Method of controlling a light field display

Abstract

A control method of a light field display. The light field display comprises a display module, a variable focus lens and a control unit. The display module comprises a light source module and a display unit. The control method comprises the following steps: inputting a focal length signal to the variable focus lens by the control unit to make the variable focus lens periodically switch between a plurality of specific focal lengths. According to one of the plurality of specific focal lengths, inputting a corresponding display signal to the display unit of the display module by the control unit to make the display module generate one of a plurality of image lights, wherein the plurality of image lights have different imaging distances after passing through the variable focus lens respectively corresponding to the plurality of specific focal lengths. According to one of the plurality of specific focal lengths, inputting a corresponding response time signal to the display module by the control unit to make the one of the plurality of image lights emitted by the display module pass through the variable focus lens within one of a plurality of response times, so that the light field display projects the one of the plurality of image lights and images at the corresponding imaging distance. The control method is simple and can make the light field display provide better viewing quality.

Description

TECHNICAL FIELD

[0001] The present application relates to a control method, and particularly relates to a control method of a light field display. BACKGROUND

[0002] A light field near eye display (LFNED) is one of the display technologies that can solve the vergence accommodation conflict (VAC) at present. The LFNED can be divided into two architectures, i.e. a time-multiplexed architecture and a spatial-multiplexed architecture. The time-multiplexed architecture uses a variable focus lens element to repeatedly change the virtual image position in a short time, so that the human eye feels a multi-depth perception. The variable focus lens element of the time-multiplexed architecture may, for example, include a liquid crystal tunable lens, a fluid-based tunable lens with constant volume, a fluid-based tunable lens with variable volume, or a fully elastomeric tunable lens. The spatial-multiplexed architecture uses a microlens array to project the corresponding parallax images on the display panel. In the current spatial-multiplexed architecture of the LFNED, a microlens array is placed on an OLED display to generate a light field image. The microlens array projects the light field sub-images of the display panel to the retina of the user, and then the user can see the virtual image light field image stacked by many sub-images. Therefore, the imaging quality of the entire microlens array directly affects the light field image effect.

[0003] In addition, in the time-multiplexed architecture light field near-eye display, the control of the zoom lens element is mainly triggered by the clock circuit of the main control board to synchronize the zoom lens element with the image transmission (SYNC). The main control board uses current or voltage input control according to the type of the zoom lens element. Moreover, the diopter change of the zoom lens element has a response time, and the input of different step functions and change frequencies will affect the time for the diopter of the zoomed lens element to enter the steady state after zooming. Therefore, in the past literature, most of the attempts to solve this problem are by optimizing the control. Empirically, the actual output signal is far from the ideal step function output, so it is necessary to go through the complicated optimization control to generate an output close to the ideal step function output. However, it is almost impossible to achieve perfect step function output, and this is only for simple step functions. Secondly, the zoom power of most zoom lens elements will decrease significantly with the increase of the working frequency, greatly reducing the imaging range of the optical system.

[0004] The background section of this document is included in advance to provide information related to the present application. The content of the background section is not an admission that the content of the background section is prior art to the present application, or that the content of the background section is related to the prior art of the present application. SUMMARY

[0005] The present application provides a control method for a light field display, which is relatively simple.

[0006] Other objects and advantages of the present application can be further understood from the technical features disclosed by the present application.

[0007] To achieve the above one or part or all of the purposes or other purposes, an embodiment of the present application provides a control method of a light field display. The light field display comprises a display module, a variable focus lens and a control unit. The display module comprises a light source module and a display unit. The control method comprises the following steps: inputting a focal length signal to the variable focus lens by the control unit, so that the variable focus lens periodically switches between a plurality of specific focal lengths. According to one of the plurality of specific focal lengths, inputting a corresponding display signal to the display unit of the display module by the control unit, so that the display module generates one of a plurality of image lights, wherein the plurality of image lights have different imaging distances after passing through the variable focus lens corresponding to the plurality of specific focal lengths respectively. According to one of the plurality of specific focal lengths, inputting a corresponding response time signal to the display module by the control unit, so that one of the plurality of image lights emitted by the display module passes through the variable focus lens within one of a plurality of response times, and the light field display projects one of the plurality of image lights and images at the corresponding imaging distance.

