JP2007225650A - Display device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce dazzle when a user lights an illuminating means and displays an image in a display element when rising. <P>SOLUTION: The display device 1 for controlling the brightness of the display element 3 so as to gradually increase the brightness after lighting of the illuminating means is equipped with a luminance controller 6 which gradually increases the brightness of the luminance controller 6 of the display element 3 by the two settings varying in the length of the time before the prescribed luminance is attained after the lighting of the illuminating means. The device is further equipped with a timer section 5 which performs lighting of the illuminating means. The luminance controller 6 gradually increases the brightness of the display element 3 by setting of the longer time before the attainment of the prescribed luminance of the two settings when lighting of the illuminating means by timer on. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device and a display method for controlling the brightness of a display unit to gradually increase after lighting means is turned on.

  Conventionally, display devices are equipped with a received light amount detection device so that displayed characters and figures are easy to see according to changes in the surrounding lighting environment, and the brightness is calculated according to the detected ambient brightness. There has been proposed a display device that automatically determines the brightness by using an equation (for example, Patent Document 1). Alternatively, in a lighting device for a residential lighting fixture, a lighting device that gradually brightens has been proposed in order to prevent glare caused by a sudden increase in brightness when the room lighting is turned on at night (for example, a patent) Reference 2).

Japanese Patent No. 2752309 JP-A-6-176875

  In general, when a human suddenly goes out from a dark place to a bright place having a certain luminance, he / she exhibits light adaptation characteristics. In other words, it is a transient that perceives brightness with high brightness that is dazzling at first, decreases perceived brightness with the passage of time, and perceives constant brightness with the original brightness after a certain amount of time has passed. It is known to show a response.

  By the way, in general, when a human is sleeping, the eyelid is often closed, and during sleep, the person feels darker than the surrounding illuminance. In addition, since it is assumed that humans are not in a state of feeling illuminance due to sleeping, the illuminance felt by human eyes is much darker than the actual ambient illuminance when waking up from sleep. You may think that you are feeling.

  That is, it may be assumed that the glare initially felt by a human being varies depending on the difference between the brightness in a dark place and the brightness in a bright place. Therefore, even when the brightness has the same brightness, the dazzling feeling at the time of getting up is different from the dazzling feeling at the time of waking up, and the dazzling feeling at the time of awakening that has already been awakened.

  However, Patent Literature 1 and Patent Literature 2 are dimming methods on the premise that the user is in an environment with a predetermined ambient illuminance, and do not consider the wake-up state of waking up from sleep.

  Therefore, the brightness adjustment methods disclosed in Patent Document 1 and Patent Document 2 have a problem that it is difficult to reduce glare when waking up.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a display device and a display method that reduce glare when lighting means is turned on when getting up.

  The display device of the present invention that achieves the above object is a display device that controls to gradually increase the brightness of the display unit after the lighting means is lit, and includes a luminance control unit that gradually increases the brightness of the display unit. The gist of the present invention is that the luminance control unit has two settings with different lengths of time until a predetermined luminance is reached after the lighting means is turned on.

  According to this configuration, by properly using the time to reach the predetermined brightness at the time of waking up and the time to reach the predetermined brightness at the time of waking, according to the adaptation time at the time of waking up and the adaptation time at the time of waking up The brightness of the display unit can be gradually increased, and the glare when the illumination unit is turned on when getting up can be reduced.

  In addition, the display device of the present invention further includes a timer unit that turns on the lighting unit when a timer is turned on, and the luminance control unit is configured to select the predetermined one of the two settings when the timer unit is turned on. The brightness of the display unit may be gradually increased by setting the longer time until the luminance is reached.

  The user of the display device usually wakes up frequently when the timer is turned on. Therefore, according to this configuration, it is possible to assume that the time point when the lighting unit is turned on is the time of getting up. Therefore, by determining whether or not the lighting unit is turned on by the timer being turned on, it is possible to determine whether or not the point in time when the lighting unit is turned on is a wake-up time. Therefore, when it is determined that the lighting means is turned on when the user wakes up, the luminance is slowly increased, and the glare felt when the user turns on the illuminating means when the user wakes up can be reduced.

  Here, the timer unit further includes an off-time measuring unit that measures an elapsed time from turning off the illumination unit to turning on the timer, and the luminance control unit, when the elapsed time is a predetermined time or more, The brightness of the display unit may be gradually increased by setting the longer of the two settings until reaching the predetermined luminance.

