JP2008209687A - Laser output adjustment method - Google Patents

Abstract

The resolution of an image formed on a photosensitive medium is improved.
First, the type of photographic paper on which an image is formed is determined, and the intensity of laser light required to form an image of all densities on the photographic paper based on the color development characteristics of the photographic paper P is determined. Then, the resistance value of the variable resistance of the red LD is changed so that the intensity of the laser light detected by the synchronous sensor becomes the above intensity P.
[Selection] Figure 5

Description

  The present invention relates to a laser output adjustment method in an exposure apparatus that forms an image on a photosensitive medium by performing exposure using laser light.

  In recent years, a photographic processing apparatus employing a so-called digital exposure method has been widely used. In such a digital exposure method, an image can be formed by exposing a photographic paper with light modulated based on digital image data. Accordingly, the laser light emitted from the laser light source is guided to the photographic paper disposed at the exposure position via a plurality of optical components such as a lens, a reflecting mirror, and an acousto-optic modulator (AOM). Here, in order to obtain a high-quality image, it is necessary that the laser beam guided to the photographic paper has a predetermined intensity.

Therefore, the adjustment of the output of the laser light source is performed so that the intensity of the laser beam guided to the photographic paper is equal to or higher than the predetermined intensity. In view of the above, it is necessary to increase the output of the laser light source accordingly. Conventionally, after adjusting the laser output of a single laser light source, the adjusted laser light source is mounted on the photographic processing apparatus. In addition, it is necessary to consider various variations such as color variations of the developer and the like, and the output of the laser light source tends to be larger than necessary.
JP-A-11-237568

  However, if the output of the laser light source becomes too large, there arises a problem that a sufficient dynamic range cannot be obtained when modulation is performed with a predetermined number of gradations in AOM. That is, as the output of the laser light source increases, the step value corresponding to one gradation increases, and the resolution of the image formed on the photographic paper decreases. As described above, since the laser output is conventionally adjusted for a single laser light source, it is necessary to adjust the laser output in consideration of the variation of a plurality of optical components, and this is the reason why it is formed on photographic paper. A reduction in the resolution of the generated image could not be avoided.

  Therefore, a main object of the present invention is to provide a laser output adjustment method capable of improving the resolution of an image formed on a photosensitive medium.

Means for Solving the Problems and Effects of the Invention

  The laser output adjustment method of the present invention is a laser output adjustment method in an exposure apparatus comprising a laser light source and a plurality of optical components for guiding laser light emitted from the laser light source to a photosensitive medium, It is characterized in that the intensity of the laser light emitted from the light source and reaching the exposure position via the plurality of optical components is detected, and the output of the laser light source is adjusted based on the detected intensity of the laser light.

  According to this configuration, since the output of the laser light source is adjusted based on the intensity of the laser light that is emitted from the laser light source and then reaches the exposure position via a plurality of optical components, the variation of the plurality of optical components is considered separately. There is no need to do it. For this reason, the laser output of the laser light source can be adjusted in consideration of only the variations related to the processing after the exposure processing of the photosensitive medium (for example, the sensitivity variation of the photosensitive medium and the color development variation of the developer). Can be kept relatively small. Therefore, a sufficient dynamic range can be obtained, and the resolution of an image formed on the photosensitive medium can be improved.

  In the laser output adjustment method of the present invention, the exposure apparatus controls a scanning optical element that scans a laser beam in one direction on the photosensitive medium, and a modulation timing of the laser light that is scanned on the photosensitive medium by the scanning optical element. A synchronization sensor for detecting the intensity of the laser beam emitted from the laser light source and scanned by the scanning optical element, and detecting the intensity of the laser beam based on the detected intensity of the laser beam. The output of the laser light source may be adjusted.

  According to this configuration, the intensity of the laser beam emitted from the laser light source and then scanned by the scanning optical element is detected by the synchronization sensor. Therefore, when adjusting the laser output, the intensity of the laser beam is detected by the synchronization sensor used to control the modulation timing of the laser beam when an image is formed. There is no need to separately provide detection means for adjusting the laser output.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a photographic processing apparatus in which a laser output adjustment method according to an embodiment of the present invention can be used.

