Flash lamp device

Abstract

The invention provides a flash lamp device. The flash lamp device comprises a light emitting diode array and an optical lens group, the light emitting diode array comprises a plurality of light emitting diode pixels which are arranged in an array and can be independently operated and controlled, wherein the light emitting diode pixels comprise a plurality of light emitting diode pixels with different light emitting colors. The optical lens group includes a plurality of optical lenses to collect, converge, and diverge light beams from the light emitting diode array.

Description

Technical Field

[0001] The invention relates to a light source device, and in particular to a flash lamp device. Background Art

[0002] The popularity of smartphones and tablets and the pursuit of photography quality require the use of additional light sources to increase the ambient brightness in low-light scenes so that the imaging device can obtain sufficient imaging information. Among them, the flash module is an indispensable device. The flash lens group with appropriate optical design can adjust the light angle, improve light efficiency and improve uniformity.

[0003] Currently, the single-color temperature flash used in mobile devices mostly uses yellow phosphor coated on a blue light-emitting diode (LED). The blue light excites the yellow phosphor to generate white light and produce a range fill light effect. However, the use of this light source has the following disadvantages: (1) The excitation spectrum lacks green and red light bands, resulting in poor color rendering; (2) The image color is distorted and tends to be cold; (3) The color temperature cannot be changed according to the scene; (4) The fill light range is fixed and the beam shape cannot be changed according to the focal length of the lens used or the target object. Therefore, in the pursuit of improving the imaging quality of mobile devices, improving the flash module is an inevitable challenge that must be faced. Summary of the invention

[0004] The present invention is directed to a flash device, which provides illumination that can achieve the advantages of improved color rendering, adjustable color temperature and adjustable fill light range.

[0005] One embodiment of the present invention provides a flash device, including a light emitting diode array and an optical lens assembly. The light emitting diode array includes a plurality of light emitting diode pixels arranged in an array and independently operable and controlled, wherein the light emitting diode pixels include light emitting diode pixels of a plurality of different light emitting colors. The optical lens assembly includes a plurality of optical lenses for collecting, converging and diverging light beams from the light emitting diode array.

[0006] In the flash device of the embodiment of the present invention, a plurality of LED pixels arranged in an array and independently operable and controlled are used, and these LED pixels include LED pixels of multiple different luminous colors. Therefore, by independently controlling the light emission or non-light emission of different LED pixels, or by independently controlling the luminous intensity ratio of different LED pixels, the illumination provided by the flash device of the embodiment of the present invention can achieve the advantages of improved color rendering, adjustable color temperature, and adjustable fill light range. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic diagram of a light path of a flash device according to an embodiment of the present invention;

[0008] Figure 2 yes Figure 1 A cross-sectional schematic diagram of a flash device;

[0009] FIG. 3A to FIG. 3D A schematic diagram of an arrangement of light-emitting diode pixels of different color temperatures in a light-emitting diode array;

[0010] Figure 4 for Figure 1 A curve diagram of the modulation transfer function of the imaging of the irradiated target surface on the light emitting diode array through the optical lens group;

[0011] Figure 5 for Figure 1 A curve diagram of vertical axis chromatic aberration of the imaging of the irradiated target surface on the light emitting diode array through the optical lens group;

[0012] Figure 6 for Figure 1 A graph showing the illumination uniformity of a target surface 1 meter away from the flash device relative to the half field angle when all the LED pixels in the LED array are turned on and set to the same light intensity;

[0013] Figure 7 for Figure 1 A graph showing the illumination gain value of the flash device relative to the light emitting diode array without an optical lens assembly versus the half field of view angle;

[0014] Figure 8 yes Figure 1 Flowchart of operation when the flash device is applied to a camera. DETAILED DESCRIPTION

[0015] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0016] Figure 1 is a schematic diagram of the optical path of a flash device according to an embodiment of the present invention, and Figure 2 yes Figure 1 A cross-sectional diagram of a flash unit. Figure 1 and Figure 2 The flash device 100 of the present embodiment includes a light emitting diode array 110 and an optical lens group 120. The light emitting diode array 110 includes a plurality of light emitting diode pixels 112 arranged in an array and independently operable and controlled, wherein the light emitting diode pixels 112 include light emitting diode pixels of a plurality of different light emitting colors (in Figure 1For example, the optical lens group 120 includes two light-emitting diode pixels of different light-emitting colors, such as the light-emitting diode pixel 112a and the light-emitting diode pixel 112b. Figure 1 For example, the optical lens L1, L2, L3 and L4 are used to collect, converge and diverge the light beam 111 from the light emitting diode array 110.

