JPH10319895A - Display device, display method, and medium recording display control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent flicker and to enable preventing unnatural coloring by preventing that a ratio of a non-lighting state to a lighting state is made infinity. SOLUTION: Light emission luminance based on quantization data is made (a), reflection luminance by external light is made (b), when an essential ration of a non-lighting state to a lighting state is indicated as b:a+b, a non-lighting state is controlled not so as to be infinity. In this display device, a driving circuit 60 controls luminance of each LED 71, but this is controlled with a time ratio of a lighting state and a putting-out state. And when a picture is displayed by controlling strength of a light emitting member such as the LED 71 and the like based on data to which a video signal and the like are quantized, occurrence of a region a luminance ratio is made infinity in a variation range of luminance is prevented by performing process varying a start point of quantization from 0 to 1 in an inverse γ compensation filter 40 performing inverse γcompensation and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, a display method, and a display control program for controlling the luminous luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel to display pixels. Related to a medium on which is recorded.

[0002]

2. Description of the Related Art Conventionally, as this type of display device, a display device disclosed in Japanese Patent Application Laid-Open No. Sho 59-208587 is known.
The display device disclosed in the publication performs pixel display by arranging light-emitting elements whose luminance can be controlled in a plane and controlling the luminance of each light-emitting element in accordance with the luminance of the pixel. At this time, the original video signal is quantized in 64 steps to control the luminance, and the minimum luminance state is a non-lighting state.

[0003]

In the above-mentioned conventional display device, an image having a high contrast is used by using the lighting state from the non-lighting state to the lighting state with the maximum luminance. Under the influence of the above, a state in which the non-lighting state and the lighting state are repeated after a very short period occurs, and a viewer of the image feels as if flickering in a dark part. In addition, among the RGB element colors, when the non-lighting state is stable for a certain color and flickers for the other colors, if the flickering part occurs, the color of the element color that turns on the light may be added. There is. That is, if the red element color flickers and the other element colors do not flicker, the flicker acts to add red to that part, giving an unnatural feeling.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a display device, a display method, and a medium recording a display control program which can eliminate flicker and prevent unnatural coloring. And

[0005]

In order to achieve the above object, the invention according to claim 1 controls the light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel. A display device for displaying a pixel by means of a display device, comprising: a light emission luminance a based on quantized data;
The ratio of the original unlit state to the lit state is b: a +
When represented by b, the non-lighting state is controlled so that this ratio does not become infinite.

In the invention according to claim 1 configured as described above, the pixel display is performed by controlling the light emission luminance of the light emitting members arranged in a plane based on the input data obtained by quantizing the pixel luminance. Emission luminance a based on the quantized data,
Assuming that the reflected luminance is b due to external light, the ratio between the unlit state and the lit state of each light emitting member is represented by b: a + b.
At this time, the reflection luminance b approaches "0" without limit at night, so that the ratio becomes infinite. Of course, strictly speaking, the reflection luminance “b” at night does not become 0, but it can be said that this ratio is practically infinite. Therefore, when the non-lighting state and the lighting state are repeated due to noise or the like, the flicker is clearly seen due to the infinite luminance ratio. However, in the invention according to claim 1, the non-lighting state is controlled so that this ratio does not become infinite. If the luminance ratio between the non-lighting state and the non-lighting state does not become infinity, a large change does not occur visually, and flicker can be suppressed.

[0007] The light emitting members arranged in a plane means what is called two-dimensionally arranged in a matrix, and need not be a flat surface. Further, the two-dimensional arrangement does not need to be at the position of the orthogonal lattice point. In the quantized data, the unlit state and the lit state are clearly distinguished, but various methods can be applied as a specific method for preventing the luminance ratio between the unlit state and the non-lit state from becoming infinite. is there. As an example, the invention according to claim 2 is the display device according to claim 1, wherein the non-lighting state and the lighting state when the reflection luminance b of the external light decreases as the original light emission luminance c at the time of non-lighting. B + c:
The configuration is such that a + b does not become infinite.

