Patent ID: 12254800

DESCRIPTION OF THE EMBODIMENTS

FIG.1Ais a schematic structural diagram of a multi-layer display module according to an embodiment of the present invention, andFIG.1Bis a schematic three-dimensional view of the multi-layer display module ofFIG.1A. Please refer toFIG.1AandFIG.1B. The multi-layer display module100of this embodiment includes a first display panel110, a second display panel120and a driving device130. The second display panel120is located on one side of the first display panel110and overlapped with the first display panel110, and includes a plurality of display pixels122and light-transmitting areas124located between the display pixels122.

In this embodiment, the second display panel120may further include circuits that are electrically connected to the display pixels122, the circuits may include scan lines, data lines and some drive circuits, which are well known to those with ordinary knowledge in the field. In order to keep the diagram concise, the plurality of circuits are no longer drawn.

In addition, a space between the first display panel110and the second display panel120is d. A display screen of the first display panel110forms a viewing screen with a display screen of the second display panel120through the light-transmitting areas124. The driving device130is configured to simultaneously provide image signals to the first display panel110and the second display panel120to display the display image of the first display panel110and the display image of the second display panel120respectively. For example, the driving device130is configured to simultaneously provide image signals to the first display panel110and the second display panel120to display the first image and the second image respectively, and to provide object image signals to the first display panel110or the second display panel120, and display the object image. The object image displayed on the first display panel is the first object image, the object image displayed on the second display panel is the second object image. The first image forms a viewing screen with the second image and the object image through the light-transmitting areas124. Specifically, in one embodiment, the orthographic projection of the second display panel120on the first display panel110completely overlaps the first display panel110, thereby providing a better viewing image.

In this embodiment, the plurality of display pixels122include a plurality of micro light-emitting diodes. Micron-level micro light-emitting diodes as display pixels can have better luminance and higher transmittance to allow the first image to pass through. Each display pixel122includes at least three micro light-emitting diodes with different light colors.

For example, each display pixel122may include a red micro-LED, a green micro-LED, and a blue micro-LED. In addition, in this embodiment, the luminance of the first image is greater than the luminance of the second image. For example, a ratio of the luminance of the first image to the luminance of the second image falls within the range of 1.2 to 2.

In one embodiment, the first display panel110can emit a maximum rated luminance of L1, the second display panel120can emit a maximum rated luminance of L2, and L1 is greater than L2. For example, the ratio of L1 to L2 falls within the range of 1.2 to 2.

In this embodiment, the first image is a background image, and the second image is a main image. Since a space between the first display panel110and the second display panel120is d, the second image (main image) appears in front of the first image (background image), which has an effect similar to a three-dimensional display.

In some embodiments, the luminance of the main image is greater than the luminance of the background image, so that the main image can be more eye-catching to an external viewer50to achieve a three-dimensional visual effect of the front and rear images.

In this embodiment, the resolution of the second image is smaller than or equal to the resolution of the first image, and thus it is easier for the external viewer50to distinguish the first image from the second image, thereby achieving a better stereoscopic display effect.

In one embodiment, the luminance of the first image is controlled by a voltage signal, and the luminance of the second image is driven by a current signal. For example, the first display panel110is a liquid crystal display, which controls luminance by the voltage signal, and the second display panel120is a micro light-emitting diode display, whose micro light-emitting diodes can be driven by the current signal which precisely controls the presentation of main image.

In this embodiment, the transmittance of the second display panel120is greater than the transmittance of the first display panel110. In this way, it is easier for the external viewer50to view the first image displayed by the first display panel110through the second display panel120.

FIG.2Ais a schematic side view of a multi-layer display module according to another embodiment of the present invention andFIG.2Bis a schematic front view of the multi-layer display module ofFIG.2A. In another embodiment, please refer toFIG.2AandFIG.2B, the dimension of the first display panel110is larger than the dimension of the second display panel120.

For example, the dimension of the long side of the first display panel110is D1, the dimension of the long side of the second display panel120is D2, the space between the first display panel110and the second display panel120is d, and the multi-layer display module100acomplies with D1−D2≥2*√{square root over (3)}*d. In this way, the external viewer50can view the first image displayed by the first display panel110through the second display panel120at any angle under the 120° angle of view.

