GB2579029A

GB2579029A - Improved display for mobile devices with a front facing camera

Info

Publication number: GB2579029A
Application number: GB1818608.0A
Authority: GB
Inventors: Jüttner Christian
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-11-15
Filing date: 2018-11-15
Publication date: 2020-06-10
Also published as: GB201818608D0

Abstract

The application provides a display device. The display device includes a display panel, 21, 21a, which includes a display surface and a rear surface that is opposite the display surface. The display device also includes an adjustable light transmittance layer, 32, positioned behind the rear surface of the display panel. The display device further includes a camera module, 12, located behind the adjustable light transmittance layer. The display device is adapted to provide a display state and a camera state. In the display state, the adjustable light transmittance layer blocks light rays from an object positioned in front of the display surface from reaching the camera module. In the camera state, the adjustable light transmittance layer and the display panel allows light rays from the object to pass through the display panel and the adjustable light transmittance layer to reach the camera module. The adjustable light transmittance layer may comprise an electro-chromic material. Also disclosed is a camera module for a mobile device incorporating an adjustable light transmittance layer.

Description

IMPROVED DISPLAY FOR MOBILE DEVICES WITH A FRONT FACING CAMERA

The application relates to an improved display unit for a mobile device. In particular, the application relates to an im5 proved display unit for a mobile electronic device with one or more front facing cameras.

Mobile electronic devices, such as mobile phones, phablets, or tablet computers often contain a front-facing camera that is directed at a front side of the mobile electronic devices and a display screen, for examples, an organic light-emitting diode (OLED) display, which is placed at a front side of the mobile electronic device. The display screen often does not occupy the full front side of the mobile electronic devices be-cause a border is required at the top and/or at the bottom of the front side to accommodate a lens of the front-facing camera.

It is an object of the application to provide an improved dis-play device. It is believed that the display device can be improved by providing the display device with an electrochromic device. The electrochromic device allows a front facing camera that is placed behind the display device to be not visible to a user who is positioned in front of the display device when the display device emits high intensity or brightness of colours and when the display device is not in use or energized. The electrochromic device can allow the camera to receive light rays from objects, which are placed in front of the display device when a part of the display device, which is next to the camera, is placed in a transparent state.

The application provides an improved display device for a mobile device. The mobile device often refers to a portable computing device that a user can carry it with one hand. Examples of the mobile device include a mobile phone, a handheld com-puter, such as a computing notebook or a computing tablet.

The display device includes a display panel, which includes a display surface and a rear surface that is opposite the display surface. The display surface serves to display or show information in the form of text and/or images to a user who is positioned in front of the display device. The text and the images are provided by the mobile device.

The display device also includes an adjustable light transmittance layer. The adjustable light transmittance layer is positioned next to a part of the rear surface of the display panel.

The display device further includes a camera module. The camera module is directed at the adjustable light transmittance layer. In other words, the camera module faces the adjustable light transmittance layer and the display panel. The camera module is intended for capturing images of an object that is positioned in front of the display panel.

The display device is adapted to provide a display state and a camera state.

In the display state, the adjustable light transmittance layer is adapted to block light rays from an object that is positioned in front of the display surface from reaching the camera module. In detail, the adjustable light transmittance layer is placed in an opaque state, wherein the adjustable light transmittance layer becomes opaque. The opaque light transmittance layer receives light rays from the object. The opaque light transmittance layer acts to prevent the light rays from passing through the adjustable light transmittance layer to reach the camera module. This means the camera module does not capture any light rays from the object that is positioned in front of the display panel.

The opaque light transmittance layer also prevents any light rays from the surroundings, which the camera module reflects, from passing through the adjustable light transmittance layer to reach a user who is positioned in front of the display panel. This allows the camera module to be not visible to the user.

In the camera state, the adjustable light transmittance layer and the display panel allows essentially all or most light rays from the object, which is positioned in front of the dis-play panel, to pass through the display panel and the adjustable light transmittance layer to reach the camera module.

In detail, the part of the display panel is placed in a transparent state, wherein light-emission elements of the part of the display panel are turned off and the light-emission elements become essentially transparent. The transparent light-emission elements allow essentially all light rays from the object to pass through the transparent part to reach the adjustable light transmittance layer. The adjustable light transmittance layer is also placed in a transparent state, wherein the transparent light transmittance layer allows essentially all the light rays that it receives from the transparent part of the display panel to pass through the transparent light transmittance layer to reach the camera module. This means that the camera module can capture images of the object.