  A photographic processing apparatus 1 shown in FIG. 1 is a photographic processing apparatus that employs a digital scanning exposure method using a laser beam, and includes an image input unit 20, a printer unit 30, a processor unit 40, and a finishing processing unit 50. It has. Further, the photo processing apparatus 1 is loaded with paper magazines 31 and 32, and the photographic paper 2 which is a long photosensitive medium housed in the magazines is in a path 18 indicated by a one-dot chain line in FIG. Then, it is conveyed to a cutter 34 described later. The photographic paper 2 cut to a predetermined length along the width direction by the cutter 34 is conveyed along the path 18 from the printer unit 30 to the finishing processing unit 50 via the processor unit 40.

  The image input unit 20 performs various processes such as a reading process of an analog image recorded in each frame of the film and a digital conversion process for the read image data, or a reading process of a digital image recorded in an image storage device such as a flash memory. Processing is performed. In the printer unit 30, exposure processing based on digital image data is mainly performed on the photographic paper 2. In the processor unit 40, the exposed photographic paper 2 is subjected to processing such as development, bleach-fixing, and stabilization. In the finishing processing unit 50, the photographic paper 2 on which the image discharged from the processor unit 40 has been exposed is subjected to a drying process, and the photographic paper 2 that has been dried and discharged from the discharge port 19 is sorted for each order. .

  The image input unit 20 receives a film loading unit 21 on which a film is loaded, a scanner light source unit 22 in which a light source for irradiating the film is stored during scanning, and a digital image input from an image storage device such as a flash memory. And a terminal (not shown). An imaging element (not shown) such as a CCD for taking a film image is disposed below the film mounting unit 21. An image signal output from the image sensor is digitally converted by an A / D converter (not shown), and then supplied to an image control apparatus 100 described later.

  The printer unit 30 accommodates each of the wound long photographic papers 2 and selectively uses two paper magazines 31 and 32, and an advance unit that pulls out the photographic paper 2 from the paper magazines 31 and 32. 33, a cutter 34 for cutting the photographic paper 2 having a predetermined width drawn from the paper magazines 31 and 32 into a desired length according to the print size along the width direction, and a photosensitive emulsion layer of the photographic paper 2 are formed. A printing unit 35 for printing a desired character on an unfinished surface (back surface), and a chucker 36 for conveying the photographic paper 2 cut to a desired length in parallel in two to three rows up to the front stage of the exposure position; , An exposure unit 3 for performing exposure processing on the photographic paper 2, a plurality of roller pairs 37 for conveying the photographic paper 2, and a motor 38 for driving the roller pairs 37.The plurality of roller pairs 37 are arranged at intervals shorter than the shortest length at which the photographic paper 2 may be cut so that the cut photographic paper 2 does not fall off.

  The processor unit 40 includes processing tanks 41a to 41f for performing development, bleach-fixing, and stabilization processes on the photographic paper 2 supplied from the printer unit 30, and processing liquids stored in the processing tanks 41a to 41f. Waste liquid and replenisher tanks 42 a to 42 d, a plurality of roller pairs 43 for transporting the photographic paper 2, and a motor (not shown) for driving the roller pairs 43.

  The finishing processing unit 50 has a heater 51 for quickly drying the photographic paper 2 discharged from the processor unit 40 and a belt for conveying the photographic paper 2 discharged from the discharge port 19 in the direction perpendicular to the paper surface of FIG. A conveyor 52, a plurality of roller pairs 53 for conveying the photographic paper 2 and a motor (not shown) for driving the roller pairs 53 are provided. Note that, like the plurality of roller pairs 37, the plurality of roller pairs 43 and 53 are spaced at intervals shorter than the shortest length at which the photographic paper 2 may be cut so that the cut photographic paper 2 does not fall off. Is arranged in.

  The photo processing apparatus 1 shown in FIG. 1 includes a control unit 10 that controls the operation of each unit, a display 23 that displays various information about the photo processing apparatus 1 and notifies the operator, and an input operation to the photo processing apparatus 1. And a personal computer (personal computer) 25 including a keyboard 24 for performing the above. As will be described in detail later, the control unit 10 includes an image control apparatus 100 (see FIG. 3) that mainly controls image data corresponding to an image exposed by the exposure unit 3. .

  Next, a detailed configuration of the exposure unit 3 included in the photographic processing apparatus 1 of the present embodiment will be described. FIG. 2 is a view showing a schematic configuration of an exposure unit included in the photographic processing apparatus shown in FIG.