[0008] Based on the above, in an embodiment of the present application, the control method of the light field display makes the variable focus lens periodically switch between a plurality of specific focal lengths, and controls the time when each image light can pass through the variable focus lens according to the response time corresponding to the specific focal length. Therefore, compared with using a step function to regulate image output, the control method of the embodiment of the present application uses a simple periodic function, is not limited by the length of the steady state time controlled by the variable focus lens, makes the control method simpler, and makes the actual imaging position of the image light close to the theoretical value.

[0009] In order to make the above features and advantages of the present application more obvious and easy to understand, the following embodiments are described in detail below, and the accompanying drawings are described as follows.

DRAWINGS

[0010] Figure 1 is a flowchart of the control method of the light field display according to an embodiment of the present application.

[0011] Figure 2 is a block diagram of the light field display according to an embodiment of the present application.

[0012] Figure 3 is a schematic diagram of different specific focal lengths and their corresponding optimal imaging distance ranges in the control method of the light field display according to an embodiment of the present application.

[0013] Figure 4 is a curve diagram of a focal length characteristic function in the control method of the light field display according to an embodiment of the present application.

[0014] Figure 5is a schematic diagram of time difference corresponding to a range of optimal imaging distance according to a focal length characteristic function in a control method of a light field display according to an embodiment of the present application.

[0015] Figure 6 is a graph of a luminance characteristic function in a control method of a light field display according to an embodiment of the present application.

[0016] Figure 7 is a graph of a contrast characteristic function in a control method of a light field display according to an embodiment of the present application.

[0017] SYMBOL DESCRIPTION

[0018] 10: light field display

[0019] 100: display module

[0020] 110: light source module

[0021] 120: display unit

[0022] 200: variable focus lens

[0023] 300: control unit

[0024] AS: adjustment signal

[0025] B3, B4: luminance value

[0026] Bth: minimum luminance value

[0027] B': maximum luminance value

[0028] DS: display signal

[0029] FS: focal length signal

[0030] I: illumination light

[0031] IL: image light

[0032] L1, L2, L3, L4: specific focal length

[0033] L3 - : nearest imaging position

[0034] L3 + : farthest imaging position

[0035] L(T): focal length characteristic function

[0036] M: straight line

[0037] S100, S120, S140: step

[0038] TS: response time signal

Detailed Implementation Methods

[0039] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the present invention.

[0040] Figure 1 This is a flowchart of a control method for a light field display according to an embodiment of the present invention. Figure 2 This is a block diagram of a light field display according to an embodiment of the present invention. Please refer to... Figure 1 and Figure 2 An embodiment of the present invention provides a control method for a light field display 10. The light field display 10 includes a display module 100, a variable focus lens 200, and a control unit 300. The display module 100 includes a light source module 110 and a display unit 120.

[0041] In this embodiment, the light source module 110 provides illumination light I, which is incident on the display unit 120. The light source module 110 is, for example, one or more laser diodes (LDs), light-emitting diodes (LEDs), or other suitable light sources. Illumination light I is, for example, red, green, blue, or other suitable colored light, or a combination thereof. The display unit 120 is located in the transmission path of illumination light I and is used to convert illumination light I into image light IL. The display unit 120 is, for example, a spatial light modulator such as a digital micromirror device (DMD), a liquid crystal-on-silicon panel (LCOS panel), or a liquid crystal panel (LCD). Furthermore, the variable focus lens 200 is, for example, a liquid crystal lens or a liquid lens.

[0042] In the present embodiment, the control unit 300 described above is, for example, a microcontroller unit (MCU), a single-chip microcontroller, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a programmable controller, a programmable logic device (PLD), or other similar devices or a combination of these devices, without limitation. In addition, in an embodiment, the functions of the control unit 300 can be implemented as a plurality of program codes. The program codes are stored in a memory and executed by the control unit 300. Alternatively, in an embodiment, the functions of the control unit 300 can be implemented as one or more circuits. The present application is not limited to the manner of implementing the functions of the control unit 300 by software or hardware.

