JP2915125B2 - Light source for photo printing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for a photographic printing device, and more particularly to a light source device of a photographic printing device for printing an image from a color film onto a color printer photosensitive material.

[Problems to be solved by the prior art and the invention]

2. Description of the Related Art Conventionally, there has been known a photographic printing apparatus (printer) for printing an original image recorded on a color filter (negative film, reversal film) or the like on a color print photosensitive material (color paper). This printer includes a light source device, a control unit for controlling the amount of exposure to color paper, and an optical system for forming an image on color paper.

Here, an example of the light source device will be described with reference to FIG. The light source device includes a tungsten bulb 16 as a light source that generates white light. Tungsten bulb 16 has
Cold mirror formed radially and having a reflective surface inside
14 are installed. On the emission side of the tungsten light bulb 16, a mirror box 11 including a hollow rectangular column-shaped cylinder having a reflection surface 10 formed on the entire inner surface and diffusion plates 12A and 12B attached to both ends of the cylinder is arranged. . Between the tungsten bulb 16 and the mirror box 11, a dimming filter 18 composed of a Y (yellow) filter, an M (magenta) filter, and a C (cyan) filter, each having a uniform density, and Y, M, A cut filter 20 having a C filter is disposed.

A part of the direct light from the tungsten bulb 16 and a part of the reflected light reflected by the cold mirror 14 pass directly through the light control filter 18 and a part of the light passes through the diffusion plate 12A attached to one end of the mirror box 11. Incident on the mirror box 11. The light that has entered the mirror box 11 is reflected by the reflection surface 10 formed on the inner surface of the mirror box 11, and emitted from the diffusion plate 12B at the other end. In the mirror box 11, light is diffused and mixed in order to prevent color unevenness due to light that has passed through the light control filter 18 and light that has not passed.
The light emitted from the diffusion plate 12B is applied to a film (not shown) disposed above the mirror box 11, and applied to the color paper via the film and the image forming optical system to print the original image.

The specific energy spectral characteristics of the tungsten light bulb are, for example, as shown in FIG. 3, where the short wavelength side is low and the long wavelength side is high. Therefore, for example, in the case of color paper for a color negative film, the spectral sensitivity characteristics are basically balanced by increasing the sensitivity of the blue-sensitive layer and lowering the red-sensitive layer as shown in FIG.

Therefore, the sensitivity of the three colors of the color paper of the three colors of light emitted from the light source device is completely matched, and the three cut filters are used in printing from a standard original plate without using a dimming filter. , Enter the optical path at about the same time, the print exposure time is the shortest.

However, this is not so easy in practice. For example, a color paper has respective sensitivity characteristics depending on manufacturing and development, and is not always as shown in FIG. Also, in the light source device, the spectral characteristics change due to many factors. That is, the color temperature and luminous intensity of the tungsten lamp vary, and the spectral reflection characteristics of the cold mirror do not reflect a part of the wavelength range necessary for printing as shown in FIG. The spectral reflection characteristics are different. As for the spectral reflection characteristics of the mirrors in the mirror box, for example, as shown in FIG. 6A, the entire required wavelength range is not flat, and this also differs depending on the manufacturing batch. The reflection by the cold mirror 14 is performed only once, or the reflection by the mirror 10 in the mirror box is performed a plurality of times, and is absorbed each time.
The spectral characteristics of the reflected light gradually change as shown in FIGS.

Due to the change of each related element, the luminous intensity of the three colors of the light source and the three-color sensitivity of the color paper become inconsistent, and even when printing from a standard original plate, one or two of the three cut filters are used. The time required for one cut filter to enter the optical path becomes longer.

The cut filter 20 is a dichroic filter, and its spectral transmission and reflection characteristics do not transmit 100% of the wavelength to be transmitted but partially reflect the wavelength to be transmitted as shown in the example of FIG. Due to the non-ideal spectral transmission and reflection characteristics of the cut filter, the color balance of the print is slightly lost.

The dimming filter 18 changes the balance of the three colors of the light source so as to eliminate the deviation in the timing of entering the optical path of the three cut filters. In a standard original plate, the three cut filters are simultaneously in the optical path. In order to enter (the so-called “dead heat removal”), a part of the light control filter is inserted in the optical path in advance, adjusted, and fixed.

However, this dimming filter is also the same dichroic filter as the cut filter, and its spectral transmission and reflection characteristics do not transmit 100% of the wavelength to be transmitted as shown in the example of FIG. As the amount increases, the loss of light amount increases.

This loss of light amount prolongs the print exposure time and reduces efficiency. In order to prevent this, if a tungsten bulb is made to have a higher output or a voltage is increased, heat generation is increased, stability is reduced, and the life of the bulb is shortened.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an efficient light source device that shortens the print exposure time by minimizing the insertion amount of a dimming filter into an optical path.

