Self-emissive element panels, LED panels, and planetariums that use them.

Abstract

The LED panel has multiple LED pixel units arranged in a row. Each LED pixel unit has: a normal element, including a red LED element, a green LED element, and a blue LED element; and a low-brightness element for outputting a brightness lower than the minimum brightness of the normal element.

Description

TECHNICAL FIELD

[0001] The present application relates to a self-luminous element panel, an LED panel, and a planetarium using them, and more particularly, to a self-luminous element panel having a high dynamic range, an LED panel, and a planetarium using them. BACKGROUND

[0002] In the past, an image of a celestial body or the like was projected by a projector onto a dome-shaped screen in a planetarium. In recent years, LEDs (Light Emitting Diodes) have begun to be increasingly used as light sources of projectors instead of the past bulbs and discharge lamps.

[0003] Furthermore, in a planetarium, in addition to projection of a celestial body by a projector, there are performed in-theater illumination at the time of entrance and exit of an audience, illumination of a scene during the day and at night, and the like. In particular, by gradually changing the brightness of illumination, a subtle change in brightness from the evening to the night is staged.

[0004] Moreover, light sources of these illuminations have also begun to increasingly use LEDs. An LED is generally dimmed by PWM (pulse width modulation) control. In PWM control, the brightness of an LED is specified by the pulse width of a PWM signal of a digital circuit.

[0005] However, unlike an incandescent lamp, the brightness of an LED is exactly proportional to the pulse width of a PWM signal. Therefore, when an LED is dimmed by PWM control, particularly at a low brightness, there is a problem that the brightness of the LED is seen to change in stages. For example, in a 12-bit resolution PWM signal, the pulse width at the smallest brightness is 1 / 4096. Moreover, the pulse width at one level brighter than this is 2 / 4096, and the brightness is twice as much. As a result, in a low light amount region, the brightness is seen to change in stages.

[0006] Furthermore, since the human eye can sufficiently recognize the brightness even at the smallest pulse width, there is a problem that the illumination suddenly disappears from the brightness at the smallest pulse width at the time of fade-out.

[0007] In view of the above problem, it is considered to increase the bit resolution of a PWM signal. However, if the bit resolution is increased, in order to cope with small pulse widths, a current needs to be switched at high speed. As a result, not only is noise easily generated, but also it is easily affected by external noise. In particular, in a low light amount region, sometimes flicker is generated due to external noise, or the brightness changes.

[0008] Thus, in Japanese Patent Application Publication No. 2015-088412, in order to smoothly change the light amount of an LED, a driving circuit having a plurality of current limiting circuits each of which has a current flowing therethrough set to a respective different current setting value and a pulse width modulation circuit is connected to the LED, and in a low light amount region, the pulse width of the circuit having a small current setting value is mainly controlled, and in a high light amount region, the pulse width of the circuit having a large current setting value is mainly controlled. SUMMARY

[0009] In the conventional planetarium, an image of a celestial body is projected onto a dome-shaped screen by a projector. For this, a planetarium in which an LED panel arranged so as to spread on the inner surface of the dome displays a celestial body has been proposed.

[0010] In the planetarium in which an image of a celestial body is projected, an observer visually recognizes the image of the celestial body which is diffusely reflected on the surface of the dome-shaped screen by light projected thereon, and in contrast, in the planetarium in which the LED panel is arranged, the observer directly visually recognizes the LED element which displays the image of the celestial body. Thus, the planetarium in which the LED panel is arranged can display a very clear image of a celestial body.

[0011] On the other hand, in the actual night sky, there are bright celestial bodies such as the moon and stars, and dark celestial bodies such as the Milky Way. The brightness of the dark celestial bodies such as the Milky Way is only about several millionth of the brightness of the bright celestial bodies. Thus, if the night sky is to be faithfully reproduced by the planetarium, a dynamic range which is greatly different from that required for an LED panel which displays a normal television image or the like is required in the LED panel.

