JP2006305753A - Exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure system which can execute stable tone expression by scanning the inside of one pixel by a plurality of the number of times without carrying out complicate control by a simple constitution. <P>SOLUTION: At an exposure part 6 which executes tone expression by scanning the inside of one pixel by a plurality of the number of times in a photograph processor 50, a multiplication division part 41R outputs data of every 10 bits to a D/A converter 29R. At the D/A converter 29R, each of the input 10-bit data is subjected to D/A conversion and output to an AOM driver 15R. At the AOM driver 15R, each data of 10 bits is input to each of a low density processing part 43Ra and a high density processing part 43Rb with different magnifications set therein. The data multiplied by 1/1024 times and one time at each processing part 43R are output as they are via a modulation part 44R. At an AOM 12R, scanning of two times is carried out on the basis of each of the output data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure apparatus that performs exposure processing on a photosensitive material with a light beam modulated based on image data, and more particularly to an exposure apparatus that performs exposure processing within a pixel by a plurality of scans.

  Conventionally, as an exposure method for printing a photograph, based on image data obtained by reading an image contained in a photographic film with a scanner or image data obtained by photographing with a digital camera, red, green, and blue An exposure apparatus that employs a method of printing an image according to image data on a photographic paper by irradiating the chromatic paper on a photographic paper for each pixel is used.

In such an exposure apparatus, exposure of a scanning exposure method in which a two-dimensional image is printed on a photographic paper by irradiating light from a light source in the main scanning direction of the photographic paper while conveying the photographic paper in the sub-scanning direction. There is a device.
Here, as an exposure apparatus that performs scanning exposure, for example, there is an apparatus that uses laser light sources corresponding to respective colors of red (R), green (G), and blue (B) as light sources. In such an exposure apparatus, digital image data is converted into analog data by a D / A converter, and laser light of each color is modulated and output based on the analog data.

  The modulation of the laser light is performed by an AOM (Acousto-Optic Modulator) corresponding to each color. The laser light modulated by each AOM is deflected in the main scanning direction by a deflector such as a polygon mirror, and is irradiated onto the photographic paper via an optical system such as an fθ lens. At this time, the two-dimensional color image is finally printed on the photographic paper by simultaneously conveying the photographic paper in the sub-scanning direction.

Patent Document 1 discloses an exposure apparatus that employs such a scanning exposure method. Here, one image data is converted into a predetermined number of exposure amount data by a plurality of LUTs (Look Up Tables), and an amount of information processed by the D / A converter is obtained by performing the same number of scans. To reduce the cost of the device.
Japanese Patent Laid-Open No. 6-208067 (published July 26, 1994)

However, the conventional exposure apparatus has the following problems.
That is, in the exposure apparatus disclosed in the above publication, image data corresponding to each line scan is processed by four independent LUTs, and then output for each scan is performed. Is divided into four 10-bit data and subjected to multiple exposure processing so that equivalent gradation expression is obtained, so that the control may be complicated.

  An object of the present invention is to provide an exposure apparatus capable of performing stable gradation expression by scanning a pixel a plurality of times without performing complicated control with a simple configuration.

  An exposure apparatus according to a first aspect of the present invention is an exposure apparatus that performs exposure processing based on image data and performs gradation expression by scanning a single pixel a predetermined number of times, and includes a D / A converter and a modulation A circuit and a light modulation element. The D / A converter converts the image data divided every predetermined number of times from digital data to analog data. The modulation circuit outputs a modulation signal of a light beam obtained by processing the converted analog data with a different number of magnifications equal to a predetermined number of times set in advance. The light modulation element receives the output from the modulation circuit and modulates the light beam.

Here, in an exposure apparatus that expresses gradation by scanning one pixel a plurality of times, each scan is performed based on image data processed at different magnifications with respect to the same number of D / A converted image data. The modulated signal of the light beam corresponding to is output.
Here, the light modulation element modulates the intensity of the R, G, and B component laser light. For example, an acousto-optic modulation element (AOM), an electro-optic modulation element (EOM), or a magneto-optic modulation is used. An element (MOM) or the like is included. The modulation circuit includes an AOM driver for driving the light modulation elements (AOM, EOM, MOM).