[0008] In the invention according to claim 2 configured as described above, based on the quantized data, even when the light is originally turned off, the light emission state becomes the light emission luminance c so that the external luminance can be obtained. B + c: a, which is the ratio between the unlit state and the lit state, even when the light reflection luminance b is reduced.
+ B does not become infinite. In other words, even if the quantized data is in the non-lighting state, the light emitting state is set, thereby preventing infinity.

As another example based on the same concept, the invention according to claim 3 controls the light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel. The display device is configured to display input data indicating an unlit state with a minimum luminance. Also in the invention according to claim 3 configured as described above, the pixel display is performed by controlling the light emission luminance of the light emitting member arranged in a plane based on the input data obtained by quantizing the pixel luminance. Is also displayed with the minimum luminance. As a result, the complete non-lighting state disappears, and the ratio between the minimum luminance at the time of the non-lighting state and the minimum luminance of the lighting state does not become infinite in input data.

As described above, there are various specific methods for preventing the ratio of the luminance at the time of the non-lighting state to the minimum luminance at the time of the lighting state from becoming infinity in terms of input data. Can be adopted. As an example, the invention according to claim 4 is configured such that in the display device according to any one of claims 1 to 3, the luminance of the light emitting member is uniformly increased by a predetermined amount. In the invention according to claim 4 configured as described above, by uniformly increasing the luminance of the light emitting member by a predetermined amount, even if the input data indicates a non-lighting state, the lighting state is increased by the increased luminance. Becomes This increase in luminance may be uniformly increased at the data stage, or may be increased as an offset amount in the light emitting member. In this case, the increase may be a functional increase in which the increase gradually decreases.

Further, according to a fifth aspect of the present invention, in the display device according to any one of the first to fourth aspects, the display device has a conversion table for converting the input data, and the conversion table has an unlit state. Is not provided. In the invention according to claim 5 configured as described above, when the computer has a conversion table for converting the input data when handling the quantized data, the input data is converted by the conversion table. Since the conversion table does not include data indicating the non-lighting state, the non-lighting state always disappears after the conversion.

The data representing the non-lighting state in this case is as follows.
It is not necessary to necessarily limit the value to “0”, and any value may be used as long as it represents the luminance of the non-lighting state as the luminance of the light emitting member. Further, according to a sixth aspect of the present invention, in the display device according to any one of the first to fifth aspects, the display device further comprises a conversion filter for converting the input data, and the filter inputs data representing an unlit state. In this case, the data is converted into lighting data having a predetermined minimum luminance.

[0013] In the invention according to claim 6 having the above structure, there is provided a conversion filter for converting the input data, and when data representing a non-lighting state is input to the filter, a predetermined minimum luminance is obtained. Is converted to lighting data,
As a result, the light emitting member is turned on with the minimum brightness without being turned off. Further, the invention according to claim 7 is:
The display device according to any one of claims 1 to 6, wherein the starting point of the quantized data is "1".

Conventionally, the non-lighting state has occurred because the quantized data has a starting point of "0". However, in the invention according to the seventh aspect, the starting point of the quantized data is originally "0". Since it is "1", it does not have the non-lighting state. The invention according to claim 8 is the display device according to any one of claims 1 to 7, further comprising auxiliary lighting in addition to the light emitting member, and turning on the auxiliary lighting to turn off the pixels. It is configured to have the minimum luminance even in the state.

In the invention according to claim 8 configured as described above, an auxiliary illumination is provided in addition to the light emitting member, and the light emitting member itself is turned off based on the quantized input data. Even if the auxiliary lighting is turned on, the auxiliary lighting is turned on, and even when the pixels are in a non-lighting state, the display surface of the display device has a luminance equal to or higher than a certain value so that the ratio with the lighting state does not become infinite. Will have. According to a ninth aspect of the present invention, in the display device according to any one of the first to eighth aspects, when the reflection luminance of the external light is equal to or more than a predetermined value, the non-lighting state of the light emitting member is caused. When the value is equal to or less than a predetermined value, the non-lighting state of the light emitting member is prevented from occurring.

It can be said that whether or not the luminance ratio between the non-lighting state and the lighting state becomes infinite does not matter if the reflection luminance of the external light is sufficient. For this reason, in the invention according to claim 9 configured as described above, based on whether or not the reflection luminance of the external light is equal to or more than a predetermined value, the non-lighting state of the light emitting member is determined when the reflection luminance is equal to or more than the predetermined value. There is no problem even if it occurs, on the other hand, the non-lighting state of the light emitting member does not occur so that the luminance ratio between the non-lighting state and the lighting state does not become infinite in the practical sense because the reflection luminance is equal to or less than a predetermined value. To do.