[0012] However, the brightness of the LED panel realized by a PWM signal of 12-bit resolution is only 4096 gradations, and even 16-bit resolution is only 65536 gradations. Thus, in the case where the conventional LED panel is arranged so as to spread on the inner surface of the dome, it is difficult to display from the bright celestial bodies such as planets to the dark celestial bodies such as the Milky Way in reality. In particular, unlike the projection-type planetarium, the observer directly views the LED panel, and thus even the lowest brightness of the LED element is too bright, and it is difficult to display the dark celestial bodies in reality.

[0013] This is not limited to the LED, and the same applies to a display panel using other self-emitting elements such as an organic EL element.

[0014] The present application has been achieved in view of such circumstances, and an object thereof is to provide a self-emitting element panel having a high dynamic range, an LED panel, and a planetarium using the same.

[0015] The self-light-emitting element panel of the present application has a plurality of self-light-emitting pixel units arranged, each of which has: normal elements including a red element based on a self-light-emitting element, a green element based on a self-light-emitting element, and a blue element based on a self-light-emitting element; and a low-luminance element for performing output with a lower luminance than the lowest luminance of the normal elements.

[0016] Further, in the planetarium of the present application, the self-light-emitting element panel or the LED panel of the present application is disposed on the inner surface of the dome.

[0017] Thus, according to the self-light-emitting element panel, the LED panel, and the planetarium of the present application, in each pixel unit constituting the panel, a low-luminance element is provided in addition to normal elements.

[0018] Further, in view of the fact that the dynamic range of human eyes for brightness is extremely wide, but a person cannot perceive color at low illuminance, the low-luminance element can be constituted by a white element. Thus, the low-luminance element can be implemented by a single kind of white element. As a result, compared with the case where the low-luminance element is constituted by elements of each color of the three primary colors, the cost of the panel can be reduced.

[0019] According to the present application, a self-light-emitting element panel, an LED panel, and a planetarium using them having a high dynamic range can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view of the inside of a dome of a planetarium of an embodiment of the present application, viewed from below.

[0021] Figure 2 is a schematic view of an arrangement pattern example of LED elements in an LED panel of an embodiment of the present application.

[0022] Figure 3 is a circuit diagram showing an example of a drive circuit of an LED panel.

[0023] Figure 4 is a chart showing an example of a pulse width of a PWM control signal with respect to a dimming instruction value.

[0024] Figure 5A is an example of an LED pixel unit constituting an LED panel, and is a plan view of the LED pixel unit.

[0025] Figure 5B is an example of an LED pixel unit constituting an LED panel, and is a cross-sectional view along the A-A line of Figure 5A .

[0026] Figure 6A is another example of an LED pixel unit constituting an LED panel, and is a plan view of the LED pixel unit.

[0027] Figure 6B This is another example of the LED pixel units that make up an LED panel, which are along... Figure 6A A cross-sectional view of the BB line.

[0028] Figure 7 This is a schematic diagram illustrating an example of the arrangement of LED elements in an LED panel according to another embodiment of the present invention.

[0029] Figure 8 This is an exploded perspective view schematically illustrating other structural examples of an LED panel. Detailed Implementation

[0030] Hereinafter, with reference to the accompanying drawings, the LED panel and planetarium of the present invention will be described.

[0031] exist Figure 1 The diagram shows a schematic representation of a planetarium according to an embodiment of the present invention. In this embodiment, there is no optical star projector in the central part of the dome 2, and LED panels 1 are distributed throughout the inner surface of the dome 2. Each LED panel 1 is driven by an LED driving circuit 3.

[0032] In addition, Figure 1 The diagram schematically illustrates an example of LED panels 1 arranged in a grid pattern along the meridians and parallels, but the shape and arrangement of the LED panels 1 are not limited thereto. Furthermore, the surface of each LED panel 1 can be flat, but is preferably curved to match the curvature of the dome 2.

