JP2007183437A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent developed color using a photographic sensitive material while the constitution of a light source device is made as simple as possible. <P>SOLUTION: The light source device 21 is provided on an image exposure device EX which exposes and forms an image on the photographic sensitive material PS, and has a semiconductor laser element directly modulated based on image data as a light source, wherein the wavelength of emitted light from the semiconductor laser element is set so as to become wavelength showing lowered sensitivity by deviating the wavelength of light obtained when the photographic sensitive material PS is irradiated with emitted light from the semiconductor laser element to a side where the decreasing degree of the sensitivity relative to the change of the wavelength of the light is more gentle than the wavelength of light showing the maximum sensitivity in the spectral sensitivity characteristic of the photographic sensitive material PS. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light source device that is provided in an image exposure apparatus that exposes and forms an image on a photographic photosensitive material and that uses a semiconductor laser element that is directly modulated based on image data as a light source.

Such a light source device is an apparatus for irradiating light directly modulated by image data onto a photographic photosensitive material using an emitted beam of a semiconductor laser element as a light source, and exposing and forming an image on the photographic photosensitive material.
In an image exposure apparatus using such a light source device, a spontaneous emission region in the drive current-light output characteristics of a semiconductor laser element (region where the drive current of the semiconductor laser element is smaller than the oscillation threshold current of the semiconductor laser element) When the semiconductor laser device is driven to emit light, the response characteristics deteriorate. Therefore, as described in Patent Document 1 below, the laser oscillation region (drive current of the semiconductor laser device) in the drive current-optical output characteristics of the semiconductor laser device is described. It is desirable to secure a wide range of the dynamic range as much as possible in a region larger than the oscillation threshold current of the semiconductor laser element.

For this purpose, it is necessary to increase the maximum light output of the semiconductor laser device as much as possible, and to drive the light output as much as possible.
When the semiconductor laser device is driven in such a form, too much light is irradiated to the photographic photosensitive material, and it becomes impossible to express a proper gradation in a high density region. In the following Patent Document 1, the emitted light of the semiconductor laser element is attenuated by a filter because good color development that faithfully reproduces image data cannot be obtained.
As described above, as a configuration for attenuating the emitted light of the semiconductor laser element, in addition to a method using a filter (color filter or ND filter), the emitted light of the semiconductor laser element is branched by a beam splitter to A method in which only a part of the emitted light is used for exposure of the photosensitive material, a method using a plurality of such beam splitters, and a configuration in which the emitted light of the semiconductor laser element is guided to the subsequent optical system by an optical fiber. Then, a method of attenuating by adjusting so as to reduce the coupling efficiency between the semiconductor laser element and the optical fiber can be considered.
JP-A-5-188310

However, the conventional configuration requires a mechanism for attenuating the emitted light of the semiconductor laser element, and there is an inconvenience that the apparatus configuration becomes complicated.
The present invention has been made in view of such circumstances, and an object of the present invention is to make it possible to obtain good color development with a photographic photosensitive material while simplifying the configuration of the apparatus as much as possible.

  A first invention of the present application is provided in an image exposure apparatus that exposes and forms an image on a photographic photosensitive material, and includes a semiconductor laser element that is directly modulated based on image data. The wavelength of the light irradiated to the photographic photosensitive material by the emitted light is more gradual in the degree of decrease in sensitivity to changes in light wavelength than the light wavelength at which the sensitivity is maximum in the spectral sensitivity characteristics of the photographic photosensitive material. The emission wavelength of the semiconductor laser element is set so that the wavelength is shifted and the sensitivity is lowered.

