CN113015891A - Sensor at lower part of display - Google Patents
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- CN113015891A CN113015891A CN202080002035.2A CN202080002035A CN113015891A CN 113015891 A CN113015891 A CN 113015891A CN 202080002035 A CN202080002035 A CN 202080002035A CN 113015891 A CN113015891 A CN 113015891A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
- G01S17/26—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F18/00—Pattern recognition
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J2001/4238—Pulsed light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J2001/4242—Modulated light, e.g. for synchronizing source and detector circuit
Abstract
A sensor (100) under the display (10), comprising: a photosensor (200) including a light irradiation section (210) that irradiates modulated sensing light for sensing an object located outside the display (10), and a light receiving section (220) that detects external reflection light reflected by the object of the modulated sensing light and generates a pixel current; a sensor polarizing layer (110) which is arranged above the optical sensor (200) and has a polarizing axis inclined at a first angle; and a sensor retardation layer (120) disposed on the upper portion of the sensor polarizing layer (110), and having a slow axis inclined at the first angle with respect to a polarizing axis of the sensor polarizing layer (110).
Description
Technical Field
The present invention relates to a sensor disposed under a display.
Background
Optical sensors are used not only in mobile electronic devices such as mobile phones and tablet computers, but also in video electronic devices such as televisions and monitors. The light sensor includes, for example, an illuminance sensor, a proximity illuminance sensor, and the like. The proximity sensor is a light sensor that measures a distance between a user and the electronic device, and the illuminance sensor is a light sensor that senses brightness around the electronic device. A proximity illumination sensor that combines an optical approach to the proximity sensor with an illumination sensor implements both sensors within a single package.
In recent years, designs in which displays almost occupy the entire front surface of an electronic device have been increased. Although the size of the display becomes larger as a demand for a large screen increases, it is still necessary to secure at least a partial area of the front surface to configure the camera, particularly the proximity illuminance sensor. A proximity sensor using ultrasonic waves or the like can be applied to a structure in which a front surface is covered with a display, but it is difficult to integrate a function of sensing illuminance. On the other hand, although the illuminance sensor may be located in a region other than the front surface, it may not sense ambient light due to a housing for protecting the electronic device. Therefore, although the most ideal position for providing the proximity illuminance sensor is the front surface of the electronic device, in a design in which the display occupies the entire front surface, it is difficult to ensure a position for disposing the proximity illuminance sensor that is commonly used.
Disclosure of Invention
The object of the present invention is to provide a sensor that can be applied to the lower part of a display of such a design that the front surface is occupied by the display as a whole.
An embodiment of the invention provides a sensor arranged in a lower portion of a display comprising pixels generating light, a display retarder layer arranged in an upper portion of the pixels, and a display polarizer layer. The sensor at the lower portion of the display may include: a photosensor including a light irradiation section that emits modulated sensing light and irradiates an object located outside the display, and a light receiving section that detects externally reflected light reflected by the object of the modulated sensing light and generates a pixel current; a sensor polarizing layer disposed on an upper portion of the optical sensor and having a polarizing axis inclined at a first angle; and a sensor retardation layer disposed on an upper portion of the sensor polarizing layer and having a slow axis inclined at the first angle with respect to a polarizing axis of the sensor polarizing layer. Here, the reflected light may reach a light receiving part through the display, the sensor polarizing layer, and the sensor retardation layer.
As an embodiment, the light irradiation part may include: a light source signal generating section for generating a basic light source driving signal for repeating a continuous on interval and a continuous off interval; a carrier signal generation unit that generates a carrier signal having a frequency greater than a frequency of the basic light source drive signal; a signal modulation unit that generates a modulated light source drive signal by frequency-modulating the continuous on interval of the basic light source drive signal using the carrier signal; and a light source, wherein the modulated light source driving signal is switched on and off at the frequency of the carrier signal during the continuous switching-on interval to generate the modulated sensing light.
As an embodiment, the sensor at the lower portion of the display may further include: a band-pass filter that removes a frequency component of the carrier signal from the pixel current; an amplifier that amplifies the pixel current from which the frequency component of the carrier signal has been removed; and an analog-to-digital converter converting the amplified pixel current into a digital signal.
As an embodiment, the sensor polarizing layer may include a first sensor polarizing layer having a polarizing axis inclined at the first angle and a second sensor polarizing layer having a polarizing axis inclined at a second angle. Here, the light receiving part may include a first light receiving part disposed at a lower portion of the first sensor polarizing layer and detecting the external reflection light and internal reflection light of the sensing light reflected inside the display, and a second light receiving part disposed at a lower portion of the second sensor polarizing layer and detecting the external reflection light and the internal reflection light.
In one embodiment, the sensor retardation layer and the first sensor polarizing layer may pass the external reflection light and the internal reflection light at a blocking transmittance ratio of the internal reflection light, and the sensor retardation layer and the second sensor polarizing layer may pass the blocking transmittance ratio of the external light other than the external reflection light and the internal reflection light.
As an embodiment, the brightness of the external reflection light can be calculated by the blocking transmission ratio of the external light and the blocking transmission ratio of the internal reflection.
As an embodiment, the sensor polarizing layer and the sensor retardation layer may convert the sensing light into sensing sensor circular polarized light so that the sensing light passes through the polarizing layer of the display, and the sensing sensor circular polarized light is converted into sensing display linear polarized light having the same polarizing axis as the polarizing axis of the polarizing layer of the display through the display retardation layer.
As an example, the slow axis of the sensor retarder may be parallel to the slow axis of the display retarder, and the polarization axis of the display polarizer may be inclined at a second angle with respect to the slow axis of the display retarder.
As an embodiment, the sensor delay layer may include: a first sensor retardation layer disposed on an upper portion of the sensor polarizing layer and having a slow axis inclined at the first angle with respect to a polarizing axis of the sensor polarizing layer; and a second sensor retardation layer disposed on the upper portion of the sensor polarizing layer corresponding to the second photoreceivers, and having a slow axis inclined at a second angle with respect to a polarizing axis of the sensor polarizing layer. Here, the light receiving part may include: a first light receiving unit which is disposed at a position where light having passed through the first sensor retardation layer and the sensor polarizing layer reaches, and which detects internally reflected light in which the external reflected light and the sensing light are reflected inside a display; and a second photoreceiver disposed at a position where light having passed through the second sensor retardation layer and the sensor polarizing layer reaches, and detecting the external reflected light and the internal reflected light.
In one embodiment, the first sensor retardation layer and the sensor polarizing layer may pass the external reflection light and the internal reflection light at a blocking transmittance ratio of the internal reflection light, and the second sensor retardation layer and the sensor polarizing layer may pass the blocking transmittance ratio of the external light other than the external reflection light and the internal reflection light.