[0017] In the flash device 100 of the present embodiment, a plurality of LED pixels 112 arranged in an array and independently operable and controlled are used, and the LED pixels 112 include LED pixels 112a and 112b of different luminous colors. Therefore, by independently controlling the light emission or non-light emission of different LED pixels 112, or by independently controlling the light intensity ratio of different LED pixels 112, the illumination provided by the flash device 100 of the present embodiment can achieve the advantages of improved color rendering, adjustable color temperature, and adjustable fill light range.

[0018] Specifically, in the present embodiment, the LED pixels 112 include LED pixels 112a and 112b of different color temperatures arranged in a staggered manner. In the present embodiment, the flash device 100 further includes a controller 130, which is electrically connected to the LED array 110 and is used to control the light intensity ratio and light emitting area of ​​the LED pixels 112a and 112b of different color temperatures by controlling the current driving the LED pixels 112. For example, the color temperature of the light beam 111a emitted by the LED pixel 112a is higher than the color temperature of the light beam 111b emitted by the LED pixel 112b. Therefore, by controlling the intensity ratio of the light beams 111a and 111b emitted by the LED pixels 112a and 112b, or controlling one of the LED pixels 112a and 112b to emit light while the other does not emit light, a plurality of light beams 111 of different color temperatures can be formed. That is, in the present embodiment, the LED pixel 112a is a high color temperature white light LED, and the LED pixel 112b is a low color temperature white light LED. However, in other embodiments, the LED pixel 112 may also be a LED of other colors, such as red, green, and blue LEDs. In addition, for example, if the LED pixels 112 in a local area of ​​the LED array 110 are controlled, while the LED pixels 112 in other areas do not emit light, or the LED pixels 112 in the entire LED array 110 are controlled to emit light, the light-emitting area of ​​the LED array 110 can be controlled and adjusted, and the illumination range provided by the flash device 100 can be controlled and adjusted. In one embodiment, the controller 130 is used to determine the light-emitting area of ​​the LED array 110 according to the focal length of the imaging lens of a camera equipped with the flash device 100 or the shape of the target object, and thus determine the illumination range of the flash device 100. In one embodiment, the LED pixel 112 is, for example, a micro LED, but the present invention is not limited thereto. In other embodiments, the LED pixel 112 may also be a LED of other sizes.

[0019] In this embodiment, the controller 130 responds to the low light environment of the flash device 100 and adjusts the color temperature of the light beam 111 emitted by the LED array 110 according to different environmental color temperatures, object colors, skin depths of portraits, or special effects.

[0020] FIG. 3A to FIG. 3D Schematic diagram of the arrangement of LED pixels of different color temperatures in an LED array. Figure 1 , Figure 2 and FIG. 3A to FIG. 3DThe staggered arrangement of the LED pixels 112a and 112b of the LED array 110 with different color temperatures is, for example, a staggered arrangement in a chessboard format (eg, Figure 3A ), annular staggered arrangement (such as Figure 3B ), staggered arrangement of columns (such as Figure 3C ) or staggered rows (e.g. Figure 3D ), but the present invention is not limited thereto.

[0021] In the present embodiment, the optical lens group 120 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged in sequence from the target surface 60 to the LED array 110 along the optical axis I. In the present embodiment, the optical lens group 120 further includes a protective glass 122 disposed between the fourth lens L4 and the LED array 110. In the present embodiment, the optical lens group 120 further includes an aperture 124 disposed between the second lens L2 and the third lens L3. In the present embodiment, the total thickness T1 of the optical lens group 120 is, for example, less than 8.5 mm, wherein the total thickness T1 is the distance between the target side surface S1 of the first lens L1 and the light-emitting surface of the LED array 110 on the optical axis I, wherein the target side surface S1 is the surface of the first lens L1 facing away from the LED array 110, that is, the surface of the first lens L1 facing the target surface 60. In one embodiment, the total thickness T1 is, for example, 8.44 mm. In addition, in the present embodiment, the f-number of the optical lens group 120 is less than 0.98.

[0022] In the present embodiment, the first lens L1 is a Fresnel lens having a concentric annular sawtooth surface (e.g., a concentric annular sawtooth surface surrounding the optical axis I) and having positive optical power, that is, having positive refractive power. In the present embodiment, the refractive powers of the second lens L2, the third lens L3, and the fourth lens L4 are negative, positive, and positive, respectively. In addition, in the present embodiment, the second lens L2 is a biconcave lens, the third lens L3 is a biconvex lens, and the fourth lens L4 is a positive meniscus lens with the convex surface facing the irradiation target surface 60.

