ILLUMINATION-TYPE ROTATIONAL CONTROL DEVICE

Abstract

A rotatable control knob for actuating a rotary switch includes a slit serving as a pointer display element. An illuminating portion of a light guiding unit attached to the control knob is disposed in the slit. A strip light-guiding portion extends spirally from the illuminating portion is secured to the inner surface of the control knob. Thus, light emerging from a planar light-emitting unit disposed under the control knob is incident on the lower surface of the strip light-guiding portion and is guided through the strip light-guiding portion to the illuminating portion. This allows the illuminating portion illuminated with high intensity in the slit so as to function as an indicator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an illumination-type rotational control device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of main parts of the illumination-type rotational control device.

FIG. 3 is a perspective view of a light guiding unit in the illumination-type rotational control device.

FIG. 4 is a plan view of the light guiding unit.

FIG. 5 illustrates paths of light emerging from a planar light-emitting unit and incident on the light guiding unit.

Claims

1. An illumination-type rotational control device comprising: a rotatable control knob having a tubular member with a top plate and a pointer display element;a light guiding unit integral with the control knob;a planar light-emitting unit configured to direct light on the light guiding unit,wherein the light guiding unit has an illuminating portion disposed in the pointer display element and a strip light-guiding portion annularly extending along an inner surface of the control knob; andthe light guiding unit configured to allow light emerging from the planar light-emitting unit to be incident on a lower surface of the strip light-guiding portion, and to guide the light to the illuminating portion.

2. The illumination-type rotational control device according to claim 1, wherein the strip light-guiding portion tapers such that a length of the strip light-guiding portion in a direction parallel to a rotational axis of the control knob decreases with distance from the illuminating portion.

3. The illumination-type rotational control device according to claim 2, wherein both the upper and lower surfaces of the strip light-guiding portion are inclined with respect to respective planes orthogonal to the rotational axis of the control knob.

4. The illumination-type rotational control device according to claim 1, wherein the planar light-emitting unit has an annular light exiting surface which allows light emitted from a light source to emerge obliquely toward the lower surface of the strip light-guiding portion.