As an embodiment, the slow axis of the first sensor retardation layer may be parallel to the slow axis of the display retardation layer, and the polarizing axis of the display polarizing layer is inclined at the second angle with respect to the slow axis of the display retardation layer, where the second angle is an angle obtained by rotating the first angle by 90 degrees.
As an example, the blocking transmittance of the external light may be measured in a state where the light irradiation section is turned off.
As an example, the blocking transmittance of the internal reflection may be measured in a state where the external reflection light is not present.
The illuminance sensor according to the embodiment of the present invention can be applied to an electronic device of such a design that the display occupies the entire front surface.
Drawings
The invention will be described below with reference to an embodiment shown in the drawings. For the sake of understanding, the same constituent elements are denoted by the same reference numerals throughout the drawings. The structures shown in the drawings are illustrative of embodiments of the invention only and do not limit the scope of the invention. In particular, some components are shown in the drawings with some exaggeration to facilitate understanding of the invention. Since the drawings are for the purpose of understanding the present invention, it is to be understood that widths, thicknesses, and the like of components shown in the drawings may vary in actual implementation.
Fig. 1 is a diagram schematically showing the structure of a sensor and the structure of a light irradiation unit in the lower part of a display.
Fig. 2 is a diagram schematically showing a method of processing modulated sensor light.
Fig. 3 is a diagram schematically showing an embodiment of a sensor as a lower portion of a display when modulated sensing light is in an OFF (OFF) state.
Fig. 4 is a diagram schematically illustrating an embodiment of a sensor as a lower portion of a display when modulated sensing light is in an ON (ON) state.
Fig. 5 is a diagram schematically illustrating another embodiment of a sensor as a lower portion of a display when modulated sensing light is in an off state.
Fig. 6 is a diagram schematically showing another embodiment of a sensor as a lower part of a display when modulated sensing light is in an on state.
Fig. 7 is a view for schematically explaining a case where light irradiated from a sensor at a lower portion of a display is reflected inside the display as another embodiment of the sensor at the lower portion of the display.
Fig. 8 is a diagram schematically showing still another embodiment of a sensor as a lower portion of a display when modulated sensing light is in an off state.
Fig. 9 is a diagram schematically showing still another embodiment of a sensor as a lower portion of a display when modulated sensing light is in an on state.
Fig. 10 is a view for schematically explaining a case where light irradiated from a sensor at a lower portion of a display is reflected inside the display as still another embodiment of the sensor at the lower portion of the display.
Detailed Description
While the invention is capable of various modifications and embodiments, specific embodiments thereof are shown in the drawings and will be described herein in detail. It should be understood that it is not intended to limit the present invention to the particular embodiments, but to include all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. In particular, functions, features, embodiments to be described below with reference to the drawings can be implemented alone or in combination with another embodiment. It should be noted, therefore, that the scope of the present invention is not limited by the illustrated embodiments.
On the other hand, with respect to terms used in this specification, expressions such as "substantially", "almost", "about" and the like are expressions considering a difference (margin) allowed at the time of actual implementation or an error that may occur. For example, for "substantially 90 degrees", it should be construed that an angle capable of obtaining the same effect as that at 90 degrees is also included. As another example, "substantially free" should be construed to include to the extent that it can be ignored, if at all.
On the other hand, without being particularly mentioned, "side" or "horizontal" is used to indicate a left-right direction in the drawings, and "vertical" is used to indicate an up-down direction in the drawings. In addition, the angle, the incident angle, and the like are based on a virtual straight line perpendicular to a horizontal plane shown in the drawing, unless otherwise specified.
In the following, in all the figures, the hatching shown in the retardation layer indicates the direction of the slow axis, and the hatching shown in the polarizing layer schematically indicates the direction of the polarizing axis with respect to the slow axis extending in the horizontal direction. On the other hand, it is shown that the slow axis of the display retardation layer and the slow axis of the sensor retardation layer both extend in the horizontal direction, or the slow axis of the display retardation layer and the slow axis of the sensor retardation layer extend in the vertical direction. This is simply shown to aid understanding, it being understood that the slow axis of the sensor retarder need not be aligned with the slow axis of the display retarder.
Fig. 1 is a diagram schematically showing the structure of a sensor under the display, and fig. 1(a) shows the sensor under the display, and fig. 1(b) shows the light irradiation section 210.
The sensor 100 at the lower portion of the display includes a sensor polarizing layer 110, a sensor retardation layer 120, and a light sensor 200. The optical sensor 200 functions as a proximity sensor, and includes a light irradiation unit 210 and a light receiving unit 220. The light irradiation part 210 may include a light source generating sensing light belonging to a near infrared or infrared band. The light receiving unit 220 can detect the sensing light (hereinafter, referred to as reflected light) reflected by the external object. For example, the light receiving unit 220 may be constituted by a single photodiode, or may be constituted by a plurality of photodiodes. When the photodiode is formed of a plurality of photodiodes, the photodiode can be divided into two or more regions, and the frequency band of light detected in each region may be different. To avoid interference, the light irradiation part 210 and the light receiving part 220 may be optically separated. Although not shown, a collimator lens for improving the straightness of the sensing light may be disposed above the light irradiation unit 210, and a condenser lens for condensing the reflected light may be disposed above the light receiving unit 220.
The sensor polarizing layer 110 is disposed on the upper portion of the optical sensor 200, and has a polarizing axis inclined at a first angle, for example, +45 degrees, with respect to the slow axis of the sensor retardation layer 120. The sensor retardation layer 120 is disposed on the sensor polarizing layer 110, and has, for example, a slow axis extending in a horizontal direction and a fast axis extending in a vertical direction. The slow axis of the sensor retardation layer 120 and the slow axis of the display retardation layer may be substantially parallel.
The sensor polarizing layer 110 and the sensor retardation layer 120 can emit the sensing light generated by the light irradiation section 210 to the outside through the display 10. The sensor polarizing layer 110 and the sensor retardation layer 120 can allow the reflected light to pass through the display and reach the light receiving portion 220.
The light irradiation section 210 may include a light source signal generation section 211, a carrier signal generation section 212, a signal modulation section 213, and a light source 214.
The light source signal generating section 211 generates a basic light source driving signal for turning on or off the light source 214. The primary light source drive signal may be of frequency FLThe square wave signal of (1). The basic light source driving signal comprises continuous turn-on intervals for turning on the light source and continuous turn-off intervals for turning off the light source. Duration T of successive on intervals1And duration T of successive off intervals2May be the same or different.