  As shown in FIG. 2, the exposure unit 3 includes a blue LD (Laser Diode) 71B, a green SHG (Second Harmonic Generation) laser unit 71G, and a red LD 71R in a housing 70. The blue LD 71B, the green SHG laser unit 71G, and the red LD 71R can emit laser beams of minute diameter light beams having wavelengths of blue component, green component, and red component, respectively.

  Inside the green SHG laser unit 71G, although not shown, a second harmonic is extracted from a solid laser such as a YAG laser and a second harmonic corresponding to the laser beam of the green component from the laser beam emitted from the solid laser. A wavelength variable unit composed of a wave generation unit and the like is provided, and a laser beam of this second harmonic component is emitted. In the configuration of this embodiment, a solid-state laser is used as a means for emitting a basic laser beam. However, the present invention is not limited to this, and for example, an LD can be used.

  On the other hand, the blue LD 71B and the red LD 71R can directly emit laser beams of a blue component and a red component, respectively. Further, on the emission side of the blue LD 71B and the red LD 71R, lens groups 72B and 72R for shaping the blue laser beam and the red laser beam emitted therefrom and guiding them to the light entrances of the next AOM 73B and AOM 73R, respectively. Has been placed. Instead of the blue LD 71B and the red LD 71R, a blue SHG laser unit and a red SHG laser unit configured in the same manner as the green SHG laser unit 71G can be used. Further, the laser beam intensity may be modulated by directly modulating the outputs from the blue LD 71B and the red LD 71R without providing the AOM 73B and the AOM 73R for the blue LD 71B and the red LD 71R.

  Laser beams emitted from the blue LD 71B, the green SHG laser unit 71G, and the red LD 71R are guided to the light entrances of acousto-optic modulators (AOMs) 73B, 73G, and 73R, and each laser beam is imaged. After being modulated in accordance with the data, the light intensity of each laser beam is adjusted in the light control sections 74B, 74G, and 74R. Thus, in the present embodiment, the blue LD 71B, the green SHG laser unit 71G, and the red LD 71R, and the AOM 73B, 73G, and 73R function as a light source in pairs.

  The AOMs 73B, 73G, and 73R are optical modulators that utilize a so-called acousto-optic diffraction, which is a diffraction phenomenon caused by a refractive index distribution created in a transparent medium by a sound wave acting as a phase diffraction grating. The intensity of the diffracted light is modulated by changing the intensity. Accordingly, the AOM drivers 83B, 83G, and 83R (see FIG. 3) are connected to the AOMs 73B, 73G, and 73R, respectively, and the amplitude is modulated from these AOM drivers 83B, 83G, and 83R according to the image data. A high frequency signal is input. Then, an ultrasonic wave corresponding to the high-frequency signal is propagated in the acousto-optic medium, and when the laser beam is transmitted through the acousto-optic medium, diffraction occurs due to the acousto-optic effect, and the amplitude of the high-frequency signal is Intense laser beams are emitted from the AOMs 73B, 73G, and 73R as diffracted light.

  The dimmers 74B, 74G, and 74R are configured by, for example, an ND filter or a rotating plate provided with a plurality of openings having different sizes. Light emitting elements such as semiconductor lasers and solid-state lasers have a predetermined light amount range in which light can be emitted in a stable state. Therefore, by adjusting the light amount by the light control units 74B, 74G, and 74R, the color development characteristics of photographic paper Accordingly, it is possible to perform exposure in a light amount range that provides a wide dynamic range.

  The laser beams emitted from the light control units 74B, 74G, and 74R are reflected in the direction toward the reflection mirror 76 by the dichroic mirrors 75B and 75G or the mirror 75R. Here, each of the dichroic mirrors 75B and 75G has a property of reflecting only a laser beam having a wavelength of a blue component or a green component and transmitting light having a wavelength other than that. On the other hand, the mirror 75R may be any mirror that reflects the red component of the incident light. In the present embodiment, since a red laser beam consisting of only the wavelength of the red component is incident on the mirror 75R, a mirror that totally reflects the incident light is used as the mirror 75R.

  Therefore, the red laser beam reflected by the mirror 75R and transmitted through the dichroic mirrors 75G and 75B and the green laser beam reflected by the dichroic mirror 75G are transmitted through the dichroic mirror 75B and reach the reflecting mirror 76. That is, the blue laser beam traveling from the dichroic mirror 75B toward the reflection mirror 76 becomes a combined laser beam composed of laser beams of red, green, and blue components modulated according to image data.

