the display surface of the display device is detected. And designing the size of the frame mode according to the object to be detected. Each frame pattern shown in fig. 7 is a frame of 8 × 8 pixels, white portions indicating pixels that emit light, and gray portions indicating pixels that do not emit light. In the example shown in the figure, 8 types of frame patterns in which one frame is composed of six light-emitting pixels are prepared. These frame patterns are stored in the memory 109 of the display device 100. The controller 103 sequentially reads out from the memory 109 and controls light emission of the pixels using a single frame pattern.

However, in the pattern illumination, in order to reduce crosstalk, it is necessary to prepare a complicated frame pattern or various frame patterns. In this respect, in the present embodiment, reduction in crosstalk is achieved with fewer frame patterns.

Fig. 8 is a diagram of an example of pixel driving in fingerprint authentication. In fig. 8, a frame pattern composed of a non-light emitting portion 1902 shown in gray and a light emitting portion 1904 shown in white is displayed on a display 1901. An emission signal line for controlling emission of the display 1901 extends along an x-axis, and a data signal line through which a data signal flows extends along a y-axis. In the case of using the frame mode, all the emission signal lines are enabled to let the emission signal flow so that emission of the pixels of the portion 1904 that emit light is controlled by the data signal from the data signal line. The user places a finger on the lighting section 1904 for authentication processing.

Next, the principle of fingerprint authentication will be described with reference to fig. 9. Fig. 9 shows a cross-sectional structure of a display in which a finger 901 is placed on a display surface 902, and drive control is performed along a time axis t. In fig. 9 (a), PD a1 is initially connected to the AFE. The 7 OLEDs a2 to g2 all emit light, and the PD a1 receives light reflected from the finger 901 and transfers current corresponding to the intensity of the light to the AFE.

Next, in (b) of fig. 9, PD b1 is connected to the AFE. The 7 OLEDs a2 to g2 all emit light, and the PD b1 receives light reflected from the finger 901 and transfers current corresponding to the intensity of the light to the AFE. Similarly, the PDs connected to the AFE move in sequence, and the light intensity is measured from the current flowing from each PD in the AFE. Also, the above-described process is performed for the OLED and the PD arranged in the direction perpendicular to the sheet surface of fig. 9.

Fig. 10 is a graph virtually showing the intensity of light received from the PD a1 to the PD g1 shown in fig. 9, in which the horizontal axis represents the position of the OLED. For example, the PD a1 receives strong reflected light based on the OLED a2 and then receives strong reflected light based on the OLED b2, but it is difficult to receive reflected light based on the OLEDs c2 to g 2. Further, in consideration of the relationship with the finger 901, the PD located directly below the fingerprint valley receives light weaker than the PD located directly below the fingerprint ridge. Since the intensity of light received by each PD is the sum of reflected lights from all OLEDs, it can be understood that light received by the PD d1 is weak with reference to (a) of fig. 10. Fig. 10 (b) is a graph 1002 in which the intensity of light received by the PD is plotted. Here, the horizontal axis represents the relative position of the PD. Referring to (b) of fig. 10, when there is no valley, the value of the measurement result of the valley portion is lower compared to the curve 1001 of the measurement result. Therefore, it can be understood that a valley exists near PD d 1. However, a relative difference between the measured values of fingerprint ridges and fingerprint valleys of 0.1 indicates a low signal-to-noise ratio, resulting in blurring.

Next, with reference to fig. 11, a method of driving a display device according to the present embodiment is described taking fingerprint authentication as an example. Fig. 11 shows a cross-sectional structure of a display in which a finger 901 is placed on a display surface 902, and drive control is performed along a time axis t. The drive control shown in fig. 11 employs the CDM drive method, and in all the states shown in (a) of fig. 11 and (b) of fig. 11, all the PDs a1 to g1 are connected to the AFE. First, in (a) of fig. 11, all OLEDs except the OLED a2 emit light, and light received by all PDs is measured by the AFE. Next, in (b) of fig. 11, all OLEDs except the OLED b2 emit light, and light received by all PDs is measured by the AFE. Similarly, the OLED to be inhibited from emitting moves in the y-axis direction in turn, the emission of the OLED g2 is stopped in (g) of fig. 11, and all the light received by the PD is measured by the AFE. Similarly, the above-described processing is also performed for those OLEDs and PDs disposed in the direction perpendicular to the sheet surface of fig. 11. In this way, a movement process of emission stop of the OLED disposed along the emission signal line is realized, which is realized along the y-axis.