The light emitted from the semiconductor laser element is monochromatic light, and usually a semiconductor laser element having a wavelength capable of irradiating the photosensitive material with light that matches the peak wavelength at which the sensitivity is maximum in the spectral sensitivity characteristics of the photosensitive material is selected. However, a semiconductor laser element that can irradiate light deviating from this peak wavelength is selected.
That is, the same effect as attenuating the emitted light of the semiconductor laser element is obtained by using a low sensitivity part in the spectral sensitivity characteristics of the photographic photosensitive material, and even if the light output of the semiconductor laser element is strong, Appropriate color development can be obtained on a photographic material.
In addition, the wavelength of the semiconductor laser device is shifted in this way so that the degree of decrease in sensitivity to a change in the light wavelength is shifted more gently than the peak wavelength.
As shown in FIGS. 3 to 5, many of the spectral sensitivity characteristics of a photographic photosensitive material change in the light wavelength between a wavelength region shorter than the peak wavelength and a wavelength region longer than the peak wavelength. There is a characteristic that the degree of decrease in sensitivity to is considerably different. In any of the cases shown in FIGS. 3 to 5, the drop in sensitivity to the wavelength change (change to the long wavelength side) is abrupt on the longer wavelength side than the peak wavelength, and the wavelength change on the short wavelength side. The drop in sensitivity to (change to the short wavelength side) is not so steep.
Since the spectral sensitivity characteristics have such characteristics, the wavelength of light applied to the photographic photosensitive material is shifted to the opposite side by setting the sensitivity decrease to a more gradual side from the sensitivity peak wavelength. In comparison with the case where the light emission wavelength of the semiconductor laser element is varied, the variation in sensitivity of the photographic photosensitive material is suppressed.

According to a second invention of the present application, in addition to the configuration of the first invention, the wavelength of the light irradiated to the photographic photosensitive material by the light emitted from the semiconductor laser element is a spectral sensitivity of the photographic photosensitive material. In terms of characteristics, on the short wavelength side from the light wavelength at which the sensitivity becomes maximum, the degree of decrease in sensitivity increases again from the light wavelength at which the degree of decrease in sensitivity once becomes moderate with respect to the change from the light wavelength to the short wavelength side. The emission wavelength of the semiconductor laser element is set so as to exist within the wavelength range up to the optical wavelength.
That is, as a specific example of the spectral sensitivity characteristics of a photographic photosensitive material, when the spectral sensitivity characteristics of photographic paper as illustrated in FIGS. 3 to 5 are examined in more detail, the sensitivity shifts from the maximum peak wavelength to the short wavelength side. After the sensitivity is lowered with respect to the change to the short wavelength side, the sensitivity declines gradually from a certain wavelength, and after a moderate period, the sensitivity falls again.
Since the photographic photosensitive material has such spectral sensitivity characteristics, the emission wavelength of the semiconductor laser element varies by setting the wavelength of the light irradiated to the photographic photosensitive material in the section where the decrease in sensitivity is moderate. However, the variation in sensitivity of the photographic light-sensitive material is further suppressed.

The third invention of the present application uses a semiconductor laser element of 650 nm band as the semiconductor laser element in addition to the configuration of the second invention.
That is, when a semiconductor laser element that emits red laser light is used as a light source for red exposure and a semiconductor laser element in the 650 nm band is employed as the red semiconductor laser element, the semiconductor laser in the spectral sensitivity characteristics of FIGS. The element has a light emission wavelength in a section where the sensitivity decreases slowly, and fluctuations in sensitivity of the photographic photosensitive material can be suppressed even if the light emission wavelength of the semiconductor laser element varies.
Moreover, semiconductor laser elements of this wavelength band are mass-produced at a relatively low cost as light sources for optical disks, which can contribute to a reduction in apparatus costs.

According to the first aspect of the invention, the mechanism for attenuating the emitted light of the semiconductor laser element by selecting the emission wavelength of the semiconductor laser element so as to irradiate the photosensitive material with light having a wavelength with low sensitivity of the photographic photosensitive material. Can be eliminated, or even if it is provided, a simple configuration can be obtained, and a good color can be obtained with a photographic photosensitive material while simplifying the apparatus configuration as much as possible.
In addition, by using the low sensitivity region on the side where the degree of decrease in sensitivity to changes in light wavelength is more gradual, fluctuations in the sensitivity of photographic photosensitive materials can be suppressed even if the emission wavelength of the semiconductor laser element varies. Management regarding the sensitivity of the material becomes easy.