For example, when D / A converting image data divided into upper 10-bit image data and lower 10-bit image data, the upper 10-bit image data is multiplied by 1, that is, modulated as it is. Output as a signal. On the other hand, the lower 10-bit image data is output by 1/1024 times (1/2 ¹⁰ times) as a modulation signal.
Accordingly, it is possible to perform exposure processing using the upper 10-bit image data as high-density portion data and the lower 10-bit image data as low-density portion data. Then, as described above, the image data is output in a plurality of times, for example, in higher bits and lower bits, so that it is not necessary to combine the divided data into one using a multiplier or the like. An exposure apparatus that operates stably with the configuration can be obtained. In addition, by scanning the image data in one pixel in multiple times, the number of output bits in the D / A converter can be reduced and an inexpensive D / A converter can be used. Can be planned.

An exposure apparatus according to a second aspect of the present invention is the exposure apparatus according to the first aspect of the present invention, further comprising a dividing unit that divides the image data input to the D / A conversion unit into the same number of data as the predetermined number of times. ing.
Here, for example, the image data is divided into data corresponding to the upper bits and data corresponding to the lower bits, and the magnification of the light beam corresponding to each scan is switched for each image data in two stages. Output modulation signal.

Specifically, when 20 bits of image data is divided into 10 bits and output in the dividing unit, the upper 10 bits of image data is multiplied by 1, that is, output as a modulation signal as it is. . On the other hand, the lower 10 bits of image data are multiplied by 1/1024 and output as a modulation signal.
As a result, when image data input in a divided manner is output with different magnifications, and when gradation is expressed by scanning one pixel twice, a low density corresponding to lower bit data Part and a high-density part corresponding to upper bit data can be expressed in combination.

An exposure apparatus according to a third aspect of the invention is the exposure apparatus according to the second aspect of the invention, wherein the dividing unit divides image data having a certain number of bits representing the gradation of one pixel into a plurality of stages and modulates the data. Output for.
Here, the dividing unit divides image data having a certain number of bits representing the gradation of one pixel into a plurality of data and outputs the data to the modulation circuit.

  Thus, for example, when dividing 15-bit image data into three 5-bit data corresponding to a low density portion, a medium density portion, a high density portion, etc. The divided data can be output with different magnifications. As a result, even an exposure apparatus that scans one pixel three times or more can perform exposure processing based on data obtained by applying different magnifications for each scan.

An exposure apparatus according to a fourth invention is the exposure apparatus according to the first invention, wherein two or more D / A converters are provided.
Here, two or more D / A converters for outputting D / A converted image data to the modulation circuit are provided.
As a result, image data input in advance in two or more systems can be converted by the D / A converter and output to the modulation circuit.

An exposure apparatus according to a fifth invention is the exposure apparatus according to any one of the first to fourth inventions, wherein the D / A converter has image data and a supplement for supplementing the image data. Data is input.
Here, the image data that is the basis for performing the exposure process and the supplementary data necessary for the image data for performing the exposure process are input to the D / A converter.

  Thereby, for example, when the supplementary data is 8 bits and the image data is 12 bits, the separating unit can divide the data into higher 10 bits and lower 10 bits for output. Further, when two systems of D / A conversion units are provided, supplementary data for 8 bits and image data for 12 bits can be output to separate D / A conversion units.

According to the exposure apparatus of the first aspect of the invention, it is not necessary to use a multiplier or the like by outputting image data divided into, for example, upper bits and lower bits in a plurality of times, so that stable operation is achieved with a simple configuration. An exposure apparatus can be obtained.
According to the exposure apparatus of the second invention, when one pixel is scanned twice to express gradation, a low density portion corresponding to lower bit data and a high density portion corresponding to upper bit data Can be expressed in combination.

According to the exposure apparatus of the third invention, even if the exposure apparatus scans one pixel three times or more, it can perform exposure processing based on data obtained by applying different magnifications for each scan. .
According to the exposure apparatus of the fourth invention, image data input in advance in two or more systems can be converted by the D / A converter and output to the modulation circuit.

  According to the exposure apparatus of the fifth aspect of the invention, for example, when the supplementary data is 8 bits and the image data is 12 bits, the separating unit can divide the data into higher 10 bits and lower 10 bits for output. .

