BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and a head-mounted display.

2. Description of the Related Art

A conventionally known liquid-crystal display is used in a head-mounted display (HMD) that is mounted to cover the eyes of a user. A known example of such a liquid-crystal display is described in International Publication No. 2018/181908. The head-mounted display in International Publication No. 2018/181908 includes a liquid-crystal display and a lens that forms an image displayed on the liquid-crystal display onto the user's eyes. Regulating the focal distance of the lens allows the user to see an enlarged image (or virtual image) that appears on a virtual display whose screen size is much larger than the screen size of the liquid-crystal display.

SUMMARY OF INVENTION

In an HMD, since a liquid-crystal display and user's eyes are close to each other, and the user virtually recognizes an enlarged image, the liquid-crystal display for the HDM is required to have high definition (or high resolution). On the other hand, when the liquid-crystal display is enhanced to have high resolution, a lightproof portion, which divides each pixel, takes up a large area within the plane of a liquid-crystal panel. The liquid-crystal panel hence has degraded light transmittance. As a result, the liquid-crystal display has low brightness, and thus causing degradation in display quality. In fact, enhancing the amount of light emitted from LEDs (which are an example of a light source) to avoid brightness reduction increases LED power consumption.

SUMMARY OF INVENTION

Based on these circumstances, it is an object of an aspect of the present invention to prevent degradation in display quality and reduce power consumption.

(1) A display device according to a preferred embodiment of the present invention includes a display panel having a display region for image display. The display device also includes an illumination device that has a plurality of light sources and casts light upon the display panel. The display device also includes a control substrate that includes a regulator that regulates the amount of light emitted from the light sources. The display region is sectioned into a plurality of sections in the form of concentric circles. The regulator regulates the amount of light in such a manner that one of the sections that is adjacent to the middle of the concentric circles is irradiated with a relatively large amount of light, and in such a manner that another one of the sections that is adjacent to the outer edge of the concentric circles is irradiated with a relatively small amount of light.

(2) In another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (1), such that the regulator decreases the amount of light stepwise from the section adjacent to the middle of the concentric circles toward the section adjacent to the outer edge of the concentric circles.

(3) In still another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (1) or (2), such that the light sources are separated into groups in such a manner that the groups correspond to the respective sections, and is configured such that the regulator regulates the amount of light for each of the groups.

(4) In yet another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (3), such that the light sources are LEDs, and that the LEDs are connected in series for each of the groups.

(5) In further another preferred embodiment of the present invention, the display device is configured, in addition to any of Preferred Embodiments (1) to (4), such that the regulator regulates the amount of light by controlling a light-source driving unit that supplies a current to the light sources to drive the light sources.

(6) In still yet another preferred embodiment of the present invention, the display device is configured, in addition to any of Preferred Embodiments (1) to (5), such that the concentric circles have a center that coincides with the center of the display region. The concentric circles serve as boundaries of the sections.

(7) In still further another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (6), such that each of the sections is provided with a reference of allowance with regard to the number of defects and the number of foreign substances.

(8) In still yet further another preferred embodiment of the present invention, the display device is configured, in addition to any of Preferred Embodiments (1) to (5), such that the control substrate includes a calculator that calculates the amount of light for each of the sections in accordance with information about a viewpoint. The information is supplied from a detector disposed outside. The display device is configured such that the regulator regulates the amount of light in accordance with a result calculated by the calculator.

(9) In another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (8), such that the concentric circles have a center that coincides with the viewpoint. The concentric circles serve as boundaries of the sections.

(10) In still another preferred embodiment of the present invention, the display device is configured, in addition to Preferred Embodiment (8) or (9), such that the regulator regulates the amount of light by controlling a light-source driving unit that supplies a current to the light sources to drive the light sources, and is configured such that the calculator calculates a value of the current, supplied from the light-source driving unit to the light sources.

(11) In further another preferred embodiment of the present invention, the display device is configured, in addition to any of Preferred Embodiments (1) to (10), such that the illumination device includes a light guide plate that guides the light emitted from the light sources, and is configured such that the light sources are arranged in parallel in a predetermined direction so as to face a light-entrance surface of the light guide plate.

(12) In yet another preferred embodiment of the present invention, the display device is configured, in addition to any of Preferred Embodiments (1) to (10), such that the illumination device includes a diffusion plate that diffuses the light emitted from the light sources, and is configured such that the light sources are arranged in parallel in a planar manner so as to face one of a pair of surfaces of the diffusion plate. The surface is remote from the display panel.

(13) A head-mounted instrument according to a preferred embodiment of the present invention includes a head-mounted instrument to be mounted onto the head of a user. The head-mounted instrument includes the display device according to any of Preferred Embodiments (1) to (7) and Preferred Embodiment (11), and includes a lens that forms an image displayed on the display device onto the eyes of the user.

(14) A head-mounted instrument according to a preferred embodiment of the present invention includes a head-mounted instrument to be mounted onto the head of a user. The head-mounted instrument includes the display device according to any of Preferred Embodiments (8) to (10), and a lens that forms an image displayed on the display device onto the eyes of the user.

In another preferred embodiment of the present invention, the head-mounted display is configured such that the detector is a camera.

An aspect of the present invention can prevent degradation in display quality and reduce power consumption.