According to the second aspect of the invention, the wavelength of the light irradiated to the photographic photosensitive material is set in a section where the decrease in sensitivity is moderate, and the sensitivity of the photographic photosensitive material to the variation in the emission wavelength of the semiconductor laser element is set. Variations can be further suppressed, and management of the photographic light-sensitive material becomes easier.
According to the third aspect of the invention, the apparatus structure can be further reduced by simplifying the structure of the apparatus and reducing the cost of the semiconductor laser element, and a good color can be obtained with a photographic photosensitive material. Furthermore, management relating to the sensitivity of the photographic material can be facilitated, and the management cost of the apparatus can be reduced.

Hereinafter, an embodiment in which the light source device of the present invention is provided as a light source for exposure in a photographic print system will be described with reference to the drawings.
The photo print system DP exemplified in this embodiment is known as a so-called digital minilab machine, and as shown in the block configuration diagram of FIG. 2, a photo print is prepared with various image data input devices. An image input device IR that captures image data for image processing, and an exposure / development device EP that performs exposure processing on photographic paper 2 that is an example of a photographic photosensitive material PS based on the image data input by the image input device IR; It is composed of

[Schematic configuration of image input device IR]
As schematically shown in FIG. 2, the image input device IR includes a film scanner 3 that reads a frame image of a photographic film and outputs it as digital image data, a memory card reader, a magneto-optical disk drive, a CD-R drive, and the like. An external input / output device 4 provided with the image data input device, and a main control device 5 which is constituted by a personal computer and controls the film scanner 3 and the external input / output device 4 and manages the entire photo print system DP. In addition, the main control device 5 includes a monitor 5a for displaying a simulated image simulating a finished print image and various control information, manual setting of exposure conditions, etc., and input operation of control information. Is connected to an operation console 5b.

[Overall configuration of exposure / development apparatus EP]
The exposure / development apparatus EP includes an image exposure apparatus EX that exposes and forms an image on the emulsion surface of the photographic paper 2 inside the housing, and a development processing apparatus PP that develops the photographic paper 2 exposed by the image exposure apparatus EX. And a photographic paper transport system PT for transporting the photographic paper 2 drawn out from the photographic paper magazine 6 to the development processing apparatus PP by a number of transport rollers 9 or the like.
Although not shown, a sorter is provided outside the housing of the exposure / development apparatus EP to classify the photographic paper 2 that has been developed and dried by the development processor PP into orders. A conveyor 10 for conveying the photographic paper 2 discharged from the PP photographic paper discharge port to the sorter is provided on the upper surface of the casing.
Further, in the middle of the conveyance path of the photographic paper conveyance system PT, a cutter 11 for cutting the long photographic paper 2 drawn from the photographic paper magazine 6 into a set print size, and a plurality of conveyance rows of the photographic paper 2 are conveyed. A sorting device 12 for sorting into rows is provided.

[Configuration of image exposure apparatus EX]
The image exposure apparatus EX is composed mainly of an exposure unit 13 that exposes and forms an image on the photographic paper 2 and an exposure control apparatus 14 that controls the exposure unit 13.
[Configuration of Exposure Unit 13]
The exposure unit 13 employs a so-called laser beam scanning exposure method in which an intensity-modulated light beam is scanned on the photographic paper 2 and an image is exposed and formed on the photographic paper 2, and the schematic configuration thereof is shown in FIG. Shown in block diagram.
The exposure unit 13 includes a red light source device 21, a green light source device 22, a blue light source device 23, and an acoustic for intensity-modulating the light beams emitted from the green light source device 22 and the blue light source device 23. The optical modulation element 24 (hereinafter abbreviated as “AOM element 24”), a mirror 25 that bends the optical path of the light beam, a spherical lens 26, a cylindrical lens 27, and a motor (not shown) are rotationally driven. A polygon mirror 28 and a lens group 29 having an f-θ characteristic and a surface tilt correction function are provided.

