JPH05272995A - Instrument - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce electromagnetic noise generated in discharge lamps. [Structure] The scale plate main body 2a is formed of a metal plate and is grounded via a ground wire 2b. A through hole 7 is formed at a position where the scale 6 is formed on the scale plate body 2a, and a resin piece 8 for the scale is fitted and fixed in the through hole 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument for improving visibility by illuminating a scale plate with a discharge lamp installed on the back surface thereof, and more particularly to an instrument for reducing electromagnetic noise.

[0002]

2. Description of the Related Art Conventionally, as an example of this type of instrument, there is one in which a discharge lamp is installed behind a scale plate. This is a low-cost synthetic resin molded plate with a light-transmitting property, and the light from the discharge lamp behind it is transmitted through the scale plate to illuminate its front side, improving visibility. .

The discharge lamp is designed to be lit at a high frequency in order to improve efficiency.

[0004]

However, in such a conventional instrument, since the discharge lamp is lit at a high frequency, the lamp voltage-lamp current of the discharge lamp is distorted. Therefore, even if a sinusoidal alternating current is supplied to the discharge lamp from the high-frequency lighting circuit, the discharge lamp emits high-frequency distortion components as radiation noise, which causes a problem in that noise is generated in televisions, radios, and the like.

Further, when the discharge lamp receives a radio wave from a radio device or the like, there is a problem that the light emission near the electrode plate of the discharge lamp increases and the illuminance uniformity is lowered, so that the visibility is lowered.

In particular, when the discharge lamp is pulse-lighted to improve efficiency, radio waves from a wireless device or the like may be superposed on the pulse and flow into the discharge lamp to reduce the luminous efficiency.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an instrument capable of reducing electromagnetic noise generated in a discharge lamp.

[0008]

The present invention is configured as follows to solve the above problems.

That is, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) is a scale plate which forms a scale on the surface of the scale plate main body, and a discharge lamp which illuminates the scale plate from its rear surface. In the instrument having the above, the scale plate main body is formed of a metal plate and is grounded, a through hole is formed in the scale plate main body at a position where the scale is formed, and a transparent member for the scale is fitted into the through hole. It is characterized by being fixed.

The invention according to claim 2 of the present application (hereinafter referred to as the second invention) is a scale plate for forming a scale on the surface of the scale plate main body, and a discharge lamp for illuminating the scale plate from the back side thereof. In the instrument having and, the scale plate body is formed of a synthetic resin molding plate having a light-transmitting property, and at least a part of the discharge lamp is covered, while a grounded conductor is provided on the scale plate body. It is characterized by

[0011]

[Action]

<First Invention> When a discharge lamp is lit and emits light, the emitted light transmits through a scale translucent member fitted and fixed in a translucent hole of a scale plate body, and illuminates the translucent member for scale itself. At the same time, the surface side of the scale plate body is illuminated to improve visibility.

Further, since the electromagnetic wave noise generated by the discharge lamp is captured by the metal scale plate main body in front of the discharge lamp and then grounded, the electromagnetic wave noise can be reduced.

<Second Invention> When a discharge lamp is lit and emits light, the emitted light is transmitted through a translucent synthetic resin graduation plate main body in front of the discharge lamp to illuminate the surface side thereof, Increase visibility.

Further, the electromagnetic wave noise generated when the discharge lamp is lit is captured by the conductor covering at least a part of the discharge lamp and grounded, so that the electromagnetic wave noise is reduced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a front view of an embodiment in which the first invention of the present application is applied to a vehicle-mounted speedometer, and FIG. 3 is a side view thereof, in which the instrument 1 is, for example, a semicircular scale. A pointer 3 is rotatably provided in the central portion on the front surface side of the plate 2, and a fluorescent lamp 4 having a reverse U-shape, which is a discharge lamp, is provided substantially concentrically behind the scale plate 2. The fluorescent lamp 4 is electrically connected to the lighting circuit 5 and is lit at high frequency.

The scale plate 2 is made of a conductive metal plate, and a semicircular scale plate body 2a is grounded via a ground wire 2b. The scale plate main body 2a has a pointer 3 on the outer peripheral portion on the surface side.
Are provided at a required pitch.