In one embodiment, D1 is the dimension of the long side of the display area of the first display panel110, and D2 is the dimension of the long side of the display area of the second display panel120. In this embodiment, the luminous opening angles of the display pixels122of the second display panel120are larger than the luminous opening angles of the display pixels112of the first display panel110. The smaller luminous opening angles of the first display panel110helps the light energy to be concentrated and to penetrate effectively the second display panel120for observation by the external viewer50. The smaller luminous opening angles of the first display panel110can reduce the large-angle ineffective light transmitting to the side wall and avoid wasting light energy.

FIG.3Ais a schematic structural diagram of a multi-layer display module according to another embodiment of the present invention, andFIG.3Bis a schematic diagram of the transmission spectrum of the optical film and the peak wavelengths of light emitted by sub-pixels of various colors inFIG.3A. In another embodiment, please refer toFIG.3AandFIG.3B. The multi-layer display module100bfurther includes an optical film150, which is disposed between the first display panel110and the second display panel120. The optical film150has high reflectivity for light emitted by the second display panel120. For example, the reflectivity is greater than or equal to 90%. In addition, in this embodiment, the optical film150has high transmittance for light emitted by the first display panel110, and the transmittance is, for example, greater than or equal to 90%.

Specifically, in this embodiment, the plurality of display pixels112of the first display panel110have a plurality of first sub-pixels, and the plurality of display pixels122of the second display panel120have a plurality of second sub-pixels, a peak wavelength of the same color light emitted by the first sub-pixel and a peak wavelength of the same color light emitted by the second sub-pixel are different. High transmittance of wavelength range of the optical film150corresponds to each wavelength of the plurality of first sub-pixels of the first display panel110, and high reflectivity of wavelength range of the optical film150corresponds to each wavelength of the plurality of the second sub-pixels of the second display panel120.

In this embodiment, each display pixel122of the second display panel120may include a red sub-pixel R2, a green sub-pixel G2and a blue sub-pixel B2(the plurality of sub-pixels are second sub-pixels). Each display pixel112of the first display panel110may include a red sub-pixel R1, a green sub-pixel G1, and a blue sub-pixel B1(the plurality of sub-pixels are first sub-pixels).

In one embodiment, the peak wavelength of the red sub-pixel R1is, for example, 630 nm. The peak wavelength of the red sub-pixel R2is, for example, 610 nm. The peak wavelength of the green sub-pixel G1is, for example, 540 nm. The peak wavelength of the green sub-pixel G2is, for example, 520 nm. The peak wavelength of the blue sub-pixel B1is, for example, 440 nm. The peak wavelength of the blue sub-pixel B2is, for example, 460 nm. As shown inFIG.3B, the optical film150has high transmittance, that is, low reflectivity, for light emitted by the red sub-pixel R1, the green sub-pixel G1and the blue sub-pixel B1of the first display panel110, and the optical film150has low transmittance, that is, high reflectivity for light emitted by the red sub-pixel R2, the green sub-pixel G2and the blue sub-pixel B2of the second display panel120.

FIG.4is a schematic three-dimensional view of a multi-layer display module according to another embodiment of the present invention. In another embodiment, please refer toFIG.4, the multi-layer display module100cincludes a third display panel160located on a side of the second display panel120away from the first display panel110. In this embodiment, the first display panel110, the second display panel120, and the third display panel160are arranged in sequence with gaps between them toward the eyes of the external viewer50.

In this embodiment, the transmittance of the third display panel160is greater than the transmittance of the second display panel120, and the luminance of the second display panel120is greater than the luminance of the third display panel160. In one embodiment, the transmittance of the third display panel is greater than 50%. The present invention does not limit the number of display panels to two or three. In other embodiments, there can also be more than four display panels arranged in sequence with gaps between them toward the eyes of the external viewer50. The closer the display panel to the external viewer50is, the greater the transmittance of the display panel is, so as to have a better display effect.

Please refer toFIG.1AandFIG.1Bagain. In this embodiment, the multi-layer display module100further includes an image composition control unit140. The image composition control unit140is configured to calculate the first distance DS1from an external viewer50to the first display panel110and second distance DS2from the external viewer50to the second display panel120respectively based on relative position information of the external viewer50. Increasing (for example, increasing proportionally) a dimension of the first object image displayed on the first display panel110or reducing (for example, reducing proportionally) a dimension of the second object image displayed on the second display panel120make the external viewer50have the same viewing angle for the first object image and the second object image according to the first distance DS1and the second distance DS2.