[0043] In the present embodiment, the control method includes the following steps. In step S100, the control unit 300 inputs a focal length signal FS to the variable focus lens 200 to periodically and continuously switch the variable focus lens 200 between a plurality of specific focal lengths. In step S120, the control unit 300 inputs a corresponding display signal DS to the display unit 120 of the display module 100 according to one of the plurality of specific focal lengths, so that the display module 100 generates one of the plurality of image lights IL, wherein the plurality of image lights IL have different imaging distances after passing through the variable focus lens 200 corresponding to the plurality of specific focal lengths. In step S140, the control unit 300 inputs a corresponding response time signal TS to the display module 100 according to one of the plurality of specific focal lengths, so that one of the plurality of image lights IL emitted by the display module 100 passes through the variable focus lens 200 within one of the plurality of response times, and the light field display 10 projects one of the plurality of image lights IL and images at the corresponding imaging distance.

[0044] The following will be described in detail how to determine the response time corresponding to different specific focal lengths by using a periodic function, so that the control method of an embodiment of the present application can output image light close to the theoretical value of the imaging position.

[0045] Figure 3 is a schematic diagram of different specific focal lengths and their corresponding imaging distance ranges in a control method of a light field display according to an embodiment of the present application. Please refer to Figure 3 , Figure 3The variable focus lens 200 can be switched between certain focal lengths L1, L2, L3 or L4. Different certain focal lengths L1, L2, L3 or L4 have different functional forms in the modulation transfer function (MTF) graph. In general, the larger the modulation value on the vertical axis, the better the image quality or image contrast. When the modulation value is greater than or equal to 0.3, the blur / clearness of the image light IL passing through the variable focus lens corresponding to the certain focal length has made it impossible for the human eye to distinguish the difference between different modulation values. That is, the certain modulation value greater than or equal to 0.3 and less than or equal to 1.0 determines the preferred imaging distance range of each certain focal length L1, L2, L3, L4, where the preferred imaging distance range represents the clear and acceptable image of the human eye at the closest position and the farthest position relative to the variable focus lens 200. Taking the certain focal length L3 as an example, the two intersection points between the certain focal length L3 and the straight line M with a modulation value of 0.3 determine the preferred imaging distance range of the certain focal length L3 on the imaging distance axis, i.e. the range from the closest imaging position L3 - to the farthest imaging position L3 + . In addition, since the intersection point between the certain focal length L4 and the straight line M with a modulation value of 0.3 only forms the closest imaging position of the certain focal length L4, the farthest imaging position corresponding to the certain focal length L4 can be defined by the maximum focal length of the variable focus lens 200.

[0046] That is, in the present embodiment, the closest imaging position and the farthest imaging position are the intersection points between the modulation transfer function of each certain focal length L1, L2, L3 or L4 and the straight line M with a certain modulation value, and the preferred imaging distance range corresponding to each certain focal length L1, L2, L3 or L4 is defined by the minimum value and the maximum value of the intersection points on the imaging distance axis or the minimum value and the maximum focal length of the variable focus lens 200. The certain modulation value is greater than or equal to 0.3 and less than or equal to 1.0.

[0047] Figure 4 is a graph of a focal length characteristic function according to an embodiment of a control method of a light field display. Figure 5 is a diagram of a time difference corresponding to a preferred imaging distance range obtained according to a focal length characteristic function according to an embodiment of a control method of a light field display. Please refer to Figure 4 and Figure 5 , then, based on the closest imaging position and the farthest imaging position corresponding to each certain focal length L1, L2, L3, L4, the control unit 300 controls the focal length of the variable focus lens 200 to change between different certain focal lengths L1, L2, L3, L4 through the focal length signal FS. Since there are difficulties in signal processing for the step function, it is preferable to select a periodic function to generate the focal length signal FS. For example,Figure 4 and Figure 5 The focal length characteristic function L(T) is a sine function (sin function). Thus, the preferred imaging distance range (i.e. the range between the nearest imaging position and the farthest imaging position) corresponding to each specific focal length L1, L2, L3, L4 under the focal length characteristic function L(T) corresponds to the time difference ΔT1, ΔT2, ΔT3, ΔT4, respectively. For example, the time required for the virtual image corresponding to the specific focal length L3 to move from the nearest imaging position L3 - to the farthest imaging position L3 + under the focal length characteristic function L(T) is ΔT3. Moreover, these time differences ΔT1, ΔT2, ΔT3, ΔT4 will determine the response time Δt1, Δt2, Δt3, Δt4 of the display unit 120 corresponding to the emission of the image light IL at each specific focal length L1, L2, L3, L4 (i.e. the response time signal TS in step S140). Although using a periodic function to generate the focal length signal FS and calculate the response time Δt1, Δt2, Δt3, Δt4 of the output of the image light IL from the display unit 120 is not a perfect theory, limiting the response time Δt1, Δt2, Δt3, Δt4 by a specific modulus can make the human eye unable to determine the error of the imaging position.