The improved display device provides several benefits. The im-proved display device allows a front facing camera that is placed behind a display panel of a mobile device to be not visible to a user who is positioned in front of the display panel. This allows the display panel to occupy essentially an entire area of a front surface of the mobile device. In other words, the mobile device can have a larger display panel with-out increasing overall size of the mobile device.

The display device can include at least one opaque layer that is attached to one part of the rear surface of the display panel. The adjustable light transmittance layer is attached to another part of the rear surface of the display panel. The opaque layer can blend with the adjustable light transmittance layer, which is placed in the opaque state to provide a substantially uniform opaque rear surface of the display panel. In other words, the opaque adjustable light transmittance layer also provides an essentially black background of the display panel, which is in front of the camera module. This black background and the opaque layer, which are substantially uniform, provide a uniform light-absorbing surface to allow the display panel to provide images of good contrast.

Different implementations of the display panel are possible. In one implementation, the display panel includes a passive-matrix organic light-emitting diodes (PMCLEDs) panel. In another implementation, the display panel includes an active-ma-trix organic light-emitting diodes (AMOLEDs) panel.

The adjustable light transmittance layer often includes an electrochromic element. The electrochromic element can include naphthalene-diimide-based mesoporous MOF-74 analogs. Such an adjustable light transmittance layer is also called an electrochromic layer.

When the display device is placed in the display state, the display panel can emit light rays of images. The emitted light rays allow a user who is positioned in front of the display panel to view the images on the display panel.

The application also provides an adjustable light transmit-tance layer for a display panel. The adjustable light transmittance layer includes a first major surface and a second major surface that is opposite the first major surface. The first major surface is adapted for positioning next to a rear surface of a part of a display panel. The adjustable light transmittance layer provides a:,ransparent state and an opaque state. In the transparent state, the first major surface is intended for receiving light rays from an object that is positioned in front of the display panel. The received light rays then travel from the first major surface to the second major surface. The second major surface is adapted for transmitting or directing the received light ray to a camera module. In the opaque state, the adjustable light transmittance layer is adapted to block light rays from the object from reaching the camera module.

The adjustable light transmittance layer often includes an electrochromic element. The electrochromic element can include naphthalene-diimide-based mesoporous MOF-74 analogs.

The application also provides an improved camera module for a mobile device. The camera module includes an image sensing element with an adjustable light transmittance layer, which is directed at an object in front of the camera module to receive light rays from the object. The adjustable light transmittance layer provides a transparent state and an opaque state. In the opaque state, the adjustable light transmittance layer receives light rays from the object and it is adapted to block essentially all the received light rays from passing through the adjustable light transmittance layer. In the transparent state, the adjustable light transmittance layer is adapted to allow essentially all the received light rays to pass through the light transmittance layer to reach the image sensing element.

The adjustable light transmittance layer acts to electrically control the light transmittance to the image sensing element. It serves as an electric shutter to electrically control the light exposure time of the camera module, without incorporat-ing mechanical components such as motors and gears of an electric shutter.

The camera module can further include at least one lens for focusing or concentrating light rays from objects, which are 15 positioned in front of the camera module, onto the image sensing element.

The adjustable light transmittance layer can be provided such that the lens is positioned between the adjustable light transmittance layer and the image sensing element. In one implementation, the adjustable light transmittance layer is provided between the lens and the image sensing element.

In one special embodiment, the adjustable light transmittance layer is adapted to further provide at least one translucent state. In the at least one translucent state, the adjustable light transmittance layer is adapted to allow a part of the light rays from the object, which reach the light transmittance layer, to pass through the light transmittance layer to reach the image sensing element. In other words, the adjustable light transmittance layer acts as a camera aperture to control amount of light being received by the image sensing element.