For example, as shown inFIG.5A, if a first object image111is originally displayed on the first display panel110, the dimension of first object image111generates a viewing angle θ1for the eyes of the external viewer50. When the multi-layer display module creates the effect that the object image is closer to the external viewer50, the object image can be switched from the first display panel110to the second display panel120, that is, the second display panel120is configured to display the second object image121the same as the first object image111, as shown inFIG.5B.

However, since the dimension of the first object image111is the same as the dimension of the second object image121and the second object image121is closer to the eyes of the external viewer50, the second object image121will give a larger angle view angle θ2to the eyes of the external viewer50(where θ2>θ1). As a result, when the object image switches from the first display panel110to the second display panel120, the external viewer50suddenly feel the object image becoming larger, and the dynamic display effect of the multi-layer display module unnatural.

Therefore, in this embodiment, as shown inFIG.6, in case1, the first object image111can be displayed on the first display panel110, and then the image composition control unit140can reduce the dimension of the second object image121displayed on the second display panel120based on the position of the external viewer50(such as the above-mentioned first distance DS1and second distance DS2) to obtain the same viewing angle as the first object image111when a state of the first object image111displayed on the first display panel110is switched to a state of the second object image121displayed on the second display panel120.

The first object image111and the second object image121are corresponding images. In this way, when the object image switches from the first display panel110to the second display panel120, the external viewer50will not suddenly feel that the object image becoming larger. Instead, the external viewer50will feel that the multi-layer display module100of this embodiment has natural dynamic display effect.

In addition, in case2, the second object image121can also be displayed on the second display panel120, and then the image composition control unit140can increase the dimension of the first object image111displayed on the first display panel110based on the position of the external viewer50(such as the above-mentioned first distance DS1and second distance DS2) to obtain the same viewing angle as the second object image121when a state of the second object image121displayed on the second display panel120is switched to a state of the first object image111displayed on the first display panel110.

In this way, when the object image switches from the second display panel120to the first display panel110, the external viewer50will not suddenly feel that the object image becoming smaller. Instead, the external viewer50will feel that the multi-layer display module100of this embodiment has natural dynamic display effect.

In one embodiment, the image composition control unit140gradually changes the dimension of the first object image111displayed on the first display panel110or the dimension of the second object image121displayed on the second display panel120respectively so that the external viewer50has the same viewing angle for the first object image111and the second object image121.

In another embodiment, in case1, after switching the state of the first object image111displayed on the first display panel110to the state of the second object image121displayed on the second display panel120, the image composition control unit140can increase gradually the dimension of the second object image121displayed on the second display panel120, giving the external viewer50a gradually increasing viewing angle for the second object image121and an visual effect that the second object image121is getting closer and closer to the external viewer50.

In addition, in another embodiment, in case2, after switching the state of the second object image121displayed on the second display panel120to the state of the first object image111displayed on the first display panel110, the image composition control unit140can reduce gradually the dimension of the first object image111displayed on the first display panel110, giving the external viewer50a gradually reducing viewing angle for the first object image111and an visual effect that the first object image111is getting farther and farther away from the external viewer50.

In another embodiment, in case1, before switching the state of the first object image111displayed on the first display panel110to the state of the second object image121displayed on the second display panel120, the image composition control unit140can increase gradually the dimension of the first object image111displayed on the first display panel110, giving the external viewer50a gradually increasing viewing angle for the first object image111and an visual effect that the first object image111is getting closer and closer to the external viewer50.

In another embodiment, in case2, before switching the state of the second object image121displayed on the second display panel120to the state of the first object image111displayed on the first display panel110, the image composition control unit140can reduce gradually the dimension of the second object image121displayed on the second display panel120, giving the external viewer50a gradually reducing viewing angle for the second object image121and an visual effect that the second object image121is getting farther and farther away from the external viewer50.

In another embodiment, in case1, before switching the state of the first object image111displayed on the first display panel110to the state of the second object image121displayed on the second display panel120, the image composition control unit140can increase gradually the dimension of the first object image111displayed on the first display panel110, and in case1, after switching the state of the first object image111displayed on the first display panel110to the state of the second object image121displayed on the second display panel120, the image composition control unit140can increase gradually the dimension of the second object image121displayed on the second display panel120, giving the external viewer50a continuously and gradually increasing viewing angle for the first object image111and the second object image121and an visual effect that the object image is getting closer and closer to the external viewer50.