[0048] That is, in the present embodiment, the control method further comprises the following steps: determining each response time according to the time difference ΔT1, ΔT2, ΔT3 or ΔT4 corresponding to the preferred imaging distance range under the focal length characteristic function L(T), and the control unit 300 outputs the corresponding response time signal TS to the display unit 120 according to the response time.

[0049] In an embodiment, the above-mentioned focal length characteristic function can be: L(T) = a x sin(bT + c), where a, b and c are characteristic parameters, and T is the time period.

[0050] In addition to determining the time difference ΔT1, ΔT2, ΔT3 or ΔT4 according to the focal length characteristic function L(T) and a specific modulus, whether the actual response time Δt1, Δt2, Δt3, Δt4 corresponding to each specific focal length L1, L2, L3, L4 is preferred also needs to be determined by the minimum brightness and minimum contrast that can be perceived by the human eye. That is, if the minimum brightness and minimum contrast that can be perceived by the human eye are met, the time difference ΔT1, ΔT2, ΔT3 or ΔT4 is equal to the response time Δt1, Δt2, Δt3 or Δt4. Otherwise, if the minimum brightness and minimum contrast that can be perceived by the human eye are not met, the response time Δt1, Δt2, Δt3 or Δt4 is adjusted according to the minimum brightness and minimum contrast that can be perceived by the human eye.

[0051] Figure 6is a graph of a luminance characteristic function in a control method of a light field display according to an embodiment of the present application. Figure 6 The luminance characteristic function B(ΔT) illustrated in FIG. 1 is: where d, g, and h are luminance characteristic parameters, and ΔT is a time difference. Please refer to Figure 6 According to the luminance characteristic function B(ΔT) described above, the luminance values B1, B2, B3, B4 of the images received by the human eyes can be calculated respectively according to the time differences ΔT1, ΔT2, ΔT3, ΔT4 corresponding to the ranges of the best imaging distances according to the focal length characteristic function L(T). For example, Figure 6 The luminance values corresponding to the time differences ΔT3, ΔT4 in FIG. 1 are B3, B4 respectively. Among the luminance values B1, B2, B3, B4 corresponding to the time differences ΔT1, ΔT2, ΔT3, ΔT4, the maximum value is defined as a maximum luminance value. Since the luminance characteristic function B(ΔT) in this embodiment is an increasing function, the luminance value calculated from the maximum value ΔTmax among the time differences ΔT1, ΔT2, ΔT3, ΔT4 can be the maximum luminance value. For example, in FIG. 1, Figure 5 According to the focal length characteristic function L(T), the maximum time difference is ΔT4, so the time difference ΔT4 is the maximum value ΔTmax, and the luminance value B(ΔTmax) (equal to B4) is the maximum luminance value. In addition, Figure 6 Bth on the vertical axis in FIG. 1 is the minimum luminance value that can be perceived by the human eyes. Therefore, if the luminance values corresponding to the time differences ΔT1, ΔT2, ΔT3, ΔT4 are lower than the minimum luminance value Bth, the response times Δt1, Δt2, Δt3, Δt4 corresponding to the time differences can be adjusted to the time corresponding to the minimum luminance value Bth (calculated according to the luminance characteristic function B(ΔT)) or the time corresponding to the maximum luminance value B(ΔTmax). Alternatively, in an embodiment, the response times Δt1, Δt2, Δt3, Δt4 need to be greater than or equal to the time corresponding to the minimum luminance value Bth (calculated according to the luminance characteristic function B(ΔT)) and less than or equal to the time corresponding to the maximum luminance value B(ΔTmax).