The above-described process of not causing a non-lighting state based on input data obtained by quantizing the luminance of a pixel is also effective for the process of quantizing a video signal representing luminance. According to a tenth aspect of the present invention, the video signal is converted into quantized data based on the quantized data in order to convert the fluctuation range of the video signal representing the luminance into a range in which the luminance of the light emitting member can be adjusted. The light emitting member is configured not to cause a non-lighting state.

In the tenth aspect of the present invention, the brightness range is effectively quantized in order to obtain the maximum contrast in the original quantization. By preventing such a situation, the state of the infinite luminance ratio between the non-lighting state and the lighting state is eliminated, and the flicker is suppressed. In addition, it is easy to understand that a method of not causing the above-mentioned non-lighting state based on the quantized input data is not limited to a substantial device, and can also function as the method. For this reason, the invention according to claim 11 is a display method for controlling the light emission luminance of a light emitting member arranged in a plane on the basis of input data obtained by quantizing the luminance of a pixel to display a pixel. The non-lighting state is controlled so that this ratio does not become infinite when the ratio between the original non-lighting state and the lighting state is expressed as b: a + b as the emission luminance a based on the luminance and the reflection luminance b due to external light. It is configured as a method.

That is, there is no difference in that the present invention is not necessarily limited to a substantial device but is also effective as a method. By the way, as described above, such a display device may exist alone or may be used while being incorporated in a certain device. Yes, it can be changed as appropriate, such as software or hardware. When software for controlling a display device is realized as an example of realizing the idea of the present invention, the software naturally exists on a recording medium on which such software is recorded, and it must be said that the software is used.

As an example thereof, the invention according to claim 12 records a display control program for controlling the light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel to display a pixel. In the medium, the ratio between the original unlit state and the lit state is b: a as the emission luminance a based on the quantized data and the reflection luminance b due to the external light.
When represented by + b, the non-lighting state is controlled so that this ratio does not become infinite.

Of course, the recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future. Also, the duplication stages of the primary duplicated product, the secondary duplicated product, and the like are equivalent without any question. In addition, the present invention is still used even when the supply method is performed using a communication line, and the same applies to a case where the information is written on a semiconductor chip.

Further, even when a part is implemented by software and a part is implemented by hardware, there is no difference in the concept of the invention, and it is necessary to record a part on a recording medium. It may be in a form that is appropriately read in accordance with it.

[0023]

As described above, according to the present invention, since the ratio between the unlit state and the lit state is not infinite, flickering is prevented, and at the same time, the element is colored in a specific element color to cause unnaturalness. A display device capable of preventing an image from being formed can be provided.

Further, according to the second aspect of the present invention, the light emission luminance c can be given even at the time of non-lighting. Further, according to the third aspect of the invention, it is possible to display and realize the input data indicating the non-lighting state with the minimum luminance. Furthermore, according to the invention according to claim 4, it can be realized by an extremely easy method of uniformly increasing the luminance by a predetermined amount. Furthermore, according to the fifth aspect of the present invention, it is possible to realize the present invention very simply by eliminating the data indicating the non-lighting state in the conversion table of the input data.

Further, according to the invention according to claim 6,
This can be realized only by a filter that converts data representing a non-lighting state into lighting data having a predetermined minimum luminance when input.
Further, according to the invention of claim 7, since the starting point of the quantized data is merely "1", it can be realized very easily even for existing data. Further, according to the invention according to claim 8, the auxiliary lighting is turned on, so that the display device has the minimum luminance even when the pixels are not turned on.
There is no need to modify the light emission luminance of the existing light emitting member, and the realization becomes easy.

Further, according to the ninth aspect of the present invention,
In order to prevent the non-lighting state of the light emitting member from being caused only when the reflection luminance of the external light is equal to or lower than a predetermined value, the width of the contrast when the reflection luminance of the external light is equal to or higher than the predetermined value is made as large as possible. be able to. Further, according to the invention of claim 10, by applying the present invention to a case where a video signal is quantized, it is possible to prevent flickering or the like when displayed later as a video.