In another embodiment, in case2, before switching the state of the second object image121displayed on the second display panel120to the state of the first object image111displayed on the first display panel110, the image composition control unit140can reduce gradually the dimension of the second object image121displayed on the second display panel120, and in case2, after switching the state of the second object image121displayed on the second display panel120to the state of the first object image111displayed on the first display panel110, the image composition control unit140can reduce gradually the dimension of the first object image111displayed on the first display panel110, giving the external viewer50a gradually reducing viewing angle for the first object image111and the second object image121and an visual effect that the object image is getting farther and farther away from the external viewer50.

As described in the above embodiments, the multi-layer display module100can provide natural dynamic display effects.

In this embodiment, the multi-layer display module100further includes a pupil tracking device170is configured to measure the relative position information between the external viewer50and the multi-layer display module100and provide the relative position information to the image composition control unit140.

The pupil tracking device170may include a camera, an image sensor, a distance sensor, or any suitable position sensor. In the multi-layer display modules100d,100eand100fofFIGS.7A,7B and7C, the pupil tracking device includes sensing elements172embedded between the plurality of the display pixels112in the first display panel110and sensing elements174,174a, or174bembedded between the plurality of the display pixels122in the second display panel120.

For example, inFIG.7Aof the multi-layer display module100d, the sensing elements172and the sensing elements174are disposed on the first display panel110and the second display panel120, respectively. The sensing elements172and the display pixels112are arranged alternatively, and the sensing elements174and the display pixels122are arranged alternatively.

InFIG.7Bof the multi-layer display module100e, the sensing element172may appear once at least every two display pixels112, and the sensing element174may appear once every at least two display pixels122.

InFIG.7Cof the multi-layer display module100f, the sensing elements can be divided into two groups, which are respectively composed of sensing elements174aand174b. These two groups can sense different eyeballs respectively. The sensing elements172,174,174aor174bare, for example, sensing pixels, which may include photodiodes.

Please refer toFIG.1AandFIG.1B. In this embodiment, the driving device130includes an image database. Image data in the image database has the first frame and the second frame listed in the same time sequence. the driving device130converts the first frame and the second frame into the image signals after decoding and after the first display panel110and the second display panel120are provided, the first display panel110and the second display panel120are played synchronously based on timing sequence information included after providing the image signals to the first display panel and the second display panel.

In one embodiment, the transmittance of the second display panel120is T2, the luminance of the first display panel110is L1, the luminance of the second display panel120is L2, and the multi-layer display module100complies with T2>40% and

0.8≤L⁢1L⁢2*(1-T⁢2),
so as to ensure that the external viewer50can have basically sufficient recognition luminance. when viewing the image of the first display panel110.

In some embodiments, the first display panel110emits a maximum rated luminance of L1, and the second display panel120emits a maximum rated luminance of L2.

In one embodiment, the plurality of display pixels122include a plurality of micro light-emitting diodes, the luminance of the first display panel110is L1, the luminance of the second display panel120is L2, the transmittance of the second display panel120is T2, and the multi-layer display module100complies with

0.8≤L⁢1L⁢2*(1-T⁢2)≤1.2.
When

L⁢1L⁢2*(1-T⁢2)
is greater than or equal to 0.8, the external viewer50will have basically enough recognition luminance to watch the image of the first display panel110. When

L⁢1L⁢2*(1-T⁢2)
is less than or equal to 1.2, it can avoid over-correction, causing the first display panel110wasting unnecessary energy.

In one embodiment, the plurality of display pixels122include a plurality of micro light-emitting diodes, the luminance of the first display panel110is L1, the luminance of the second display panel120is L2, the transmittance of the second display panel120is T2, and the multi-layer display module Group100complies with

0.8≤L⁢1*T⁢2L⁢2≤1.2.
Such a design allows the external viewer50to view the images of the first display panel110and the second display panel120with relatively consistent image luminance.

In some embodiments, the first display panel110emits a maximum rated luminance of L1, and the second display panel120emits a maximum rated luminance of L2.