[Means for solving the problem]

The present invention provides a light source that generates white light, a cylindrical mirror box having a reflection surface formed on an inner surface thereof, and a color balance of light incident on the mirror box that is disposed between the light source and the mirror box. In the light source device for a photographic printing apparatus having a light control filter to be adjusted, a plurality of mirror boxes each having a different spectral reflection characteristic are prepared, and at least one of a film type, a photographic paper type, a developing condition, and a light source characteristic is provided. The above problem is solved by selecting a specific mirror box from the plurality of mirror boxes and using the selected mirror box.

[Action]

The dimming filter inserts a part of the dimming filter into the optical path to adjust the color balance of the light source so that three cut filters enter the optical path at the same time and the exposure is completed when printing from a standard original. As described above, as the insertion amount of the dimming filter into the optical path increases, the loss of light amount increases and the exposure time increases.

Therefore, a plurality of mirror boxes having different spectral reflection characteristics, for example, those having high reflection characteristics on average from short wavelength to long wavelength, those having high reflectance on the long wavelength side with respect to short wavelength, In contrast, if three types with high reflectivity on the short wavelength side are prepared, and the type with the least amount of light control filter inserted into the optical path is selected and used, the exposure can be performed without changing other conditions. Time is the shortest.

The plurality of mirror boxes have different spectral reflection characteristics. If any of the type of film, the type of photographic paper, the development conditions, and the characteristics of the light source are different, the insertion amount of the light control filter into the optical path will be different. Therefore, if a specific mirror box is selected from a plurality of mirror boxes according to at least one of the type of film, the type of photographic paper, the development conditions, and the characteristics of the light source, the insertion amount of the light control filter into the optical path can be reduced. The number of print exposure operations can be reduced, and the time required for the entire print exposure operation can be reduced.

Conventionally, it was not possible to obtain a mirror with a high reflectance on the long wavelength side for a short wavelength, but recently, with the advancement of dielectric multilayer technology, it has become possible to obtain a mirror with a high reflectance on the long wavelength side even with aluminum-deposited mirrors. became.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Since the light source device of this embodiment has substantially the same configuration as that of FIG. 2, the corresponding portions are denoted by the same reference numerals and will be described in detail.

FIG. 1 shows three types of spectral reflection characteristic curves of the reflection surface 10 of the mirror box 11 in this embodiment. This reflective surface 10 is a mirror box
A dielectric multilayer film composed of alternating layers using TiO ₂ , SiO ₂ or the like is formed on the inner surface of 11 by coating by vacuum evaporation. In this embodiment, the mirror box having the spectral reflection characteristic shown in FIG. 1A, the mirror box having the spectral reflection characteristic shown in FIG. 1B, and the mirror box having the spectral reflection characteristic shown in FIG. Three types of mirror boxes 11 are provided. The spectral reflection characteristic of the reflecting surface 10 shown in FIG. 1 (A) shows a high transmission characteristic in a near ultraviolet region of about 360 to 380 mm or less, shows a substantially constant reflectance in a short wavelength region, and has a medium wavelength and a long wavelength. In the wavelength region, the reflectance is gradually reduced. That is, it exhibits high spectral reflection characteristics on average from short wavelengths to long wavelengths. The spectral reflection characteristics shown in FIG.
It shows high spectral reflection characteristics on the short wavelength side near about 400 nm, shows a substantially constant reflectance from the short wavelength range to the middle wavelength range, and decreases in the middle wavelength and long wavelength range, to about 550 n
This is a characteristic in which the reflectance sharply decreases from around m. That is,
A short wavelength has a high long wavelength and a low spectral reflection characteristic. The spectral reflection characteristic shown in FIG. 1 (C) shows a low reflection characteristic in a short wavelength range of about 440 to 450 nm or less, the reflectance gradually increases in a middle wavelength range and a long wavelength range, and the maximum long wavelength range. This is a characteristic in which the maximum value of the reflectance is approximately 9 to 97%. That is, a short wavelength has a low spectral reflectance characteristic with a long wavelength being high.