The carrier signal generation unit 212 generates a carrier signal for frequency-modulating the basic light source drive signal. The carrier signal may be, for example, of frequency FCThe square wave signal of (1). Here, the frequency FCMay be greater than frequency FL。
The signal modulation section 213 generates a modulated light source driving signal in which the basic light source driving signal is modulated by the carrier signal. Here, the signal modulation unit 213 modulates only the continuous on period of the basic light source driving signal. The modulated light source drive signal comprises a signal at a frequency FCThe modulated on-interval of turning on and off of the light source and the continuous off-interval of turning off the light source are repeated. The duration of the continuous on interval and the duration of the modulated on interval are T1Duration of the continuous off interval is T2。
The light source 214 illuminates modulated sensing light, for example, belonging to the near infrared or infrared band, by a modulated light source drive signal. The Light source 214 may be, for example, an LED (Light Emitting Diode). The modulated sensing light is at the frequency F of the carrier signal only in the modulated on intervalCThe output pulsed light. Hereinafter, unless otherwise defined, the sensing light indicates modulated sensing light, and the reflected light indicates light that is reflected by an external object and reaches the light receiving unit 220.
Fig. 2 is a diagram schematically showing a method of processing modulated sensor light.
The light irradiation section 210 irradiates the sensing light described with reference to fig. 1 toward the bottom surface of the display. The sensing light incident to the bottom surface of the display travels to the outside through the upper surface of the display, is reflected by an external object, and is again incident to the upper surface of the display. The frequency of the induction light is FCTwo or more sections a are separated by sections B without pulsed light. Similarly, the reflected light has a frequency F belonging to the interval ACThe two or more sections a 'are separated by the section B' without pulsed light. Here, the time intervals A and A' have a duration T1The time intervals B and B' have a duration T2. The sensing light generated by the light irradiation unit 210 is unpolarized light, and the reflected light detected by the light receiving unit 220 is polarized light, which will be described in detail below.
The light receiving unit 220 generates a pixel current 221 substantially proportional to the brightness, i.e., the light amount, of the reflected light. In actual use, external light passing through the display 10 may be incident on the sensor 100 at the lower portion of the display. The amount of extraneous light is relatively large compared to the amount of reflected light and may be constant during a short time interval, such as interval a'. Thus, the pixel current 221 may include a compensation current DC under the influence of external lightoffset. The pixel current 221 includes a current a ″ corresponding to the pulsed light and the extraneous light detected during the interval a 'and a current B ″ corresponding to the extraneous light detected during the interval B'. The current A' being a minimum value DCoffsetAnd a maximum value IMax+DCoffsetAt a frequency FCCurrent in the form of repeated pulses. Here, IMaxThe maximum value of the current B' is DC, which is determined by the sensitivity of the light receiving part 220offset。
Band-pass filter 240 removes frequency F from pixel current 221CAnd (3) components. The pixel current 241 output from the band pass filter 240 may have substantially the same waveform as the basic light source driving signal. That is, the pixel current 241 may be at the maximum value I during the continuous on intervalMaxAnd output is not output in the continuous off interval.
The amplifier 250 amplifies the pixel current 241 and outputs to an analog-to-digital converter (ADC). The pixel current 251 output from the amplifier 250 may be at a maximum value I during the continuous on intervalMax_ampAnd output is not output in the continuous off interval.
The analog-to-digital converter 260 converts the pixel current 251 of the analog signal into a digital signal.
Fig. 3 is a diagram schematically illustrating when the sensing light is off in an embodiment of the sensor at the lower portion of the display. Here, the off-state of the sensing light includes not only a continuous off-interval but also an interval between pulses in a modulated on-interval.
The sensor 100 at the lower portion of the display is disposed at the lower portion of the display 10. The display 10 includes a pixel layer 13 formed with a plurality of pixels P generating light, a display polarizing layer 11 laminated on an upper portion of the pixel layer 13, and a display retardation layer 12. In order to protect the display polarizing layer 11, the display retardation layer 12 and the pixel layer 13, a protective layer formed of an opaque material such as metal or synthetic resin may be disposed on the bottom surface of the display 10. In one embodiment, the sensor 100 under the display, which is composed of the sensor polarizing layer 110, the sensor retardation layer 120, and the optical sensor 200, may be disposed in a region where a part of the protective layer is removed (hereinafter, referred to as a complete structure). As another example, the sensor polarizing layer 110 and the sensor retardation layer 120 may be manufactured in a film shape and laminated on the bottom surface of the display 10. The sensor at the lower portion of the display may be implemented in such a manner that the optical sensor 200 is attached to the bottom surface of the sensor polarizing layer 110 (hereinafter, referred to as an assembly type structure). In order to avoid redundant description, the following description will be focused on the completed structure.
The display polarizing layer 11 and the display retardation layer 12 can improve the visibility of the display 10. The extraneous light 14 incident through the upper surface of the display 10 is unpolarized. If external light 14 is incident on the upper surface of the display polarizing layer 11, only light substantially coinciding with the polarization axis of the display polarizing layer 11 can pass through the display polarizing layer 11. The external light 14 after passing through the display polarizing layer 11 is display linear polarization 15 generated by the external light. When the display linear polarization 15 generated by the external light passes through the display retardation layer 12, the display circular polarization 16 (or elliptical polarization) generated by the external light rotating in the clockwise direction or the counterclockwise direction is generated. When display circular polarization 16 generated by external light is reflected by the pixel layer 13 and enters the display retardation layer 12 again, the polarization becomes linear polarization. Here, if the polarization axis of the display retardation layer 12 is inclined by about 45 degrees with respect to the slow axis, the polarization axis of the second display linear polarization and the polarization axis of the second linear polarization are orthogonal to each other. Thus, the linearly polarized light reflected by the pixel layer 13, i.e., the external light, is blocked by the display polarizing layer 11 and cannot be emitted to the outside of the display. This can improve the visibility of the display 10.
The light incident on the sensor 100 at the lower portion of the display is display circular polarization 16 generated by extraneous light. The display circular polarization 16 generated by the external light becomes the sensor linear polarization 17 generated by the external light as it passes through the sensor retardation layer 120. The sensor linear polarization 17 produced by the extraneous light passing through the sensor polarizing layer 110 substantially without loss is referred to as the sensor linear polarization 18 produced by the extraneous light. The compensation current DC of the pixel current is generated by the sensor linear polarization 18 generated by the external light, i.e. the external light 14offset。
Fig. 4 is a diagram schematically illustrating when the sensing light is on in an embodiment of the sensor at the lower portion of the display. Here, the sensing light is turned on in a modulated on interval except for an inter-pulse interval. And at the frequency F of the carrier signalCAnd (6) outputting.
The light irradiation section 210 generates the sensing light 20. The generated sensing light 20 becomes a sensing sensor linear polarization 21 having a polarization axis inclined at a first angle as it passes through the sensor polarizing layer 110. Since the polarization axis of the induction sensor linear polarization 21 is inclined by, for example, +45 degrees with respect to the slow axis of the sensor retardation layer 120, the induction sensor linear polarization 21 becomes an induction sensor circular polarization 22 that rotates in the clockwise direction as it passes through the sensor retardation layer 120. If the first polarized light portion of the induction sensor linear polarized light 21 projected along the fast axis and the second polarized light portion of the induction sensor linear polarized light 21 projected along the slow axis pass through the sensor retardation layer 120, a phase difference of λ/4 is generated therebetween. The inductive sensor circular polarization 22 is incident inside the display through the bottom surface of the display 10.