Fig. 1 illustrates a front view of a mobile phone with a display unit and with a front facing camera module, Fig. 2 illustrates a cross section view of the mobile phone taken along a line AA of Fig. 1, Fig. 3 illustrates an exploded view of a part of an organic light-emitting diode (OLED) display module of the display unit of the mobile phone of Fig. 1, Fig. 4 illustrate a block diagram of parts of the mobile phone of Fig. 1, Fig. 5 illustrates a front view of the display unit of the mobile phone of Fig. 1 when the display unit and the camera module is switched off, Fig. 6 illustrates a cross sectional view of a portion of the display unit and The camera module of Fig. 5, Fig. 7 illustrates a front view of the display unit of the mobile phone of Fig. 1 when the display unit is switched on while the camera module is switched off, Fig. 8 illustrates a cross sectional view of the portion of the display unit and The camera module of Fig. 7, Fig. 9 illustrates a front view of the display unit of the mobile phone of Fig. 1 when the display unit is switched on while the camera module is switched on, Fig. 10 illustrates a cross sectional view of the portion of the display unit and the camera module of Fig. 9.

In the following description, details are provided to describe embodiments of the application. It shall be apparent to one skilled in the art, however, that the embodiments may be practiced without such details.

Some parts of the embodiments have similar parts. The similar parts may have same names or similar part numbers. The description of one part applies by reference to another similar part, where appropriate, thereby reducing repetition of text without limiting the disclosure.

Figs. 1 and 2 show an improved mobile phone 1. The improved mobile phone 1 includes a housing 5, a display unit 8, a front facing camera module 12, a circuit board 15, and a rechargeable battery 18. The front facing camera module 12 is called camera module for short. The display unit 8, the camera module 12, the circuit board 15, and the battery 18 are located in-side the housing 5. The camera module 12 is placed next to a rear surface of the display unit 8. The camera module 12 is directed to the display unit 8. The camera module 12, the display unit 8, and the circuit board 15 are electrically connected to the battery 18.

Referring to the display unit 8, it includes an organic light-emitting diode (OLED) display module 21 with a composite layer 24.

As better seen in Fig. 3, the OLED display module 21 includes a plurality of OLEDs. Each OLED includes a transparent cathode 50, an organic emissive layer 55, an organic conducting layer 53, a transparent anode 57, and a transparent substrate 59. The emissive layer SS is placed between the cathodes SO and the conducting layer 53 while the anodes 57 are placed between the conducting layer 53 and the substrate 59. The substrate 59 is placed adjacent to the composite layer 24. The cathodes 50 and the anodes 57 are arranged such that the cathodes 50 are essentially parallel to each other and the anodes 57 are es-sentially parallel to each other. The cathodes 50 are essentially perpendicular or orthogonal to the anodes 57 such that a part of the cathode SO, a corresponding part of the organic conducting layer 53, a corresponding part of the organic emissive layer 55, a corresponding part of the anode 57, and a corresponding part of the substrate 59 form an organic light-emitting diode (OLED). The conducting layer 53 and the emissive layer 55 are made of organic material, such as polymers. The cathodes SO and the anodes 57 are electrically connected to the circuit board 15.

Referring the composite layer 24, which is better seen in Fig. 2, it includes a rectangular opaque layer 28 with an opening, and an electrochromic layer 32 with two electrodes. For sim-plicity, the electrodes are not shown in the figures. The electrochromic layer 32 is placed in the opening of the opaque layer 28. The opaque layer 28 and the electrochromic layer 32 are adhered to the OLED display module 21. The opaque layer 26 is also called a black layer.

The electrochromic layer 32 includes a mesoporous electrochromic metal-organic frameworks (MOE) material, such as naphthalene-diimide-based mesoporous MOF-74 analogs. The electrochromic layer 32 is electrically connected to the electrodes, which are electrically connected to the circuit board 15.

Referring to the camera module 12, it includes a lens 35 with an electrochromic shutter 36 and an image sensing unit 36. The lens 35 is placed between the electrochromic shutter 36 and the image sensing unit 38. The electrochromic shutter 36 is placed next to the electrochromic layer 32 of the display unit 8.

The electrochromic shutter 36 includes an electrochromic mate-30 rial with two or more electrodes. For simplicity, the electrodes are not shown in the figures.

The image sensing unit 38 includes a plurality of image sensors.

Referring to the circuit board 15, which is better seen in Fig. 4, it includes a microprocessor 41 with a memory module 42, a camera control module 43, an electrochromic layer con-trol circuit 45, and an OLED display control circuit 48. The microprocessor 41 is electrically connected to the camera control module 43, to the electrochromic layer control circuit 45, and to the OLED display control circuit 48. The camera control module 43 is electrically connected to the electrodes of the electrochromic shutter 36. The electrochromic layer control circuit 45 is electrically connected to the electrodes of the electrochromic layer 32 while the OLED display control circuit 48 is electrically connected to the electrodes of the OLED display module 21. The memory module 42 is configured to store instructions of a software program.

