JPH01183724A - Graphic input device - Google Patents

Abstract

PURPOSE:To obtain a thin and easy-to-handle graphic input device by setting a transmissive light guiding plate in parallel onto the single side of a coordinate plate together with the straight tube fluorescent lamps set at both ends of the light guiding plate and forming a light dispersing plate on the upper surface side of the light guiding plate with a dispersion reflecting part formed on the lower surface side respectively. CONSTITUTION:The light emitted from the straight tube fluorescent lamps 3 which are turned on by the DC are made incident on a transmissive light guiding plate 2 through both end surfaces of the plate 2. Most of these incident light travel zigzag with the tilts larger than a critical angle. While some of said incident light have the tilts smaller than the critical angles through a dispersion reflecting part 5 are turned into the upward light directly or via a reflecting plate 5' and then radiated to outside through the upper surface side of the plate 2 to project a light dispersing plate 4. Thus the position of a position indicator 7 is accurately detected on a coordinate plate 1 without putting any shield between the plate 1 and the plate 2 since the lamps 3 are turned on the DC.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a graphical human-powered device used, for example, as an input device to a computer.

[Conventional technology]

In graphical input devices known as tablets or digitizers, it is desirable that the upper surface side on which a position indicator, such as a stylus pen, is positioned is bright. FIG. 7 shows an example of how the graphic input device 100 is used. For example, a drawing 10 is placed on the top surface of the device, and a position indicator 7 such as a stylus pen or a cursor 7' is positioned at a key point on the drawing 1o. Enter your current location information.

200 is a visual display terminal (VD) that monitors input coordinate data or figures based on it.
T), the figure 100 that is the subject of input is often small, and the input requires as high precision as possible, so the surface 4 on which it is placed is set so that the figure 10 is easy to see. Reference numeral 6 in Figure 0, which is often used as a light diffusing plate to project light upward, is a backbone that also serves as the outline of the graphic input device gloo.

Figure 8 shows the mechanism of a so-called backlight that emits light from a light diffusion plate 4.The light from a straight tube fluorescent lamp 3', which is normally lit with alternating current, is transferred to a shield 3 for noise removal.
0, the coordinate plate 1 above it, and the light diffusing plate 4 above it. The coordinate plate 1 is made up of a transparent insulating substrate 101 and a large number of vertical and horizontal electrodes 5102 arranged in a mesh pattern. When the position indicator 7 is positioned at an arbitrary position on the upper surface side of the coordinate plate 1 via the light diffusing plate 4, this position indicator 7 and the corresponding electrode [
102 are electromagnetically coupled to form a coordinate signal indicating the current position of the position indicator 7. This coordinate signal detects the current induced in the electrode wire 102.

It is made by processing, but in a different method of capacitive coupling, each electrode! A position information current allocated in advance to 102 is sensed by a required position indicator 7 to form a coordinate signal.

The AC-lit straight tube fluorescent lamp 3' shown in FIG. 8 projects light through a light diffusing plate 4. Since it is desired that this projection be uniform, a fluorescent lamp 3' is used as a light source for this purpose.
is suitable. However, noise is generated depending on the lighting frequency. This is caused by anode vibration in the lamp filament of the fluorescent lamp 3' and is detrimental to coordinate signal formation. The shield 30 is used to cut the noise and prevent it from moving toward the coordinate plate 1 or the position indicator 7.

[Problem to be solved by the invention]

In the conventional graphic input device 100 as shown in FIG.
Since the straight tube fluorescent lamps 3' are disposed at the bottom below the coordinate plate 1, their overall height inevitably becomes large.

Furthermore, in order to improve the uniformity of light on the light diffusing plate 4, the straight tube fluorescent lamp 3' must be moved further downward, which hinders the reduction in thickness.

An object of the present invention is to provide a thinner graphic human power device using a light guide plate such as an acrylic plate. It also solves some of the problems associated with its implementation.

[Means to solve the problem]

In the present invention, a translucent light guide plate such as an acrylic plate is arranged in parallel on one side of the coordinate plate.

Further, a direct current-operated straight tube fluorescent lamp is arranged to enter light into the interior of the light guide plate from the end face thereof. This refers to straight tube fluorescent lamps that are lit with direct current, and does not include those that are lit with alternating current.On the other hand, a light diffusing plate is arranged in parallel on the top side of the light guide plate, and diffuse reflection is reflected on the bottom of the light guide plate. form a section. The light diffusion plate is completely different from the light guide plate, and does not impair the light reflection characteristics of the top surface of the light guide plate.The diffuse reflection part is formed directly on the bottom surface of the light guide plate, Affects light reflection properties.

