JP2011249976A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of switching an image display mode and an illumination mode, and securing enough screen brightness at illumination.SOLUTION: A display device 1 which includes a transmissive screen and a light source comprising a plurality of LEDs 11-13 with different emission colors displays a color image corresponding to an image signal on the transmissive screen by lighting the LEDs 11-13 in time division. The display device 1 is provided with a main controller 31 which sets switchable between an image display mode for displaying the color image on the transmissive screen and an illumination mode for illuminating an external part by irradiation light from the light source through the transmissive screen, and a DMD controller 32 for lighting the LEDs 11-13 every period of emission from the light source in time division when the image display mode is set, and for lighting at least two LEDs out of the LEDs 11-13 simultaneously for a predetermined period every period of emission from the light source when the illumination mode is set.

Description

  The present invention relates to a display device, and more particularly to a display device that displays a color image on a transmissive screen using a solid light emitting element such as an LED (Light Emitting Diode) as a light source.

  In recent years, large-screen flat displays such as LCDs (Liquid Crystal Displays) and plasma displays are rapidly spreading as display devices. However, as the screen size increases, the weight and power consumption increase. Projector systems are often used for large screens exceeding. As such a projector system, a front projection system that projects an image onto a front screen and a rear projection system that projects an image from the back side of the screen using a transmissive screen are known.

  Front projection projectors (hereinafter referred to as front projection projectors) require an amount of light that can overcome the external light reflected on the screen, so they are not suitable for use in bright places and are assumed to be used in dark places. It was. On the other hand, a rear projection type projector (hereinafter referred to as a rear projection type projector) has a transmissive screen on which a Fresnel lens or a lenticular lens is arranged so that the light from the light source does not directly enter the eye while the front of the screen is subjected to antireflection treatment. By using it, it can be used in the same environment as a thin flat display such as an LCD or a plasma display.

  However, when LCDs, plasma displays, and rear projection projectors are used in bright environments such as outdoors, securing the screen brightness becomes a problem. In the case of an LCD, since it is not a self-luminous type, a backlight is required, and a light amount is lost due to the structure passing through a polarizing plate and a color filter. In the case of a plasma display, although it is a self-luminous type, it is turned on according to the number of light-emitting pixels, and particularly when the image color is white, it is turned on completely. It is not preferable in terms of baking and power consumption.

  On the other hand, for example, Patent Document 1 describes a rear projection type projector that is used in a bright environment such as outdoors. According to this, by changing the projection distance of the image display means used for the front projection projector, the image is reduced and the screen brightness of the transmissive screen is increased.

  Further, a technique using the above-described front projection type projector as a lighting device is known (see, for example, Patent Document 2). According to the technique described in Patent Document 2, when a pause in playback by the DVD playback unit is detected, a predetermined switching image is displayed by switching from the display image based on the image data output from the DVD playback unit. A switching image display unit and a switching image luminance setting unit for setting the luminance of the switching image based on an operation signal output from the remote control, and adjusting the luminance to an appropriate level and displaying the switching image at the time of image switching The room can be illuminated.

JP 2009-276488 A JP 2008-109609 A

  However, when the front projection type projector described in Patent Document 2 is used as a lighting device, the luminance at the time of illumination, that is, the luminance at the time of switching image display does not become higher than the white at the time of image projection by DVD reproduction, Since it is a front projection type, there is a problem that it is limited to illumination use in a dark environment. Furthermore, a conventional projector is not suitable for long-term use as a lighting device because the life of a lamp generally used as a light source is short.

  In addition, by using a rear projection type projector as described in Patent Document 1, it is considered that it can be used as a lighting device in a bright environment. The brightness cannot be higher than white at the time of projection. The reason for this will be described below.

  In projectors such as those described above, a single-panel type that uses a single DMD (Digital Micromirror Device) chip to display images for the three primary colors of RGB in a time-division manner is the mainstream. In this time division display, red (R), green (G), and blue (B) are sequentially turned on (on) and R, G, and B are simultaneously turned on (on) for each light emission cycle. There is no. Then, the R, G, and B lights that are sequentially turned on are reflected by the DMD, so that the images of the respective colors are sequentially projected onto the transmissive screen to form a color image. At this time, when displaying white with the maximum luminance, R, G, and B are all reflected by the DMD.

