JPH0230270A - Color picture reader - Google Patents

Abstract

PURPOSE:To improve the lighting start characteristic by arranging a light storage section on the surface of lamp tube in the vicinity of at least one electrode of a rare gas cold cathode discharge lamp so as to light the vicinity of the electrode by means of the said light storage member even after the light of the lamp itself is extinguished. CONSTITUTION:The light storage member 8 is coated to the lamp surface in the vicinity of the electrode 11 of rare gas cold cathode discharge lamps 1, 2, 3. Since a voltage is applied between the electrode 11 and an auxiliary electrode placed nearest the electrode 11 the moment the voltage is applied, the light start characteristic is improved by the electrode 11 being exposed to the light radiation from the light storage member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a color image reading device, and in particular to a color image reading device for reading red, blue,
This invention relates to a color image reading device that illuminates a document by sequentially and selectively lighting up three green light sources.

[Conventional technology]

Fluorescent lamps, LEDs, and the like are conventionally known as three-color light sources for color separation. In the case of ordinary fluorescent lamps that contain mercury, the type of phosphor applied can be selected, and although they have the advantage of having large emission energy, they also have very large temperature characteristics, so they cannot produce high-quality color images. Not suitable for reading devices.

On the other hand, at a practical level, LEDs have disadvantages in that blue light emitting devices are not yet available and green light emission energy is low.

Therefore, in the present invention, a light source for color reading is created using a cold cathode fluorescent lamp filled with a rare gas without temperature characteristics instead of mercury vapor.

[Problem to be solved by the invention]

By the way, cold cathode discharge tubes have a property that lighting start characteristics are poorer than hot cathode discharge tubes. This is because hot cathode discharge tubes emit thermionic electrons by heating the electrodes, improving discharge initiation characteristics, whereas cold cathode tubes have a low energy level of electrons in the electrodes, making it difficult to cause discharge. by.

For this reason, in cold cathode tubes, a radioactive substance such as N15s is coated on the electrodes to improve lighting start characteristics.

However, due to the nature of radioactive materials, various problems can be expected in their handling during production and distribution, which makes them undesirable.

The present invention eliminates such drawbacks, and its purpose is to improve the lighting start characteristics of a rare gas cold cathode discharge lamp without coating it with radioactive substances, and to realize a good light source for color reading.

[Means to solve the problem]

As a means to excite the energy state of matter,
It is well known that in addition to (1) heating, (2) radiation irradiation, and (3) light irradiation.

Therefore, in the present invention, a phosphorescent member is arranged on the tube surface near at least one electrode of a rare gas cold cathode discharge lamp, and even after the own light is extinguished, the phosphorescent member illuminates the vicinity of the electrode. improve. Further, a shielding plate is provided between the light from the luminescent member and the document surface to prevent the light from hitting the document.

〔Example〕

FIG. 1 shows an embodiment of a lamp unit according to the present invention.

Furthermore, FIG. 2 shows a schematic diagram of the rare gas cold cathode discharge lamp used in the present invention.

The fluorescent lamp is of an aperture type having an opening 26, and a phosphor 24 is provided on the inner surface of a glass tube 25 to seal in xenon gas. On the other hand, the auxiliary electrode 7 is located on the opposite side of the frontage part 26.
A ring electrode 6 is attached to one end of the ring electrode 6 while maintaining electrical connection therewith. Wires 21, 22, 23 are taken out from the electrodes 11, 12 and the auxiliary electrode 7, respectively, and 31, 32, 33 of the inverter circuit shown in FIG.
are connected to each.

When the oscillation circuit 35 is operated by the lighting circuit 36, a voltage of about 1 kV to 2 kV is applied to the lamp by the step-up transformer 34, and discharge starts. 37a.

b and c are current limiting capacitors, and 38a and b are discharge stabilizing capacitors.

Although the mechanism is to excite the phosphor 24 with ultraviolet rays generated by the discharge of xenon gas and cause it to emit light, a lighting delay as shown in FIG. 4 may occur. Here, Td is the lighting delay time. When such a lighting delay time occurs, the amount of light per main scanning line decreases compared to the normal case, and the quality of the read image deteriorates significantly.

In order to solve this problem, in the present invention, as shown in FIG. 1, a luminescent material 8 is applied to the tube surface near the electrodes of a rare gas cold cathode discharge lamp.

As can be seen from the inverter circuit in Figure 3, at the first moment when a voltage is applied, a voltage is applied between the electrode 11 and the auxiliary electrode closest to it, so the light is turned on by shining the light from the luminous material onto this electrode. Starting characteristics can be improved.

Figure 1 1.2 shows a green and blue rare gas cold cathode discharge lamp. As the red light source, in consideration of responsiveness and output power, in the present invention, light emitted by neon gas discharge is used without using a phosphor. It therefore has no auxiliary electrodes.

Further, the shielding plate 9 is installed so that the light from the auxiliary lamp does not leak onto the surface of the document.

FIG. 5 shows a conceptual diagram of an image reading device according to the present invention. The reading head 51, which includes the lamp unit 50, SELFOC lens array 52 (trademark of Nippon Sheet Glass Co., Ltd.), a contact sensor 53, and a lamp inverter 54, is moved in the sub-scanning direction to read the original 58 placed on the original platen glass 57.
can be read.

Upon receiving the reading start signal, the image reading device performs reading according to the flow shown in FIG.

First, the reading head 51 is at the home position, and the lamp is turned on here. A reference white tape for shading correction is pasted on the document surface at the home position, and by reading this part, the reading device can confirm that the lamp is lit. Therefore, even if the above-mentioned lighting delay occurs at this time, it does not pose a problem. - Once turned on, the phosphorescent member is excited, so during subsequent readings, the electrodes of the rare gas cold cathode discharge lamp are irradiated with phosphorescence, and no discharge delay occurs.

In this example, the luminous material was applied to the tube surface of the rare gas cold cathode discharge lamp, but the same effect can be obtained by applying it to the inside of the shielding plate.

FIG. 6 shows the timing of reading an image. Since a MOS type contact sensor is used here, the lamp lighting and data reading timings are different. 7th
DATA shown in the figure is color separation data of one main scanning line for each color.

〔Effect of the invention〕

According to the present invention, the lighting start characteristics of a rare gas cold cathode discharge lamp are improved, and it is possible to read a good color image.

[Brief explanation of the drawing]

FIG. 1 shows a conceptual diagram of the lamp unit of the present invention. 1... Rare gas cold cathode discharge lamp 2... Rare gas cold cathode discharge lamp 3... Rare gas cold cathode discharge lamp 4.5... Love holder 8... Luminous member 11.12... Lamp electrode (green) (blue) (red) 6...Ring electrode 9...shielding plate Figures 2 (a) and (b) show structural diagrams of the rare gas cold cathode discharge lamp used in the present invention. Ta. 7... Auxiliary electrode 24... Fluorescent material 26...
-Aperture (opening) Fig. 3 is a diagram showing the inverter circuit of the lamp used in the present invention. FIG. 4 is a diagram showing the timing of lighting delay that the present invention attempts to solve. FIG. 5 shows a conceptual diagram of a color image reading device of the present invention. FIG. 6 shows a flowchart regarding lamp lighting at the start of reading according to the present invention. FIG. 7 is a diagram showing an example of the timing of reading a color image. Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Kizobe Suzuki and 1 other person (b) Figure 2 Figure 1 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) In a device that reads a color image by selectively lighting three different light sources, the light source is a rare gas cold cathode discharge lamp, and a phosphorescent member is arranged near the electrode at at least one end of the discharge lamp. A color image reading device further comprising a shielding plate between the luminescent member and the document table.