A photographic processing apparatus equipped with an exposure apparatus according to an embodiment of the present invention will be described below with reference to FIGS.
[Configuration of Entire Photo Processing Apparatus 50]
The photographic processing apparatus according to this embodiment is a digital photographic printer that prints an original image on a photosensitive material by printing, developing and drying the photosensitive material based on the image data of the original image.

As shown in FIG. 1, the photographic processing apparatus 50 of this embodiment includes a printing unit 1, a photographic paper storage unit 2, a developing unit 3, a drying unit 4, and a PC (Personal Computer) 5.
The photographic paper storage unit 2 stores photographic paper P (see FIG. 2) as a photosensitive material supplied to the printing unit 1, and includes, for example, two paper magazines 2a for storing roll-shaped photographic paper P. 2b is provided in the upper part of the baking part 1. FIG.

These paper magazines 2a and 2b store photographic papers P having different sizes (widths).
Then, the photographic paper P corresponding to the size of the output image is supplied from the paper magazine 2a (or 2b) to the printing unit 1. In addition, a cutter may be provided in the middle of the conveyance path | route to the printing part 1 of the printing paper P, and the sheet-like printing paper P may be supplied to the printing part 1. FIG.

As shown in FIG. 2, the printing unit 1 includes an exposure unit 6 (exposure device) and conveying rollers R1 to R5.
The exposure unit 6 modulates the laser beam based on the image data, and places the photographic paper P in a direction (hereinafter referred to as the sub-scanning direction) substantially perpendicular to the scanning direction of the laser beam (hereinafter referred to as the main scanning direction). Exposure processing is performed so that the photographic paper P is scanned twice within one pixel while being conveyed (see FIG. 6). Image data for modulating the laser light is obtained by, for example, a scanner or a digital camera that reads a photographic film. The configuration of the exposure unit 6 will be described in detail later.

The transport rollers R1 to R5 send the photographic paper P supplied from the photographic paper storage unit 2 to the developing unit 3 via the exposure unit 6. For example, the photographic paper P stored in the paper magazine 2a is sequentially transported by the transport rollers R1, R2, R3, and R4, and the photographic paper P stored in the paper magazine 2b is transported by the transport rollers R5, R2, R3, and R4. It is sequentially conveyed by R4.
The developing unit 3 develops the image printed on the photographic paper P by conveying the photographic paper P subjected to the printing process in the printing unit 1 while being immersed in various development processing solutions.

The drying unit 4 dries the photographic paper P developed by the developing unit 3 by blowing hot air, for example.
The PC 5 has a function of saving image data of an original image, a function of performing data processing on the image data, and the like. Further, the PC 5 functions as a man-machine interface for the entire photo processing apparatus, and for example, an actual print condition can be input or settings / settings of the photo processing apparatus can be input via the PC 5. Is possible.

In addition to the above, the photographic processing apparatus includes a plurality of control CPUs (not shown) that control the operation of the photographic processing apparatus 50 as a whole.
In the photographic processing apparatus according to the present embodiment, the exposure, development processing, and drying processing of the photographic paper P are continuously performed under unified management by the control of the CPU. Therefore, it is possible to continuously print a large number of photographs without placing an operational burden on the user.

[Basic Configuration of Exposure Unit 6]
Here, the basic configuration of the exposure unit 6 which is the premise of the present invention will be described first.
As shown in FIG. 3, the exposure unit 6 includes a light source unit 7, a scanning unit 8, a transport unit 9, and a data supply unit 26 (see FIG. 4). (See FIG. 4).

Hereinafter, each configuration will be described in detail.
(Configuration of the light source unit 7)
The light source unit 7 includes light source units 7R, 7G, and 7B that supply laser beams of red (Red), green (Green), and blue (Blue) colors to the scanning unit 8, respectively.
The light source unit 7R includes a red LD (Laser Diode) 10R, a lens group 11R, an AOM (Acousto-Optic Modulator) 12R, a light control unit 13R, a mirror 14R, and an AOM driver (modulation circuit) 15R. .

The lens group 11R, the AOM 12R, and the light control unit 13R are arranged in this order on the optical axis from the red LD 10R to the mirror 14R.
The red LD 10R is a semiconductor laser that emits laser light having a red component wavelength.
The lens group 11R shapes the red laser light emitted from the red LD 10R and guides it to the light incident port of the next AOM 12R.