[0052] That is, in this embodiment, the determination of each response time Δt1, Δt2, Δt3, Δt4 includes the following steps: calculating the maximum luminance value B(ΔTmax) according to the luminance characteristic function B(ΔT). The maximum luminance value B(ΔTmax) is the maximum value ΔTmax among the time differences ΔT1, ΔT2, ΔT3, ΔT4 corresponding to the specific focal lengths L1, L2, L3, L4, and the luminance value of the maximum luminance value B(ΔTmax) is

[0053] Figure 7 is a graph of a contrast characteristic function in a control method of a light field display according to an embodiment of the present application.Figure 7 The contrast characteristic function C(B) in the present embodiment is shown as follows: where q, r, s, μ and σ are luminance characteristic parameters, and B is a luminance value. Please refer to Figure 7 The luminance values B1, B2, B3 and B4 are used to calculate the contrast C1, C2, C3 and C4 of the images corresponding to the luminance values B1, B2, B3 and B4, respectively, according to the contrast characteristic function C(B). For example, Figure 7 The contrast of the images corresponding to the luminance values B3 and B4 are C3 and C4, respectively. And Figure 7 Cth on the vertical axis is the lowest contrast that can be perceived by the human eye. Therefore, if the contrast corresponding to the luminance value is less than the lowest contrast Cth, for example, Figure 7 If the contrast C4 of the image corresponding to the luminance value B4 is less than the lowest contrast Cth, the luminance value of the image can be adjusted to the maximum luminance value B' corresponding to the lowest contrast Cth, or to the lowest luminance value Bth or the luminance value B(ΔTmax) mentioned above, and then the correct response time Δt of the image light IL output from the display unit 120 is calculated using the adjusted luminance value.

[0054] In summary, in the present embodiment, the determination of each response time Δt1, Δt2, Δt3 and Δt4 further includes the following steps: according to the contrast characteristic function C(B), it is determined whether each response time Δt1, Δt2, Δt3 and Δt4 meets the following first condition: B(ΔT)≦B(ΔTmax), B(ΔT)≧Bth, and C(B(ΔT))≧Cth.

[0055] In the present embodiment, the determination of each response time Δt1, Δt2, Δt3 and Δt4 further includes the following steps: if the first condition is met, each response time Δt1, Δt2, Δt3 and Δt4 is its time difference ΔT1, ΔT2, ΔT3 and ΔT4.

[0056] In the present embodiment, the determination of each response time Δt1, Δt2, Δt3 and Δt4 further includes the following steps: if the first condition is not met, each response time Δt1, Δt2, Δt3 and Δt4 is adjusted to the time value corresponding to B(ΔTmax) or Bth, and each response time Δt1, Δt2, Δt3 and Δt4 meets the following second condition: B(Δt)≦B(ΔTmax), B(Δt)≧Bth, and C(B(Δt))≧Cth, where Δt is each response time.

[0057] In the present embodiment, the above-mentioned determining each response time Δtl, Δt2, Δt3, Δt4 further comprises the following steps: the control unit 300 adjusts the output of the light source module 110 of the display module 100 according to the luminance value calculated from each response time Δtl, Δt2, Δt3, Δt4 (according to the luminance characteristic function B(ΔT)) and the contrast output adjustment signal AS (according to the contrast characteristic function C(B)) to the display module 100, so that the light source module 110 of the display module 100 adjusts the output of the illumination light I to the display unit 120 according to the adjustment signal AS or / and the display unit 120 of the display module 100 adjusts the output of the image light IL according to the adjustment signal AS.