In use, the OLED display module 21 is intended for displaying colour images.

Each OLED of the OLED display module 21 provides a light-emission state and a transparent state.

In the light-emission state, the microprocessor 41 directs the OLED display control circuit 48 to selectively energize an OLED. The OLED display control circuit 48 then provides a voltage potential across an anode and a cathode of the selected OLED. An electrical current then flows from the cathode to the emissive layer, to the conducting layer, and to the anode. The electrical current enables the emissive layer to gen- crate light photons. Wavelengths of the generated light pho-tons are dependent on the type of organic molecules in the emissive layer.

In the transparent state, the voltage potential across the anode and the cathode of the selected OLED is removed. The selected OLED is then not energized, and it does not emit light. The transparent cathode 50, the organic emissive layer 55, the organic conducting layer 53, the transparent anode 57, and the transparent substrate 59 of the selected DEED allow light rays from the surrounding to substantially pass through.

In one implementation, the OLED display module 21 includes a plurality of pixel units. Each pixel unit includes a red OLED, a green OLED, and a blue OLED. The red OLED has an emissive layer for emitting red light. The blue DEED has an emissive layer for emitting blue light while the green OLED has an emissive layer for emitting green light. The red OLED, the green OLED, and the blue OLED are selectively energized to emit red light rays, green light rays, and/or blue light rays. These light rays mix and form a pixel with a desired colour. The pixel refers to a small display area. The colour pixels of all pixel units together form a colour image.

The black layer 28 is intended for blocking light rays from passing through the layer 28. The black layer 28 absorbs essentially all light rays emitted from the OLEDs or any light ray from the surroundings, and it does not reflect any light ray towards the OLED display module 21.

The electrochromic layer 32 provides a transparent state and an opaque state.

In the transparent state, the microprocessor 41 directs the electrochromic control circuit 45 to provide a voltage potential across the two electrodes of the electrochromic layer 32. The electrochromic layer 32 then becomes transparent. The transparent electrochromic layer 32 allows essentially any light rays to pass through the electrochromic layer 32.

In the opaque state, another different voltage potential is applied across the two electrodes of the electrochromic layer 32. The electrochromic layer 32 then becomes opaque. The opaque electrochromic layer 32 blocks any light rays from passing through the electrochromic layer 32. The electrochromic layer 32 absorbs essentially any light ray that is di-10 rected at the electrochromic layer 32.

In an embodiment, the electrochromic layer 32 is made of naphthalene-diimide-based mesoporous MOF-74. The voltage is only applied to the electrodes of the electrochromic layer 32 for switching of the electrochromic layer 32 between the transparent state and the opaque state. The applied voltage is removed once the electrochromic layer 32 has switched from one state to another state. This can reduce energy consumption.

Figs. 5 and 6 show the mobile phone 1 being placed in an inactive state.

In the inactive state, the OLED display module 21 of the display unit 8 is placed in the transparent state. All the OLEDs of the DEED display module 21 are not energized, and they do not emit light. The OLED display module 21 is essentially transparent. This allows light rays from the surrounding to pass through the DEED display module 21 to reach the black layer 28 and the electrochromic layer 32 of the display unit 8.

The electrochromic layer 32 is placed in the opaque state. The black layer 28 and the electrochromic layer 32 together then receive the light rays that pass through the DEED display module 21 and absorb the light rays, thereby preventing the light rays from being reflected away towards a user in front of the display unit 8. This allows the display unit 8 to appear as black to the user while the camera module 12 is not visible to the user.

The camera module 12 is placed in an off state. In the off state, a voltage potential across the two electrodes of the electrochromic shutter 36 is absent and the electrochromic shutter 36 is opaque. The opaque electrochromic shutter 36 does not allow light rays to pass through, thereby preventing light rays from reaching the image sensing unit 38.

Figs. 7 and 8 show the mobile phone 1 being placed in a first 15 operation state.

In the first operation state, the OLED display module 21 is placed in the light-emission state. In the light-emission state, the OLED display module 21 emits colour light rays.