The inductive-sensor circular polarization 22 becomes inductive-display linear polarization 23 as it passes through the display retardation layer 12. Since the slow axis of the display retardation layer 12 and the slow axis of the sensor retardation layer 120 are substantially parallel, a phase difference of λ/4 is added to the first polarized light portion and the second polarized light portion of the sensor circular polarized light 22, and the phase difference therebetween becomes λ/2. Thus, the polarization axis of the induced display linear polarization 23 is rotated about 90 degrees from the first angle and tilted at a second angle, e.g., -45 degrees, with respect to the slow axis of the display retarder layer 12.
The induced display linear polarization 23 proceeds outward through the display polarizing layer 11 substantially without loss. The display polarizing layer 11 may have a polarizing axis that is inclined at a second angle, e.g. -45 degrees, with respect to the slow axis of the display retarder layer 12. Thus, the inductive display linear polarization 23 having a polarization axis that is inclined at the same angle as the polarization axis of the display polarizing layer 11 can pass through the display polarizing layer 11.
The display 10 is irradiated with the display linear polarization 23, i.e., the display light 20, reflected by the object and incident again on the display 10. For the purpose of distinction, the reflected light 30 incident on the display 10 is referred to as reflective display linear polarization. The reflective display linear polarization 30 may have a polarization axis that is tilted at a second angle, e.g., -45 degrees. Thus, reflective display linear polarization 30 having a polarization axis that is inclined at the same angle as the polarization axis of the display polarizing layer 11 can pass through the display polarizing layer 11.
In a typical usage environment, not only the reflective display linear polarization 30, but also the external light 14 enters the display 10. Thus, the incident display linear polarization 40 includes light that has passed through the display polarizing layer 11 among the external light 14 that is unpolarized light, and the reflective display linear polarization 30. The brightness of the ambient light 14 is much greater than the brightness of the reflective display linear polarization 30 and is constant. Thus, the influence of the extraneous light 14 can be compensated by the pixel current DCoffsetTo indicate. Of the external light 14 that is unpolarized light, since light having the same polarization axis as the display polarizing layer 11 passes through and light having other polarization axes is blocked, its brightness is reduced. Thus, the brightness of the incident display linear polarization 40 may be relatively greater than the brightness of the reflective display linear polarization 30.
The incident display linear polarization 40 passes through the display retardation layer 12 to become an incident display circular polarization 41 which rotates in the counterclockwise direction. As described above, since the polarizing axis of the display polarizing layer 11 is inclined at-45 with respect to the slow axis of the display retardation layer 12, a phase difference of λ/4 is generated between the first polarizing part and the second polarizing part of the incident display linear polarization 40. The incident display circular polarization 41 is incident on the sensor 100 under the display through the bottom surface of the display 10.
The incident display circular polarization 41 passes through the sensor retardation layer 120 to become the incident sensor linear polarization 42. As described above, since the slow axis of the display retardation layer 12 and the slow axis of the sensor retardation layer 120 extend substantially in parallel, a phase difference of λ/4 is added to the first polarized light portion and the second polarized light portion of the incident display circular polarized light 41, and the phase difference therebetween becomes λ/2. Thus, the polarization axis of the incident sensor linear polarization 42 is rotated about 90 degrees from the second angle and tilted at a first angle, e.g., +45 degrees, relative to the slow axis of the sensor retardation layer 120.
The incident sensor linear polarization 42 passes through the sensor polarizing layer 110 substantially without loss as sensor incident light 43. The sensor polarizing layer 110 may have a polarization relative to a transmissionThe slow axis of the sensor delay layer 120 has a polarization axis that is tilted at a first angle, e.g., +45 degrees. Accordingly, incident sensor linear polarization 42 having a polarization axis that is inclined at the same angle as the polarization axis of the sensor polarizing layer 110 can pass through the sensor polarizing layer 110. The sensor incident light 43 proceeds toward the light receiving portion 220. The light receiving unit 220 generates a pixel current substantially proportional to the luminance of the sensor incident light 43, i.e., the light amount. The sensor incident light 43 includes not only reflected light but also the sensor linear polarization 18 generated by the external light illustrated in fig. 3. The compensation current DC of the pixel current is generated by the linear polarization 18 of the sensor generated by the external lightoffset。
Fig. 5 is a view schematically showing when the sensing light is off in another embodiment of the sensor at the lower portion of the display. Here, the off-state of the sensing light includes not only a continuous off-interval but also an interval between pulses in a modulated on-interval. Since the process until the external light 14 passes through the display 10 is similar to that of fig. 3, a process after the external light 14 is incident on the sensor 101 at the lower portion of the display will be described.
The sensor 101 at the lower portion of the display includes a first sensor polarizing layer 110 and a second sensor polarizing layer 115 forming two light paths, a sensor retardation layer 120, and a light sensor 201 detecting light after passing through each light path. The optical sensor 201 includes a light irradiation part 210, a first light receiving part 220, and a second light receiving part 230.
The sensor retardation layer 120 is disposed above the first sensor polarizing layer 110 and the second sensor polarizing layer 115, and the optical sensor 201 is disposed below the first sensor polarizing layer 110 and the second sensor polarizing layer 115. The light irradiator 210 and the first photoreceivers 220 of the photosensor 201 are disposed below the first sensor polarizing layer 110, and the second photoreceivers 230 are disposed below the second sensor polarizing layer 115. As an embodiment, the sensor retardation layer 120 may be laminated on the upper surface of the first sensor polarizing layer 110 and the second sensor polarizing layer 115. The stacked sensor retardation layer 120-the first and second sensor polarizing layers 110, 115 may be attached to the bottom surface of the display 10. The light sensor 201 may be attached to the bottom surface of the first sensor polarizing layer 110 and the second sensor polarizing layer 115. As another embodiment, the light sensor 201 may be implemented by a thin film transistor. Thus, the sensor 101 under the display can be manufactured by laminating the film-shaped sensor retardation layer 120, the first and second sensor polarizing layers 110 and 115, and the optical sensor 201.
The polarizing axis of the first sensor polarizing layer 110 and the polarizing axis of the second sensor polarizing layer 115 are inclined at different angles with respect to the slow axis of the sensor retardation layer 120. The polarizing axis of the first sensor polarizing layer 110 may be inclined at a first angle, e.g., +45 degrees, with respect to the slow axis of the sensor retardation layer 120, and the polarizing axis of the second sensor polarizing layer 115 may be inclined at a second angle, e.g., -45 degrees, with respect to the slow axis of the sensor retardation layer 120.