Next, the CDM driving method will be specifically described. In fig. 11, voltages related to the outputs of PD a1, b1 … … g1 are denoted as Va1, Vb1 … … Vg 1. In addition, in fig. 11 (a), 11 (b) … …, and 11 (g), the voltage measured by the AFE is represented as Va, Vb … … Vg. The voltage output to the AFE is the sum of the voltage Va1 related to the output of PD a1 and the voltage Vg1 related to the output of PD g 1. In the case of (a) of fig. 11, the voltage Va1 associated with the output of the PD a1 directly below the OLED a2 that does not emit light is 0. Therefore, the voltage Va may be expressed as Va ═ Vb1+ Vc1+ Vd1+ Ve1+ Vf1+ Vg 1.

In the case where the second OLED b2 on the left side of fig. 11 (b) does not emit light, the voltage Vb1 of the PD b1 located directly below the OLED b2 is 0. Therefore, the voltage Vb output to the AFE can be represented as Vb equal to Va1+ Vc1+ Vd1+ Ve1+ Vf1+ Vg 1. Similarly, when the voltages c to g output to the AFE by sequentially shifting the non-emitting OLED are measured, the voltages Va to Vg measured by the AFE may be represented by the following determinant.

In the foregoing determinant, the following matrix is referred to as "CDM code".

In order to obtain the output voltages Va1 to Vg1 from the respective PDs, an inverse matrix should be applied to [ Va, Vb, Vc, Vd, Ve, Vf, Vg ], as shown below.

The intensity of light received by each PD can be obtained in this way.

Fig. 12 is a graph 1003 of the intensity of light received by the PD in fig. 11. The relative difference between the measured values of fingerprint ridges and fingerprint valleys was 0.5, indicating a significant improvement in signal-to-noise ratio and blur.

Fig. 13 shows a frame pattern used in pattern illumination provided by the present embodiment. And designing the size of the frame mode according to the object to be detected. Each of the first frame mode and the second frame mode shown in fig. 13 is a frame of 8 × 8 pixels, white portions indicate pixels that emit light, and gray portions indicate pixels that do not emit light. In the example shown in the figure, a frame pattern in which one frame is composed of 8 pixels is prepared. These frame patterns are stored in the memory 109 of the display device 100, and the controller 103 controls the emission of the pixels using the respective frame patterns in the memory 109 in turn. In the present embodiment, the emission of the OLED is controlled using the two types of frame patterns to generate a pattern similar to the 8 types of frame patterns shown in fig. 7.

Fig. 14 is a diagram of an example of pixel driving in fingerprint authentication provided by the present embodiment. The display 1401 displays a frame mode including non-light emitting portions 2102 and 2014 shown in gray and a light emitting portion 2016 shown in white. The frame pattern displayed on the display 1401 changes along the time axis t. The transmit signal lines used to control the emission of display 1401 extend along the x-axis and the data signal lines through which data signals flow extend along the y-axis. In the case of using the frame mode, all the emission signal lines are enabled to let the emission signal flow so that emission of the pixels of the portion 2106 that emit light is controlled by the data signal from the data signal line. The user places a finger on the light emitting portion 2106 for authentication processing.

Fig. 15 is a diagram of an example of pixel driving in fingerprint authentication provided by another embodiment. In the case of using the frame mode, only the transmission signal line of the portion 2104 having the light emitting portion 2106 is enabled to flow a transmission signal so that emission of pixels of the portion 2106 which emits light is controlled in accordance with a data signal from the data signal line. The user places a finger on the light emitting portion 2106 for authentication processing. In this case, other transmission signal lines are disabled so that waste of power consumption can be avoided.

Fig. 16 shows temporal changes of frame images displayed on the display device in the embodiment shown in fig. 15. In the photodiode driving process according to the present embodiment, the first frame pattern having 8 subframes is displayed, and scanning is performed in the 4 × 4 pixel portion shown by the solid line 1501. In the display processing of the first to fourth sub-frames, the first frame pattern is displayed, and the first sub-frame is formed by disabling the third transmission signal line from the top of the figure. Next, a second sub-frame is formed by disabling the fourth transmission signal line from the top of the figure. Also, the third sub-frame and the fourth sub-frame are formed by sequentially shifting the transmission signal lines to be inhibited. Next, the second frame mode is displayed, and a fifth sub-frame is formed by disabling the third transmission signal line from the top of the figure. Then, a sixth subframe is formed by disabling the fourth transmission signal line from the top of the figure. Also, the seventh sub-frame and the eighth sub-frame are formed by sequentially shifting the transmission signal lines to be inhibited.