  The combined laser beam is reflected by the reflection mirror 76, passes through the cylindrical lens 77, and then reaches the polygon mirror 78. Here, the cylindrical lens 77 is a lens that condenses the combined laser beam reflected by the reflection mirror 76 on the reflection surface of the polygon mirror 78 in the sub-scanning direction. The cylindrical lens 77 is used to perform correction (surface tilt correction) when a surface tilt error (an error in which the normal direction of the reflective surface deviates from the normal main scanning surface) occurs on the reflection surface of the polygon mirror 78. is there.

  The polygon mirror 78 is a rotating body provided such that a plurality of reflecting surfaces form a regular polygon, and is rotated by a polygon driver 78a. The combined laser beam irradiated from the reflecting mirror 76 through the cylindrical lens 77 is reflected by one reflecting surface of the polygon mirror 78 and travels in the direction of the photographic paper 2. The reflection direction of the combined laser beam on the polygon mirror 78 moves in the main scanning direction according to the rotation of the polygon mirror 78. When the reflection of the combined laser beam on one reflecting surface is finished by the rotation of the polygon mirror 78, the irradiation of the combined laser beam is transferred to the reflecting surface adjacent to the reflecting surface, and the laser beam is reflected in the main scanning direction within the same range. The direction moves. In this way, one scanning line is scanned by one reflecting surface, and the next scanning line is scanned by the adjacent reflecting surface. Therefore, the time lag between the adjacent scanning lines in the sub-scanning direction is extremely reduced. It can be made smaller.

  An fθ lens 79 is disposed on the optical path from the polygon mirror 78 toward the photographic paper 2. The fθ lens 79 is an optical system for correcting image distortion in the vicinity of both ends of the scanning surface due to the combined laser beam irradiated to the photographic paper 2 from the polygon mirror 78, and includes a plurality of lenses. The distortion of the image in the vicinity of both ends of the scanning surface is caused by the difference in the length of the optical path from the polygon mirror 78 to the photographic paper 2.

  Further, a mirror 80 and a synchronization sensor 81 are provided outside the main scanning range of the combined laser beam from the polygon mirror 78 to the photographic paper 2. The mirror 80 is disposed at a position just outside the direction of the main scanning start point when viewed from the polygon mirror 78. In other words, the combined laser beam reflected from one reflecting surface of the polygon mirror 78 first strikes the mirror 80, and immediately after that, exposure on the photographic paper 2 is performed in the main scanning direction.

  Here, the direction of the reflection surface of the mirror 80 is such that the combined laser beam from the polygon mirror 78 is reflected in the direction toward the synchronization sensor 81. The length of the optical path from the polygon mirror 78 to the synchronization sensor 81 via the mirror 80 is substantially equal to the length of the optical path from the polygon mirror 78 to the main scanning start point on the photographic paper 2. Accordingly, the intensity of the laser beam scanned by the polygon mirror 78 after being emitted from the laser light source and detected by the synchronization sensor 81 is scanned by the polygon mirror 78 after being emitted from the laser light source, and is detected on the photosensitive medium. It is considered that the intensity of the laser light reaching the exposure position is almost the same. The synchronous sensor 81 is a sensor that can detect light, and modulates the laser beam emitted from the blue LD 71B, the green SHG laser unit 71G, and the red LD 71R by the laser beam received from the polygon mirror 78 via the mirror 80. Used to adjust timing.

  FIG. 3 shows a schematic configuration of the red LD 71R. In the red LD 71R, a constant current is supplied from a constant current source, and the ratio of the current flowing through the variable resistor Ra on the transistor side and the current flowing through the LD can be changed by controlling the transistor. . Accordingly, the output of the LD can be adjusted by changing the resistance value of the variable resistor Ra. The configuration of the blue LD 71B is the same as that of the red LD 71R.

  Next, a laser output adjustment method according to the present embodiment will be described with reference to FIGS. Here, a laser output adjustment method for the red LD 71R will be described. FIG. 4 is a diagram showing an example of the color development characteristics of photographic paper. FIG. 5 is a flowchart showing an operation procedure of the laser output adjustment method according to the present embodiment.