[0033] Figure 2 This diagram illustrates an example of the arrangement of LED elements in LED panel 1. As shown, multiple LED pixel units are arranged on LED panel 1. Each LED pixel unit includes: a normal element 10, comprising a red LED element 11, a green LED element 12, and a blue LED element 13; and a low-brightness element 20, used to output a brightness lower than the minimum brightness of the normal element 10. Furthermore, the low-brightness element 20 is composed of a white LED element 21.

[0034] exist Figure 2 In the diagram, red LED element 11 is schematically represented by a circle marked with a horizontal line, green LED element 12 by a circle marked with a vertical line, blue LED element 13 by a circle marked with a diagonal line, and white LED element 21 by a white circle. Furthermore, in... Figure 2 In this context, each low-brightness element 20 is displayed smaller than each normal element 10, but the size of the low-brightness element 20 is not limited thereto.

[0035] In addition,Figure 2 In the figure, low-brightness elements 20 are arranged between the ordinary elements (11, 12, 13) arranged in a matrix. More specifically, along the tilt direction of the figure, the LED elements of any color of the ordinary elements (11, 12, 13) and the white LED elements 21 of the low-brightness elements 20 are arranged alternately, and along the longitudinal and transverse directions of the figure, columns of LED elements of any color of the ordinary elements (11, 12, 13) and columns of white LED elements 21 are arranged alternately.

[0036] In addition, Figure 2 The image shows an example where the normal element 10 is arranged in a grid pattern and the normal element 10 and the low-brightness element 20 are arranged alternately, but the arrangement pattern of the normal element 10 and the low-brightness element 20 is not limited to this. In addition, the normal element 10 may include not only red LED element 11, green LED element 12 and blue LED element 13, but may also include elements of other colors such as white elements, yellow elements and so on.

[0037] The minimum brightness of each white LED element 21 constituting the low-brightness element 20 is preferably less than 1 / 100 of the minimum brightness of each red LED element 11, green LED element 12, and blue LED element 13 constituting the normal element 10. Thus, even in a planetarium, dark celestial objects such as the Milky Way can be realistically represented by the LED panel 1.

[0038] Thus, in each LED pixel unit constituting the LED panel 1, in addition to the usual elements 10 (11, 12, 13), a low-brightness element 20 (21) is also provided.

[0039] Here, the low-brightness element 20 is composed of a single type of white LED element 21. This is because although the human eye has a very wide dynamic range relative to brightness, human vision can hardly perceive color under low illumination. For example, the Milky Way is actually a collection of celestial bodies of various colors, but it appears white to the human eye. Therefore, by using a single type of white LED 21 to constitute the low-brightness element 20, the cost of the LED panel can be reduced compared to using LED elements of each of the three primary colors.

[0040] Figure 3 This figure shows an example of a driving circuit for LED panel 1. As shown, the driving circuit includes a first PWM signal generator 31a for general components 10 and a second PWM signal generator 31b for low-brightness components 20.

[0041] The PWM signal output from the first PWM signal generator 31a switches the switching element 32a, which is connected in series with the normal element 10. On the other hand, the PWM signal output from the second PWM signal generator 31b switches the switching element 32b, which is connected in series with the low-brightness element 20. Figure 3 In the example shown, switching elements 32a and 32b are composed of PNP transistors. However, switching elements 32a and 32b are not limited to PNP transistors; for example, they could also be composed of TFTs.

[0042] The drive circuit also includes a limiting resistor 33a connected in series with the normal component 10 and a limiting resistor 33b connected in series with the low-brightness component 20. If the resistance value of the limiting resistor 33b connected in series with the low-brightness component 20 is set to, for example, 1000 times the resistance value of the limiting resistor 33a connected in series with the normal component 10, then for the same pulse width of the PWM control signal, the drive current flowing through the low-brightness component 20 can be made to be 1 / 1000 of the drive current flowing through the normal component 10. As a result, the brightness of the low-brightness component 20 can be made much smaller than the brightness of the normal component 10.