The electrochromic layer 32 is placed in the opaque state. The electrochromic layer 32 and the black layer 28 together prevent the light rays from the OLED display module 21 from being reflected back towards the user, who is positioned in front of the display unit 8. The user receives light rays directly from the OLED display module 21. The camera module 12 is not visible to the user.

Figs. 9 and 10 show the mobile phone 1 being placed in a sec-30 ond operation state.

In the operation state, a camera region 21a of the OLED display module 21 is placed in the transparent state while other regions of the OLED display module 21 is placed in the light-emission state, wherein the camera region 21a is next to the electrochromic layer 32. In other words, the camera region 21a is transparent while the other regions provide colour images.

The electrochromic layer 32 is placed in the transparent state. The electrochromic layer 32 is transparent.

The transparent camera region 21a of the OLED display module 21 and the transparent electrochromic layer 32 provides an op-tical pathway for allowing light rays from a scene, which can include an object that is in front of the ODES display module 21 to reach the electrochromic shutter 36 of the camera module 12.

The camera module 12 is placed in an on state. In the on state, the microprocessor 41 directs the camera control module 43 to provide a voltage potential across the two electrodes of the electrochromic shutter 36. The voltage potential causes the electrochromic shutter 36 to change or switch to a trans-parent state. This allows pulses of light rays from the scene to pass through the electrochromic shutter 36 and to reach the lens 35. Later, a different voltage potential across the electrodes of the electrochromic shutter 36 is applied and the electrochromic shutter 36 then changes from transparent to opaque.

The lens 35 then receives the light rays and focuses or directs the received light rays onto the image sensing unit 38.

The image sensing unit 38 later converts the received light rays into digital signals that carry information of the scene. The image sensing unit 38 afterwards sends the converted digital signals to the microprocessor 41.

In this situation, the user of the mobile phone 1 can capture images of the scene in front of the display unit 8 with the camera module 12 while watching other images on the display unit 8.

Instead of electrically controlling the light transmittance of the electrochromic shutter 36, in a stepwise manner, between the transparent state and the opaque state, the electrochromic shutter 36 can also be electrically controlled to provide an infinite variety of light transmittance.

In one implementation, the electrochromic shutter 36 is configured to switch gradually from the opaque state to the transparent state for adjusting an exposed time of the image 15 sensing unit 38 to the light rays from the scene.

In another implementation, the electrochromic shutter 36 is configured to switch between the opaque state and the transparent state with a predetermined frequency for adjusting the exposed time of the image sensing unit 38 to the light rays from the scene.

In a further implementation, the electrochromic shutter 36 is configured to further provide ar_ least one translucent state.

In the at least one translucent state, the electrochromic shutter 36 provides different patterns or degree of transparency. The electrochromic shutter 36 acts to receive light rays from an object in front of the OLED display module 21 and to allow a part of the received light rays to pass through the electrochromic shutter 36 to reach the image sensing unit 38.

By controlling the light exposed time of the image sensing unit 38 with the electrochromic shutter 36, the electrochromic shutter 36 does not include mechanical components such as motors and gears of a mechanical shutter.

Different placements of the electrochromic shutter 36 are pos-sible. The electrochromic shutter 36 can be placed between the lens 35 and the image sensing unit 38. In a special implementation, the lens 35 is a lens assembly comprising multiple lens and an electrochromic shutter is placed between two lenses of the lens assembly.

In another embodiment, the mobile phone 1 includes two or more front facing camera modules. The front facing camera modules include at least one front facing camera module 12. In a special embodiment, the other front facing camera module includes a camera with a lens and a mechanical shutter.

The OLED display module 21 can include a passive matrix OLEDs (FMOLEDs) or an active-matrix OLEDs (AMOLEDs). The OLED display module 21 can also be replaced by other display device 20 that is configured to enter a transparent state.

In a special embodiment, the mobile phone 1 is replaced by a computing tablet, a handheld computer such as a computing notebook, or other mobile devices, which include a display 25 module and at least one front facing camera module.

The improved mobile phone 1 provides several benefits.

This configuration of the improved mobile phone 1 allows a display unit 8 to occupy essentially an entire area of a front surface of the mobile phone 1 and a front facing camera module 12 that is not visible to a user. In other words, this allows the mobile phone 1 to have a larger display unit. This is useful because this allows the user to have a large viewing area while not increasing overall size of the mobile phone 1. If the phone is too large, it may be more difficult for the user to hold it comfortably.