  On the other hand, since R, G, and B are sequentially turned on in time division even during illumination, white is the maximum luminance when all R, G, and B light is reflected by the DMD, as in image projection. . Therefore, when a single-plate projector using a single DMD chip is used as an illumination device, the luminance during illumination cannot be higher than white during image projection and is used as an illumination device in a bright place. In some cases, sufficient screen brightness cannot be obtained.

  The present invention has been made in view of the actual circumstances as described above, and an object thereof is to provide a display device capable of switching between an image display mode and an illumination mode and capable of obtaining sufficient screen brightness during illumination. To do.

  In order to solve the above-mentioned problems, a first technical means of the present invention includes a transmission screen and a light source composed of a plurality of solid state light emitting elements having different emission colors, and lights the plurality of solid state light emitting elements in a time-sharing manner. A display device for displaying a color image corresponding to an image signal on the transmissive screen, the image display mode for displaying the color image on the transmissive screen, and the transmissive light by irradiation light from the light source. Mode setting means for setting the illumination mode to illuminate the outside through a mold screen, and when the image display mode is set, the plurality of solid state light emitting elements are time-divided for each light emission period of the light source. When the lighting mode is set, at least two solid light emitting elements of the plurality of solid light emitting elements are kept in the same period for each light emission period of the light source. Is obtained is characterized in that a lighting control means for lighting the.

  The second technical means is characterized in that, in the first technical means, the lighting control means lights the plurality of solid state light emitting elements at different lighting ratios when the illumination mode is set. .

  A third technical means is characterized in that, in the first technical means, the lighting control means lights the plurality of solid state light emitting elements continuously when the illumination mode is set.

  According to a fourth technical means, in any one of the first to third technical means, an integrated lighting time value of each of the plurality of solid state light emitting elements in the illumination mode is the plurality of solid state light emission states in the image display mode. It is characterized by being larger than the integrated value of the lighting time of each element.

  According to a fifth technical means, in any one of the first to fourth technical means, the light emission colors of the plurality of solid state light emitting elements are three types of red, green, and blue. .

  According to a sixth technical means, in any one of the first to fifth technical means, the mode setting means sets the display device to the illumination mode in accordance with an operation instruction by a user. is there.

  A seventh technical means includes the human sensor according to any one of the first to fifth technical means, and the mode setting means detects the approach of a human by the human sensor. The display device is set to the illumination mode.

  The eighth technical means includes a timekeeping unit in any one of the first to fifth technical means, and the mode setting means detects the time when the predetermined time has been reached by the timekeeping part. The display device is set to the illumination mode.

  A ninth technical means includes the brightness sensor according to any one of the first to fifth technical means, and the mode setting means detects that ambient brightness has become dark by the brightness sensor. In this case, the display device is set to the illumination mode.

  According to a tenth technical means, in any one of the first to ninth technical means, the display device includes a unit including the transmissive screen and the light source as one display unit, and a plurality of the display units are provided. The screen aggregate is configured as a single unit, and the screen aggregate is characterized in that at least one of the plurality of display units is set to the illumination mode.

  According to the present invention, in a display device that includes a transmissive screen and a solid light emitting element such as an LED as a light source and lights each solid light emitting element in a time-sharing manner, an image display mode and an illumination mode are set. In the illumination mode, at least two solid state light emitting elements can be turned on at the same time, so that sufficient screen brightness can be obtained during illumination.

It is the figure which showed typically schematic structure of the display apparatus which concerns on this invention. It is a figure which shows the structural example of the optical engine shown in FIG. FIG. 2 is a block diagram for explaining a configuration example of a main part of a control system of the display device shown in FIG. 1. It is a figure for demonstrating an example of the light emission timing of the light source with which a display apparatus is provided. It is a figure which shows the structural example of the display apparatus which concerns on other embodiment of this invention.

  Hereinafter, preferred embodiments according to a display device of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram schematically showing a schematic configuration of a display device according to the present invention, in which 1 denotes the display device. The display device 1 displays an image by a single-plate rear projection projector using a single DMD chip, and includes a transmissive screen 2, a reflector mirror 5, and an optical engine 10. In the transmissive screen 2, a lenticular lens 3 disposed on the viewer side and a Fresnel lens 4 disposed on the light source side are disposed facing each other. A transparent protective sheet can be disposed on the viewer side surface of the lenticular lens 3. In the lenticular lens 3, a black portion extending in the horizontal direction and a lens portion through which light from the light source passes are alternately arranged. The Fresnel lens 4 is formed of a concentric lens corresponding to the center of the projection optical axis from the light source, and the projection light from all directions is guided so as to enter the lens portion of the lenticular lens 3.