[Effect]

Light emitted from a direct current-operated straight tube fluorescent lamp enters the light guide plate through the end face thereof. The light inside the light guide plate is reflected between the upper and lower surfaces of the light guide plate.

If this reflection is below the critical angle, the light will only travel in a zigzag pattern and will not be emitted from the plate surface of the light guide plate.Actually, at least some of the light will be reflected at a large angle by the diffuse reflection section on the bottom surface of the light guide plate. The light is converted and radiated upward through the upper surface of the light guide plate and the light diffuser plate above it. In this way,
As a result, a portion of the light traveling along the plate surface of the light guide plate leaks out from the upper surface thereof. This leakage rate is determined by the shape of the diffuse reflection part,
By changing and adjusting the arrangement density, light is emitted as uniformly as possible both near and far away from one lamp on the light diffusing plate, increasing the degree of uniformity of the light.

One lamp filament of a direct current-operated straight tube fluorescent lamp serves as an anode, and the other filament serves as a cathode. Unlike in AC lighting, the anode is not switched alternately between both lamp filaments, reducing the level of noise due to anode vibration. For this reason, the conventional Fig. 8
A shield equal to 0 is not required. If there is no shield, the light from the straight tube fluorescent lamp will efficiently enter the end face of the light guide plate.

〔Example〕

The embodiments shown in FIGS. 1 and 2 will be described. Note that the conventional component numbers in FIGS. 7 and 8 will be used as much as possible to avoid duplication of explanation.

1 in the figure is an electromagnetic coupling type coordinate plate, and 2 is a light guide plate arranged in parallel on the upper surface side thereof.

The light guide plate 2 is a transparent acrylic resin plate. 3 is light guide plate 2
This is a DC-lit straight tube fluorescent lamp that is placed near the left and right end faces of the lamp. Although illustration of this DC lighting circuit is omitted, a known one is used as is.

Specifically, the voltage of the AC power supply is connected to the aftereffect rectifier circuit through a ballast choke coil, and the DC output is connected to a straight tube fluorescent through a smoothing capacitor in parallel and a smoothing choke coil in series. Lead to ramp 3. A direct current glow starter is placed alongside the straight tube fluorescent lamp 3. Although not shown, components such as ballast choke coils are placed on the outside or end of the straight tube fluorescent lamp 3, and the upper surface of the light guide plate 2 is provided with a mesh-like shield to prevent noise from being radiated outside. A light diffusing plate 4 is arranged in parallel on the side. The light diffusing plate 4 is a translucent, opaque synthetic resin plate, and is normally stacked on the upper surface of the light guide plate 2. Injecting adhesive between them is not possible as this would eliminate the air space between them. A diffuse reflection section 5 is formed on the lower surface of the light guide plate 2 . This is done by roughening the entire lower surface (roughening the surface of the surface), and the roughening is done in the form of fine striations that are directional in the far and near directions of the straight tube fluorescent lamp 3. Instead of the six stripes, a fine pale milky-white dotted pattern may be arranged so as to become denser as the distance from the straight tube fluorescent lamp 3 increases.
' is a reflecting plate arranged in parallel on the lower surface side of the light guide plate 2. This reflective plate is a milky white synthetic resin plate. Reflector 5″
Although this is not indispensable in implementing the present invention, it should be provided in order to increase the efficiency of upward radiation of light. The coordinate plate 1 is arranged below the reflecting plate 5'. Conventional 8th
The seat S 1 in the figure must be transparent, but the one in Figures 1 and 2 does not need to be transparent at all. 6 is the backbone, and 6' is the outer frame. The height of the surface 6' is higher than the surface of the light diffusing plate 4 when the straight tube fluorescent lamp 3 is housed therein. 7 is a position indicator that emits magnetic flux from the tip, for example, the light diffusing plate 4.
It is desirable that the 0 position indicator 7 applied to the drawing 10 placed in the coordinate board 1 be as close as possible to the coordinate board 1.

Light diffuser plate between 4. The total thickness of the light guide plate 2, the diffuse reflection section 5, and the reflection plate 5' is designed to be 10 mm or less.