Furthermore, the camera module 12 has no mechanical shutter.

This can reduce the production cost of the mobile phone 1.

Although the above description contains much specificity, this should not be construed as limifing the scope of the embodi-ments but merely providing illustration of the foreseeable embodiments. The above stated advantages of the embodiments should not be construed especially as limiting the scope of the embodiments but merely to explain possible achievements if the described embodiments are put into practice. Thus, the scope of the embodiments should be determined by the claims and their equivalents, rather than by the examples given.

REFERENCE LIST

1 mobile phone housing 8 display unit 12 camera module circuit board 18 battery 21 organic light-emitting diodes (OLED) display module 21a camera region of the SLED display module 24 composite layer 28 opaque layer 32 electrochromic layer lens 36 electrochromic shutter 38 image sensing unit 41 microprocessor 42 memory module 43 camera control module 45 electrochromic control circuit 48 SLED display control circuit cathode 53 organic conducting layer organic emissive layer 57 anode 59 substrate

Claims

CLAIMS1. A display device comprising a display panel, the display panel comprising a display surface and a rear surface, which is opposite the display surface, an adjustable light transmittance layer being positioned next to the rear surface of the display panel, and a camera module directing at the adjustable light trans-10 mittance layer, wherein the display device is adapted to provide a display state and a camera state, - in the display state, the adjustable light transmit- tance layer blocks light rays from an object that is po-sitioned in front of the display surface from reaching the camera module, - in the camera state, the adjustable light transmit- tance layer and the display panel allows light rays from the object to pass through the display panel and the ad-justable light transmittance layer to reach the camera module.
2. The display device according to claim 1 further comprising at least one opaque layer being attached to the rear sur25 face of the display panel.
3. The display device according to claim 1 or 2, wherein the display panel comprises a passive-matrix organic light-emitting diodes (PMOLEDs) panel.
4. The display device according to claim 1 or 2, wherein the display panel comprises an active-matrix organic light-emitting diodes (AMOLEDs) panel.
S. The display device according to one of the above-men-tioned claims, wherein the adjustable light transmittance layer comprises an electrochromic element.
6. The display device according to claim 5, wherein the electrochromic element comprises naphthalene-diimide-based mesoporous MOF-74 analogs.
7. The display device according to one of the above-men10 tioned claims, wherein in the display state, the display panel emits light rays.
8. An adjustable light transmittance layer comprising a first major surface and a second major surface being opposite the first ma-jor surface, the adjustable light transmittance layer providing a transparent state and an opaque state, in the transparent state, the first major surface being adapted for positioning next to a rear surface of a display panel in order to receive light rays from an object that is positioned in front of the display panel, the second major surface being adapted for transmitting the light ray to a camera module.in the opaque state, the adjustable light transmit-tance layer is adapted to block light rays from the object from reaching the camera module.
9. The adjustable light transmittance layer according to 30 claim 8, wherein the adjustable light transmittance layer comprises an electrochromic element.
10. The adjustable light transmittance layer according to claim 9, wherein the electrochromic element comprises naphthalene-diimide-based mesoporous MOF-74 analogs.
11. A camera module for a mobile device, the camera module comprising an image sensing element with an adjustable light transmittance layer being directed at an object for receiving light rays from the object, wherein the adjustable light transmittance layer provides a transparent state and an opaque state, - in the opaque state, the adjustable light transmit-tance layer is adapted to block essentially all light rays from the object from passing through the adjustable light transmittance layer, - in the transparent state, the adjustable light transmittance layer is adapted to allow essentially all light rays from the object to pass through the light transmittance layer to reach the image sensing element.
12. The camera module according to claim 11 further compris-ing at least one lens for focusing the received light rays onto the image sensing element.
13. The camera module according to claim 12, wherein the adjustable light transmittance layer is provided such that the at least one lens is between the adjustable light transmittance layer and the image sensing element.
14. The camera module according to claim 12, wherein the adjustable light transmittance layer is provided between the at least one lens and the image sensing element.
15. The camera module according to one of claims 11 to 14, wherein the adjustable light transmittance layer further provides at least one translucent state, in the at least one translucent state, the adjusta-ble light transmittance layer is adapted to allow a part of the light rays from the object to pass through the light transmittance layer to reach the image sensing element.