According to the above-described embodiments, by combining the CDM driving method with pattern illumination, it is possible to increase the signal-to-noise ratio and reduce blurring. In addition, the combination of the CDM driving method and pattern illumination may simplify driving control.

The above-described embodiments can be applied to a configuration in which the PD circuit has an amplifier transistor and a configuration in which the PD circuit does not have an amplifier transistor, to prove the same effect.

(second embodiment)

A second embodiment of the present invention is described below. In the present embodiment, at least two adjacent transmission signal lines are simultaneously enabled. Then, the prohibited transmission signal lines are sequentially moved with time. For example, in an array composed of 9 OLEDs and 9 PDs, in the case where drive control is performed to disable two adjacent transmission signal lines, CDM codes for representing voltages output to the AFE may be represented as follows:

in the CDM driving method according to the present embodiment, as described in the first embodiment, the voltage output to the AFE is measured 9 times while sequentially moving the two PDs stopping emission to obtain the measurement voltages Va, Vb, Vc, Vd, Ve, Vf, Vg, Vh, and Vi. By applying the inverse matrix of the above CDM code to [ Va, Vb, Vc, Vd, Ve, Vf, Vg, Vh, Vi ], the voltage of each of the 9 PDs can be obtained.

(third embodiment)

The third embodiment of the present invention is described below. In the present embodiment, by flowing an emission signal using a frame mode, only an emission signal line including a light emitting portion is enabled, and emission control of a pixel portion which emits light is controlled in accordance with a data signal of a data signal line. At the same time, the other transmission signal lines are disabled. At this time, power consumption can be further reduced by disabling the sense signal line for reading data.

Fig. 17 shows an example of a timing chart when performing drive control for disabling emission signal lines in an array composed of 9 OLEDs and 9 PDs. When fingerprint authentication is performed for the first to ninth transmission signal lines, only the transmission signals Em1 to Em9 are turned on or off, and the transmission signals Em10 to EmN of the tenth and subsequent transmission signal lines are all inhibited. As for the sensing signals as the scan signals for reading data, only the first to ninth signals Sense1 to Sense9 are enabled or disabled, and the emission signals Sense10 to SenseN of the tenth and subsequent emission signal lines are disabled.

The gate driving circuit according to the present embodiment may employ a gate driver on array (GOA) substrate. The GOA employs a driving method in which a gate driving circuit is directly integrated on an array substrate without external connection and line-by-line scanning of gates is realized. The GOA technology can improve the integration level, thereby shortening the manufacturing process and increasing the product cost. Fig. 18 shows a configuration example of a GOA of a display device. In the GOA, the emission scan GOA and the gate scan GOA are disposed in the middle of an active region included in the pixel array. The emission scanning GOA is a GOA that drives an emission signal. The gate scanning GOA is a GOA of driving scanning signals (an Init signal, a write signal, and a detection signal which is a scanning signal of read data). The emission scan GOA is connected to odd lines on the active region and sequentially drives emission signal lines. The gate scanning GOA is connected to even lines on the active region and sequentially drives the sensing signal lines. In the present embodiment, only the transmission signal lines of the portion for fingerprint authentication are scanned, and for the scanning signal lines, only the transmission signal lines of the component for fingerprint authentication are scanned.

Fig. 19 is a diagram of another configuration example of the gate driver circuit. As shown in fig. 19, the GOA driving circuit may be composed of a plurality of emission scanning GOAs and a plurality of gate scanning GOAs. In this case, drive control is performed so as to scan only the emission scanning GOA connected to the emission signal line of the means for fingerprint authentication and the gate scanning GOA connected to the scanning signal line. During the verification process, other GOAs are always disabled. In this way, power consumption in the authentication process can be reduced.

(fourth embodiment)

The fourth embodiment of the present invention is described below. In the above-described embodiment shown in fig. 2, there is the transistor T8, and the transistor T8 is connected between the PD and the read line Data Sense (Data Sense) when reading Data. Then, scanning of data reading is performed by applying the sensor signal as a scanning signal to the gate of T8. However, in the case of the CDM driving method, all PDs are connected to the AFE along the vertical direction of the display in one data read from the PDs. This eliminates the need to scan along the vertical direction of the display. Therefore, in the present embodiment, the transistor T8 is removed, and drive control is performed so that all PDs are simultaneously connected to the AFE along the vertical direction of the display. In the 7T1C + PD circuit shown in fig. 20, a switch 2001 is provided between the anode of the PD and the AFE. The switch 2001 is controlled by a switch signal to connect the anode to ELVDD when fingerprint detection is not performed and to connect the anode to AFE when fingerprint detection is performed. Other PDs along the vertical direction of the display are also controlled by the switching signals. Removing one TFT from the 7T1C +1T + PD circuit in this manner may provide a simpler configuration.