  The image light enlarged and projected from the optical engine 10 is irradiated to a reflector mirror 5 provided in an inclined state facing the transmissive screen 2, and the image light reflected by the reflector mirror 5 is transmitted to the transmissive screen. 2 is projected on the back. The transmissive screen 2 displays an image on the front surface thereof by image light that is enlarged and projected.

  FIG. 2 is a diagram showing a configuration example of the optical engine 10 shown in FIG. The optical engine 10 includes LEDs 11, 12, and 13, which are examples of a plurality of solid state light emitting elements having different emission colors, as a light source. The emission color of the LED 11 is green (G), the emission color of the LED 12 is red (R), and the emission color of the LED 13 is blue (B). The display device 1 includes a transmissive screen 2 and a light source including LEDs 11, 12, and 13, and turns on the LEDs 11, 12, and 13 in a time-sharing manner, whereby a color image corresponding to an image signal is applied to the transmissive screen 2. indicate.

  More specifically, the LEDs 11, 12, and 13 that are light sources are sequentially turned on at a predetermined timing, and R, G, and B monochromatic lights are irradiated in a time-sharing manner. The R, G, B light from the light source is converted into parallel light by the collimator lens 14, and the R, G, B light is on the same optical axis by the dichroic mirrors 15, 16 that reflect only the corresponding color. Is guided to. The light guided on the same optical axis passes through the rod lens 17 and the fly-eye lens 18, is reflected by the mirror 19, and further passes through the convex lens 20 so as to become a predetermined diffused light, and passes to the DMD 21. Incident.

  In the DMD 21, one micromirror constitutes one pixel, and a large number of micromirrors are two-dimensionally arranged according to the number of pixels. Further, the DMD 21 is controlled such that the deflection angle of each micromirror changes in a binary manner (on / off) in accordance with the image signal.

  That is, the deflection angle of the micromirror is turned on according to the image signal in synchronization with the lighting of the R light source, the G light source, and the B light source. For example, when the R light source is turned on, in synchronization with this, the micromirror is turned on for the pixel including the R component of the image signal, and the light from the R light source is reflected by the micromirror. At this time, the micromirror is turned off for pixels not including the R component of the image signal, and the light from the R light source is absorbed by a light absorbing plate (not shown). Similarly, the light from the G light source and the B light source is also reflected by the micromirror.

  Then, the reflected light (image light) of R, G, and B sequentially reflected by the micromirror is incident on the projection lens 22 configured by the magnifying optical system, is magnified by the projection lens 22 at a predetermined diffusion angle, and is transmitted. Projected on the screen 2. In this way, a single color image can be formed by sequentially projecting monochromatic image light of R, G, and B colors onto the transmissive screen 2. Note that the micromirror forms monochromatic image light corresponding to each of R, G, and B on the transmission screen 2 corresponding to the lighting period (light emission period) of each of the R light source, the G light source, and the B light source. During the light emission period, the amount of light can be changed in units of pixels by changing the on-time of the micromirror, that is, the time of reflection toward the transmissive screen 2.

  In the above description, R, G, and B LEDs are used as the solid-state light emitting elements of the light source, but a laser light source may be used instead of the LEDs. Moreover, you may use several LED and laser per color, or may combine LED and a laser.

  FIG. 3 is a block diagram for explaining a configuration example of a main part of the control system of the display device 1 shown in FIG. In the figure, 31 is a main controller, 32 is a DMD controller, 33 is an LED driver unit, 34 is an operation unit, 35 is a human sensor, 36 is a timer, and 37 is a brightness sensor. The main controller 31 is a control unit configured with a CPU, a memory, and the like for controlling the display device 1. The DMD controller 32 controls on / off of the micromirror of the DMD 21 and also controls the LED driver unit 33 to control lighting of the light source composed of the LEDs 11, 12, and 13. The operation unit 34 includes operation buttons and the like for the user to perform various operations on the display device 1, and may be a remote controller, for example.