According to the eleventh aspect of the present invention, it is possible to provide a display method capable of preventing a flicker and preventing an unnatural image by being colored with a specific element color. . Further, according to the twelfth aspect of the present invention, there is provided a medium recording a display control program capable of preventing a flicker and preventing an unnatural image from being colored with a specific element color. Can be.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing a large-sized outdoor LED display device to which a display device according to an embodiment of the present invention is applied, and FIG. 2 shows a waveform of a composite video signal input to the LED display device. This is shown in the figure.

In FIG. 1, a video signal processing circuit 10 receives a composite video signal, outputs an RGB primary color drive signal, and outputs a synchronization signal to a timing signal generation circuit 20. Timing signal generation circuit 20
Generates a timing signal to each circuit described later based on the input timing of the synchronization signal.
A timing signal for sampling and performing A / D conversion is generated for the A / D conversion circuit 30 to which each of the GB primary color drive signals is input.

The A / D conversion circuit 30 is provided for each of the RGB primary color drive signals. The A / D conversion circuit 30 samples the primary color drive signals sequentially input as analog signals on the basis of the timing signal and converts them into 8-bit digital signals. Convert. The primary video drive signal is also provided with the original video signal offset level as shown in FIG. 2, but at the time when 256 gradations are formed by 8 bits, the offset level is subtracted to improve the resolution. Have been. Therefore, in order to maximize the contrast of the original image, the non-lighting state where the luminance is “0” level is changed to the maximum luminance state where the luminance is “255” level.

The result of conversion by the A / D conversion circuit 30 is inverse γ for returning the γ-corrected signal sent from the transmitting side to the original.
After being input to the correction filter 40 and subjected to predetermined conversion in accordance with the timing signal from the timing signal generation circuit 20, the conversion result is recorded in the screen memory 50 provided for each frame of RGB. It has become. The inverse γ correction filter 40 is constituted by a ROM, and outputs data stored at the same address in response to an 8-bit address input. This data is the so-called γ
Although it corresponds to the corrected signal, the present invention differs from the existing inverse γ correction as described later. In addition,
The screen memory 50 includes the above-described timing signal generation circuit 2
A timing signal is input from 0, a predetermined storage address is designated by an internal counter, and data is stored in the storage address.

Then, based on the data stored in the screen memory 50, the driving circuit 60
71 is driven. The LED 71 is provided as one unit for each pixel, one for blue and one for green,
Two are provided for red. This is because the emission luminance of red is lower than those of the other two colors. However, the configuration of each pixel can be changed as appropriate, and the display panel 71 is configured by LEDs capable of full-color display with one chip. Is also good. The drive circuit 60 adjusts the brightness of each LED 71. In the case of the present embodiment, the drive circuit 60 adjusts the brightness by the time ratio between the light-on state and the light-off state. In other words, it is always lit when the luminance level is at the maximum state of "255", and is always unlit at the minimum state of the luminance level "0". Note that the blinking state for adjusting the luminance has a repetition frequency extremely high, so that flicker does not pose any problem. In this case, the timing of the lighting state and the timing of the turning off state are also determined by the timing signal from the timing signal generation circuit 20 described above.

In the present embodiment, the brightness is adjusted by the time ratio between the light-on state and the light-off state. However, a configuration using a light emitting member that converts digital data representing the brightness into analog and adjusts the brightness with an analog voltage value is used. It is good. Here, the above-described inverse γ correction filter 40 will be described.
The gamma correction itself is performed by the video signal voltage (V1
) Is a correction applied on the signal output side of the television broadcast station or the like according to the display luminance (S) characteristic S = V1 ** 2.2 (1), and V1 = V0 ** ( -2.2) (2) Correction is performed based on the following relational expression. If the display is performed by a cathode ray tube based on the video signal voltage subjected to the γ correction, the relationship between the original video signal voltage (V0) and the display luminance (S) becomes linear. Therefore, when a display unit (light-emitting diode, plasma display panel, liquid crystal, etc.) other than the cathode ray tube is provided, S = V0 ** (− 2.2) (3), so that inverse γ correction is required. Becomes For example,
If the video signal voltage-luminance characteristics are linear, the relationship between the output video signal voltage VOUT and the input video signal voltage VIN should be VOUT = VIN ** 2.2 (4).