[0043] Furthermore, the second PWM signal generator 31b used for the low-brightness element 20, especially in the low-brightness region, outputs a PWM control signal with a pulse width smaller than that of the PWM control signal output by the first PWM signal generator 31a for the same dimming command value.

[0044] Here, in Figure 4 The diagram shows examples of the duty cycles of the PWM control signals output by the first and second PWM signal generators 31a and 31b for the input level of the dimming signal. Figure 4 The horizontal axis of the graph represents the input level with the maximum value set to 1.0, and the vertical axis represents the duty of the PWM control signal. Figure 4 Curve I in the graph represents the duty of the PWM control signal output by the second PWM signal generator 31b in response to the input level of the dimming signal, and curve II represents the duty of the PWM control signal output by the first PWM signal generator 31a in response to the input level of the dimming signal.

[0045] In the low-light-intensity region (e.g., when the input level is below 0.35), as shown by curve I, as the input level increases from 0, firstly, the duty of the PWM signal output from the second PWM signal generator 31b for the low-brightness element 20 increases from 0 to 1.0. Thus, in the low-light-intensity region, the normally off element 10 remains unchanged, and only the low-brightness element 20 is dimmed. Therefore, as schematically shown in the graph by curve III, dimming in the low-light-intensity region proceeds smoothly.

[0046] Next, if the duty level becomes 1.0, the low-brightness element 20 reaches maximum brightness. Then, as shown by curve II, as the input level further increases, the duty level of the PWM signal output from the first PWM signal generator 31a used by the usual element 10 rises. Thus, as schematically represented by curve III in the table, the LED panel dimming is smoothly performed from the low light intensity region to the maximum brightness.

[0047] In this way, by driving the normal element 10 and the low-brightness element 20 respectively with different PWM signal generators 31a and 31b, the brightness of the low-brightness element 20 becomes much smaller than that of the normal element 10. As a result, it is possible to provide an LED panel with a high dynamic range and a planetarium using this LED panel.

[0048] exist Figure 2 as well as Figure 3 In the example shown, the brightness of the low-brightness element 20 is reduced by making the drive current of the low-brightness element 20 smaller than that of the normal element 10. In this case, since the drive current of the low-brightness element 20 is extremely weak, the circuit board is required to have high insulation, and it is also susceptible to current leakage caused by the deterioration of insulation over the years.

[0049] Therefore, an example will be described in which the brightness of the low-brightness element 20 is not slightly reduced by the driving current of the low-brightness element 20.

[0050] Figure 5A as well as Figure 5B This represents an example of an LED pixel unit 1b constituting an LED panel 1. For example... Figure 5A As shown, the LED pixel unit 1b comprises one red LED element 11, one green LED element 12, one blue LED element 13, and one low-brightness element 20 constituting the general element 10, arranged on a rectangular substrate 40. However, the outline of the LED pixel unit 1b is not limited to a rectangle. Furthermore, the arrangement of the LED elements 11-13 and the low-brightness element 20, as well as the outline shape of each element, are not limited to this. Furthermore, the number of LED elements of each color constituting the LED pixel unit is not limited to one. Furthermore, the ratio of the number of LED elements of each color is not limited to this. Figure 6A as well as Figure 6B The example shown is the same.

[0051] like Figure 5B As shown, in the LED pixel unit 1b, the low-brightness element 20 includes a white LED element 21, a perforated plate 22 disposed on the white LED element 21, and a diffuser plate 23 covering the pinholes 22a of the perforated plate 22. Additionally, in Figure 5AThe illustration of diffuser plate 23 is omitted in the text.

[0052] By using the perforated plate 22 to reduce the brightness of the low-brightness element 20, even when the white LED element 21 is driven with a drive current at the same level as that of the red LED element 11, green LED element 12, and blue LED element 13 of the normal element 10, the brightness of the low-brightness element 20 can be sufficiently reduced. Thus, a high dynamic range can be achieved without making the drive current of the low-brightness element 20 too weak.

