JPH086364A - Lighting system - Google Patents

Abstract

PURPOSE:To reduce the difference of the toner color separation rate and improve the color reproducing fidelity of an image by providing multiple light sources different in the distribution of luminescence intensity so that the difference of the sensitivity of the color light conducting toner for wavelengths of blue, green, and red is made smaller than the difference of the sensitivity of one light source. CONSTITUTION:A halogen lamp 1 as the first light source having a reflector 3 and a fluorescent lamp 2 as the second light source are arranged face to face in a shielding plate 4 concurrently serving as a support case in this lighting system, and a self-focusing lens 5 for guiding the reflected light from a document to a photoreceptor is arranged between the halogen lamp 1 and the fluorescent lamp 2 so as to penetrate the lower section of the shielding plate 4. The distribution of the luminescence intensity of the halogen lamp 1 is strong for the green and red light and weak for the blue light. The distribution of the luminescence intensity of the fluorescent lamp 2 is strong for the blue and green light. When the document is illuminated by the light from both lamps, the difference of the toner color separation rate is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device used in a one-shot color image forming apparatus using a photosensitive toner.

[0002]

2. Description of the Related Art Generally, by combining the background color of a document, the spectral sensitivity of a photoconductor and the spectral energy distribution of a light source,
The effect of the background color of the original appears on the copied image. For example, if the background color of the original is red, and the sensitivity of the photoconductor is large in the short wavelength (blue) region and small in the long wavelength (red) region, the background color of the original appears as a copy image. I will end up. Therefore, if a light source in which the emission intensity of the light source is larger in the long wavelength region than in the short wavelength region, such as a halogen lamp,
Although the influence of the background color is reduced, the spectral energy distribution of these light sources also spreads to the short wavelength side, so if the original image is a color in the relatively short wavelength region, the image will be erased. . Conventionally, in order to solve this, there is a method of enhancing the sensitivity on the long wavelength side by using a light source in which the spectral energy distribution is in the short wavelength region and a light source in the long wavelength region to remove the background color. Invented (JP-A-58-2195)
44).

Further, in general, a light source such as a fluorescent lamp or a halogen lamp can be instantly started up and relighted, but since the luminous efficiency is low, when the sensitivity of the photoconductor is low,
It takes time to form an image. On the other hand, a high-intensity discharge lamp such as a metal halide lamp can reduce the time required for image formation even if the efficiency is high and the sensitivity of the photoconductor is low, but it is not practical because it takes time to start and relight. For example, when a halogen lamp is used, there is a problem that if the number of copies is large, it takes too much time, and when a metal halide lamp is used, there is a problem that a normal single copy requires a long waiting time. Conventionally, in order to solve this, for example, a halogen lamp and a metal halide lamp are used, and the first copy of the first sheet is performed by using a halogen lamp that can be instantly turned on, and while the copy of the first sheet is being performed. A method has been devised in which a metal halide lamp, which takes a long time to start up, is turned on and a high-intensity metal halide lamp is used from the second copy (JP-A-3-137629).

[0004]

On the other hand, in a one-shot color image forming method using a photosensitive toner such as a conductive toner for color, three color toners of yellow, magenta and cyan are used, and a blue color is used as the toner. Color images are formed by giving light sensitivity to light of each wavelength of green, green, and red.

However, the photosensitivity of these toners is not the same (the photosensitivity of cyan is lower than that of yellow and magenta), and the distribution of the light emission intensity of the light source also differs depending on the light emission color. Therefore, there is a problem in that it is not possible to obtain a copied image that faithfully reproduces the color of the image, even if the conventional device described above is used.

An object of the present invention is to provide an illuminating device capable of obtaining a copy image which faithfully reproduces the color of the image in consideration of such problems in the conventional color image formation.

[0007]

SUMMARY OF THE INVENTION The present invention is an illumination device for an image forming apparatus, which utilizes color photoconductive toners having light sensitivity to light of blue, green and red wavelengths, respectively.
The difference in sensitivity of color photoconductive toner for each wavelength is
To be less than the difference in sensitivity for one light source,
The illumination device includes a plurality of light sources having different light emission intensity distributions.

[0008]

According to the present invention, for example, a halogen lamp for green and red light and a fluorescent lamp for blue light are used as a plurality of light sources. The difference in the ratio becomes small, and the color of the image can be faithfully reproduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a block diagram of a lighting device according to a first embodiment of the present invention. That is, the illuminating device used for the one-shot color copying machine is generally provided below the contact glass 6 which constitutes the document table of the copying machine so as to be movable for exposure. This illuminating device has a halogen lamp 1 as a first light source, which has a reflecting plate 3 in a light shielding plate 4 which also serves as a support case and which shields light from the light source so as not to unnecessarily leak, and a second Fluorescent lamps 2 as light sources are arranged so as to face each other, and light reflected from the original is passed through a photoconductor (not shown) so as to penetrate the lower part of the light shielding plate 4 between the halogen lamp 1 and the fluorescent lamp 2. ) And the like are arranged.

The light emitted from the above-mentioned halogen lamp 1 is condensed to some extent by the reflection plate 3 and applied to the original placed on the contact glass 6, and at the same time, the light emitted from the fluorescent lamp 2 is also emitted. Similarly, the original is irradiated, and each light reflected by the original is incident on the SELFOC lens 5, and is further irradiated on the surface of the photoconductor through a mirror, an imaging lens and the like (not shown).

Here, the distribution of the emission intensity of one of the halogen lamps 1 is such that green or red light is strong and blue light is considerably weak.
The distribution of the emission intensity of the other fluorescent lamp 2 differs depending on the type of the phosphor used in the lamp, but the blue and green light intensities are relatively strong. For example, the phosphor composition 3Sr as shown in (Table 1) is used. ₃ (PO ₄ ) ₂ · SrCl ₂ : Eu ²⁺ , (Sr.Ca.
Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , BaMg ₂ Al ₁₆ O
₂₇ : A lamp having a peak in blue is obtained by using Eu ²⁺ or the like.