  In this way, if the elapsed time is equal to or longer than the predetermined time, the elapsed time can be assumed to be the sleeping time for which the user is sleeping, so it is determined whether or not the time when the timer is turned on is when the user wakes up The probability is improved, and the glare that is felt when the user turns on the illumination means when getting up can be reduced.

  In addition, the display device of the present invention further includes a time acquisition unit that acquires the actual time, and the luminance control unit determines that the actual time acquired by the time acquisition unit is greater than or equal to a predetermined time. When the time is within a predetermined time range, the brightness of the display unit may be gradually increased by setting the longer of the two settings until reaching the predetermined luminance.

  According to this configuration, when the actual time is within a predetermined time range, it can be assumed that the user is getting up, so the probability of determining whether or not the point in time when the lighting means is turned on is when the user is getting up Can be further improved, and the glare that the user feels when waking up can be reduced.

  In addition, the display device of the present invention further includes an ambient illuminance detection unit that detects ambient illuminance of the display device, and the luminance control unit includes at least one of the two settings according to the detected value of the ambient illuminance. The setting with the longer time until reaching the predetermined luminance may be changed, and the brightness of the display unit may be gradually increased by the changed setting.

  In general, the ambient illuminance is often different even at the same time. For example, the illuminance of the surrounding environment at the time of getting up may vary depending on the season, the weather, or the pulling of the curtains in the room. Therefore, by measuring the ambient illuminance, the brightness of the display can be gradually increased according to the characteristics of the human eye that the display feels differently depending on the illuminance of the surrounding environment. You can reduce the glare you feel.

  In addition, here, the luminance control unit changes the setting of the longer one of the two settings until reaching the predetermined luminance according to the detected change rate of the ambient illuminance value. The brightness of the display unit may be gradually increased according to the changed setting.

  In this way, the brightness of the display unit is gradually increased according to the characteristics of the human eye with respect to changes in the ambient illuminance value at the time of getting up, so that glare when the lighting means is turned on at the time of getting up is reduced. For example, when you wake up and immediately turn on the room lighting or darken the room lighting, the brightness of the display gradually increases according to the characteristics of the human eye with respect to changes in ambient illuminance values. can do.

  The present invention can also be regarded as a display method. In other words, after the lighting unit is turned on, the display method is controlled so as to gradually increase the brightness of the display unit, and the two settings differ in the length of time until the predetermined brightness is reached after the lighting unit is turned on. The gist of the invention is that a luminance control step of gradually increasing the brightness of the display unit is provided based on either one of the above.

  In addition, the display method of the present invention further includes a step of turning on the lighting unit when the timer is turned on, and the luminance control step includes the predetermined luminance of the two settings when the lighting unit is turned on when the timer is turned on. The brightness of the display unit may be gradually increased by setting the longer time to reach.

  The display method of the present invention further includes an ambient illuminance detection step of detecting ambient illuminance of the display device, wherein the luminance control step includes at least the above-described two settings according to the detected value of the ambient illuminance. The setting with the longer time until reaching the predetermined luminance may be changed, and the brightness of the display unit may be gradually increased based on the changed setting.

  Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment, when the wake-up time is determined by turning on the timer and the brightness of the display unit is gradually increased, the second embodiment determines the wake-up time by the actual time when the timer is turned on, and the brightness of the display unit. In the case where the brightness is gradually increased, the third embodiment is an embodiment in which the brightness of the display unit is gradually increased by detecting the ambient illuminance of the display device and changing the setting of the time until reaching the predetermined luminance. Indicates.

(First embodiment)
A case where the time of rising is determined by turning on the timer and the brightness of the display unit is gradually increased will be described based on the first embodiment. FIG. 1 is an external perspective view of a display device according to a first embodiment of the present invention. As shown in FIG. 1, the display device 1 is schematically configured by a housing 2, a display unit 3, a switch 4, a timer unit (not shown), an operation knob 5a, and a circuit block (not shown).

A display unit 3, a switch 4, and an operation knob 5a are attached to the housing 2. The display unit 3 is composed of a transmissive liquid crystal panel, and illumination means (not shown) is arranged on the back.
The circuit block is composed of a predetermined electronic circuit and is installed inside the housing 2. The switch 4 is a knob for switching whether the illumination means is turned on or off. The operation knob 5a is a knob for setting the time until the illumination unit is turned on, and functions as an operation knob of the timer unit 5 described in FIG. 2, and is displayed at a position where the user of the display device 1 can visually recognize. While looking at a digital display (not shown), the time until the illumination means is turned on can be set by operation.