[0023] In the present embodiment, two opposite surfaces of each of the second lens L2, the third lens L3 and the fourth lens L4 are aspherical surfaces, and the two opposite surfaces respectively face the irradiation target surface 60 and the LED array 110. In addition, in the present embodiment, the largest diameter of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 does not exceed 6.52 mm.

[0024] In this embodiment, the target side surface S1 of the first lens L1 is a Fresnel surface, and the light source side surface S2 of the first lens L1 is a plane, wherein the light source side surface S2 refers to the surface of the first lens L1 facing the LED array 110, that is, the surface of the first lens L1 facing away from the target surface 60. Since the flash device 100 on the portable electronic device has a thickness limitation, the characteristics of the thin optical element of the Fresnel lens are utilized to fully utilize the limited space, and the sawtooth Fresnel lens can prevent the user from seeing the internal component structure from the outside to the inside, increase the aesthetics, and can be mass-produced through plastic injection molding. The target side surface S3 and the light source side surface S4 of the second lens are both concave surfaces. The target side surface S6 and the light source side surface S7 of the third lens L3 are both convex surfaces, and the third lens L3 is mainly used to change the light path deflection angle. The target side surface S8 of the fourth lens L4 is a convex surface, and the light source side surface S9 of the fourth lens L4 is a concave surface. The fourth lens L4 is mainly used to shape the light beam 111 emitted by the micro-LED array 110.

[0025] The relevant curvature radius, thickness (the thickness value of the row where the target side S1 is located is the center thickness of the lens L1 on the optical axis I, the value of the row where the light source side S2 is located is the air gap between the lens L1 and the lens L2 on the optical axis I, and so on), the refractive index of the material used for each lens, and the Abbe parameter of the optical element of the light emitting diode array 110 are shown in Table 1.

[0026]

[0027] Table 1

[0028] Except that the surface S10 of the protection glass 122 is a plane and the surface S0 of the irradiated target surface 60 is a plane, the target side surface S3 and the light source side surface S4 of the second lens L2, the target side surface S6 and the light source side surface S7 of the third lens L3, and the target side surface S8 and the light source side surface S9 of the fourth lens L4 are all aspherical surfaces. The surface shape of each aspherical surface can be described by the following formula (1):

[0029]

[0030] Wherein, formula (1) is the formula for even-order aspheric surfaces, c is the curvature of the aspheric surface near the optical axis, k is the cone coefficient, r is the radial coordinate, α i is the 2i-order aspheric coefficient (for example, α2 is the 4th-order aspheric coefficient, α3 is the 6th-order aspheric coefficient, and so on). z represents the distance from the coordinate point to the aspheric vertex in the optical axis direction at a height radius of r with the central optical axis as the starting point. The values ​​of the cone and aspheric coefficients of the aspheric lens are shown in Table 2.

[0031] S3 S4 S6 S7 S8 S9 k 0.000 0.000 -0.499 -586.307 -34.161 2575.171 <![CDATA[α2]]> 1.62E-02 0.482 -0.288 -5.41E-02 3.280 1.78E-02 <![CDATA[α3]]> 1.68E-03 0.973 -1.388 2.93E-02 9.331 4.99E-03 <![CDATA[α4]]> 4.18E-06 8.331 3.994 -1.15E-02 15.748 -1.53E-03 <![CDATA[α5]]> -6.30E-05 38.916 -3.433 2.42E-03 -12.006 1.53E-04 <![CDATA[α6]]> 8.20E-06 -20.786 -3.603 -2.12E-04 -2.170 -3.00E-05 <![CDATA[α7]]> -3.08E-07 21.135 7.924 2.03E-06 9.316 <![CDATA[α8]]> -491.408 -1.104 -3.15E-08 -4.154 <![CDATA[α9]]> 1065.334 -5.270 -0.072 <![CDATA[α 10 ]]> -523.559 2.703 0.025

[0032] Table 2

[0033] Figure 4 for Figure 1 The modulation transfer function curve of the imaging of the target surface through the optical lens group on the light-emitting diode array, where 46.0 degrees, 23.0 degrees and 0.0 degrees represent the curves at these field angles, and the tangential direction and sagittal direction represent the curves corresponding to the light in these two directions. Please refer to Figure 1 , Figure 2 and Figure 4 In this embodiment, the viewing angle of the optical lens group 120 is greater than 90 degrees, wherein the viewing angle is, for example, Figure 2 The half field angle θF is twice as large as the half field angle θF, and the average modulation transfer function of the optical lens group in the tangential direction and the sagittal direction is less than 0.3 at the cut-off frequency, such as Figure 4 As shown, the cut-off frequency is the side length D1 of the light-emitting surface of any one of the light-emitting diode pixels 112 (such as Figure 1 In one embodiment, the side length D1 is less than 75 microns. A modulation transfer function less than 0.3 indicates that the image is blurred. Since light is reversible, when the image of the target surface 60 on the LED array 110 through the optical lens group 120 is blurred, the LED array 110 on the target surface 60 through the optical lens group 120 will also be blurred. Therefore, the illumination areas 62a and 62b of the LED pixels 112a and 112b respectively formed on the target surface 60 will also be blurred and at least partially overlap each other, which will cause the illumination area 62a with a high color temperature and the illumination area 62b with a low color temperature to be mixed into the desired color temperature illumination.