Here, it is necessary to adjust the color balance of the light source when the type of the color paper or the development conditions are changed, when the tungsten bulb 16 is replaced, or the like. The adjustment involves adjusting the insertion amount of the three dimming filters 18 with a standard master plate to take the dead heat of the three cut filters 20. It is preferable to select the mirror box 11 that is used in order and that minimizes the insertion amount of the light control filter 18. For example, when the type of the color paper is changed to one having a large specific sensitivity of the red-sensitive layer, a large number of cyan filters for reducing the amount of red light must be inserted in the optical path. However, a light amount loss of blue light and green light occurs according to the insertion amount of the cyan filter. Here, FIG. 1 (B) having a high reflectance on the short wavelength side.
By using the mirror box 11 having the spectral reflection characteristic shown in (1), only the amount of red light can be reduced, the insertion amount of the cyan filter is small, and the loss of the amount of blue light and green light is small. Next, when the specific energy of the red light decreases, the characteristics of the tungsten light bulb 16 include many yellow filters and magenta filters that reduce the amount of blue light and green light other than the red light in the optical path, thereby increasing the overall balance. Must be taken. However, depending on the insertion amount of the yellow filter and the magenta filter, the yellow filter causes a loss of the amount of green light and red light, and the magenta filter causes a loss of the amount of light of blue light and red light, resulting in an overall loss of light amount. Here, the amount of red light can be increased by using the mirror box 11 having the spectral reflection characteristic shown in FIG. 1 (C) having a high reflectance on the long wavelength side, and the yellow filter and the magenta filter can be inserted. The amount is small, and the light loss is small.

As described above, the adjustment of the light control filter is performed when the production batch or type of the color paper to be used is changed, when the development conditions are changed, when the type of film to be printed is changed, or when the tungsten light source of the light source is used. Is changed, and the like, but the loss of light amount is reduced by selecting one of the three types of mirror boxes that minimizes the amount of light control filter inserted into the optical path.

According to the present embodiment, the loss of the light source light amount is reduced by selecting the mirror box 11 that minimizes the insertion amount of the dimming filter 18 into the optical path, and the light amount irradiated on the color paper becomes larger than before. As a result, the set exposure time can be shortened, and the time of the entire print exposure operation can be shortened.

Even if the exposure time of the standard negative film cannot be set shorter than a certain value due to the hardware structure of the printer, the exposure time of the high-density original plate, which requires a long exposure time, can be shortened. To be peeled off.

In the embodiment, the mirror box 11 provided with three types of reflection surfaces having different spectral reflection characteristics has been described. However, the present invention is not limited to the above-described spectral reflection characteristics and types, and two or four or more types of mirrors are provided. Box 11 may be provided. In the recent vacuum deposition method, a reflection surface having a desired spectral reflection characteristic can be easily formed almost as desired, so that a number of mirror boxes 11 having various spectral reflection characteristics are prepared in advance, and among them, It is more effective to select and use. If the required characteristics are known in advance, a mirror box 11 having a specific spectral reflection characteristic may be prepared. Further, instead of replacing the entire mirror box 11, the reflection surface may be replaced.

Although the present invention selects and uses mirror boxes having different spectral reflection characteristics, it is also possible to select tungsten lamps with cold mirrors having different spectral reflection characteristics. However, it is not preferable because the production is difficult and the cost increases.

Although the above description has been made with reference to a subtractive color printer, the present invention can also be applied to an additive color printer.

Further, the present invention can be applied not only to a printer having a dimming filter and a cut filter separately but also to a printer in which one set of three-color filters is used as a dimming filter and a cut filter.

According to the above embodiment, in order to select and use a mirror box that reduces the insertion amount of the dimming filter into the optical path,
The effects of lowering the total lighting pressure of the tungsten lamp and stabilizing it for a long period of time and using a tungsten lamp with low power consumption and low heat generation can be obtained.

〔The invention's effect〕

The present invention selectively uses a mirror box that reduces the insertion amount of the dimming filter into the optical path, so that the light amount loss of the light source device is reduced, the print exposure time is shortened, and the efficiency can be improved. The effect is obtained.

[Brief description of the drawings]

1 is a spectral reflection characteristic curve of a reflection surface inside a mirror box according to an embodiment of the present invention, FIG. 2 is a schematic sectional view of a light source unit, FIG. 3 is a specific energy curve of a tungsten bulb, and FIG. FIG. 5 is a spectral sensitivity characteristic curve of a color paper, FIG. 5 is a spectral reflection characteristic curve of a cold mirror, FIG. 6 is a spectral reflection characteristic curve of a reflection surface inside a mirror box and a spectral reflection characteristic curve of repetition thereof, and FIG. 7 is a dichroic. It is a spectral transmission and reflection characteristic curve of a filter. 11 ... Mirror box, 12 ... Diffusion plate, 14 ... Cold mirror, 16 ... Tungsten bulb, 18 ... Dimmable filter, 20 ... Cut filter.

Claims (1)

(57) [Claims] 1. A light source for generating white light, a cylindrical mirror box having a reflection surface formed on an inner surface thereof, and a light source for light incident on the mirror box disposed between the light source and the mirror box. In a light source device for a photographic printing apparatus having a dimming filter for adjusting a color balance, a plurality of mirror boxes having different spectral reflection characteristics are prepared, and a film type, a photographic paper type, a developing condition, and a light source characteristic are prepared. Wherein a specific mirror box is selected from the plurality of mirror boxes and used according to at least one of the following.