The light incident on the sensor 101 at the lower part of the display is display circular polarized light 16 generated by the external light. The display circular polarization 16 generated by the external light passing through the sensor retardation layer 120 becomes the sensor linear polarization 17 generated by the external light. The sensor linear polarization 17 generated by the external light passing through the first sensor polarizing layer 110 substantially without loss is referred to as the sensor linear polarization 18 generated by the first external light, and a part of the sensor linear polarization 17 generated by the external light passing through the second sensor polarizing layer 115 is referred to as the sensor linear polarization 19 generated by the second external light.
Sensor retardation layer 120-first sensor polarizer layer 110 forms a first optical path and sensor retardation layer 120-second sensor polarizer layer 115 forms a second optical path. The first and second light paths act differently for display circular polarization 16 generated by extraneous light. The first light path passes display circular polarization 16 generated by extraneous light. In contrast, the second light path blocks most of the display circular polarization 16 generated by the extraneous light and passes only a portion. As with the extraneous light 14, the first light path passes the extraneous light, while the second light path blocks the extraneous light, as will be described in detail below.
The linear polarized light 18 generated by the first external light and the linear polarized light 19 generated by the second external light satisfy the proportional relation1：K1(wherein, K1<1). Here, K1Is the ratio of the blocking transmission of the external light. The sensor linear polarization 18 generated by the first external light and the sensor linear polarization 19 generated by the second external light are different only in light path, and since they are generated by the display circular polarization 16 generated by the same external light, the luminance between the two satisfies a linear proportional relationship or a non-linear proportional relationship. The non-linear scaling may be due to a variety of reasons, such as structural characteristics of the display 10, the wavelength range of the extraneous light 14, and so forth. Proportional relationship 1 between sensor linear polarization 18 generated by the first external light and sensor linear polarization 19 generated by the second external light: k1Substantially the same may be applied to the reflected light 30. That is, the same proportional relationship 1 is satisfied between the luminance of the reflected light 30 measured by the first light receiving part 220 and the luminance of the reflected light 30 measured by the second light receiving part 230: k1。
The first optical path and the second optical path may be adjacent or separated. That is, the first and second sensor polarizing layers 110 and 115 may be disposed under the single sensor retardation layer 120, and the first and second photoreceivers 220 and 230 may be formed on the single photosensor 201. On the other hand, the second light receiving part 230 may be formed on another photosensor that is separated from the first light receiving part 220. A retardation layer (not shown) having a slow axis extending parallel to the slow axis of the sensor retardation layer and the second sensor polarizing layer 115 may be disposed on the second light receiving part 230.
Fig. 6 is a diagram schematically showing when the sensing light is on in another embodiment of the sensor in the lower part of the display. Here, the sensing light is turned on in a modulated on interval except for an inter-pulse interval. Since the process until the reflected light reaches the sensor 101 at the lower portion of the display is similar to that of fig. 4, the process after the reflected light enters the sensor 101 at the lower portion of the display will be described. Here, the description will be made assuming that there is no internal reflection.
The incident display circular polarizations 41, 41 'pass through the sensor retardation layer 120 as first incident sensor linear polarization 42 and second incident sensor linear polarization 42'. As described above, since the slow axis of the display retardation layer 12 and the slow axis of the sensor retardation layer 120 extend substantially in parallel, a phase difference of λ/4 is added to the first polarized light portion and the second polarized light portion of the incident display circular polarized light 41, 41', and the phase difference therebetween becomes λ/2. Thus, the polarization axes of the first incident sensor linear polarization 42 and the second incident sensor linear polarization 42' are rotated by about 90 degrees from the second angle and tilted at a first angle, e.g., +45 degrees, with respect to the slow axis of the sensor retardation layer 120.
The first incident sensor linear polarization 42 proceeds through the first sensor polarizing layer 110 substantially without loss to the first photoreceivers 220, whereas the second incident sensor linear polarization 42' is largely blocked by the second sensor polarizing layer 115 and only partially proceeds to the second photoreceivers 230. The first sensor polarizing layer 110 may have a polarizing axis that is inclined at a first angle, e.g., +45 degrees, with respect to the slow axis of the sensor retardation layer 120. Thus, first incident sensor linear polarization 42 having a polarization axis that is tilted at the same angle as the polarization axis of first sensor polarizing layer 110 is able to pass through first sensor polarizing layer 110. In contrast, the second sensor polarizing layer 115 may have a polarizing axis that is inclined at a second angle, e.g., -45 degrees, with respect to the sensor retardation layer 120. Thus, a majority of the second incident sensor linear polarization 42' having a polarization axis that is rotated 90 degrees relative to the polarization axis of the second sensor polarizing layer 115 is blocked by the second sensor polarizing layer 115, and only a portion is able to pass through the second sensor polarizing layer 115.
The first incident sensor linear polarization 42 that passes through the first sensor polarizing layer 110 substantially without loss is referred to as first sensor incident light 43, and a portion of the incident sensor linear polarization 42 'that passes through the second sensor polarizing layer 115 is referred to as second sensor incident light 43'. The first sensor incident light 43 includes not only the reflected light 30 but also the sensor linear polarization 18 generated by the first extraneous light, i.e., the extraneous light 14. The second sensor incident light 43' includes sensor linear polarization 19 generated by the second incoming light.
The optical sensor 201 includes a first light receiving part 220 corresponding to a first optical path and a second light receiving part 230 corresponding to a second optical path. For example, the first light receiving part 220 generates a first pixel current substantially proportional to the luminance of the first sensor incident light 43, i.e., the light amount, and the second light receiving part 230 generates a second pixel current substantially proportional to the luminance of the second sensor incident light 43'.
Fig. 7 is a diagram for schematically illustrating a case where light irradiated from a sensor at a lower portion of a display is reflected inside the display in another embodiment of the sensor at the lower portion of the display. Here, the description will be given assuming that there is no external reflected light reflected by an external object.
The sensing light reflected inside the display (hereinafter, referred to as "internally reflected light") causes a serious error in the brightness of the light measured by the first light receiving unit 220 and the second light receiving unit 230. The internal reflected light and the external reflected light differ in various aspects, such as the brightness (or intensity) of the light, the time to reach the light receiving portion, and the like. When using proximity sensors for sensors in the lower part of the display, the influence caused by internal reflections needs to be taken into account.
The induced light 20, 20 'generated by the light irradiation part 210 of the sensor 101 under the display becomes induced sensor circular polarized light 22, 22' as it passes through the first sensor polarizing layer 110 and the sensor retardation layer 120. The inductive sensor circular polarizations 22, 22' may be reflected inside the display 10 and again incident on the sensor 101 below the display. A variety of structures formed of a material that transmits or reflects light are mixed in the display 10. Thereby, a part of the inductive sensor circular polarization 22, 22' can be internally reflected back to the sensor 101 below the display. The first sensing beam 20 is a beam irradiated at an angle internally reflected to the first light receiving part 220, and the second sensing beam 20' is a beam irradiated at an angle internally reflected to the second light receiving part 230.