FIG. 3 shows the contents of the conversion table in the case where the inverse γ correction shown in equation (4) is applied. With the horizontal axis X as input data and the vertical axis Y as corrected output data, conversion in the case of 256 gradations is supported by a simple relational expression of Y = 255 (X / 255) ** 2 (5) I have. However, in such a correspondence relationship, when the output data Y is “0”, L
The ED 71 is turned off, and when the output data Y is “1”, the LED 71 is turned on. When quantization is performed excluding the offset level of the video signal shown in FIG. 2 and the offset level of the video signal is set to “0”, the output data Y becomes “0” due to noise in the video signal. Or "1". Assuming that the light emission luminance a of the LED 71 when the output data Y is “1” [candela / square meter] and the reflection brightness b due to external light b [candela / square meter], when the output data Y is “0” b [candela / square meter] ], And when the output data Y is “1”, it becomes (a + b) [candela / square meter]. When there is a certain degree of reflected brightness b due to external light, such as during daytime, this ratio is small, so that even if the output data Y becomes "0" or "1", there is no problem for the viewer. However, when the external light decreases at night, it becomes sufficiently negligible compared to the minimum luminance of the LED 71. In this case, the contrast ratio when the output data Y becomes "0" or "1" becomes extremely large. As described above, since the frequency at which flickering is repeated to adjust the luminance is extremely high, flicker does not occur. However, since the fluctuation of the output data Y is performed in frame units, the frequency is low and can be sufficiently sensed by human eyes. Then, as the surroundings become darker, the flickering becomes clearer.

On the other hand, even if the output data Y fluctuates between "1" and "2", this does not cause any problem. The reason that no problem occurs is that when the output data Y is “1”, (a + b)
In [Candela / square meter], output data Y is "2"
If (2a + b) [candela / square meter] is obtained at the time of, the luminance ratio will only double even if the reflection luminance b of the external light is “0”. In this embodiment, for this reason, the conversion formula of equation (5) is not used, and Y = (255-1). (X / 255) ** 2 + 1 (6) as shown in FIG. The conversion formula is adopted and is recorded in the inverse γ correction filter 40. Equation (6) indicates that when the adjustable brightness range of the LED 71 is from the “0” level to the “255” level,
Even at the minimum value, it means that the luminance of the “1” level is given, and even if the luminance of the LED 71 changes, the fluctuation ratio falls within a relatively small range of about several times.

Next, the operation of this embodiment having the above configuration will be described. When a composite video signal output from a television tuner or the like through intermediate frequency processing or the like is input to the video signal processing circuit 10, the video signal processing circuit 1
0 outputs a synchronizing signal to the timing signal generating circuit 20 and outputs RGB signals based on the sequentially input video signals.
And outputs the primary color drive signal. The primary color drive signals of each color are A / D converted by the A / D conversion circuit 30 at a sampling timing according to the arrangement of the LEDs 71 on the display panel 70. At this point, the digital signal is converted as a linear digital value with respect to the pure intensity in the video signal.

The conversion result of the A / D conversion circuit 30 is input to an address of an inverse γ correction filter 40 composed of a ROM, and the conversion data stored at the same address becomes data representing the luminance of each pixel, and becomes a screen memory. It is stored at 50 predetermined addresses. As shown in FIG. 4, the converted luminance value is any one of the “1” level to the “255” level, and a so-called “0” level non-lighting state does not occur. Of course, since the brightness adjustment itself of the LED 71 is performed based on the time ratio between the light-on state and the light-off state, a non-lighting state occurs in a strict sense, but an improper sense of whether or not it can be detected by human vision. No lighting condition occurs.