  The main characteristic part of the present invention is to enable switching between the image display mode and the illumination mode and to obtain a sufficient screen brightness at the time of illumination. As a configuration for this, the display device 1 illuminates the outside through the transmissive screen 2 with an image display mode in which a color image is displayed on the transmissive screen 2 and light emitted from a light source including the LEDs 11, 12, and 13. When the mode setting means for setting the illumination mode to be switchable and the image display mode are set, the LEDs 11, 12, and 13 are turned on in a time-sharing manner for each light emission cycle of the light source, and when the illumination mode is set, the light source Lighting control means for lighting at least two of the LEDs 11, 12, and 13 simultaneously for a predetermined period for each light emission period. The mode setting means is realized by the main controller 31, and the lighting control means is realized by the DMD controller 32.

  In the above, the main controller 31 can switch between the image display mode and the illumination mode in accordance with an operation instruction from the user. For example, it is assumed that the user is displaying an image on the display device 1, that is, the case where the “image display mode” is set. The image at this time may be a television image when the display device 1 has a tuner function, or may be an image read from a recording medium such as a DVD. Then, when the user presses the “mode switching button” from the operation unit 34 such as a remote controller, the “image display mode” is switched to the “illumination mode”. In this case, the display device 1 functions as an illumination device that stops image display and illuminates the outside via the transmission screen 2.

  That is, in FIG. 3, the main controller 31 that has received the mode switching operation signal from the operation unit 34 switches to and sets either the “image display mode” or the “illumination mode” based on this operation signal. The mode setting signal is transmitted to the DMD controller 32. The DMD controller 32 controls lighting of the LEDs 11, 12, and 13 based on the mode setting signal, and controls on / off of the micromirror of the DMD 21.

  Note that switching to the “illumination mode” is not limited to the above example. For example, when a person approaches, when a predetermined time comes, or when the surrounding brightness becomes dark, The display device 1 may be automatically shifted to the “illumination mode” using the above as a trigger. Specifically, when the human sensor 35 detects that a person is approaching, the display device 1 is set to the “illumination mode”. The human sensor 35 uses a general infrared ray, detects a distance to an object (human) located in front of the display device 1, converts this to a voltage, and supplies the voltage to the main controller 31. Then, when the voltage value is larger than the threshold value, the main controller 31 determines that a person has approached and shifts the display device 1 to the “illumination mode”. For example, assume a case where a display device is configured with a plurality of screens as shown in FIG. 5 described later, and this display device is applied to a ticket vending machine or the like. When it is detected that a person has approached the ticket vending machine, the operability and visibility can be improved by shifting the screen near the operation unit operated by the person to the “illumination mode”.

  Further, when the timer 36 detects that the predetermined time has been reached, the display device 1 may be set to the “illumination mode”. The predetermined time may be set to a time when the surroundings are dark, such as 6 pm (18:00). When the main controller 31 detects that the time measuring unit 36 has reached 6:00 pm, the main controller 31 shifts the display device 1 to the “illumination mode”. For example, when the display device 1 is a hanging television from the ceiling, when it is detected that the surroundings are dark, the display device 1 can be shifted to the “illumination mode” and the display device 1 can be used as a security light (nightlight). .

  Further, when it is detected by the brightness sensor 37 that the surrounding brightness is dark, the display device 1 may be set to the “illumination mode”. The brightness sensor 37 detects ambient brightness (brightness), converts it into a voltage, and supplies it to the main controller 31. When the voltage value is smaller than the threshold value (that is, dark), the main controller 31 determines that the surrounding has become dark and shifts the display device 1 to the “illumination mode”.

  In FIG. 3, in the above “illumination mode”, the DMD controller 32 turns on all the micromirrors constituting the DMD 21 and simultaneously lights at least two of the R, G, and B light sources for a predetermined period. . At this time, the three light sources may be turned on at different lighting ratios, or the three light sources may be turned on continuously. Thereby, sufficient screen brightness can be obtained during illumination. That is, in the “image display mode”, there is a restriction that the respective colors of R, G, and B are sequentially turned on, so that it is not possible to simultaneously emit two or more colors, but in the “illumination mode”, R, G, and B Since there is no restriction that each color is turned on sequentially, two or more colors can be turned on simultaneously unlike the “image display mode”. This will be specifically described with reference to FIG.

