JPS6041505B2 - linear illumination light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a linear illumination light source for illuminating a transmitted document or the like in a photoelectric conversion system of a facsimile or the like.

FIG. 1 shows a photoelectric conversion section of a conventional facsimile transmitter or the like.

A transmission document 2 is illuminated with a fluorescent lamp 1, and an image is formed on a photoelectric conversion device 4 such as an image sensor by a lens 3 to obtain a photoelectric conversion signal. In this case, the poppy light lamp 1 used to illuminate the transmitted document 2 is inexpensive, but it has a short lifespan, and since the ends of the tube are darker than the center, a tube that is considerably longer than the width of the document is required. There were drawbacks such as the increased size of the device. FIG. 2 shows an example in which a hot cathode holder and a light tube are used in order to eliminate this drawback, and a longitudinal sectional view thereof is shown.

In FIG. 2, reference numeral 5 denotes a container that is elongated in the longitudinal direction of the paper, and the interior thereof is kept in a vacuum. This container 5 consists of a transparent glass substrate 5a and a face glass 5b having a U-shaped cross section and closely attached to the glass substrate 5a. Portions other than the optical window 5c are formed opaque. There is a transparent window 5c inside the bottom of the face glass 5b.
An anode electrode 6 is formed on both sides of the anode electrode 6, and a poppy light film 7 is further formed on the surface of the anode electrode 6. Mesh-shaped grid electrodes 8 are provided above the poppy light film 7 at predetermined intervals, and filaments 9 are further provided above the grid electrodes 8 at predetermined intervals. Lead wires (not shown) are drawn out of the container 5 from the anode electrode 6, the grid electrode 8, and the filament 9, and are connected to a power source, respectively. Further, a reflective film 10 is formed on the inner surface of the side surface of the face glass 5b. The transmission document 2 is configured to move on the outer surface of the glass substrate 5a in the direction of the arrow at a constant speed. In such a configuration,
When a current is passed through the filament 9, thermoelectrons are emitted, and when a predetermined positive voltage is applied to the grid electrode 8 and the anode electrode 6,
The thermoelectrons are accelerated by the grid electrode 8 and collide with the anode electrode 6.

As a result, the poppy light film 7 on the anode electrode 6 is stimulated to emit light, and the emitted light is a direct light and a reflected light reflected by the reflective film 10 passes through the glass substrate 5a and illuminates the transmission document 2. do. At this time, a portion of the point P on the transmission original 2 facing the center of the glass substrate 5a is illuminated most brightly. Point P is a long line spanning the width of the document, and is
Reflected light corresponding to the contrast of white or black passes through the light-transmitting window 5c and is guided out of the container 5.
The light is focused and imaged on the photoelectric conversion device 4. Then, the optical force conversion device 4 scans the image in the length direction and outputs a time-series electrical signal. In this light source device, almost the entire bottom surface of the container 5 emits light, and reflected light is also added from the light reflecting film 10 on the side surface.Furthermore, since the light source is closely adjacent to the transmission document, the facing distance is As a result, the surface of the transmitted document can be uniformly illuminated with high illuminance using less power.

Further, the length of the container 5 is almost the same as the width of the transmission document 2, so that it can be made small. However, in this structure, the glass substrate 5a
Since the image of the transmitted document 2 is formed through the two glass plates of the face glass 5b and the face glass 5b, the resolution is degraded due to the influence of spherical aberration.

Furthermore, the focal point V position changes due to the effects of warping, waviness, unevenness, etc. of the glass substrate 5a and the face glass 5b, resulting in a decrease in resolution. Further, there is a drawback that the contrast is reduced due to reflection on the surfaces of the glass substrate 5a and the face glass 5b. In order to solve these drawbacks, the present invention uses a heat shaded light tube as a light source and directs the light to the document surface through a light guide that forms a part of the container, thereby achieving condensation without going through a glass plate. The object of the present invention is to provide a linear illumination light source that is 4-shaped, efficient, and does not cause resolution degradation.

FIG. 3 shows an embodiment of the present invention, in which reference numeral 11 denotes a container that is elongated in the longitudinal direction of the paper, and the interior thereof is kept in a vacuum.