As a result, even when the luminance becomes “0” when the offset level is considered assuming that the video signal shown in FIG. 2 is inputted, the light emission luminance of the LED 71 is at the “1” level. Is secured. On the other hand, the primary color drive signal input to the A / D conversion circuit 30 also fluctuates, for example, when noise is added to the video signal. Therefore, the input data of the inverse γ correction filter 40 fluctuates in a dark portion, but the output data of the inverse γ correction filter 40 only fluctuates at a value of “1” or more, and the fluctuation ratio becomes infinite. There is nothing. This fluctuation is not a large fluctuation for a person watching the display panel 70 even at night, and does not give a flickering sensation.

On the other hand, this secondary effect has the further effect of eliminating unnatural coloring. Conventionally, when a primary color drive signal is generated based on a video signal, variations occur among RGB colors. As in the case of the above-described luminance ratio, if the variation between the colors is within an allowable range, the variation itself cannot be felt,
If the luminance ratio between the colors becomes infinite, as in the case where red emits light and green and blue do not emit light, the user will surely feel coloring. For example, suppose a human head is reflected in a video. In this case, the pixels of the hair part have a low luminance because they represent black, and the original luminance is “1” for red, “1” for green,
Assume that blue is “1”. At this time, even if only the red color becomes “2” due to the deviation of the balance and becomes “1” higher than the luminance of green and blue, the difference in the balance is hardly perceived. However, red is "1", green is "0",
When blue becomes "0", it is the same in that only red is increased by "1" from the brightness of green and blue,
The hair looks red because of the infinite luminance ratio.

On the other hand, since the output data of the inverse γ correction filter 40 is at least “1”, it is possible to avoid the unnaturalness that a specific color is added to a dark color portion. When the data subjected to the inverse γ correction with the starting point of the luminance being “1” is written for each pixel of each of the RGB colors, the drive circuit 60 determines the lighting period and the lighting period of the LED 71 on the display panel 70 according to the data. Change the ratio of Thereby, LE
The emission luminance of D71 is proportional to the brightness of the original subject.

Incidentally, the conversion of the expression (6) and the LED display device shown in FIG. 1 are merely an embodiment of the present invention. When quantizing video signals, etc., the conventional idea is to set the range from the unlit state to the maximum luminance state in order to secure the width of contrast, but the luminance ratio becomes infinite It is the concept of the present invention that no fluctuation range is provided. As an example, in the case of Expression (6), the starting point is set to “1” as the gradation value of quantization. In this case, the processing is performed at the same time as applying the inverse γ correction filter, but it is not always necessary to perform the processing at the same time. FIG. 5 shows an example in which a starting point correction filter 42 is provided together with an inverse γ correction filter 41 based on the equation (5). The correction equation changes depending on the properties of the light emitting member. Therefore, in a broad sense, it is also effective to separately provide an inverse γ correction for compensating for the luminance characteristic of the light emitting member and a filter whose starting point is “1” for the quantized data.

It is also effective to perform the conversion shown in equation (6) after writing the normal quantized data to the screen memory 51. FIG. 6 shows a schematic configuration of the LED display device in such a case. The read data from the screen memory 51 is converted by the inverse γ correction filter 43 before being input to the drive circuit 60. On the other hand, it is not necessarily possible to realize the quantization data without some kind of correction. FIG. 7 shows an example in which the quantization data is realized without any processing. The screen memory 51 is shown in FIG.
As in the case shown in FIG. 7, quantized data is written with the offset level subtracted from the primary color drive signal and the like. This data is input to one input terminal 61a of the comparator 61. Here, the input terminal 61a
In this method, the least significant bit is turned on while shifting the data by one bit, thereby increasing the data to “double + 1”. On the other hand, the output data of the inverse γ correction table 62 composed of a ROM is input to the other input terminal 61 b of the comparator 61.
The count output of the bit counter 63 is input. The clock 63 is input to the counter 63,
Since a reset input is applied every six clocks CLK, the counter output is repeatedly counted in the range of "0 to 255" as shown in FIG. FIG. 9 shows the stored contents of the inverse γ correction table 62, the contents of which are the same as those in the case of the equation (5), but are simply doubled as data.

That is, the output data of the screen memory 51 is "doubled + 1", and is compared with data obtained by "doubling" the inverse output of the count output of the clock CLK. As a result, even if the data is at the “0” level as the luminance, a minimum “1” is added, and the lighting period is corrected to a period in which the inverse γ correction is applied. Such a comparator 61 and the inverse γ correction table 6
By providing 2 and the counter 63 in the drive circuit, the relationship substantially as shown in FIG. 4 can be obtained without processing the quantized data.