  FIG. 4 is a diagram for explaining an example of the light emission timing of the light source provided in the display device 1. FIG. 4A shows the light emission timing of the light source in the image display mode, and FIG. 4B shows the light emission timing of the light source in the illumination mode. In the “image display mode” of FIG. 4A, one light emission cycle of the light source is T, the lighting time of the R light source is T1, the lighting time of the G light source is T2, and the lighting time of the B light source is T1. The light quantity of each light source is determined according to the lighting time of each light source. Each light source is turned on in a time-sharing manner for each light emission period T. In this example, there is a relationship of T1: T2 = 1: 2. That is, since R, G, and B are lit at a ratio of 1: 2: 1, white light can be obtained when image display is performed at this lighting ratio. Further, since the light emission period T is time-divided by the lighting times of R, G, and B, the integrated value of the lighting times of R, G, and B is 2T1 + T2 = 4T1, which matches the light emission period T.

  On the other hand, in the “illumination mode” of FIG. 4B, one light emission cycle of the light source is set to T, which is the same as in the “image display mode”, the R light source lighting time is T1 ′, and the G light source lighting time is T2 ′. Let the lighting time of the B light source be T1 ′. In this “illumination mode”, control is performed so that at least two light sources are turned on simultaneously for a predetermined period. In this example, the R light source and the G light source are turned on simultaneously during time T1 ', and the G light source and the B light source are also turned on simultaneously during time T1'. In the case of this example, in FIGS. 4A and 4B, T1 ′ = 1.5T1 and T2 ′ = 1.5T2.

  When normal white light is desired in this “illumination mode”, R, G, and B are turned on at a ratio of 1: 2: 1 as in the “image display mode” of FIG. In this case, the integrated value of the lighting times of R, G, and B is 2T1 ′ + T2 ′ = 3T1 + 1.5T2 = 6T1. In the “image display mode” in FIG. 4A, since the integrated value of the lighting time is 4T1, the integrated lighting time in the “illumination mode” is 1.5 times the integrated lighting time in the “image display mode”. It is possible to obtain a light amount that is 1.5 times the light amount in the “image display mode”.

  Further, in the “illumination mode”, when all of R, G, and B are continuously lit, the integrated values of the R, G, and B lighting times are 4T1 × 3 = 12T1, and the “illumination mode” The accumulated lighting time is three times as long as the accumulated lighting time in the “image display mode”, and a light amount that is three times the light amount in the “image display mode” can be obtained. Moreover, by adjusting the lighting times of R, G, and B, not only white but also general illumination colors such as a light bulb color and a daylight color can be freely reproduced.

  In FIG. 4B, the R and B lighting times are shorter than the G lighting time, but the R and B lighting times may be the same as the G lighting time. In this example, an off period in which all of R, G, and B are not lit is provided, but it may be continuously lit for the entire period. In addition, since the lighting times of R, G, and B can be appropriately increased or decreased, the hue in the “illumination mode” can be changed to a desired hue.

  In this way, by controlling the integrated value of the lighting time of each light source in the “illumination mode” to be larger than the integrated value of the lighting time of each light source in the “image display mode”, the luminance at the time of illumination is controlled by the image. Since the luminance can be higher than white at the time of projection, sufficient screen (screen) luminance can be obtained when used as a lighting device in a bright place.

  FIG. 5 is a diagram illustrating a configuration example of a display device according to another embodiment of the present invention. The display device 1 'of this example is a screen in which a unit including the transmissive screen 2 and the LEDs 11, 12, 13 shown in FIG. 1 is formed as one display unit, and a plurality of display units 6a to 6d are integrally arranged. Configured as an aggregate. Specifically, in the display device 1 ′, one display unit corresponds to the display device 1 in FIG. 1, and four display devices 1 are integrally connected. Accordingly, each of the display units 6a to 6d can be set by switching the “image display mode” or the “illumination mode”.

  In FIG. 5, in the screen aggregate constituting the display device 1 ′, at least one display unit among the plurality of display units 6 a to 6 d is set to the illumination mode. The display device 1 ′ includes an operation panel 7. In this example, in order to improve the operability and visibility of the operation panel 7 by the user U, the display unit 6 d closest to the operation panel 7 is set to “lighting mode”. Is set.

  Of course, all the display units 6a to 6d may be set to the “lighting mode”, and which display unit is set to the “lighting mode” can be appropriately set based on the operation by the user U. In this way, by setting a part of the screen aggregate to the “illumination mode”, it is possible to perform appropriate illumination for the user. Further, by setting the entire surface of the screen assembly to the “illumination mode”, a wider range of illumination can be performed.