[0058] In the present embodiment, the above-mentioned inputting the focal length signal FS to the variable focus lens 200 by the control unit 300 to make the variable focus lens 200 periodically and continuously switch between the corresponding plurality of specific focal lengths Ll, L2, L3, L4 also comprises the following steps: the variable focus lens 200 periodically modulates its diopter according to the sinusoidal driving signal (for example Figure 4 The sinusoidal function shown) so that the plurality of image lights IL from the display module 100 have different imaging distances corresponding to these specific focal lengths Ll, L2, L3, L4 at different times by passing through the variable focus lens 200.

[0059] Table 1

[0060] a 0.1 b 0.5 c 0.1 d 3 g 0.05 h 0.01 q 0.2 r 0.6 s 0.2 μ 0.2 σ 0.1 Δtmax 0.268 Δtmin 0.122 Bmax 2.500 Bmin 2.000 Cmax 0.372 Cmin 0.682

[0061] Table 2

[0062]

[0063] For example, a, b and c in the above-mentioned Table 1 are characteristic parameters of a set of focal length characteristic functions L(T), d, g and h are luminance characteristic parameters of a set of luminance characteristic functions B(ΔT), and q, r, s, μ and σ are luminance characteristic parameters of a set of contrast characteristic functions C(B). Δtmax and Δtmin are respectively the maximum response time and the minimum response time that can be obtained according to the above-mentioned characteristic parameters under the satisfaction of the above-mentioned first condition formula and the second condition formula. Bmax and Cmax are the luminance value and the contrast corresponding to Δtmax, and Bmin and Cmin are the luminance value and the contrast corresponding to Δtmin. In an embodiment, Bmax here can be set as the minimum luminance value Bth or the luminance value B(ΔTmax), and Δtmax and Cmax can be the time difference and the contrast corresponding to the minimum luminance value Bth or the luminance value B(ΔTmax).

[0064] Table 2 shows a set of specific focal lengths L1, L2, L3, L4, time differences AT1, AT2, AT3, AT4 calculated according to the focal length characteristic function L(T), luminance values B1, B2, B3, B4 calculated according to the luminance characteristic function B(AT) respectively, and contrast values C1, C2, C3, C4 calculated according to the contrast characteristic function C(B) respectively. The logical judgment represents whether the luminance values B1, B2, B3, B4 and the contrast values C1, C2, C3, C4 corresponding to the time differences AT1, AT2, AT3, AT4 satisfy the first condition and the second condition. Since the luminance value B1 and the contrast value C1 calculated according to the specific focal length L1 satisfy the first condition and the second condition, the response time At1 of the display unit 120 corresponding to the specific focal length L1 is equal to the time difference AT1 generated by the corresponding optimal imaging distance range. Since the luminance values B2, B3, B4 and the contrast values C2, C3, C4 calculated according to the specific focal lengths L2, L3, L4 cannot satisfy the first condition and the second condition simultaneously, the response times At2, At3, At4 of the display units corresponding to the specific focal lengths L2, L3, L4 are set to be the response time Atmax.

[0065] In summary, in an embodiment of the present application, the control method of the light field display device periodically and continuously switches the variable focus lens between a plurality of specific focal lengths, and controls the time for each image light to pass through the variable focus lens according to the response time of the display unit corresponding to the specific focal length. Therefore, compared with using a step function to control the image output, the control method of the embodiment of the present application uses a simple periodic function and is not limited by the length of the steady state time of the variable focus lens control, so that the control method is relatively simple, and the actual imaging position of the image light is close to the theoretical value when the error value cannot be judged by the human eye.

[0066] In addition, the control method of the embodiment of the present application optimizes the response time by using the luminance characteristic function B(AT), the minimum luminance value Bth that can be perceived by the human eye, the contrast characteristic function C(B), and the minimum contrast value Cth that can be perceived by the human eye. Therefore, the control method of the embodiment of the present application can provide the light field display device with the best viewing quality.