This container has a substrate 11a, a side plate 11b that is in close contact with the substrate 11a, and a portion of the lower part is sandwiched between the side plates 11b, and the surface except for the upper and lower end surfaces is covered with a light reflecting film 10, and the interior is It consists of a light guide 11c which is transparent. An anode electrode 6 is formed on the inner surface of the substrate 11a, and a roughly fluorescent film 7 is formed on the surface of the anode electrode 6. Further, mesh-like lattice crab poles 8 are provided above the fluorescent film 7 at predetermined intervals, and filaments 9 are further provided above the lattice electrodes 8 at predetermined intervals. Although not shown, lead wires are drawn out of the container 5 from the anode electrode 6, the grid electrode 8, and the filament 9, and are connected to the fin sources, respectively. Through the above steps, the linear illumination light source 20 according to the present invention is constructed. Note that t indicates the thickness of the light guide 11c. FIG. 4 is a longitudinal sectional view of an embodiment in which a linear illumination light source 20 according to the present invention is incorporated into a light crab conversion mechanism of a facsimile transmitter. The transmission document 2 is adapted to move at a constant speed in the direction of the arrow, and the light emitted from the linear illumination light source 20 according to the present invention directly illuminates the surface of the transmission document 2. The reflected light from the transmission document 2 is focused by a lens 3 and imaged on a photoelectric conversion device 4 . Then, the photoelectric conversion device 4 scans the transmission original 2 in the front-back direction of the paper surface, and outputs a time-series electric signal. Because of this structure, the light emitted from the mana light film 7 is not damaged on the way, and some of it is directly emitted, and some of it is emitted from the side plate 11b.
The light is guided to the upper end surface of the light guide 11c while being reflected by the inner surface of the light guide 11c and the light reflecting film 10 of the light guide 11c.

Therefore, effectively, the upper end surface of the light guide 11c emits light almost the same as the light emitting surface of the poppy/light film 7. Further, since the thickness t of the light guide 11c is as thin as a few ribs, the restriction on arrangement is less than 4 mm, making it possible to bring the upper end surface close to the illumination area of the document surface. Therefore, an illumination effect almost equivalent to that obtained when the light emitting surface of the poppy light film 7 is placed near the surface of the transmission document 2 can be obtained, and the efficiency is extremely high. Further, since the length of the container 11 and the light film 7 emit light almost uniformly, the length of the container 11 can be approximately the same as the width of the document, and the container can be made compact. Furthermore, since no glass plate is interposed between the surface of the transmission document 2 and the optical system, there is an advantage that there is no deterioration in resolution or contrast. As explained above, the linear illumination light source of the present invention uses a hot cathode lamp/light tube as a light source, and the light is guided by a light guide that forms a part of the vacuum container, so it can be formed compactly and at low cost. It has the advantage that high illumination can be obtained using electric power, and there is no deterioration in resolution or contrast.

Therefore, if used in a photoelectric conversion system of a facsimile transmitter, etc., it is possible to construct a compact, highly efficient illumination device that does not cause resolution deterioration or contrast deterioration.

[Brief explanation of the drawings] Fig. 1 is a perspective view showing a photoelectric conversion section of a conventional facsimile transmitter, etc., and Fig. 2 is a longitudinal section of the main part of the photoelectric conversion section using a hot cathode and a light tube. 3 are longitudinal cross-sectional views showing one embodiment of the present invention, and FIG. 4 is a schematic diagram showing the configuration of an example in which the linear illumination light source according to the present invention is applied to a facsimile machine. In the figure, 2 is the original to be sent, 6 is the anode electrode, 7 is the brush, light beam,
8 is a grid electrode, 9 is a filament, 1 is a light reflecting film, 1
1a is a substrate, 11b is a side plate, 11c is a light guide, 20
'It is a linear illumination light source. Figure 1 Figure 2 Figure 3 Figure 3

Claims (1)

[Claims] 1. A substrate, an anode electrode formed on the substrate, a fluorescent film formed on the anode electrode, a grid electrode provided above the fluorescent film at a predetermined interval, and the grid electrode. A filament is provided at a predetermined distance above the substrate, a side plate stands perpendicular to the substrate and has a light reflecting film on its inner surface, and a portion of the lower portion is sandwiched between the side plate. The substrate, the side plate, and the light guide form a vacuum container, and the light emitted from the fluorescent film is reflected by the light guide. A linear illumination light source that is guided to an illumination area on a transmitted document by a guide.