  As described above, according to the present invention, in a display device that includes a transmissive screen and a solid light emitting element such as an LED as a light source and lights each solid light emitting element in a time-sharing manner, an image display mode and illumination are displayed. In the illumination mode, at least two solid state light emitting elements can be turned on at the same time, so that sufficient screen brightness can be obtained during illumination.

  In the image display mode, a solid-state light emitting element such as an LED of each color (R, G, B) is used as a light source, and a color image is displayed by sequentially lighting R, G, B, and further, R, G By providing an illumination mode in which at least two of B and B are turned on simultaneously, a brighter screen brightness than that in the image display mode can be realized.

  In addition, since a solid-state light emitting element is used as a light source, the life of the light source is much longer than that of a lamp light source of a conventional projector, and is longer than that of a fluorescent lamp generally used as an illumination light source. Enable use. Since a solid-state light emitting element is used, the applied voltage is low (several volts per element), so that it can be used as a battery-operated emergency light.

  In particular, when a user's work such as driving through or giving out a card such as a ticket vending machine is required, the display device of the present invention can use the display screen as illumination, so the user's operability and visibility can be improved. Can be improved.

  Compared to LCDs and plasma displays, the lighting mode of the present invention has a high light utilization efficiency and can be freely adjusted for light control and color. It can also be used as a night light when you are not watching TV.

DESCRIPTION OF SYMBOLS 1,1 '... Display apparatus, 2 ... Transmission type screen, 3 ... Lenticular lens, 4 ... Fresnel lens, 5 ... Reflector mirror, 6a-6d ... Display unit, 7 ... Operation panel, 10 ... Optical engine, 11-13 ... LED (light source), 14 ... collimator lens, 15, 16 ... dichroic mirror, 17 ... rod lens, 18 ... fly eye lens, 19 ... mirror, 20 ... convex lens, 21 ... DMD, 22 ... projection lens, 31 ... main controller, 32 ... DMD controller, 33 ... LED driver unit, 34 ... operation unit, 35 ... human sensor, 36 ... timing unit, 37 ... brightness sensor.

Claims (10)

A transmissive screen and a light source composed of a plurality of solid-state light emitting elements having different emission colors are provided, and a color image corresponding to an image signal is displayed on the transmissive screen by lighting the plurality of solid-state light emitting elements in a time-sharing manner. A display device,
A mode setting means for setting the image display mode for displaying the color image on the transmissive screen and the illumination mode for illuminating the outside through the transmissive screen with irradiation light from the light source; and
When the image display mode is set, the plurality of solid state light emitting elements are turned on in a time-sharing manner for each light emission period of the light source, and when the illumination mode is set, the plurality of solid state elements for each light emission period of the light source. A display device comprising: lighting control means for simultaneously lighting at least two of the light emitting elements for a predetermined period.   The display device according to claim 1, wherein the lighting control unit lights the plurality of solid state light emitting elements at different lighting ratios when the illumination mode is set.   The display device according to claim 1, wherein the lighting control unit lights the plurality of solid state light emitting elements continuously when the illumination mode is set.   4. The display device according to claim 1, wherein an integrated value of lighting times of each of the plurality of solid state light emitting elements in the illumination mode is a lighting value of each of the plurality of solid state light emitting elements in the image display mode. A display device characterized by being larger than the integrated value of time.   5. The display device according to claim 1, wherein light emission colors of the plurality of solid state light emitting elements are three types of red, green, and blue.   6. The display device according to claim 1, wherein the mode setting unit sets the display device to the illumination mode in accordance with an operation instruction by a user.   The display device according to any one of claims 1 to 5, further comprising a human sensor, wherein the mode setting unit is configured to display the display device when the human sensor detects that a human is approaching. A display device that is set to an illumination mode.   The display device according to any one of claims 1 to 5, further comprising a timer, wherein the mode setting unit detects the display device when the timer has detected a predetermined time. A display device that is set to an illumination mode.   6. The display device according to claim 1, further comprising a brightness sensor, wherein the mode setting unit detects that the brightness of the surroundings has become dark by the brightness sensor. A display device, wherein the display device is set to the illumination mode.   The display device according to claim 1, wherein the display device includes a unit including the transmissive screen and the light source as one display unit, and a plurality of the display units are integrally disposed. The display device is configured as a screen assembly, and at least one display unit of the plurality of display units is set to the illumination mode.

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