  FIG. 2 shows a functional block diagram of the first embodiment of the present invention. The codes described in FIG. 2 correspond to the codes described in FIG. The circuit block performs functions as the luminance control unit 6 and the light source control unit 7. The light source 8 includes a fluorescent lamp, a light emitting diode, or an incandescent bulb, and is attached to the back surface of the display unit 3 to function as an illumination unit.

  Next, the operation of each functional block configured using FIG. 2 will be described. The user of the display device 1 manually operates the operation knob 5a and sets the time until the light source 8 is turned on while viewing the digital display. Here, the time until the light source 8 is turned on is defined as the scheduled lighting time. The timer unit 5 has a subtraction timer function. When the scheduled lighting time reaches 0, the timer unit 5 is turned on and outputs lighting instruction information to the luminance control unit 6. The luminance control unit 6 obtains lighting instruction information and outputs the luminance control information to the light source control unit 7. The light source control unit 7 obtains brightness control information and controls the brightness of the light source 8. For example, the brightness of the light source 8 is controlled by changing the pulse width and the number of pulses (inverter control) in the case of a fluorescent lamp or a light emitting diode, and in the incandescent light bulb by increasing or decreasing the current. To control. The light source 8 controls the luminance of the image on the display unit 3 by irradiating light controlled from the back surface of the display unit 3. The display unit 3 displays an image that the user appreciates, such as a still image or a moving image made up of characters, figures, and images. Of course, the timer unit 5 may be operated by a remote controller (not shown).

  Next, in the gradual increase in the brightness of the display unit 3, a description will be given of performing a gradual increase when waking up and when waking up. FIG. 3 shows the relationship between the elapsed time from when the light source 8 as the illumination means starts to turn on and the luminance of the image on the display unit 3. As shown in the figure, the luminance of the image on the display unit is controlled by the length of the time setting until the predetermined luminance is reached. In the examples, the relationship between the elapsed time and the brightness is expressed linearly for the sake of simplicity.

  A straight line “a” in FIG. 3 indicates that the time t1 rises from the luminance 0 of the screen of the display unit 3 and reaches a predetermined luminance L1. A straight line “b” in FIG. 3 indicates that the time t2 rises from the luminance 0 of the screen of the display unit 3 and reaches a predetermined luminance L1.

  When the lighting control information is obtained from the timer unit 5 when the timer unit 5 is turned on, the luminance control unit 6 determines that the user is getting up, and the light source control unit 7 is based on the luminance control information from the luminance control unit 6. In addition, the brightness of the light source 8 is controlled so that the brightness of the screen of the display unit 3 becomes a straight line b in FIG. When the light source 8 is turned on by the switch 4, the luminance control unit 6 determines that it is awakening when there is no lighting instruction information from the timer unit 5, and outputs the luminance control information to the light source control unit 7. The control unit 7 controls the brightness of the light source 8 so that the luminance of the screen of the display unit 3 becomes the straight line a in FIG.

  When it is determined that the brightness control unit 6 is in the wake-up state, the light source control unit 7 controls the brightness of the light source 8 based on the brightness control information from the brightness control unit 6, and in this embodiment, the brightness is set to a predetermined brightness. The luminance of the screen of the display unit 3 is gradually increased so that the time until it reaches the time t2 in FIG. When it is determined that the brightness control unit 6 is awake, the light source control unit 7 controls the brightness of the light source 8 based on the brightness control information from the brightness control unit 6, and the time required to reach a predetermined brightness Is gradually increased so that the time t1 in FIG.

  In this way, when the brightness of the display unit 3 is gradually increased, it is possible to increase the luminance according to the adaptation time at the time of waking up and at the time of waking up. By slowly increasing the brightness of the display screen by setting the time, the glare is reduced, and if it is awake, the shorter time is set to make it suitable for the adaptation time at awakening. Thus, visibility can be secured by increasing the brightness of the screen of the display unit 3.

(Second embodiment)
Next, a case where the wake-up time is determined based on the actual time when the timer is turned on and the brightness of the display unit is gradually increased will be described based on the second embodiment. FIG. 5 is a functional block diagram of the second embodiment.