[Configuration of Light Source Device 21 for Red]
As schematically shown in FIG. 6, the red light source device 21 includes a semiconductor laser element 31 that emits red laser light as a light source, a condensing lens 32 that condenses the emitted light from the semiconductor laser element 31, and a semiconductor laser. A beam splitter 33 for branching a part of the emitted light from the element 31 for detecting the amount of emitted light, and a photodiode 34 for detecting the light intensity of the red laser light branched by the beam splitter 33 are provided. .
The semiconductor laser element 31 used in the red light source device 21 has a light emission wavelength of 650 nm, and is emitted from the semiconductor laser element 31, unlike the green light source device 22 and the blue light source device 23. The photographic paper 2 is irradiated with the laser light at the same wavelength.
In the spectral sensitivity characteristics of the photographic paper 2 supplied by each photosensitive material manufacturer, the sensitivity for red is maximum at around 700 nm, but in this embodiment, the wavelength from which the sensitivity is maximum is used. The semiconductor laser element 31 having a shifted emission wavelength is used.
The direction in which the wavelength is shifted is on the side where the degree of decrease in sensitivity with respect to the change in light wavelength is more gradual. In this embodiment, the wavelength is shorter than the light wavelength at which the sensitivity is maximum in the spectral sensitivity characteristics of the photographic paper 2. It is shifted to the side.

The reason for this will be described with reference to FIGS. 3 to 5 showing the spectral sensitivity characteristics of the photographic paper 2 supplied from each photosensitive material manufacturer.
3 to 5, the horizontal axis indicates the wavelength, and the vertical axis indicates the specific sensitivity based on an appropriate sensitivity value in logarithm.
In each figure, the spectral sensitivity characteristic of the photosensitive layer for blue light is indicated by a curve SB, the spectral sensitivity characteristic of the photosensitive layer for green light is indicated by a curve SG, and the spectral sensitivity characteristic of the photosensitive layer for red light is indicated by a curve SR. In the spectral sensitivity characteristic (curve SR) for the red photosensitive layer, the wavelength at which the sensitivity becomes maximum is indicated by “λ _P ”. It should be noted that the color development of each layer has a relationship that is complementary to the color of light to be exposed.

Although details will be described later, in the present embodiment, the semiconductor laser element 31 is directly modulated by the LD drive circuit 45. When the semiconductor laser element 31 is directly modulated, from the viewpoint of the response speed of the semiconductor laser element 31, etc. It is desirable to use the semiconductor laser device 31 in the laser oscillation region as much as possible (region where the drive current is larger than the oscillation threshold current). For this purpose, the high-power semiconductor laser device 31 is used up to the rated light output. Will do.
Therefore, if the photographic paper 2 is irradiated with the light beam as it is, the light intensity is too strong to form an appropriate image by exposure.
For this reason, a light beam having a wavelength deviated from “λ _P ” is printed on any printing paper 2 that is assumed to be used so that the color development is relatively weakened even when strong light is applied to the printing paper 2. A semiconductor laser element 31 having an emission wavelength that irradiates the paper 2 is selected.

However, the curve SR indicating the spectral sensitivity characteristic of the red photosensitive layer is a sensitivity on the longer wavelength side than “λ _P ” in any of the photographic papers 2 of FIGS. 3 to 5 that are assumed to be used in the present embodiment. If the emission wavelength of the semiconductor laser element is set so that a light beam having a wavelength in such a region is irradiated, the photographic paper 2 may be changed when the emission wavelength of the semiconductor laser element 31 fluctuates due to element variation or the like. While the fluctuation of sensitivity becomes large, the drop in sensitivity is relatively gentle on the shorter wavelength side than “λ _P ”, and the fluctuation of the sensitivity of the photographic paper 2 as described above can be suppressed. .
Therefore, the wavelength of the semiconductor laser element 31 is set so that the wavelength of the light irradiated to the photographic paper 2 by the light emitted from the semiconductor laser element 31 is shifted to the shorter wavelength side than “λ _P ” and the sensitivity is lowered. The emission wavelength is set.