1 and 2, the light emitted from the direct current-lit straight tube fluorescent lamp 3 enters the light guide plate 2 from the end face thereof, and most of the light travels in a zigzag manner with an inclination greater than the critical angle. do. On the other hand, some of the light that happens to have an inclination of less than the critical angle in the diffuse reflection section 5 is radiated out from the top surface of the light guide plate 2 either directly or after being turned upward by the reflection plate 5'. .

The light diffusing plate 4 is illuminated. Since the straight tube fluorescent lamp 3 is lit by direct current, it and the coordinate board 1. It is possible to accurately detect the position of the position indicator 7 on the coordinate plate 1 without placing a shield between the light guide plate 2 and the like. Straight tube fluorescent lamp 3
The light from the light guide plate 2 is incident within the thickness range of the light guide plate 2. Since this range is narrow, placing a shield there will result in a loss of light, which is not good. The reason why the straight tube fluorescent lamp 3 is made to operate with direct current is to omit the shield as a noise filter. In addition, in order to increase the incidence efficiency from the end face of the light guide plate 1, the straight tube fluorescent lamp 3 is a reflective type in which the @ side of the light guide plate 1 is released by ua, and reflective films are arranged in other directions. It is better to do so.

In the embodiment shown in FIG. 3, the light from the straight tube fluorescent lamp 3 is emitted by the reflection R8, and the reflected light is directed toward the end surface of the light guide plate 1. In the embodiment shown in FIG. 4, a prism 9 is used in place of the reflecting mirror 8. In the embodiment shown in two or more FIGS.

There is no need to arrange the straight tube fluorescent lamp 3 at the same height as the light guide plate 2 and right next to it. For this reason, the outer frame upper surface part 6' of the backbone 6 can be made flat at the same height as the light diffusing plate 4, which is convenient when a large drawing is spread on it. is a modified embodiment of FIG.

In the embodiment shown in FIG. 5, a light guide plate 2 is placed below the coordinate plate 1, and only a light diffusing plate 4 is placed above the coordinate plate 1. In the case of this figure 5, it is necessary to use an expensive translucent coordinate plate 1 as in figure 8, but the only thing on the coordinate plate 1 is the light diffusing plate 4, and the coordinate plate 1 is g! l indicator 7
The embodiment shown in FIG. 6, which has high precision because the coordinates are close to each other, uses a wide-area coordinate plate 1. In this case, simply using a pair of straight tube fluorescent lamps 3 facing each other will not provide enough light in the center, so a total of four fluorescent lamps 3 are used in each direction.

〔Effect of the invention〕

The present invention arranges a transparent light guide plate in parallel on one side of the coordinate plate, and arranges a direct current-lit straight tube fluorescent lamp that enters light into the light guide plate from the end face of the light guide plate, A light diffusing plate is arranged in parallel on the upper surface of the light guide plate, and a diffuse reflection part is formed on the lower surface of the light guide plate. According to this, the graphic input device is thinner and easier to use than previous devices. can be obtained

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the device of the present invention, FIG. 2 is a partially cutaway plan view thereof, FIG. 3 is a sectional view showing another embodiment, FIG. 4 is a sectional view showing another embodiment, and FIG. FIG. 5 is a sectional view showing a new embodiment, FIG. 6 is a partially cutaway plan view showing an embodiment other than the above, FIG. 7 is a perspective view showing a general graphic input device and VDT, and FIG. 8 1 is a sectional view showing a conventional input device. In the figure, 1 is a coordinate plate, 2 is a light guide plate, 3 is a straight tube fluorescent lamp, 4 is a light diffusion plate, and 5 is a diffused reflection part 9 Figure 4 $ 5 Concave

Claims (1)

[Claims] 1. A coordinate plate having a large number of vertical and horizontal electrode wires stretched around an insulating substrate, and a position indicator for selectively positioning the coordinate plate at an arbitrary position on the upper surface side of the coordinate plate. , a graphic input device that forms a coordinate signal indicating the current position of the position indicator by electromagnetically or electrostatically coupling a position indicator and a corresponding electrode wire; A light guide plate is arranged in parallel, a direct current-lit straight tube fluorescent lamp that enters light into the guide light plate from the end face of the light guide plate is distributed, and a light diffusing plate is arranged in parallel on the upper surface side of the light guide plate, A graphic input device characterized in that a diffuse reflection section is formed on the lower surface of the light guide plate. 2. The graphic input device according to claim 1, wherein a light guide plate is disposed above the coordinate plate. 3. The graphic input device according to claim 1, wherein the insulating substrate is transparent and a light guide plate is disposed below the coordinate plate.