The internally reflected sensor circularly polarized light 50 passes through the sensor retardation layer 120 as internally reflected sensor linearly polarized light 51. The polarization axis of the internally reflected sensor linear polarization 51 is rotated about 90 degrees from the polarization axis of the inductive sensor linear polarization 21. Thus, the polarization axis of the internally reflected sensor linear polarization 51 may be substantially perpendicular to the polarization axis of the first sensor polarizing layer 110, and a substantial portion of the internally reflected sensor linear polarization 51 may be substantially blocked by the first sensor polarizing layer 110. The internally reflected sensor linear polarization 52 that passes without being blocked can be detected by the first light receiving part 220.
In contrast, the internally reflected sensor circularly polarized light 50 'passes through the sensor retardation layer 120 as internally reflected sensor linearly polarized light 51'. The polarization axis of the internally reflected sensor linear polarization 51' is rotated about 90 degrees from the polarization axis of the inductive sensor linear polarization 21. Thus, the polarization axis of the internally reflected sensor linear polarization 51' is substantially parallel to the polarization axis of the second sensor polarizing layer 115, and can pass through the second sensor polarizing layer 115.
The proportional relationship between the brightness detected by the first and second light receiving parts 220 and 230, respectively, satisfies K due to the internally reflected sensor linear polarization 51' that passes without being blocked2: 1 (wherein, K)2<1). Here, K2Is the barrier transmission ratio of internal reflection.
Barrier transmittance K of external light1And the barrier transmission ratio K of internal reflection2For correcting the brightness of the first sensor incident light 43 as measured by the sensor 101 in the lower portion of the display. When the sensor 101 at the lower portion of the display operates as a proximity sensor, not only the first sensor incident light 43 and the second sensor incident light 43', but also the internally reflected sensor light 52, 51' enters the first light receiving unit 220 and the second light receiving unit 230. The measurement values of the light receiving parts 220 and 230 are not only due to the internally reflected sensing light 52 incident to the first light receiving part 220 but also due to the internally reflected sensing light 51' incident to the second light receiving part 230.
Assuming that the brightness of the incident light 43 from the first sensor is A, the brightness of the incident light 43' from the second sensor is K1And (4) x A. On the other hand, when the brightness of the internally reflected sensor light 51' is B, the brightness of the internally reflected sensor light 52 is K2×B。
The brightness C of the light detected by the first light receiving part 220 is based on the first sensor incident light 43 and the internally reflected sensing light 52.
[ EQUATION 1 ]
C＝A+K2×B
On the other hand, the brightness D of the light detected by the second light receiving part is based on the second sensor incident light 43 'and the internally reflected sensing light 51'.
[ equation 2 ]
D＝K1×A+B
The luminance a of the first sensor incident light 43 can be calculated according to equations 1 and 2 in the following manner.
[ equation 3 ]
The brightness of the first sensor incident light 43 is used to calculate the distance to an external object or determine whether the distance is close to the external object.
Fig. 8 is a view schematically showing a sensor as a lower part of the display when the sensing light is off, according to still another embodiment. Here, the off-state of the sensing light includes not only a continuous off-interval but also an interval between pulses in a modulated on-interval. Since the process until the external light 14 passes through the display 10 is similar to that of fig. 3, a process after the external light 14 is incident on the sensor 102 at the lower portion of the display will be described.
The sensor 102 at the lower portion of the display includes a first sensor retardation layer 120 and a second sensor retardation layer 125 forming two light paths, a sensor polarizing layer 110, and a light sensor 201 detecting light after passing through each light path. The optical sensor 201 includes a light irradiation part 210, a first light receiving part 220, and a second light receiving part 230.
The first sensor retardation layer 120 and the second sensor retardation layer 125 are disposed on the upper portion of the sensor polarizing layer 110, and the optical sensor 201 is disposed on the lower portion of the sensor polarizing layer 110. The optical sensor 201 includes a light irradiation part 210, a first light receiving part 220, and a second light receiving part 230. The first photoreceivers 220 is disposed at a position where light emitted from the first sensor retardation layer 120 reaches after passing through the sensor polarizing layer 110, and the second photoreceivers 230 is disposed at a position where light emitted from the second sensor retardation layer 125 reaches after passing through the sensor polarizing layer 110. As an example, the sensor 102 at the lower portion of the display may be manufactured by laminating the first sensor retardation layer 120 and the second sensor retardation layer 125 on the upper surface of the sensor polarizing layer 110. The stacked sensor polarizing layer 110 and the first and second sensor retardation layers 120, 125 may be attached to the bottom surface of the display 10. The photo sensor 201 may be attached to the bottom surface of the sensor polarizing layer 110. As another embodiment, the light sensor 201 may be implemented by a thin film transistor. Thus, the sensor 102 under the display can be manufactured by laminating the film-shaped first sensor retardation layer 120 and the film-shaped second sensor retardation layer 125, the sensor polarizing layer 110, and the optical sensor 201.
The slow axis of the first sensor delay layer 120 is substantially orthogonal to the slow axis of the second sensor delay layer 125. The polarizing axis of the sensor polarizing layer 110 may be inclined at a first angle, e.g., +45 degrees, with respect to the slow axis of the first sensor retardation layer 120, and may also be inclined at a second angle, e.g., -45 degrees, with respect to the slow axis of the second sensor retardation layer 125.
The light incident on the sensor 100 at the lower portion of the display is display circular polarization 16 generated by extraneous light. The display circular polarization 16 generated by the external light passes through the first sensor retardation layer 120 to become the sensor linear polarization 17 generated by the first external light, and passes through the second sensor retardation layer 125 to become the sensor linear polarization 17' generated by the second external light. Since the slow axis of the first sensor retardation layer 120 is orthogonal to the slow axis of the second sensor retardation layer 125, the polarization axis of the sensor linear polarization 17 generated by the first extraneous light can also be orthogonal to the polarization axis of the sensor linear polarization 17' generated by the second extraneous light. Accordingly, the sensor linear polarization 17 generated by the first external light passes through the sensor polarizing layer 110 and advances toward the first photoreceivers 220, whereas most of the sensor linear polarization 17' generated by the second external light is blocked by the sensor polarizing layer 110 and only a part of it advances toward the second photoreceivers 230. The sensor linear polarization 17 generated by the first external light passing through the sensor polarizing layer 110 without substantially losing is referred to as the sensor linear polarization 18 generated by the first external light, and a part of the sensor linear polarization 17 'generated by the second external light passing through the sensor polarizing layer 110 is referred to as the sensor linear polarization 19' generated by the second external light.
The first sensor retardation layer 120-the sensor polarizing layer 110 form a first optical path, and the second sensor retardation layer 125-the sensor polarizing layer 110 form a second optical path. The first and second light paths act differently for display circular polarization 16 generated by extraneous light. The first light path passes display circular polarization 16 generated by extraneous light. In contrast, the second light path blocks most of the display circular polarization 16 generated by the extraneous light and passes only a portion. As with the extraneous light 14, the first light path passes the extraneous light and the second light path blocks the extraneous light, as will be described in detail below.