Examining the spectral sensitivity characteristic of the curve SR in more detail, when the process of the change in sensitivity from the “λ _P ” on the short wavelength side is followed, the degree of decrease in sensitivity is once with respect to the change in the light wavelength to the short wavelength side. It can be seen that there is a portion like a “shoulder” that becomes gentle and then the degree of decrease in sensitivity increases again. That is, in the spectral sensitivity characteristics shown in FIG. 3 to FIG. 5, “λ _S ”, which is the light wavelength at which the degree of decrease in sensitivity is increased again, from “λ _L ”, which is the light wavelength at which the degree of decrease in sensitivity once becomes moderate. The wavelength range up to “Δλ”.
The emission wavelength of the semiconductor laser element 31 is set so that the wavelength of the light irradiated to the photographic paper 2 by the light emitted from the semiconductor laser element 31 is within this wavelength range “Δλ” (that is, the “shoulder” portion). By setting, color development can be suppressed even if the photographic paper 2 is irradiated with strong light, and sensitivity fluctuations of the photographic paper 2 can be further suppressed even if the emission wavelength of the semiconductor laser element 31 varies.
In order to utilize this “shoulder” portion, a semiconductor laser element 31 having a light emission wavelength of 650 nm band which is mass-produced at a low cost is used.

[Configuration of Green Light Source Device 22 and Blue Light Source Device 23]
Although the green light source device 22 and the blue light source device 23 have the same basic configuration and are not illustrated, a near infrared semiconductor laser element that emits near infrared laser light and a near infrared semiconductor laser element The second harmonic generation device for generating the second harmonic of the emitted laser beam and other optical components are included.
The green light source device 22 and the blue light source device 23 differ only in the emission wavelength of the near-infrared semiconductor laser element, and the other configurations are common, and both of them emit light emitted from the near-infrared semiconductor laser element. A light beam having a half wavelength is emitted.

[Configuration of Exposure Control Device 14]
As schematically shown in FIG. 1, the exposure control device 14 exposes red, green and blue exposure image data input from the image input device IR in order to control the exposure unit 13 having the above configuration. A look-up table 41 for correcting image data in consideration of the exposure characteristics of the unit 13, an image data memory 42 for storing the image data corrected by the look-up table 41 for each of red, green and blue colors, red, A D / A converter 43 which is provided for each color of green and blue and D / A converts the output data of the image data memory 42, and AOM modulated in accordance with an input signal from the D / A converter 43 for green and blue An AOM control circuit 44 that generates a drive signal for the element 24, and red light according to an image signal input from the D / A converter 43 for red A LD driving circuit 45 for modulating the driving current of the semiconductor laser element 31 of the device 21 is provided.

As schematically shown in FIG. 6, the LD driving circuit 45 includes a high frequency superimposing circuit 51 for suppressing the mode hop noise of the semiconductor laser element 31 and a current / current for converting the output current of the photodiode 34 into a voltage signal. In addition to the voltage conversion circuit 52 and the operational amplifier 53 that controls the drive current of the semiconductor laser element 31 so that the intensity of the emitted light from the semiconductor laser element 31 changes according to the input image signal, the operational amplifier is omitted from illustration. A transistor or the like for adjusting the energization current of the semiconductor laser element 31 by the output of 53 is provided.
An image signal from the D / A converter 43 and a signal from the current / voltage conversion circuit 52 are input to the input of the operational amplifier 53, and the signal input from the current / voltage conversion circuit 52 is input to the operational amplifier 53. The drive current of the semiconductor laser element 31 is controlled so as to coincide with the image signal input from the converter 43.
That is, the semiconductor laser element 31 is directly modulated by the image signal from the D / A converter 43 generated based on the image data.
As described above, the maximum drive current supplied to the semiconductor laser element 31 is set to be a drive current that can obtain a light output with a full rating of the semiconductor laser element 31.
Since the output signal of the high frequency superimposing circuit 51 has a frequency sufficiently higher than the response frequency band of the feedback loop constituted by the photodiode 34 and the current / voltage conversion circuit 52, the high frequency superimposing circuit 51 is a semiconductor based on the operational amplifier 53. The output control of the laser element 31 is not affected.