The AOM 12R is a light modulator utilizing a so-called acousto-optic diffraction, which is a diffraction phenomenon in which a refractive index distribution created in a transparent medium by sound waves works as a phase diffraction grating, and by changing the intensity of applied ultrasonic waves, Modulates the intensity of diffracted light. An AOM driver 15R is connected to the AOM 12R.
The AOM driver 15R supplies a high frequency signal to the AOM 12R in synchronization with a pixel clock described later. The high-frequency signal is obtained by modulating the amplitude according to image data corresponding to each dot in the main scanning direction of the photographic paper P. Therefore, when a high frequency signal is input from the AOM driver 15R to the AOM 12R, an ultrasonic wave corresponding to the high frequency signal is propagated in the acoustooptic medium.

When laser light passes through such an acousto-optic medium, diffraction occurs due to the action of the acousto-optic effect, and laser light having an intensity corresponding to the amplitude of the high-frequency signal is emitted from the AOM 12R as diffracted light. As a result, the AOM 12R emits a laser beam having a light amount corresponding to the image data for each pixel of the photographic paper P.
The light control unit 13R adjusts the laser light modulated according to the image data emitted from the AOM 12R (performs fine adjustment of the light amount), and includes, for example, an ND filter and a plurality of openings having different sizes. It is comprised by the rotating plate etc. which were provided.

A light emitting element such as a semiconductor laser or a solid-state laser has a light amount range in which light can be emitted in a stable state. Therefore, the light control by the light control unit 13R is wide according to the color development characteristics of the photographic paper. Exposure can be performed in a light amount range that provides a dynamic range.
The mirror 14R reflects the laser beam emitted from the light control unit 13R in the direction in which the scanning unit 8 is disposed. Any mirror may be used as the mirror 14R as long as it reflects the red component of the incident light.

In the present embodiment, since the red laser light having only the wavelength of the red component is incident on the mirror 14R, a mirror that totally reflects the incident light is used as the mirror 14R.
On the other hand, the light source unit 7G includes a green SHG (Second Harmonic Generation) laser unit 10G, an AOM 12G, a light control unit 13G, a dichroic mirror 14G, and an AOM driver 15G.

The AOM 12G and the light control unit 13G are arranged in this order on the optical axis from the green SHG laser unit 10G to the dichroic mirror 14G.
The green SHG laser unit 10G functions as a light source that emits a laser beam having a green component wavelength. The green SHG laser unit 10G includes a solid-state laser such as a YAG laser and a second-order harmonic generation unit that extracts a second-order harmonic from laser light emitted from the solid-state laser, although not shown. The wavelength variable part etc. to be provided are provided. For example, when a laser beam having a wavelength of 1064 nm is emitted from a YAG laser, a laser beam having a wavelength of 532 nm (green component) is generated in the second harmonic generation unit, and the laser beam having the second harmonic component is generated. Emitted. In this embodiment, a solid-state laser is used as a means for emitting basic laser light, but the present invention is not limited to this. For example, an LD can be used.

The green SHG laser unit 10G has a function equivalent to that of the lens group 11R provided in the light source unit 7R.
The AOM 12G and the light control unit 13G have the same configuration as the AOM 12R and the light control unit 13R described in the light source unit 7R. That is, the AOM 12G is connected to an AOM driver 15G that supplies a high-frequency signal whose amplitude is modulated in accordance with image data input in synchronization with a pixel clock described later to the AOM 12G. The AOM 12G modulates the laser light emitted from the green SHG laser unit 10G according to the high-frequency signal supplied from the AOM driver 15G, and emits the light for each pixel of the photographic paper P with a light amount corresponding to the image data. Let

The light control unit 13G performs fine adjustment of the amount of laser light emitted from the AOM 12G.
The dichroic mirror 14G reflects the green component laser light emitted from the light control unit 13G in the direction in which the scanning unit 8 is disposed. This dichroic mirror 14G has a property of reflecting only light of the wavelength of the green component and transmitting light of other wavelengths. The dichroic mirror 14G is disposed on the optical path from the mirror 14R to the scanning unit 8 in the light source unit 7R, and the red laser light reflected by the mirror 14R passes through the dichroic mirror 14G and is scanned. To.