Please refer toFIG.2AandFIG.2B, in the multi-layer display module100a, the dimension of the long side of the first display panel110is D1, and the first display panel110has the first pixel resolution P1. The dimension of the long side of the second display panel120is D2, and the second display panel120has the second pixel resolution P2. The space between the first display panel110and the second display panel120is d, and the transmittance of the second display panel120is T2. The multi-layer display module100acomplies with T2>40%, P1≠P2 and

D⁢2*T⁢2≥d≥D⁢2❘"\[LeftBracketingBar]"P⁢1-P⁢2❘"\[RightBracketingBar]"*P⁢2.
The second display panel120has a transmittance of T2 less than 100%, which will partially block light emitted from the first display panel110and cause the image quality of the first display panel110to degrade (image quality includes image luminance, sharpness, color saturation, etc.).

In order to maintain sufficient image quality of the first display panel110, d cannot be too large, that is, the optical path from light emitted by the first display panel110to the second display panel120should be limited, so that light emitted by the first display panel110can transmit toward the external viewer50and pass through the second display panel120as early as possible, thereby reducing the light staying in the divergent propagation process and avoiding excessive deterioration in image quality instead of passing through the second display panel120with too much divergent propagation which results in deterioration in image quality. Therefore, the lower T2 is, the smaller d is and the better image quality is. For example, when T2=60%, d can be set as 27 cm, and when T2=40%, d can be set as 18 cm.

In addition, whether the viewing effect of reduced image quality of the first display panel110will affect the subjective perception of the viewer compared with the native viewing effect (difference of image quality) of the second display panel120depends on the viewing distance. When the viewing distance is further away, the difference in subjective perception between the first display panel110and the second display panel120will become smaller (the difference will be evened out).

In this case, a relatively large space d will be allowed. The farther the viewing distance is, the more the viewing distance has a positive correlation with the dimension of the second display panel120. When the second display panel120is becoming larger, the viewing distance should be correspondingly farther to obtain a more comfortable viewing effect.

On the contrary, the smaller the second display panel120is, the viewing distance should be corresponding. to get closer for more comfortable viewing. In other words, the dimension of the second display panel120is positively related to the viewing distance, and the viewing distance is positively related to the acceptable image quality difference.

That is, the dimension of the second display panel120is positively related to the acceptable image quality difference. At the same time, as mentioned above, the transmission T2 is positively related to the acceptable image quality difference. (The smaller the dimension of the second display panel120is, the closer you need to view the second display panel120. The easier the difference in image quality is to be noticed, the narrower the space d is to reduce the difference in image quality).

Both the dimension of the second display panel120and T2 will limit the dimension of the space d. It is necessary to ensure that the space d should not be too large and to prevent the degradation extent of the image quality of the first display panel110(the difference in subjective perception between the first display panel110and the second display panel120) from being too significant.

Therefore, the product of D2 and T2 is taken as the upper limit of the space d, where unit of measurement for D2 and the space d is centimeter (cm). Therefore, it is a better situation that the multi-layer display module100acomplies with D2*T2≥d. For example, in one embodiment, T2=60%, D2=50 cm, then d=27 cm (less than 30 cm).

On the other hand, the pixel resolution (unit, for example, pixels per inch, PPI) of the first display panel110and the second display panel120may be different. The pixel resolution P1 of the first display panel110is, for example, 50 PPI˜500 PPI. The pixel resolution P2 of the second display panel120is, for example, 50 PPI˜500 PPI. When the difference between P1 and P2 is becoming larger (the absolute value of P1 minus P2), the human eye will detect the difference of relative position between the first display panel110and the second display panel120through image displayed on the first display panel110and image displayed on the second display panel120, and the human eye will feel different distance between the first display panel110and the second display panel120. In the dimension of the arrangement direction of the first display panel110and the second display panel120, a three-dimensional visual experience is achieved due to the difference of relative position between the first display panel110and the second display panel.120. At least one of P1 and P2 does not reach retinal resolution. When the pixel resolution P1 of the first display panel110and the pixel resolution P2 of the second display panel120both reach retinal resolution, it is difficult for the human eye to detect the difference of relative position between the first display panel110and the second display panel120.

The pixel resolution P2 of the second display panel120is greater than or equal to the pixel resolution P1 of the first display panel110. The larger the pixel resolution P2 is, the denser the number of micro light-emitting diodes per inch in the second display panel120is and the better image quality the second display panel120can provide, and the closer the viewer can watch at this time.

When the first distance DS1and the second distance DS2are both reduced, effect of depth of field can be achieved with a smaller space d (the comparison benchmark is smaller, and the difference in d will be more significant). Therefore, P2 and the space d are approximately inversely proportional to each other.