[0013]

[Table 1]

FIG. 2 shows the phosphor composition 3Sr ₃ (P
O _{4) 2} · SrCl _2: is a diagram showing a distribution of luminous intensity of a fluorescent lamp using a Eu ^2+. In this embodiment, this is used to form the lighting device.

Next, experimental results of image formation using the illumination device of the above-mentioned embodiment will be described together with a comparative example with reference to (Table 2).

First, when an image was output only by a halogen lamp as Comparative Example 1, the color separation rate of the yellow toner was as low as 82% as compared with other magenta and cyan toners, and the output image of the yellow toner was the entire image. An image was obtained that was covered and had a yellowish color compared to the original.

Next, as a comparative example 2, when an image was output only with a fluorescent lamp, the color separation ratio of the cyan toner was 78% lower than that of the other yellow and magenta toners.
In the output image, the cyan toner covered the entire image, and a bluish image was obtained as compared with the original.

Next, when an image is output using both a halogen lamp and a fluorescent lamp as in this embodiment, the color separation ratios are 95% for yellow toner, 98% for magenta toner, and 95% for cyan toner, respectively. An image having a color which is good on average and which is faithful to the original color was obtained.

[0019]

[Table 2]

Although the first embodiment uses the halogen lamp and the fluorescent lamp as the light source, the present invention is not limited to this, and an image of a color faithful to the color of the original can be obtained.
As long as the light sources have different emission intensity distributions, other combinations of light sources such as a red fluorescent lamp and a blue fluorescent lamp may be used. Further, the number of light sources is not limited to two, and three or more light sources having different emission intensity distributions may be used.

FIG. 3 is a block diagram of an illumination device according to a second embodiment of the present invention. In this embodiment, the first shown in FIG.
In addition to the lighting device of the embodiment, a cooling fan 7 for cooling the fluorescent lamp 2, a temperature sensor 8 for detecting the temperature of the fluorescent lamp 2, and a cooling fan 7 according to the temperature detected by the temperature sensor 8. Fan controller 9 that controls the rotation speed
Is provided.

Next, the operation of the lighting device of the second embodiment will be described.

The purpose of this embodiment is to maintain the optimum luminous efficiency in consideration of the fact that the luminous efficiency of the fluorescent lamp 2 is greatly affected by temperature. In general, the luminous efficiency of the fluorescent lamp 2 has a peak at a certain temperature, and decreases when the temperature is higher or lower than that temperature.

Therefore, the temperature of the fluorescent lamp 2 is maintained by the heat generated from the halogen lamp 1 at a temperature at which the luminous efficiency is optimum. At this time, in order to prevent the temperature from rising too high, the temperature is detected by the temperature sensor 8 and the cooling capacity of the cooling fan 7 is adjusted via the fan controller 9 according to the detected temperature. By doing this, fluorescent lamp 2
The temperature of can be maintained at the optimum temperature.

In the second embodiment, the cooling fan 7, the temperature sensor 8 and the fan controller 9 are used to adjust the temperature of the fluorescent lamp 2 to the optimum temperature.
Not limited to this, the cooling capacity of the cooling fan may be calculated in advance based on the optimum temperature of the fluorescent lamp, the amount of heat generated by the halogen lamp, etc., and the cooling fan may be operated based on the calculated cooling capacity. Good. In this case, the temperature sensor 8
Also, the fan controller 9 is unnecessary.

In the second embodiment, the cooling fan is used as a method for lowering the temperature of the fluorescent lamp, but the present invention is not limited to this, and another cooling device such as an electronic cooler may be used.

Although the number of light sources is two in the second embodiment, the number of light sources is not limited to two, and may be three or more. In this case, one halogen lamp and one fluorescent lamp
One is mandatory.

In each of the above embodiments, the illuminating device is applied to a color copying machine. However, the present invention is not limited to this, and the illuminating device is applied to another color image forming device such as a color printer having the same principle. Of course good.

[0029]

As is apparent from the above description, according to the present invention, the difference in the sensitivity of the color photoconductive toner for each wavelength is smaller than the difference in the sensitivity of one light source. Since a plurality of light sources having different distributions are provided, there is an advantage that a copy image that faithfully reproduces the color of the image can be obtained.

Further, there is an advantage that the luminous efficiency can be improved by using the heat of the halogen lamp to maintain the temperature of the fluorescent lamp at a temperature at which the luminous efficiency is optimum.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of light emission characteristics of a fluorescent lamp used in the lighting apparatus of the first embodiment.

FIG. 3 is a configuration diagram of a lighting device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Halogen lamp 2 Fluorescent lamp 3 Reflector 4 Light-shielding plate 5 Selfoc lens 6 Contact glass 7 Cooling fan 8 Temperature sensor 9 Fan controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuko Akiba 1-2-2 Tamatsukuri Chuo-ku, Osaka City, Osaka Prefecture Mita Industry Co., Ltd.

Claims (3)

[Claims] 1. An illumination device for an image forming apparatus, which uses color photoconductive toners having photosensitivity to light of wavelengths of blue, green and red, respectively. An illuminating device comprising a plurality of light sources each having a different emission intensity distribution so that the difference in toner sensitivity is smaller than that in one light source. 2. The lighting device according to claim 1, wherein at least one of the plurality of light sources is a halogen lamp and at least one is a fluorescent lamp. 3. The illumination device according to claim 2, wherein the temperature of the fluorescent lamp is maintained at a temperature at which the luminous efficiency is optimized by utilizing the heat of the halogen lamp.