  FIG. 5 is a functional block diagram in which a time acquisition unit 9 is further added to the functional block configuration shown in FIG. The time acquisition unit 9 is installed inside the housing 2. The real time acquisition method based on Japan Standard Time or the like acquires the real time from a built-in clock (not shown) of the time acquisition unit 9. Alternatively, the display device 1 is provided with a connection unit (not shown) that can be connected to a network such as the Internet, and obtains time from a method for obtaining the actual time from the network and a device for obtaining time information transmitted by radio waves from the transmitting station. It may be incorporated in the unit 9 to acquire the actual time.

  If the actual time when the luminance control unit 6 obtains the lighting instruction information from the timer unit 5 when the timer is on is within a predetermined time range, it is determined that the user is getting up, and the light source control unit 7 Based on the brightness control information, the brightness of the light source 8 is controlled so that the screen brightness of the display unit 3 becomes the time t2 in FIG. If the actual time when the luminance control unit 6 obtains the lighting instruction information from the timer unit 5 when the timer is on is out of the predetermined time range, it is determined that it is awakening, and the light source control unit 7 The brightness of the light source 8 is controlled on the basis of the brightness control information, and the brightness of the screen of the display unit 3 is gradually increased so as to become time t1 in FIG.

  For example, when the predetermined time range is from 4 am to 9 am, which is generally estimated to be a wake-up time, for example, when the timer is turned on at 7 am, the luminance is within the predetermined time range. The control unit 6 determines that it is when the user wakes up, and the light source control unit 7 controls the brightness of the light source 8 based on the luminance control information from the luminance control unit 6 so that the time t2 in FIG. 3 is reached. The screen brightness of the display unit 3 is gradually increased.

  In this way, it is possible to increase the probability of determining whether or not the light source 8 was turned on when it was rising, and when it is determined that it is rising, the screen brightness of the display unit 3 is slowly increased. When gradually increasing, glare immediately after lighting when waking up can be reduced.

(Third embodiment)
Next, a case where the brightness of the display unit is gradually increased by detecting the ambient illuminance of the display device and changing the setting of the time until reaching a predetermined luminance will be described based on the third embodiment. FIG. 6 is a functional block diagram of the third embodiment. FIG. 6 further includes an ambient illuminance detection unit 10 in addition to the functional block configuration shown in FIG. FIG. 7 is an external perspective view of the display device of the third embodiment. The display device 1a is obtained by further attaching an ambient illuminance detection unit 10 to the display device 1 shown in FIG.

  The ambient illuminance detection unit 10 detects the illuminance around the housing 2. For example, it is composed of a photoelectric conversion element such as a photosensor. As shown in FIG. 7, the ambient illuminance detection unit 10 is installed on the top of the housing 2. Of course, as long as the illuminance around the display device 1a can be detected, the display device 1a may be attached to the side surface, front surface, and back surface of the housing 2 as viewed from the observer.

  The luminance control unit 6 changes the time t2 shown in the graph of FIG. 3 according to the value of the ambient illuminance obtained by the ambient illuminance detection unit 10, and the display unit 3 changes depending on the time until the changed predetermined luminance is reached. Gradually increase the brightness.

  According to this configuration, for example, when the user wakes up when the room is dark, such as a winter morning or a cloudy morning, or when the curtains of the room are closed, the setting value of the time until reaching a predetermined brightness is set. By increasing the luminance, the luminance of the display unit slowly rises, so that the user can wake up comfortably without feeling dazzling. On the other hand, if you wake up when the room is brighter, such as summer morning or sunny morning, compared to winter morning or cloudy morning, you can reduce the value of the time setting until reaching the predetermined brightness, Since the brightness of the display unit rises early, the visibility of the display unit can be ensured.

  As described above, according to the first to third embodiments of the present invention, it is possible to reduce the glare that the user feels when waking up. As mentioned above, although the Example of this invention was described, this invention is not limited to such an Example at all, Of course, it can implement with a various form in the range which does not deviate from the meaning of this invention.

  A modification will be described below. The first modified example is a modified example of the first example, the second example, and the third example. The second modified example is a modified example of the second example. This modification is a modification of the third embodiment.

(First modification)
In the above embodiment, as shown in FIG. 3, the screen brightness of the display unit 3 from 0 to a predetermined brightness L1 is linearly raised, but may be raised in a curved line.

  The above-mentioned light adaptation characteristics of the human eye are first perceived as high brightness brightness due to a transient response, and the perceived brightness brightness decreases with time, and then the constant brightness brightness is reduced. It is known that the transient response to the perceived adaptation state is approximated by a quadratic function.

  Therefore, the brightness brightness of the display unit 3 is set in a curve of a quadratic function so that the brightness brightness perceived by human eyes is opposite to the brightness brightness perceived in the light adaptation characteristic. It may be increased. In this way, the brightness can be increased close to the characteristics of the human eye.