[0034] Figure 5 for Figure 1 The curve diagram of the vertical axis chromatic aberration of the image of the illuminated target surface on the light emitting diode array through the optical lens group, wherein the curve marked as R is the vertical axis chromatic aberration of red light (whose wavelength is 656.27 nanometers), the straight line marked as G is the vertical axis chromatic aberration of green light (whose wavelength is 587.56 nanometers), and the curve marked as B is the vertical axis chromatic aberration of blue light (whose wavelength is 486.13 nanometers). Figure 5 It can be seen that the vertical axis chromatic aberration C1 of the optical lens group 120 on the LED array 110 is smaller than the side length D1 of the light emitting surface of any of the LED pixels 112 (eg Figure 1 shown).

[0035] Figure 6 for Figure 1When all LED pixels in the LED array are turned on and set to the same light intensity, the illumination uniformity of the target surface 1 meter away from the flash device is plotted against the half field of view angle. Figure 1 and Figure 6 , the uniformity of illumination can be defined as regional illumination / maximum illumination×100%. The flash device 100 of this embodiment can project a maximum light beam with a diagonal direction exceeding 90 degrees, and can still maintain 20% of the maximum illumination at the maximum viewing angle. In this embodiment, the current intensity of these LED pixels 112 increases from the center of the LED array 110 to the periphery to compensate for the difference in light intensity uniformity caused by the optical lens group 120.

[0036] Figure 7 for Figure 1 A graph of the illumination gain value of the flash device in FIG. 1 relative to the light emitting diode array without an optical lens assembly relative to the half field angle, wherein Figure 7 In the example, all LED pixels in the LED array are turned on and set to the same luminous intensity, and the illumination refers to the illumination on the target surface at a distance of 1 meter from the flash device (or LED array). Figure 1 and Figure 7 , the illumination gain value of the illumination beam 111 projected by the flash device 100 is greater than the illumination gain value of the light beam 111 emitted by the LED array 110 without passing through the optical lens set 120, wherein the gain value can be defined as the illumination of the device under test / the illumination of the LED array without the optical lens set. Figure 7 It can be seen that after using the designed optical lens set 120 , the central light energy can be amplified to a larger viewing angle, so that the illumination gain value of the flash device at a large viewing angle can be greater than the illumination gain value when the optical lens set 120 is not used.

[0037] Figure 8 yes Figure 1 The operation flow chart of the flash unit when it is used in a camera. Figure 1 and Figure 8, the operation flow of the flash device 100 when applied to a camera may include the following steps. First, execute step 701 to start shooting. Next, execute step 702 to set the shooting mode, adjust the shooting focal length, and select the lens to be used. This step can be executed by the controller 130. Next, execute step 703 to identify the scene, determine whether fill light is needed, and detect the ambient color temperature and the target object. This can be executed by the controller 130. If step 703 determines that the flash device 100 is not needed to fill light, then directly proceed to step 706, which is shooting, that is, the camera performs the action of shooting an image. If step 703 determines that the flash device 100 is needed to fill light, then proceed to step 704, which is to control the open area, power and action seconds of the light emitting diode array according to the ambient color temperature, the target object and the shooting focal length. This can be executed by the controller 130. Then, step 705 is performed to expose the mixed high and low color temperature light sources (ie, high color temperature LED pixels 112a and low color temperature LED pixels 112b) and generate a specific color temperature fill light beam 111. Next, step 706 is performed, and the controller 130 commands the camera to execute the action of capturing an image.

[0038] In one embodiment, when the shooting scene is in an environment where the illumination is insufficient and fill light is required, the light source of a specific area in the LED array 110 can be turned on through the currently selected lens. For example, when using a wide-angle lens, all the LED pixels 112 in the LED array 110 need to be turned on to meet the large-range fill light; when switching to a telephoto lens, due to the relatively small field of view, only the LED pixels 112 in the center area of ​​the LED array 110 can be turned on for fill light. In addition, according to the system detection environment, object color or portrait skin color depth, by adjusting the ratio of high and low color temperature light sources in the LED array 110 and through the designed optical lens group, a uniform fill light beam 111 with an appropriate color temperature that meets the environment, object or portrait can be generated to meet the needs of various low-light source photography.