That is, the light traveling from the dichroic mirror 14G toward the scanning unit 8 is composed of red component laser light and green component laser light modulated in accordance with image data.
The light source unit 7B has substantially the same configuration as the light source unit 7G, and includes a blue SHG laser unit 10B, an AOM 12B, a light control unit 13B, a dichroic mirror 14B, and an AOM driver 15B.

The AOM 12B and the light control unit 13B are arranged in this order on the optical axis from the blue SHG laser unit 10B to the dichroic mirror 14B.
The blue SHG laser unit 10B functions as a light source that emits laser light having a blue component wavelength, and has substantially the same configuration as the green SHG laser unit 10G.
The AOM 12B and the light control unit 13B have the same configuration as the AOM 12R and 12G and the light control units 13R and 13G described in the light source units 7R and 7G. That is, the AOM 12B is connected to an AOM driver 15B that supplies a high-frequency signal whose amplitude is modulated in accordance with image data input in synchronization with a pixel clock described later to the AOM 12B.

The AOM 12B modulates the laser light emitted from the blue SHG laser unit 10B according to the high-frequency signal supplied from the AOM driver 15B, and emits the light for each pixel of the photographic paper P with a light amount corresponding to the image data. Let
The light control unit 13B finely adjusts the amount of laser light emitted from the AOM 12B.
The dichroic mirror 14B reflects the blue component laser light emitted from the light control unit 13B in the direction in which the scanning unit 8 is disposed. The dichroic mirror 14G has a property of reflecting only light of the blue component wavelength and transmitting light of other wavelengths. The dichroic mirror 14B is disposed on the optical path from the mirror 14R and the dichroic mirror 14G to the scanning unit 8, reflected by the mirror 14R and transmitted through the dichroic mirror 14G, and the dichroic mirror 14G. The reflected green laser light passes through the dichroic mirror 14B and reaches the scanning unit 8.

That is, the light traveling from the dichroic mirror 14B toward the scanning unit 8 is composed of laser light of red, green, and blue components modulated according to image data.
As a result, the mirror 14R and the dichroic mirrors 14G and 14B constitute a condensing unit that condenses the laser beams of the respective colors on the same axis.
In the light source unit 7, when laser light of each color of R, G, and B is emitted from the red LD 10R, the green SHG laser unit 10G, and the blue SHG laser unit 10B, the laser light of each color is transmitted by the AOM 12R, 12G, and 12B. , Modulated in accordance with the image data corresponding to each dot in the main scanning direction of the photographic paper P, and the light amount corresponding to the image data becomes a light control unit 13R / 13G / 13B, mirror 14R and dichroic mirror 14G / 14B. Then, the light is incident on the scanning unit 8 described below as a unit.

(Configuration of the scanning unit 8)
The scanning unit 8 includes a reflection mirror 16, a cylindrical lens 17, a polygon mirror 18, and an fθ lens 20.
A cylindrical lens 17 is disposed on the optical axis from the reflection mirror 16 to the polygon mirror 18, and an fθ lens 20 is disposed on the optical path from the polygon mirror 18 to the photographic paper P.

The reflection mirror 16 reflects the laser light of the red component, the green component, and the blue component reflected by the mirror 14R and the dichroic mirrors 14G and 14B in the light source units 7R, 7G, and 7B in the direction in which the polygon mirror 18 is disposed.
The cylindrical lens 17 focuses the laser beam reflected by the reflection mirror 16 on the reflection surface of the polygon mirror 18.

The polygon mirror 18 is a regular polygonal columnar rotating body having a plurality of reflecting surfaces on its side surface, and is rotated by a polygon driver 19 controlled by the overall control unit 51 (see FIG. 4). The resolution (number of dots) of the photographic paper P in the main scanning direction can be adjusted by adjusting the rotation speed of the polygon mirror 18.
The fθ lens 20 corrects image distortion in the vicinity of both ends of the scanning surface due to the laser light applied to the photographic paper P from the polygon mirror 18. Note that 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 18 to the photographic paper P.

  The laser beams of R, G, and B colors emitted from the light source unit 7 are irradiated onto one reflecting surface of the polygon mirror 18 through the reflecting mirror 16 and the cylindrical lens 17 by the configuration of the scanning unit 8 as described above. Then, it is reflected by the reflecting surface and proceeds in the direction of the photographic paper P. Then, the reflection direction of the laser light from the polygon mirror 18 changes in the main scanning direction according to the rotation of the polygon mirror 18, so that the photographic paper P is scanned in the main scanning direction.