Further, in the sense that a fluctuation range where the luminance ratio becomes infinite is not provided, an offset amount can be set in the drive circuit 64 as shown in FIG. 10, and the luminance according to the offset amount is uniformly set. It is also possible to adopt a configuration in which the number is increased. In this case, if the LED 71 is used, a period in which the LED 71 is turned on regardless of data may be provided, or a voltage corresponding to the offset amount may be applied to the light emitting bulb 72 having a filament as shown in FIG. good.
As shown in this example, the light emitting member is not limited to the LED 71, and a member such as the light emitting bulb 72, which can control the light emission luminance within a predetermined luminance range from the non-lighting state, can be used.

Until now, the luminance ratio of the light-emitting member that is lit based on the quantized data itself has not been infinite, but it is a problem for the viewer whether or not the pixel flickers. Yes, it can be considered as a pixel. For this reason, in the LED unit 73 shown in FIGS. 11 to 13, although no special brightness control is performed on the LEDs 73 a of the respective colors of RGB, a white LED 73 b is provided separately from these, and the LED 73 b is always turned on. Try to give the minimum brightness.

The LED unit 73 includes a substrate 73c into which each LED 73b can be inserted and fixed from the front side in order to maintain positioning and light-shielding properties between the colors. The conventional board only mounts the RGB LEDs from the front side, but the white 73 is provided on the center of the rear face of the board 73c.
A holding hole 73c1 is formed in which the ED 73b can be inserted and fixed. The holding hole 73c1 has a through hole 7c facing the front side.
3c2 is formed. This through hole 73c2 is
3b is formed to be small in order to adjust the light emission luminance, and emits light at the luminance when "1" is given as luminance data to each of the RGB LEDs 73a.

In such a configuration, the white LED 73b
Is always lit. Therefore, while the luminance range in the conventional state changes in the range of the maximum luminance from the light-off state,
Since the minimum brightness of the offset amount will be given,
A region where the luminance ratio becomes infinite in the fluctuation range does not occur.
Further, the control system using the quantized data does not need to be modified at all, and can be easily changed. Needless to say, the light-emitting member that is always turned on is not limited to the LED 73b, and may be provided with another illumination source to guide the light. Further, an illumination source for illuminating the display surface with low luminance may be provided outside the display device.

Until now, a non-lighting state is always prevented from occurring in the LED 71 and the like. However, if the reflection luminance b of the external light cannot be said to be "0", the contrast becomes larger as the luminance range becomes larger. Be rich. FIG. 14 includes, instead of the inverse γ correction filter 40 shown in FIG. 1, an inverse γ correction filter 44a that stores both the table conversion table shown in FIG. 3 and the table conversion table shown in FIG.
Causes the inverse gamma correction filter 44a to select one of them. The input voltage of one input terminal of the comparator 44b is varied by a phototransistor 44c that detects the intensity of external light, and the voltage of the other input terminal is adjustable by a variable resistor 44d. . The phototransistor 44c is exposed outside to detect the intensity of external light.

With this configuration, when the intensity of the external light is weak, the current flowing through the phototransistor 44c decreases, and the input voltage to the comparator 44b decreases. Then, the voltage value becomes smaller than the voltage value set at the other input terminal by the variable resistor 44d, and the output signal representing the comparison result causes the inverse γ correction filter 44a to select the table conversion table shown in FIG. . On the other hand, when the intensity of the external light is high, the current flowing through the phototransistor 44c increases, and the input voltage to the comparator 44b increases. Then, since the voltage becomes higher than the voltage value set at the other input terminal by the variable resistor 44d, the comparison result is inverted, and the inverse γ
This causes the correction filter 44a to select the table conversion table shown in FIG.

As described above, when displaying an image by controlling the intensity of the light emitting member such as the LED 71 based on the data obtained by quantizing the image signal or the like, the inverse γ correction or the like for performing the inverse γ correction is performed.
The starting point of quantization by the correction filter 40 is changed from “0” to “1”.
In order not to create an area where the luminance ratio becomes infinite in the luminance fluctuation range by performing processing such as changing the luminance, there is no flickering, and it is caused by the balance deviation between each element color. Unnatural coloring can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a large-sized outdoor LED display device to which a display device according to an embodiment of the present invention is applied.