In other words, the configuration of the space d must be based on the initial image quality of the first display panel110because the image quality of the first display panel110will be further degraded after the light emitted from the first display panel110passes through the second display panel120. The dimension of the second display panel120will affect the viewing distance. Once the viewing distance increases, the first distance DS1and the second distance DS2(as shown inFIG.1A) will increase at the same time.

In order to maintain the three-dimensional viewing effect (maintain the effect of depth of field between these two), the corresponding space d must also be increased accordingly, which will change the lower limit set by the spacing d. Therefore, the dimension D2 of the second display panel120is approximately proportional to the space d. In one embodiment, P1 is, for example, 200 PPI, and P2 is, for example, 100 PPI. Due to the different resolutions, the images perceived by the human eye will not be confused, and the distance difference between the first display panel110and the second display panel120can be clearly distinguished.

When |P1−P2| is becoming smaller, the image display details between the first display panel110and the second display panel120are becoming more similar, and it is less easy for the human eye to detect the difference between these two. Especially, it is relatively necessary to increase the space d to ensure that the first display panel110and the second display panel120have different visual depths for viewers to maintain a three-dimensional visual experience when both of these two display panels look very clear. Therefore, |P1−P2| is approximately inversely proportional to d. On the contrary, the larger |P1−P2| is, the smaller d is allowed to achieve a three-dimensional visual experience. For example, P1 is 314 PPI and P2 is 114 PPI. Based on the above, it is a better situation that the multi-layer display module100acomplies with

d≥D⁢2❘"\[LeftBracketingBar]"P⁢1-P⁢2❘"\[RightBracketingBar]"*P⁢2.

In the multi-layer display module100aof this embodiment, the multi-layer display module100acomplies with T2>40%, P1≠P2 and

D⁢2*T⁢2≥d≥D⁢2❘"\[LeftBracketingBar]"P⁢1-P⁢2❘"\[RightBracketingBar]"*P⁢2,
so that the display effects of each layer have good matching and can provide sufficient depth of field. effect, and make the first display panel110have sufficient image quality.

Please refer toFIG.2AandFIG.2B. In this embodiment, P1 is not an integer multiple of P2, or P2 is not an integer multiple of P1. A pitch of the display pixels112of the first display panel110is PH1, and A pitch of the display pixels122of the second display panel120is PH2. There is a non-integer multiple relationship between PH1and PH2.

In addition, in this embodiment, in the overlapping portion of the display area of the first display panel110and the second display panel120, a center position of the plurality of the display pixel122at the edge of the second display panel120relative to a center position of the plurality of the display pixel112of the first display panel110at periphery of the overlapping portion has a shift amount DV, and the shift amount DV is greater than or equal to half of the pitch PH2of the display pixels122of the second display panel120. That is, the center of the display pixels112and the center of the display pixels122are arranged alternatively with each other, which can reduce the light emitted from the first display panel110being blocked by the display pixels122of the second display panel120, thereby increasing the proportion of light emitted from the first display panel110passing through the second display panel120.

In addition, the shift amount DV must have sufficient distance, preferably greater than or equal to half of the spatial period of the display pixels122of the second display panel120, so that the orthographic projection of the display pixels122of the second display panel120are located between two adjacent display pixels112of the first display panel110.

In one embodiment, the image composition control unit140is, for example, a central processing unit (CPU), a microprocessor (microprocessor), a digital signal processor (DSP), a programmable controller, or a programmable controller. The present invention is not limited to programmable logic devices (PLD) or other similar devices or combinations of the plurality of devices.

In addition, in one embodiment, each function of the image composition control unit140may be implemented as a plurality of program codes. The plurality of program codes will be stored in a memory, and the image composition control unit140will execute the plurality of program codes. Alternatively, in one embodiment, each function of the image composition control unit140may be implemented as one or more circuits. The present invention is not limited to using software or hardware to implement each function of the image composition control unit140.

To sum up, in the embodiment of the multi-layer display module according of the present invention, the multi-layer display module complies with T2>40% and

D⁢2*T⁢2≥d≥D⁢2❘"\[LeftBracketingBar]"P⁢1-P⁢2❘"\[RightBracketingBar]"*P⁢2,
so that the display effects of each layer have good matching and can provide sufficient depth of field effect and make the first display panel have sufficient image quality.