Each graduation 6 has a plurality of through holes 7, 7 ... Penetrating in the plate thickness direction in the graduation plate main body 2a, and each of the through holes 7 is made of a transparent synthetic resin, for example, white. It is configured by tightly fitting and fixing the scale piece 8.

Therefore, when the fluorescent lamp 4 is turned on by the lighting circuit 5 and emits light, the emitted light transmits each of the graduation pieces 7 having a light transmitting property to illuminate itself.
The surface side of the scale plate 2 is illuminated to improve visibility.

Electromagnetic noise generated when the fluorescent lamp 4 is turned on is captured by the metal scale plate body 2a, which is a conductor, and is grounded via the ground wire 2b. Therefore, electromagnetic wave noise can be reduced.

Further, even if the radio wave from the radio device or the like is applied to the instrument 1, the radio wave is captured by the metal scale plate body 2a and grounded by the ground wire 2b, so that the electromagnetic wave can be reduced.

FIG. 4 is a perspective view of an embodiment of the second invention of the present application, and FIG. 5 is a side view thereof. The instrument 11 is a scale plate 1.
A fluorescent lamp 13 having an inverted U shape, which is a discharge lamp, is provided behind the lamp 2 with a slight gap. Fluorescent lamp 13
Is electrically connected to a lighting circuit (not shown) so as to be lit at a high frequency.

The graduation plate 12 is made of a synthetic resin having a light-transmitting property and is an inexpensive semi-circular synthetic resin molded plate.
A plurality of scales 14, 14 are integrally formed on the surface side of a, for example, and a pointer 15 is rotatably provided at the center of the scale plate main body 12a.

The scale plate 12 has a fluorescent lamp 13 on its rear surface.
A conductive net 16 formed by weaving a metal wire having conductivity into a net shape is attached to cover the outer periphery of the conductive net 16 with a required gap, and the conductive net 16 is grounded by a ground wire 17.

Instead of or in addition to the conductive net 16, on the front surface or the back surface of the scale plate main body 12a,
A conductive coating may be formed by coating the conductive synthetic resin almost entirely and baking it, and this coating may be grounded.

Further, a conductive metal foil may be adhered almost entirely on the front surface or the back surface of the scale plate body 12 and this may be grounded. Also by these, the electromagnetic noise generated in the fluorescent lamp 13 can be reduced.

[0027]

As described above, the first invention of the present application is
Since the electromagnetic wave noise generated by the discharge lamp is captured by the scale plate body made of a metal plate and grounded, the electromagnetic wave noise can be reduced.

Further, according to the second aspect of the present invention, the electromagnetic wave noise generated in the discharge lamp is captured by the conductor provided in the scale plate main body and grounded, so that the electromagnetic wave noise can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part of an embodiment of the first invention of the present application.

2 is a front view of an instrument incorporating the embodiment shown in FIG.

FIG. 3 is a side view of FIG.

FIG. 4 is a perspective view of an embodiment of the second invention of the present application.

FIG. 5 is a side view of FIG.

[Explanation of symbols]

 1, 11 Instrument 2, 12 Scale plate 2a, 12a Scale plate body 2b, 17 Earth wire 4, 13 Fluorescent lamp 6, 14 Scale 7 Through hole 8 Scale resin piece 16 Conductor net

Claims (2)

[Claims] 1. An instrument having a scale plate for forming a scale on the surface of the scale plate main body and a discharge lamp for illuminating the scale plate from its rear surface, wherein the scale plate main body is formed of a metal plate and grounded, A measuring instrument characterized in that a through hole is formed at a position where the scale is formed in the scale plate body, and a transparent member for the scale is fitted and fixed in the through hole. 2. An instrument having a scale plate for forming a scale on the surface of the scale plate main body and a discharge lamp for illuminating the scale plate from its rear surface, wherein the scale plate main body is made of a synthetic resin molding having a light-transmitting property. An instrument formed by a plate, which covers at least a part of the discharge lamp, and which is provided with a grounded conductor on the scale plate main body.