ILLUMINATION DEVICE

Abstract

An illumination device includes a control knob having a display portion, a tubular case combined with a back side of the control knob, a light guide plate attached to seal an upper opening of the tubular case, and LEDs disposed at a lower opening of the tubular case. Light emitted from the LEDs is applied to the display portion through the light guide plate. A plurality of retaining projections and a plurality of push-up projections are provided on an inner surface of the tubular case adjacent to the upper opening. An upper surface of an outer edge of the light guide plate is retained by lower ends of the retaining projections, and a lower surface of the outer edge is pushed up by upper ends of the push-up projections so that the light guide plate is held inside the tubular case while being bent upwardly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a control panel to which an illumination device according to an embodiment of the present invention is applied;

FIG. 2 is a cross-sectional view of the control panel, take along one direction;

FIG. 3 is a cross-sectional view of the control panel, taken along another direction;

FIG. 4 is an exploded perspective view of a control knob, a light guide plate, and a tubular case provided in the control panel; and

FIG. 5 is an explanatory view showing a structure for holding the light guide plate.

Claims

1. An illumination device comprising: a control knob having a display portion;a tubular case disposed on a back side of the control knob;a light guide plate attached to seal an upper opening of the tubular case; anda light source disposed at a lower opening of the tubular case,wherein light emitted from the light source is applied to the display portion through the light guide plate,wherein a plurality of retaining projections and a plurality of push-up projections are provided on an inner surface of the tubular case adjacent to the upper opening, andwherein an upper surface of an outer edge of the light guide plate is retained by lower ends of the retaining projections, and a lower surface of the outer edge of the light guide plate is pushed up by upper ends of the push-up projections so that the light guide plate is held inside the tubular case while being bent upwardly.

2. The illumination device according to claim 1, wherein a height of an imaginary plane linking the upper ends of the push-up projections is larger than a height obtained by subtracting a thickness of the light guide plate from a height of an imaginary plane linking the lower ends of the retaining projections.

3. The illumination device according to claim 1, wherein the upper opening of the tubular case is rectangular,wherein the push-up projections are provided at the centers of a pair of push-up inner walls opposing each other at the upper opening, andwherein the retaining projections are provided on a pair of retaining inner walls opposing each other at the upper opening and extending orthogonally to the push-up inner walls.

4. The illumination device according to claims 1, wherein upper surfaces of the retaining projections are tapered portions inclined downward.

5. The illumination device according to claim 1, wherein a stepped portion continuously extends on the inner surface of the tubular case along an inner periphery of the tubular case, and the push-up projections are provided on the stepped portion.

6. The illumination device according to claim 5, wherein a plurality of punched holes are provided in the tubular case so as to extend from an outer surface of the tubular case to lower surfaces of the retaining projections, and outer open ends of the punched holes are covered with the control knob when the control knob is snap-fitted on the tubular case.