[0039] In summary, in the flash device of the embodiment of the present invention, a plurality of LED pixels arranged in an array and independently operable and controlled are used, and these LED pixels include LED pixels of multiple different luminous colors. Therefore, by independently controlling the light emission or non-emission of different LED pixels, or by independently controlling the luminous intensity ratio of different LED pixels, the illumination provided by the flash device of the embodiment of the present invention can achieve the advantages of improved color rendering, adjustable color temperature, and adjustable fill light range.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flash device, characterized in that: include: A light emitting diode array, comprising a plurality of light emitting diode pixels arranged in an array and independently operable and controlled, wherein the plurality of light emitting diode pixels include light emitting diode pixels of a plurality of different emitting colors; as well as The optical lens group includes a plurality of optical lenses, and is used for collecting, converging and diverging the light beams from the light emitting diode array.

2. The flash device according to claim 1, characterized in that The plurality of light emitting diode pixels include light emitting diode pixels of different color temperatures arranged in a staggered manner.

3. The flash device according to claim 2, characterized in that It also includes a controller, which is electrically connected to the light emitting diode array and is used to control the light intensity ratio and light emitting area of ​​the light emitting diode pixels of the plurality of different color temperatures by controlling the current driving the plurality of light emitting diode pixels.

4. The flash device according to claim 2, characterized in that The device also includes a controller electrically connected to the LED array. The controller responds to the flash device being in a low light environment and adjusts the color temperature of the light beam emitted by the LED array according to different environmental color temperatures, object colors, skin color depths of portraits, or special effects requirements.

5. The flash device according to claim 2, characterized in that The staggered arrangement of the plurality of light emitting diode pixels of different color temperatures is a staggered arrangement in a chessboard format, a ring staggered arrangement, a column staggered arrangement or a row staggered arrangement.

6. The flash device according to claim 1, characterized in that The invention also includes a controller electrically connected to the light emitting diode array, and the controller is used to determine the light emitting area of ​​the light emitting diode array according to the focal length of the imaging lens or the shape of the target object.

7. The flash device according to claim 1, characterized in that The current intensity applied to the plurality of LED pixels increases from the center of the LED array to the periphery to compensate for the difference in light intensity uniformity caused by the optical lens group.

8. The flash device according to claim 1, characterized in that The optical lens assembly includes a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along the optical axis from the irradiated target surface to the light emitting diode array, and the total thickness thereof is less than 8.5 mm.

9. The flash device according to claim 8, characterized in that The optical lens assembly further includes a protective glass disposed between the fourth lens and the light emitting diode array.

10. The flash device according to claim 8, characterized in that The optical lens group further includes a stop located between the second lens and the third lens.

11. The flash device according to claim 8, characterized in that The aperture number of the optical lens group is less than 0.

98.

12. The flash device according to claim 11, characterized in that Among the first lens, the second lens, the third lens and the fourth lens, the largest diameter of the lens does not exceed 6.52 mm.

13. The flash device according to claim 8, characterized in that The first lens is a Fresnel lens having concentric ring-shaped sawtooth surfaces and positive optical power.

14. The flash device according to claim 8, characterized in that The second lens is a biconcave lens, the third lens is a biconvex lens, and the fourth lens is a positive meniscus lens with the convex surface facing the irradiation target surface.

15. The flash device according to claim 8, characterized in that Two opposite surfaces of each of the second lens, the third lens and the fourth lens are aspherical surfaces, and the two opposite surfaces face the irradiation target surface and the light emitting diode array respectively.

16. The flash device according to claim 8, characterized in that The vertical axis chromatic aberration of the optical lens group on the LED array is smaller than the side length of the light emitting surface of any one of the plurality of LED pixels.

17. The flash device according to claim 8, characterized in that The field of view angle of the optical lens group is greater than 90 degrees, and the modulation transfer function of the optical lens group is less than 0.3 at a cutoff frequency.

18. The flash device according to claim 17, characterized in that The cut-off frequency is the reciprocal of twice the side length of the light-emitting surface of any one of the plurality of light-emitting diode pixels.

19. The flash device according to claim 8, characterized in that The refractive powers of the second lens, the third lens and the fourth lens are negative, positive and positive in sequence.

20. The flash device according to claim 8, characterized in that The illumination gain value of the illumination light beam projected by the flash device is greater than the illumination gain value of the light beam emitted by the light emitting diode array without passing through the optical lens group.

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