The proportional relation 1 is satisfied between the sensor linear polarization 18 generated by the first external light and the sensor linear polarization 19' generated by the second external light: k1(wherein, K1<1). Here, K1Is the ratio of the blocking transmission of the external light. The sensor linear polarization 18 generated by the first external light and the sensor linear polarization 19' generated by the second external light are different only in light path, and since they are generated by the display circular polarization 16 generated by the same external light, the luminance between the two satisfies a linear proportional relationship or a non-linear proportional relationship. The non-linear scaling may be due to a variety of reasons, such as structural characteristics of the display 10, the wavelength range of the extraneous light 14, and so forth. The proportional relationship between the sensor linear polarization 18 generated by the first external light and the sensor linear polarization 19' generated by the second external light is 1: K1Substantially the same may be applied to the reflected light 30.
Fig. 9 is a view schematically showing a case where the sensing light of still another embodiment of the sensor as the lower portion of the display is on. Here, the sensing light is turned on in a modulated on interval except for an inter-pulse interval. Since the process of the reflected light reaching the sensor 102 at the lower portion of the display is similar to that of fig. 4, the process after the reflected light is incident on the sensor 102 at the lower portion of the display will be described. Here, the description will be made assuming that there is no internal reflection.
The incident display circular polarization 41 passes through the first sensor retardation layer 120 to become the first incident sensor linear polarization 42, and the incident display circular polarization 41' passes through the second sensor retardation layer 125 to become the second incident sensor linear polarization 42 ″. As described above, since the slow axis of the first sensor retardation layer 120 is orthogonal to the slow axis of the second sensor retardation layer 125, the polarization axis of the first incident sensor linear polarization 42 can also be orthogonal to the polarization axis of the second incident sensor linear polarization 42 ″. Specifically, the incident display circular polarization 41 having the phase difference of λ/4 between the first polarization part and the second polarization part can be the first incident sensor linear polarization 42 having the polarization axis substantially parallel to the polarization axis of the sensor polarization layer 110 by adding the phase difference of λ/4 to the first sensor retardation layer 120. In contrast, the incident display circular polarization 41' is phase-difference-cancelled by the second sensor retardation layer 125, and can become the second incident sensor linear polarization 42 ″ having a polarization axis substantially perpendicular to the polarization axis of the sensor polarization layer 110.
The first incident sensor linear polarization 42 passes through the sensor polarizing layer 110 substantially without loss and proceeds toward the first photoreceivers 220, whereas the second incident sensor linear polarization 42 ″ is mostly blocked by the sensor polarizing layer 110 and only partially proceeds toward the second photoreceivers 230. The sensor polarizing layer 110 may have a polarizing axis that is inclined at a first angle, e.g., +45 degrees, with respect to the slow axis of the first sensor retardation layer 120 or a polarizing axis that is inclined at a second angle, e.g., -45 degrees, with respect to the slow axis of the second sensor retardation layer 125. Thus, the first incident sensor linear polarization 42 having a polarization axis that is inclined at the same angle as the polarization axis of the sensor polarizing layer 110 can pass through the sensor polarizing layer 110. In contrast, a majority of the second incident sensor linear polarization 42 "having a polarization axis that is rotated 90 degrees relative to the polarization axis of the sensor polarizing layer 110 is blocked by the sensor polarizing layer 110, and only a portion is able to pass through the sensor polarizing layer 110.
The first incident sensor linear polarization 42 that passes through the sensor polarizing layer 110 substantially without loss is referred to as first sensor incident light 43, and a portion of the second incident sensor linear polarization 42 "that passes through the sensor polarizing layer 110 is referred to as second sensor incident light 43". The first sensor incident light 43 includes not only the reflected light 30 but also the sensor linear polarization 18 generated by the first extraneous light, i.e., the extraneous light 14. The second sensor incident light 43 "includes sensor linear polarization 19 generated by the second incoming light.
The optical sensor 201 includes a first light receiving part 220 corresponding to a first optical path and a second light receiving part 230 corresponding to a second optical path. For example, the first light receiving part 220 generates a first pixel current substantially proportional to the luminance of the first sensor incident light 43, and the second light receiving part 230 generates a second pixel current substantially proportional to the luminance of the second sensor incident light 43 ″.
Fig. 10 is a diagram for schematically illustrating a case where light irradiated from a sensor at a lower portion of a display is reflected inside the display in still another embodiment of the sensor at the lower portion of the display. Here, the description will be given assuming that there is no external reflected light reflected by an external object.
The internally reflected sensor circularly polarized light 50 passes through the first sensor retardation layer 120 to become internally reflected sensor linearly polarized light 51. The polarization axis of the internally reflected sensor linear polarization 51 is rotated about 90 degrees from the polarization axis of the inductive sensor linear polarization 21. Thus, the polarization axis of the internally reflected sensor linear polarization 51 is perpendicular to the polarization axis of the first sensor polarizing layer 110, and a substantial portion of the internally reflected sensor linear polarization 51 can be substantially blocked by the sensor polarizing layer 110. The internally reflected sensor linear polarization 52 that passes without being blocked can be detected by the first light receiving part 220.
In contrast, the internally reflected sensor circularly polarized light 50' passes through the second sensor retardation layer 125 to become the internally reflected sensor linearly polarized light 51 ″. The polarization axis of the internally reflected sensor linear polarization 51 "is substantially parallel to the polarization axis of the inductive sensor linear polarization 21. Thus, the polarization axis of the internally reflected sensor linear polarization 51 ″ is parallel to the polarization axis of the second sensor polarizing layer 115, and thus can pass through the second sensor polarizing layer 115.
The proportional relationship between the brightness detected by the first light receiving part 220 and the second light receiving part 230, respectively, satisfies K due to the internally reflected sensor linear polarization 51 ″ that passes without being blocked2: 1 (wherein, K)2<1). Here, K2Is the barrier transmission ratio of internal reflection.
Barrier transmittance K of external light1And barrier transmission ratio K of internal reflection2For correcting the brightness of the first sensor incident light 43 as measured by the sensor 102 in the lower portion of the display. When the sensor 102 at the lower portion of the display operates as a proximity sensor, not only the first sensor incident light 43 and the second sensor incident light 43 but also the internally reflected sensor light 52, 51 ″ enters the first light receiving unit 220 and the second light receiving unit 230. The internally reflected sensor light 51 ″ incident on the second light receiving unit 230 causes an error in the measurement values of the light receiving units 220 and 230, in addition to the internally reflected sensor light 52 incident on the first light receiving unit 220.