  For example, the elapsed time may be t, and the luminance L (t) may be gradually increased as the luminance calculated by Equation (1).

Formula (1)
L (t) = Lc / (1 + K / t ² )
L (t): Luminance Lc: Luminance that changes according to ambient illuminance K: Constant t: Elapsed time

  FIG. 4 is a curved graph based on the above equation (1) showing the relationship between the elapsed time since the light source 8 started to turn on and the luminance displayed on the display unit 3. In the curve c in FIG. 4, the time when the predetermined luminance L1 is reached is time t1, and the time when the curve d reaches the predetermined luminance L1 is time t2. Then, when getting up, the brightness of the screen of the display unit is gradually increased based on the curve d, and when awakening, the brightness of the screen of the display unit is gradually increased based on the curve c.

(Second modification)
In the second embodiment, the wake-up time is determined based on the actual time when the timer is turned on, but a modified example in which the wake-up time is determined based on the elapsed time until the timer is turned on will be described. Based on the elapsed time from when the light source 8 is extinguished until the timer is turned on, when the brightness control unit 6 determines that it is time to wake up, the time until the predetermined brightness at the time of wakeup is reached by the time t2, the brightness of the display unit The thickness may be gradually increased.

  The brightness control unit 6 manually operates the operation knob of the timer unit 5 to obtain the actual time when the scheduled lighting time of the light source 8 is set and the actual time when the timer unit 5 is turned on from the time acquisition unit 9. Calculate elapsed time. If the calculated elapsed time exceeds the predetermined elapsed time, the luminance control unit 6 determines that the user is getting up, and the time until the predetermined luminance is reached out of two settings for the time until the predetermined luminance is reached. The brightness of the display section is gradually increased by the longer setting. If the calculated elapsed time is within the predetermined elapsed time, the luminance control unit 6 determines that the user is awake, and the time until the predetermined luminance is reached out of the two settings for the time until the predetermined luminance is reached. The display brightness is gradually increased by the shorter setting.

  For example, when the predetermined elapsed time is 6 hours and the elapsed time exceeds 6 hours and the timer unit 5 is turned on, the luminance control unit 6 determines that it is a wake-up time, and the light source control unit 7 Output brightness control information. The light source control unit 7 controls the brightness of the light source 8, and the brightness of the screen brightness of the display unit 3 is set to the time t2 until reaching the predetermined brightness at the time of getting up in FIG. 3 or FIG. Gradually increase.

  In this way, the probability of determining whether or not when the light source 8 was turned on was at the time of waking up further increases, so by gradually increasing the brightness of the screen brightness at the time of waking up, The glare can be reduced.

(Third Modification)
In the third embodiment, the setting of the time until the predetermined luminance is reached is changed according to the ambient illuminance. However, a modification example in which the setting of the time until the predetermined luminance is reached is changed according to the change rate of the value of the ambient illuminance. explain. The ambient illuminance detection unit 10 further has a function of detecting a change rate of the value of the ambient illuminance. The ambient illuminance detection unit 10 has a time t1 until reaching the predetermined brightness at the time of awakening in FIG. 3 or FIG. The time t2 to reach may be changed, and the brightness of the screen of the display unit 3 may be gradually increased by setting the changed time.

  In this way, the setting value for the time to reach the predetermined brightness is changed according to the speed of change of the surrounding brightness. For example, when waking up, the awakening is good and the room lights are turned on immediately. In some cases, if the value of the time t2 until reaching the predetermined brightness at the time of waking up is decreased, the brightness is immediately increased, so that the visibility can be improved. Alternatively, if the value of the time t2 until reaching the predetermined brightness at the time of wakeup is increased when the weather condition suddenly changes and the room suddenly becomes dark at the time of wakeup, the brightness of the screen of the display unit 3 is Since it will rise slowly, the glare immediately after lighting can be reduced.

  Moreover, the value of time t1 until it reaches | attains the predetermined brightness | luminance at the time of awakening may be changed, and the brightness of the display part 3 may be increased gradually by the changed time t1. For example, when the light of the light source 8 is turned on at the time of awakening and the room lighting is immediately increased or the curtain of the room is opened, if the value of time t1 is decreased, the brightness is immediately increased and is visually recognized. Can improve sex. Alternatively, when the light source 8 is turned on at the time of awakening and the room lighting is immediately turned off or the room curtain is closed, increasing the value of time t1 will cause the brightness to rise slowly. Can reduce the glare felt.