[Summary of photo print production operation]
When the operator inputs image data to be printed from the film scanner 3 or the external input / output device 4, image processing or the like is appropriately performed, and the image data for exposure after image processing is transmitted to the lookup table 41.
The red, green and blue light beams intensity-modulated by the AOM element 24 and the LD drive circuit 45 based on the red, green and blue exposure image data input from the image input device IR are used for the respective optical components. The light beam that passes through and is irradiated on the reflecting surface of the polygon mirror 28 and reflected by the reflecting surface of the polygon mirror 28 that is driven to rotate is condensed on the photographic paper 2 by the lens group 29. The scanning direction (main scanning direction) of the light beam is orthogonal to the conveyance direction (sub-scanning direction) of the photographic paper 2, and a photographic image to be printed on the photographic paper 2 by the scanning of the light beam and the conveyance movement of the photographic paper 2 Is exposed and formed as a latent image. This is developed in the development processing apparatus PP and finished as a photographic print.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
(1) In the above embodiment, the case where the present invention is applied to the red light source device 21 is illustrated. However, the green light source device 22 and the blue light source device 23 also have a green light beam or a blue light beam. The present invention can be applied when intensity modulation is performed by directly modulating the near-infrared semiconductor laser element provided in each light source device instead of the AOM element 24.
Further, the green light source device 22 and the blue light source device 23 are not a method of generating the second harmonic of near infrared light, but a semiconductor laser element that emits green laser light or a semiconductor laser element that emits blue laser light. And can be applied to the case where the photographic photosensitive material PS is directly irradiated with laser light obtained by directly modulating these semiconductor laser elements.
(2) In the above embodiment, the photographic paper 2 is exemplified as the photographic photosensitive material PS. However, the present invention can be applied to various photographic photosensitive materials PS such as a photosensitive film.
(3) In the above embodiment, from the characteristics of FIGS. 3 to 5 which are characteristics of the photographic paper 2 that is assumed to be used, the wavelength of the light irradiated to the photographic paper 2 is determined in the spectral sensitivity characteristics of the photographic paper 2. The case where the wavelength is shifted to the shorter wavelength side than the light wavelength at which the sensitivity is maximum is described as an example.However, the degree of decrease in sensitivity to the change in the light wavelength is longer on the longer wavelength side than the light wavelength at which the sensitivity is maximized. When a photographic photosensitive material PS having a gradual characteristic is used, the wavelength of light applied to the photographic photosensitive material PS is longer than the light wavelength at which the sensitivity is maximum in the spectral sensitivity characteristics of the photographic photosensitive material PS. It may be configured by shifting.

1 is a schematic configuration diagram of an image exposure apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram of a photo print system according to an embodiment of the present invention. Diagram showing spectral sensitivity characteristics of photographic materials Diagram showing spectral sensitivity characteristics of photographic materials Diagram showing spectral sensitivity characteristics of photographic materials The figure which shows schematic structure, such as a light source device

Explanation of symbols

EX Image exposure device PS Photosensitive material 31 Semiconductor laser element

Claims (3)

A light source device that is provided in an image exposure apparatus that exposes and forms an image on a photographic photosensitive material and that uses a semiconductor laser element that is directly modulated based on image data as a light source,
The wavelength of the light irradiated to the photographic photosensitive material by the light emitted from the semiconductor laser element is less sensitive to changes in the light wavelength than the light wavelength at which the sensitivity is maximized in the spectral sensitivity characteristics of the photographic photosensitive material. A light source device in which the emission wavelength of the semiconductor laser element is set so that the wavelength is shifted toward a gentle side and the sensitivity is lowered.   The wavelength of the light irradiated to the photographic photosensitive material by the light emitted from the semiconductor laser element is shorter than the light wavelength at which the sensitivity is maximum in the spectral sensitivity characteristics of the photographic photosensitive material, and the shorter wavelength side of the light wavelength. The light emission wavelength of the semiconductor laser device is set so that it falls within the wavelength range from the light wavelength at which the degree of decrease in sensitivity once becomes moderate to the light wavelength at which the degree of decrease in sensitivity increases again. The light source device according to claim 1.   The light source device according to claim 2, wherein a semiconductor laser element of a 650 nm band is used as the semiconductor laser element.

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