[0053] Furthermore, in Figure 6A as well as Figure 6B Another example of the LED pixel unit 1c constituting the LED panel 1 is shown in the image. For example... Figure 6A As shown, the LED pixel unit 1c has a red LED element 11, a green LED element 12, a blue LED element 13, and a low-brightness element 20 disposed on a rectangular substrate 40, which constitute the normal element 10.

[0054] like Figure 6B As shown, in the LED pixel unit 1c, the low-brightness element 20 includes a white LED element 21 and a light-reducing filter 24 disposed on the white LED element 21. Alternatively, the entire LED pixel unit 1c can be covered with a filter that partially provides a light-reducing portion, so that the light-reducing portion is located on the white LED element 21 of the low-brightness element 20.

[0055] By using the light-reducing filter 24 to reduce the light of the low-brightness element 20, even when the white LED element 21 is driven with a drive current at the same level as that of the red LED element 11, green LED element 12, and blue LED element 13 of the normal element 10, the brightness of the low-brightness element 20 can be sufficiently reduced. Thus, a high dynamic range can be achieved without making the drive current of the low-brightness element 20 too weak.

[0056] Alternatively, a reference can also be used simultaneously. Figure 5A as well as Figure 5B Description of the pinhole plate 22, reference Figure 6A as well as Figure 6B The light reduction unit described is like the light reduction filter 24, and the reference... Figure 3 The description describes a drive circuit that reduces drive current.

[0057] Furthermore, in the above embodiment, an example of using a white LED element 21 in the low-brightness element 20 is shown, but it is not limited to this. The low-brightness element 20 can also have LED elements with three primary colors. That is, as... Figure 7As shown, the low-brightness element 20 may also include a red low-brightness LED element 25, a green low-brightness LED element 26, and a blue low-brightness LED element 27. In this way, since the low-brightness element 20 also possesses the three primary colors, high color reproduction can be achieved even in low-brightness displays. Furthermore, the low-brightness element 20 may include not only red low-brightness LED elements 25, green low-brightness LED elements 26, and blue low-brightness LED elements 27, but also elements of other colors such as white and yellow.

[0058] The red low-brightness LED element 25, the green low-brightness LED element 26, and the blue low-brightness LED element 27 are, for example, the same as in the embodiments described above, and can be obtained by referring to... Figure 3 The circuit described is used to drive it.

[0059] Furthermore, in the case where the low-brightness element 20 includes a low-brightness LED element with three colors, it can also be referred to as follows. Figure 6A as well as Figure 6B As explained, the structure involves providing a light-reducing filter film on the low-brightness element 20. That is, the LED panel can also have, for example... Figure 8 The structure shown is as follows. High-brightness columns 46 and low-brightness columns 47 are alternately arranged on the substrate 40. Red LED elements 11, green LED elements 12, and blue LED elements 13 are arranged on the high-brightness column 46, while low-brightness red LED elements 41, low-brightness green LED elements 42, and low-brightness blue LED elements 43 are arranged on the low-brightness column 47. Thus, the red LED elements 11 and the low-brightness red LED elements 41, green LED elements 12 and the low-brightness green LED elements 42, and the blue LED elements 13 and the low-brightness blue LED elements 43 are arranged in groups 45. A light filter 50 is provided to cover these LED elements. The light filter 50 has a transparent film 51 at the location corresponding to the high-brightness column 46 and a light-reducing filter film 52 at the location corresponding to the low-brightness column 47.

[0060] Thus, for example, if the red LED element 11, green LED element 12, and blue LED element 13 are configured to emit light at the same brightness as the low-brightness red LED element 41, low-brightness green LED element 42, and low-brightness blue LED element 43, the low-brightness element 20 can be achieved by providing a light-reducing filter film 52. Furthermore, Figure 8 The configuration of the components shown is an example, and the configuration can be changed as appropriate.