  First, the type of photographic paper on which an image is formed is determined (step S1). Then, based on the determined color development characteristic of the photographic paper, the intensity of the laser beam necessary for forming images of all densities on the photographic paper is determined (step S2). That is, in the photographic paper having the coloring characteristics shown in FIG. 4, the intensity of the laser beam necessary for forming images of all densities is the intensity P.

  Therefore, the resistance value of the variable resistor Ra of the red LD 71R is changed so that the intensity of the laser light detected by the synchronization sensor 81 becomes the above-described intensity P (step S3). Here, when the synchronization sensor 81 is adjusted so as to receive the laser beam having the intensity P, it is considered that the intensity of the laser beam when exposing the photographic paper can be changed in the range of 0-P. Thus, the adjustment of the laser output of the red LD 71R is completed by changing the resistance value of the variable resistor Ra of the red LD 71R so that the intensity of the laser light detected by the synchronous sensor 81 becomes the above-described intensity P. .

  Conventionally, since the laser output is adjusted in a single laser light source, it is necessary to adjust the laser output in consideration of variations of a plurality of optical components. In order to form an image having all the densities of the photographic paper, the laser output is adjusted so that the intensity of the laser beam output from the laser light source is higher than the intensity P. As a result, there has been a problem that the resolution of the image formed on the photosensitive medium is lowered. On the other hand, as can be seen from FIG. 4, in the present invention, the laser output of the laser light source is adjusted by adjusting the laser output based on substantially the same intensity P as the intensity P required to form images of all densities. Can be kept relatively small.

  Here, a case is described in which only one type of photographic paper on which an image is formed is determined, but multiple types of photographic paper may be determined as photographic paper on which an image is formed. The resistance value of the variable resistor Ra of the red LD 71R is changed on the basis of the color development characteristics of the photographic paper having the highest laser light intensity required to form images of all densities among a plurality of types of photographic paper. Thus, the laser output is preferably adjusted. In this case, all density images can be formed on all of a plurality of types of photographic paper.

  As described above, in the laser output adjustment method of the present embodiment, the output of the laser light source is adjusted based on the intensity of the laser light that is emitted from the laser light source and then reaches the synchronization sensor 81 via a plurality of optical components. Therefore, it is not necessary to consider the variation of a plurality of optical components separately. For this reason, the laser output of the laser light source can be adjusted in consideration of only the variations related to the processing after the exposure processing of the photographic paper (for example, the sensitivity variation of the photographic paper and the color development variation of the developer). Can be kept relatively small. Therefore, a sufficient dynamic range can be obtained, and the resolution of the image formed on the photographic paper can be improved.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. . For example, in the above-described embodiment, the laser output is adjusted based on the intensity of the laser beam detected by the synchronization sensor 81. However, in addition to the synchronization sensor 81, a detection unit that detects the intensity of the laser beam is provided. It may be provided separately for laser output adjustment.

It is a figure which shows schematic structure of the photographic processing apparatus which can utilize the laser output adjustment method which concerns on embodiment of this invention. It is a figure which shows schematic structure of the exposure unit contained in the photographic processing apparatus shown in FIG. It is a figure which shows schematic structure of red LD. It is a figure which shows an example of the color development characteristic of photographic paper. It is a flowchart which shows the operation | movement procedure of the laser output adjustment method which concerns on this Embodiment.

Explanation of symbols

1 Photo processing device 71R Red LD
71B Blue LD
72R Lens group 72B Lens group 76 Reflective mirror 77 Cylindrical lens 78 Polygon mirror 81 Synchronous sensor

Claims (2)

A laser output adjustment method in an exposure apparatus comprising a laser light source and a plurality of optical components for guiding laser light emitted from the laser light source to a photosensitive medium,
Detecting the intensity of the laser light emitted from the laser light source and reaching the exposure position through the plurality of optical components, and adjusting the output of the laser light source based on the detected intensity of the laser light. Laser output adjustment method. The exposure apparatus includes a scanning optical element that scans laser light in one direction on the photosensitive medium, and a synchronization sensor that controls the modulation timing of the laser light scanned on the photosensitive medium by the scanning optical element. And
The intensity of laser light emitted from the laser light source and scanned by the scanning optical element is detected by the synchronization sensor, and the output of the laser light source is adjusted based on the detected intensity of the laser light. The laser output adjustment method according to claim 1.

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