FIG. 2 is a waveform diagram of a video signal.

FIG. 3 is a graph showing conversion table contents of a conventional inverse γ correction.

FIG. 4 is a graph showing the contents of a conversion table for inverse gamma correction according to the present invention.

FIG. 5 is a main block diagram according to a modified example of the present invention.

FIG. 6 shows a large-sized outdoor LE according to another modification of the present invention.
It is a schematic block diagram of D display device.

FIG. 7 is a main part block diagram according to another modification of the present invention.

FIG. 8 is a timing chart according to the modification.

FIG. 9 is a graph showing contents of an inverse γ correction table according to the modification.

FIG. 10 is a main part block diagram according to another modification of the present invention.

FIG. 11 is an exploded perspective view of an LED unit according to another modification of the present invention.

FIG. 12 is a rear perspective view of a substrate of the LED unit according to the modification.

FIG. 13 is a sectional view of an LED unit according to the modification.

FIG. 14 is a main part block diagram according to another modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Video signal processing circuit 20 ... Timing signal generation circuit 30 ... A / D conversion circuit 40 ... Inverse gamma correction filter 50 ... Screen memory 60 ... Drive circuit 70 ... Display panel 71 ... LED

Claims (12)

[Claims] 1. A display device for displaying a pixel by controlling the light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel, comprising: a light emission luminance a based on the quantized data; When the ratio between the original non-lighting state and the lighting state is represented by b: a + b as the reflection luminance b due to external light, the non-lighting state is controlled so that this ratio does not become infinite. Display device. 2. The display device according to claim 1, wherein the original emission luminance c at the time of non-lighting is b + c, which is a ratio between the non-lighting state and the lighting state when the reflection luminance b of the external light is reduced. A display device characterized in that a + b does not become infinite. 3. A display device for displaying a pixel by controlling light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel, wherein the input data representing a non-lighting state is also provided. A display device characterized by displaying with minimum luminance. 4. The display device according to claim 1, wherein the luminance of the light emitting member is uniformly increased by a predetermined amount. 5. The display device according to claim 1, further comprising a conversion table for converting the input data, wherein the conversion table does not include data indicating a non-lighting state. A display device characterized by the above-mentioned. 6. The display device according to claim 1, further comprising a conversion filter for converting the input data, wherein the filter is configured to receive a signal indicating a non-lighting state. A display device for converting the data into lighting data having a minimum luminance. 7. The display device according to claim 1, wherein the starting point of the quantized data is “1”. 8. The display device according to claim 1, further comprising an auxiliary illumination in addition to the light-emitting member, wherein the auxiliary illumination is turned on and the auxiliary illumination is turned on even when the pixel is not turned on. A display device characterized in that the display device has brightness. 9. The display device according to claim 1, wherein the non-lighting state of the light emitting member is generated when the reflection luminance of the external light is equal to or higher than a predetermined value, and the light emission member is equal to or lower than the predetermined value. A display device that does not cause a non-lighting state of the light emitting member when 10. The light-emitting member based on the quantized data while converting the video signal representing the luminance into a range in which the luminance of the light-emitting member can be adjusted to convert the video signal into quantized data. A display device for preventing a non-lighting state from occurring in the display device. 11. A display method for controlling a light emission luminance of a light emitting member arranged in a plane based on input data obtained by quantizing the luminance of a pixel to display a pixel, wherein a light emission luminance a based on the quantization data is provided. When the ratio between the original non-lighting state and the lighting state is represented by b: a + b as the reflection luminance b due to external light, the non-lighting state is controlled so that this ratio does not become infinite. Display method. 12. A medium in which a display control program for controlling the light emission luminance of a light emitting member arranged in a plane and displaying a pixel based on input data obtained by quantizing the luminance of a pixel is recorded. When the ratio between the original non-lighting state and the lighting state is expressed as b: a + b as the emission luminance a based on the reflection luminance b due to external light, the non-lighting state is controlled so that this ratio does not become infinite. A medium having recorded thereon a display control program.