At this time, when the reflection of the laser beam on one reflecting surface is finished by the rotation of the polygon mirror 18, the irradiation of the laser beam moves to the reflecting surface adjacent to the reflecting surface, and the laser beam is reflected in the same range in the main scanning direction. The direction moves.
That is, immediately after the scanning of one scanning line on the photographic paper P is finished, the laser beam is irradiated to the scanning start point of the next scanning line.

Therefore, by exposing the photographic paper P while being conveyed by the conveyance unit 9 to be described later, the photographic paper P is two-dimensionally exposed without causing a time lag in each exposure of the scanning lines adjacent in the sub-scanning direction. It becomes possible.
The light source unit 7 and the scanning unit 8 described above emit a light beam (laser light) having a light amount corresponding to image data for each dot arranged in the main scanning direction of the photographic paper P, and the light beam is emitted from the main beam. A light beam irradiating means that scans in the scanning direction and leads to the photographic paper P is configured.

By the way, in the scanning unit 8 described above, if a surface tilt error (an error in which the normal direction of the reflecting surface deviates from the normal main scanning surface) occurs on the reflecting surface of the polygon mirror 18, the laser beam on the photographic paper P is generated. Will greatly change the image quality of the burned image.
Therefore, in the present embodiment, the laser light reflected by the reflection mirror 16 by the cylindrical lens 17 is condensed on the reflection surface of the polygon mirror 18 at substantially the center in the sub-scanning direction, and the polygon mirror The fθ lens 20 and the photographic paper P are arranged so that the laser light reflected from the light 18 is condensed on the photographic paper P after passing through the fθ lens 20.

  With such a configuration, the reflecting surface of the polygon mirror 18 and the photographic paper P are optically conjugated, so even if the light beam is deflected in the sub-scanning direction due to the surface tilt, the light beam is fθ lens 20. The image is formed at the same position on the photographic paper P in the sub-scanning direction. In other words, even if light is emitted from one point on the reflection surface of the polygon mirror 18 within a certain range in an arbitrary direction in the sub-scanning direction, an image is formed at the same position on the photographic paper P in the sub-scanning direction.

Therefore, according to the above configuration, even if there is a surface tilt error in the polygon mirror 18, it can be corrected (surface tilt correction).
In addition, even when there is a variation in inclination between the reflecting surfaces of the polygon mirror 18, the cylindrical lens 17 condenses the laser light on the reflecting surface of the polygon mirror 18 in the substantially central portion in the sub-scanning direction. Thus, the reflected light from the polygon mirror 18 can be reliably incident on the fθ lens 20 while minimizing the influence of the variation.

Incidentally, the scanning angle when one line of the photographic paper P is scanned by one reflecting surface of the polygon mirror 18 is determined by the number of surfaces of the polygon mirror 18. That is, if the number of faces of the polygon mirror 18 is M, the scanning angle is represented by 360 ° / M × 2.
In this embodiment, since M = 8, the scanning angle is 360 ° / 8 × 2 = 90 °.

  As described above, the reflection direction of the laser light on the polygon mirror 18 is swung in the range of 90 ° in the main scanning direction via the fθ lens 20 by the rotation of the polygon mirror 18. Laser light oscillated within a range of 45 ° is used for exposure of the photographic paper P. This is because if the photographic paper P is exposed with light obtained through the vicinity of both ends of the fθ lens 20, the image is likely to be distorted. The 45 ° range is a range that extends symmetrically about the normal line of the photographic paper P.

A ratio indicating how much of the light oscillated in the range of 90 ° is actually used for scanning the photographic paper P is called an effective scanning period rate. In the present embodiment, the effective scanning period rate is 45 ° / 90 ° = ½.
In addition to the above configuration, the scanning unit 8 further includes a synchronization sensor 21A and a mirror 21B.

The synchronization sensor 21A and the mirror 21B are provided outside the main scanning range of laser light from the polygon mirror 18 to the photographic paper P, respectively.
The mirror 21B is disposed at a position immediately outside the main scanning direction when viewed in the direction from the polygon mirror 18 toward the exposure (scanning) start point. Accordingly, laser light reflected from one reflecting surface of the polygon mirror 18 first strikes the mirror 21B, and is then subjected to exposure in the main scanning direction.