[0061] Furthermore, in driving the low-brightness red LED element 41, the low-brightness green LED element 42, and the low-brightness blue LED element 43, it is also possible to utilize, as shown in the reference...Figure 3 The driving circuit of the current setting resistor with such a high resistance value is used to reduce the brightness of the element, and further reduce the light by passing through the light reduction filter film 52, thereby realizing the low brightness element 20.

[0062] In addition, it can also replace the light-reducing filter film 52, as shown in the reference. Figure 5A as well as Figure 5B As explained, pinholes are used to reduce light intensity.

[0063] The present invention has been described above with reference to preferred embodiments, but the present invention is not limited to the foregoing embodiments, and various modifications can be made within the scope of the present invention.

[0064] For example, in the above embodiments, an LED panel using LED elements was described as an example. However, the above technology can also be applied to self-emissive element panels that widely use self-emissive elements, such as organic EL (organic electroluminescence) elements (OLED elements). For example, in an organic EL element panel using organic EL elements, ordinary elements including red, green, and blue elements can be formed using light-emitting layers with different emission colors, such as red, green, and blue light-emitting layers. Furthermore, ordinary elements can also be formed using a white light-emitting layer and a color filter. In addition, in low-brightness elements used to output brightness lower than the minimum brightness of ordinary elements, light-emitting layers with different emission colors, such as red, green, and blue light-emitting layers, can be used, and white organic EL elements as white self-emissive elements can also be used.

[0065] Furthermore, while the above embodiments illustrate an example of LED panels distributed throughout the inner surface of the planetarium dome, the application of the self-emissive element panel or LED panel of the present invention is not limited to planetariums; for example, it can also be applied to systems for other displays. That is, the display surface does not need to be located on the inner surface of the dome 2; the display surface can be a plane or the like. Furthermore, the displayed image is not limited to the starry sky or the like; it can be any image. For example, these panels can also be used in large signage displays or the like, where the display surface is planar and advertisements are displayed therein.

Claims

1. A self-light-emitting element panel which arranges a plurality of self-light-emitting pixel units and has a drive circuit, the plurality of self-light-emitting pixel units each have: a normal element including a red element based on a self-light-emitting element, a green element based on a self-light-emitting element, and a blue element based on a self-light-emitting element; and a low-luminance element which performs output with a luminance lower than a minimum luminance of the normal element, the drive circuit is configured to be able to dim the normal element to dim the low-luminance element, thereby performing display with a luminance lower than the minimum luminance of the normal element, and perform display with a high luminance higher than the minimum luminance of the normal element by dimming the normal element, configured to express an image by a gradation obtained based on luminances of the normal element and the low-luminance element each arranged.

2. An LED panel which arranges a plurality of LED pixel units and has a drive circuit, the plurality of LED pixel units each have: a normal element including a red LED element, a green LED element, and a blue LED element; and a low-luminance element which performs output with a luminance lower than a minimum luminance of the normal element, the drive circuit is configured to be able to dim the normal element to dim the low-luminance element, thereby performing display with a luminance lower than the minimum luminance of the normal element, and perform display with a high luminance higher than the minimum luminance of the normal element by dimming the normal element, configured to express an image by a gradation obtained based on luminances of the normal element and the low-luminance element each arranged.

3. The LED panel according to claim 2, wherein the low-luminance element includes a white LED element.

4. The LED panel according to claim 2, wherein the low-luminance element includes a red LED element, a green LED element, and a blue LED element.

5. The LED panel according to any one of claims 2 to 4, wherein the low-luminance element performs output with a luminance lower than the normal element for a drive current of the same magnitude as a drive current applied to the normal element.

6. The LED panel according to any one of claims 2 to 4, wherein the low-luminance element has a light-reducing unit.

7. The LED panel according to any one of claims 2 to 4, wherein a minimum luminance of the low-luminance element is 1 / 100 or less of a minimum luminance of the normal element.

8. A planetarium, the self-light-emitting element panel of claim 1 or the LED panel of any one of claims 2 to 7 is disposed on an inner surface of a dome.

Images