  As another modification, the display unit of the display device of the present invention in the above-described embodiment or modification includes, for example, the display unit 3 attached to the opening of the housing 2 as a transmissive screen panel, and the housing 2 The present invention can also be applied to a case where an image is projected on the display unit 3 by a so-called rear projector that projects the transmitted light or reflected light of the display body installed inside the projector onto the screen. Furthermore, the present invention can also be applied to a projector that projects an image using a screen placed on a wall or a stand as a display unit without providing a display unit in the display device.

  Alternatively, in the present embodiment, the display unit 3 and the light source 8 are separated from each other, but the display unit 3 is integrally provided with a function of self-light emission, and the display unit 3 functions as an illumination unit. The present invention can also be applied to the case where the display unit 3 is composed of an organic light emitting diode or a field emission display.

The external appearance perspective view of the display apparatus in the 1st Example of this invention-the 2nd Example. The functional block diagram of the display apparatus in 1st Example of this invention. The graph which shows the relationship between the elapsed time and the brightness | luminance in the 1st Example, 2nd Example, and 3rd Example of this invention. The graph which shows the relationship between the elapsed time and the brightness | luminance in the 1st modification of this invention. The functional block diagram of the display apparatus in the 2nd Example of this invention. The functional block diagram of the display apparatus in the 3rd Example of this invention. The external appearance perspective view of the display apparatus in the 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 1a ... Display apparatus, 2 ... Housing | casing, 3 ... Display part, 4 ... Switch, 5 ... Timer part, 5a ... Operation knob, 6 ... Luminance control part, 7 ... Light source control part, 8 ... Light source, 9 ... Time acquisition unit, 10 ... Ambient illuminance detection unit.

Claims (9)

A display device that controls the brightness of the display unit to gradually increase after the lighting means is turned on,
A luminance control unit that gradually increases the brightness of the display unit, and the luminance control unit has two settings in which the length of time until the predetermined luminance is reached after the lighting unit is turned on is different. Display device. The display device according to claim 1,
A timer unit for turning on the lighting means by turning on the timer;
The brightness control unit is configured to gradually increase the brightness of the display unit according to a setting of a longer time to reach the predetermined brightness among the two settings when the lighting unit is turned on by the timer unit. Characteristic display device. The display device according to claim 2,
The timer unit further includes an off-time measuring unit that measures an elapsed time from turning off the illumination unit to turning on the timer,
When the elapsed time is equal to or longer than a predetermined time, the luminance control unit gradually increases the brightness of the display unit by setting the longer of the two settings until reaching the predetermined luminance. A display device characterized by that. The display device according to claim 3,
It further includes a time acquisition unit that acquires the actual time,
When the elapsed time is equal to or longer than a predetermined time, and the actual time acquired by the time acquisition unit is within a predetermined time range, the luminance control unit sets the predetermined luminance among the two settings. A display device characterized by gradually increasing the brightness of the display unit by setting the longer time to reach. A display device according to any one of claims 1 to 4,
An ambient illuminance detection unit for detecting the ambient illuminance of the display device;
The luminance control unit changes a setting of a longer time to reach at least the predetermined luminance among the two settings according to the detected value of the ambient illuminance, and the setting is changed according to the changed setting. A display device characterized by gradually increasing the brightness of a display unit. The display device according to claim 5,
The luminance control unit changes the setting of the longer one of the two settings according to the change rate of the detected value of the ambient illuminance until the predetermined luminance is reached. A display device characterized by gradually increasing the brightness of the display unit by setting. A display method for controlling the brightness of the display unit to gradually increase after the lighting means is turned on,
A luminance control step of gradually increasing the brightness of the display unit based on one of two settings with different lengths of time until reaching a predetermined luminance after the lighting means is turned on. Display method. The display method according to claim 7,
Further comprising the step of turning on the lighting means by turning on a timer;
In the brightness control step, when the lighting unit is turned on when the timer is on, the brightness of the display unit is gradually increased according to a setting of a longer time to reach the predetermined brightness among the two settings. Characteristic display method. The display method according to claim 7 or 8, wherein
An ambient illuminance detection step for detecting the ambient illuminance of the display device;
The luminance control step changes a setting of a longer time until reaching the predetermined luminance among the two settings according to the detected value of the ambient illuminance, and based on the changed setting A display method characterized by gradually increasing the brightness of the display unit.

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