[0067] The above descriptions are only the preferable embodiments of the present application, and cannot limit the scope of the present application. Any simple equivalent changes or modifications according to the present application claims and descriptions are still within the scope of the present application. In addition, any embodiment or claim of the present application does not need to achieve all the purposes or advantages or features disclosed in the present application. Furthermore, the abstract and title are only used to assist the patent document search, and are not used to limit the scope of the present application. In addition, the terms "first", "second" and the like mentioned in the specification or claims are only used to name elements or distinguish different embodiments or ranges, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A control method for a light field display, characterized in that, The light field display includes a display module, a variable focus lens, and a control unit, wherein the display module includes a light source module and a display unit, and the control method includes: The control unit inputs a focal length signal to the variable focal length lens so that the variable focal length lens periodically switches between multiple specific focal lengths. Based on one of the plurality of specific focal lengths, the control unit inputs a corresponding display signal to the display unit of the display module, causing the display module to generate one of the plurality of image lights, wherein the plurality of image lights, after passing through the variable focal length lens, correspond to the plurality of specific focal lengths and have different imaging distances. Based on one of the plurality of specific focal lengths, the control unit inputs a corresponding response time signal to the display module, causing one of the plurality of image lights emitted by the display module to pass through the variable focal length lens within one of the plurality of response times, thereby causing the light field display to project one of the plurality of image lights and image at the corresponding imaging distance; The response time is determined based on the time difference between the nearest and farthest imaging positions corresponding to the focal length characteristic function, and the control unit outputs the corresponding response time signal based on the response time. The nearest imaging position and the farthest imaging position are respectively the intersection points of the line formed by the modulation transfer function and the specific modulus of the specific focal length corresponding to each response time, and are defined by the minimum and maximum values ​​of the intersection points on the imaging distance axis or the minimum value and the maximum focal length of the variable focal length lens.

2. The control method for a light field display according to claim 1, characterized in that, The focal length characteristic function is: L(T) = a × sin(bT + c) Where a, b, and c are characteristic parameters, and T is time.

3. The control method for a light field display according to claim 1, characterized in that, The specific modulus is greater than or equal to 0.3 and less than or equal to 1.

0.

4. The control method for a light field display according to claim 1, characterized in that, The determination of each response time includes: Calculate the maximum brightness value based on the brightness characteristic function. The maximum brightness value is the maximum value among the multiple time differences corresponding to the multiple specific focal lengths, and is the brightness value of the brightness characteristic function.

5. The control method for a light field display according to claim 4, characterized in that, The brightness feature function is: Where d, g, and h are brightness characteristic parameters, and ΔT is the time difference.

6. The control method for a light field display according to claim 4, characterized in that, The determination of each response time also includes: Based on the contrast feature function, determine whether each response time satisfies the following first condition: B(ΔT)≦B(ΔTmax), B(ΔT)≧Bth, and C(B(ΔT))≧Cth, Where ΔT is the time difference, ΔTmax is the maximum value among the multiple time differences, Bth is the lowest brightness value perceptible to the human eye, function C is the contrast feature function, and Cth is the lowest contrast perceptible to the human eye.

7. The control method for a light field display according to claim 6, characterized in that, The contrast feature function is: Where q, r, s, μ and σ are brightness characteristic parameters, and B is the brightness value.

8. The control method for a light field display according to claim 6, characterized in that, The determination of each response time also includes: If the first condition is satisfied, then each response time is the time difference.

9. The control method for a light field display according to claim 6, characterized in that, The determination of each response time also includes: If the first condition is not satisfied, then each response time is set to the time value corresponding to B(ΔTmax) or Bth, and each response time satisfies the following second condition: B(Δt)≦B(ΔTmax), B(Δt)≧Bth, and C(B(Δt))≧Cth, Where Δt is the response time for each response.

10. The control method for a light field display according to claim 6, characterized in that, The determination of each response time also includes: the control unit outputs an adjustment signal to the display module based on the brightness value and contrast calculated based on each response time, so that the light source module of the display module adjusts the output illumination light to the display unit according to the adjustment signal.

11. The control method for a light field display according to claim 1, characterized in that, The control unit inputs the focal length signal to the variable focal length lens to cause the variable focal length lens to periodically switch between corresponding multiple specific focal lengths. The method further includes: the variable focal length lens periodically modulates its diopter according to a sine wave drive signal, so that the multiple image lights from the display module pass through the variable focal length lens at different times and have different imaging distances.

Images