Assuming that the brightness of the first sensor incident light 43 is A, the brightness of the second sensor incident light 43' is K1And (4) x A. On the other hand, when the brightness of the internally reflected sensor light 51 ″ is B, the brightness of the internally reflected sensor light 52 is K2And (B) is multiplied by. The brightness C of the light detected by the first light receiving part 220 is based on the first sensor incident light 43 and the internally reflected sensing light 52. On the other hand, the brightness D of the light detected by the second light receiving part is based on the second sensor incident light 43' and the internally reflected sensing light 51 ″. The brightness a of the first sensor incident light 43 can be calculated using equation 3.
The above description of the present invention is illustrative, and it will be understood by those skilled in the art to which the present invention pertains that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Accordingly, it is to be understood that the above described embodiments are exemplary and not intended to be limiting. Further, the features of the present invention described with reference to the drawings are not limited to the configurations shown in the specific drawings, and may be implemented alone or in combination with other features.
The scope of the present invention is shown by the appended claims rather than by the above description, and it should be understood that all changes and modifications derived from the meaning and scope of the claims and the equivalent concept thereof are included in the scope of the present invention.
Claims (13)
1. A sensor at a lower portion of a display, the sensor at the lower portion of the display being disposed at a lower portion of the display including a pixel generating light, a display retardation layer disposed at an upper portion of the pixel, and a display polarizing layer, wherein,
the sensor at the lower portion of the display includes:
a photosensor including a light irradiation section that emits modulated sensing light and irradiates an object located outside the display, and a light receiving section that detects externally reflected light reflected by the object of the modulated sensing light and generates a pixel current;
a sensor polarizing layer disposed on an upper portion of the optical sensor and having a polarizing axis inclined at a first angle; and
a sensor retardation layer disposed on an upper portion of the sensor polarizing layer and having a slow axis inclined at the first angle with respect to a polarizing axis of the sensor polarizing layer,
the reflected light reaches a light receiving portion through the display, the sensor polarizing layer, and the sensor retardation layer.
2. The lower display sensor of claim 1,
the light irradiation section includes:
a light source signal generating section for generating a basic light source driving signal for repeating a continuous on interval and a continuous off interval;
a carrier signal generation unit that generates a carrier signal having a frequency greater than a frequency of the basic light source drive signal;
a signal modulation unit that generates a modulated light source drive signal by frequency-modulating the continuous on interval of the basic light source drive signal using the carrier signal; and
a light source, wherein the modulated light source driving signal is turned on and off at the frequency of the carrier signal during the continuous on interval to generate the modulated sensing light.
3. The lower display sensor of claim 2,
the sensor of the lower portion of the display further includes:
a band-pass filter that removes a frequency component of the carrier signal from the pixel current;
an amplifier that amplifies the pixel current from which the frequency component of the carrier signal has been removed; and
and an analog-to-digital converter converting the amplified pixel current into a digital signal.
4. The lower display sensor of claim 2,
the sensor polarizing layer includes:
a first sensor polarizing layer having a polarizing axis inclined at the first angle; and
a second sensor polarizing layer having a polarizing axis inclined at a second angle,
the light receiving unit includes:
a first light receiving unit disposed below the first sensor polarizing layer and detecting the external reflected light and the internal reflected light reflected by the sensing light inside the display; and
and a second light receiving part disposed below the second sensor polarizing layer and detecting the external reflection light and the internal reflection light.
5. The lower display sensor of claim 4,
the sensor retardation layer and the first sensor polarizing layer pass the externally reflected light and pass the internally reflected light at a barrier transmittance ratio of internal reflection,
the sensor retardation layer and the second sensor polarizing layer pass a blocking transmittance of external light other than the external reflected light and pass the internal reflected light.
6. The lower display sensor of claim 5,
the brightness of the external reflection light is calculated from the blocking transmission ratio of the external light and the blocking transmission ratio of the internal reflection light.
7. The lower display sensor of claim 1,
the sensor polarizing layer and the sensor retardation layer convert the sensing light into sensing sensor circular polarized light so that the sensing light passes through the polarizing layer of the display,
the inductive sensor circular polarized light is converted by the display retarder layer into an inductive display linear polarized light having a same polarization axis as a polarization axis of a polarizing layer of the display.
8. The lower display sensor of claim 1,
the slow axis of the sensor retarder is parallel to the slow axis of the display retarder,
the display polarizing layer has a polarizing axis that is inclined at a second angle relative to the slow axis of the display retarder layer.
9. The lower display sensor of claim 2,
the sensor delay layer includes:
a first sensor retardation layer disposed on an upper portion of the sensor polarizing layer and having a slow axis inclined at the first angle with respect to a polarizing axis of the sensor polarizing layer; and
a second sensor retardation layer disposed on the upper portion of the sensor polarizing layer corresponding to the second photoreceivers and having a slow axis inclined at a second angle with respect to a polarizing axis of the sensor polarizing layer,
the light receiving unit includes:
a first light receiving unit which is disposed at a position where light having passed through the first sensor retardation layer and the sensor polarizing layer reaches, and which detects internally reflected light in which the external reflected light and the sensing light are reflected inside a display; and
and a second photoreceiver disposed at a position where the light having passed through the second sensor retardation layer and the sensor polarizing layer reaches, and detecting the external reflected light and the internal reflected light.
10. The lower display sensor of claim 9,
the first sensor retardation layer and the sensor polarizing layer pass the externally reflected light and pass the internally reflected light at a barrier transmittance ratio of internal reflection,
the second sensor retardation layer and the sensor polarizing layer pass a blocking transmittance of external light other than the external reflected light and pass the internal reflected light.
11. The lower display sensor of claim 9,
the slow axis of the first sensor retardation layer is parallel to the slow axis of the display retardation layer,
the polarization axis of the display polarizing layer is tilted at the second angle with respect to the slow axis of the display retardation layer,
the second angle is an angle obtained by rotating the first angle by 90 degrees.
12. The sensor under display of claim 5 or 10,
the blocking transmission ratio of the external light is measured in a state where the light irradiation section is turned off.
13. The sensor under display of claim 5 or 10,
the blocking transmission ratio of the internal reflection is measured in a state where the external reflection light is not present.
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| CN108885697A (en) * | 2018-06-15 | 2018-11-23 | 深圳市汇顶科技股份有限公司 | Shield lower biometric devices and electronic equipment |
| CN109196522A (en) * | 2018-08-24 | 2019-01-11 | 深圳市汇顶科技股份有限公司 | Backlight module shields lower fingerprint identification method, device and electronic equipment |
| CN209707875U (en) * | 2019-01-16 | 2019-11-29 | 柳州阜民科技有限公司 | Electronic equipment and back light unit |
| CN109613756A (en) * | 2019-01-29 | 2019-04-12 | 华勤通讯技术有限公司 | LCD display, electronic equipment and control system |
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|---|---|
| WO2021147096A1 (en) | 2021-07-29 |
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