Fig. 21 shows an example of a timing chart when the emission signal line is driven and controlled in an array composed of 9 OLEDs and 9 PDs. The switching signal for switching the switch 2001 may be controlled to periodically connect the PD to the power supply voltage ELVDD or AFE.

(fifth embodiment)

A fifth embodiment of the combined pattern illumination and mask of the present invention is described below. Fig. 22 is a diagram showing a relationship between a combined array of OLEDs and PDs and an object in the apparatus. In fig. 22, the OLED1202 and the PD1204 are alternately arranged. In fig. 22 (a), a mask 1206 of the image sensor is disposed on the PD 1204. The mask 1206 blocks a part of the optical path of the reflected light from the object. In fig. 22 (b), an arrow shown by a dotted line indicates light which is blocked by the mask and does not reach the PD 1204. The effect of a complex mask to reduce cross-talk can be improved by moving a column of OLEDs emitting light in this way, equally in the horizontal direction in fig. 4 or fig. 5. Furthermore, the image can be easily reconstructed.

Fig. 23 is a plan view of an arrangement of PDs in the image sensor, showing a positional relationship between the PDs and the mask. Referring to fig. 23, an example of a mask is described. The mask indicated by the black dots or black lines may be configured as a plurality of vertical linear masks shown in (a) of fig. 23, or as a lattice-like mask disposed at the same position on each PD shown in (b) of fig. 23. Further, the mask may be a vertical linear mask disposed at different positions on the PDs in each PD column, as shown in (c) of fig. 23. Further, the masks may be disposed at different positions on the respective PDs as shown in (d) of fig. 23.

In another example, a collimator or pinhole may be used on the image sensor, without a lens, to reduce blur in the combination of the image sensor and the display.

In the above-described embodiment, the pixel unit driving circuit is exemplarily constituted by 7 transistors and 1 capacitor. However, whichever example above is used, the number of transistors and capacitors and the circuit configuration may vary in use.

In summary, the foregoing is merely an example of the embodiments of the present application and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement and the like made within the principle of the present application are included in the protection scope of the present application.

Claims

1. A method of driving a display device, the display device comprising: a plurality of emission signal lines disposed along the first axis and respectively providing emission signals to the plurality of light emitting elements; a plurality of data signal lines disposed along a second axis and providing data signals to cause each of the plurality of light emitting elements to emit light; a storage unit that stores a plurality of frame patterns to be displayed in an object sensing area in which an object is detected; a light receiving element that detects the object based on light from the light emitting element, wherein the plurality of frame patterns are designed based on the object, and the first axis and the second axis are perpendicular, the method comprising: for each of the plurality of frame modes,

scanning the pattern image, wherein the scanning comprises:

2. The method of claim 1, wherein the scanning comprises scanning the pattern image only with light emitting elements within the object-sensing area.

3. The method of claim 2, wherein said ceasing to emit comprises disabling light emitting elements outside of said object sensing region.

4. The method according to claim 1, wherein reading of the light receiving element is controlled in accordance with a read signal of a scanning signal line, and the stopping of emission includes inhibiting the scanning signal line outside the object sensing region.

5. The method of claim 1, wherein said ceasing emission comprises simultaneously inhibiting emission of light emitting elements in a pattern image disposed along at least two adjacent emission signal lines.

6. The method according to claim 1, wherein the light receiving elements are connected to a switch, and the measurement controls the switch so that the plurality of light receiving elements connected to one data signal line are simultaneously connected to a photometric device.

7. A display device, comprising:

a controller that displays the plurality of frame modes and displays the mode image for each of the plurality of frame modes, wherein the displaying includes:

8. The display device of claim 7, wherein the controller scans the pattern image only through light emitting elements within the object-sensing region.

9. The display device of claim 8, wherein the controller disables light-emitting elements outside the object sensing region.

10. The display device according to claim 9, wherein the controller includes a plurality of Gate On Array (GOAs), and enables only the GOAs that drive the light emitting elements within the object-sensing region.

11. The display device according to claim 7, wherein reading of the light receiving element is reading in accordance with a reading signal of a scanning signal line, and the controller disables the scanning signal line outside the object sensing region.

12. The display device according to claim 7, wherein the controller simultaneously inhibits emission of the light emitting elements in the pattern image provided along at least two adjacent emission signal lines.

13. The display device according to claim 7, wherein the light receiving elements are connected to a switch, and the controller controls the switch so that the plurality of light receiving elements connected to one data signal line are simultaneously connected to a photometric device.