  The angle of the reflecting surface of the mirror 21B is set so that when the laser light from the polygon mirror 18 strikes the mirror 21B, the reflected light from the mirror 21B enters the synchronization sensor 21A. The length of the optical path from the polygon mirror 18 to the synchronization sensor 21A via the mirror 21B is designed to be approximately equal to the length of the optical path from the polygon mirror 18 to the start point of main scanning on the photographic paper P. Has been.

  The above-described synchronization sensor 21A is a sensor that detects light. When laser light is incident from the polygon mirror 18 via the mirror 21B, the exposure control unit 30 (FIG. 4) is transmitted via the overall control unit 51 described later at the irradiation timing. Send a signal to The exposure control unit 30 can accurately grasp the scanning timing corresponding to the width of the photographic paper P to be used by monitoring the output from the synchronization sensor 21A.

(Configuration of transport unit 9)
The transport unit 9 includes a transport roller 22, a microstep motor 23, a microstep driver 24, and the like.
The conveyance roller 22 is a roller that conveys the photographic paper P, and in FIG. 3, conveys the photographic paper P in the rotation axis direction (sub-scanning direction) of the polygon mirror 18.

The micro step motor 23 is a kind of stepping motor for driving the transport roller 22 and has a feature that vibration is small, that is, transport unevenness is small. As a result, the rotation angle can be controlled very precisely, and the transport position of the printing paper P in the sub-scanning direction can be precisely controlled.
The microstep driver 24 drives and controls the rotation of the microstep motor 23 in order to transport the photographic paper P with a predetermined transport pulse. The overall control unit 51 controls the microstep driver 24 via the control unit 52 (see FIG. 4) to adjust the rotation speed of the microstep motor 23, thereby adjusting the conveyance speed of the photographic paper P in the sub-scanning direction. Then, the resolution in the sub-scanning direction is adjusted.

  It should be noted that after the exposure of one line in the main scanning direction, the transport pulse when transporting the printing paper P before the next line is exposed may be one pulse or a plurality of pulses. Further, the carrier pulse may or may not be synchronized with the detection signal from the synchronization sensor 21A. That is, the photographic paper P may be transported at a constant speed in the sub-scanning direction and so as to obtain a desired resolution in the sub-scanning direction.

In systems other than the transport unit 9 (for example, the developing unit 3), other motors such as an induction motor are used. However, all the motors for transporting the photographic paper P are all pulsed by the microstep motor 23 and the like. You may comprise with a motor.
Further, the transport unit 9 includes a position detection sensor (not shown) for detecting the position of the photographic paper P in the sub-scanning direction.

This position detection sensor is arranged upstream of the exposure position of the photographic paper P in the sub-scanning direction, detects that the leading edge or the trailing edge of the photographic paper P has passed, and passes the information to the overall control unit 51. To the exposure control unit 30.
(Configuration of data supply unit 26)
Here, the basic configuration of the data supply unit 26 will be described.

  As shown in FIG. 4, the data supply unit 26 inputs image data to AOM drivers 15R, 15G, and 15B for driving the AOMs 12R, 12G, and 12B, and includes reference clock generation circuits 27R, 27G, and 27B, Data buffer 28R / 28G / 28B, D / A converter (D / A converter) 29R / 29G / 29B, exposure controller 30, R component image data storage unit 53R, G component image data storage unit 53G and B component image data A storage unit 53B is provided.

  The reference clock generation circuits 27R, 27G, and 27B generate pixel clocks corresponding to R, G, and B, respectively. The pixel clock is a clock for controlling the timing for sequentially exposing each dot on the photographic paper P, and its frequency is the reciprocal of the time for exposing one dot (pixel) on the photographic paper P. Indicated. The number of dots to be exposed in the main scanning direction is determined by setting the frequency of the pixel clock.

  The data buffers 28R, 28G, and 28B temporarily store the image data of the R, G, and B color components from the R component image data storage unit 53R, the G component image data storage unit 53G, and the B component image data storage unit 53B. It is memory. Then, the image data is output to the D / A converters 29R, 29G, and 29B one pixel at a time in synchronization with the pixel clocks of the respective colors generated by the reference clock generation circuits 27R, 27G, and 27B.

The D / A converters 29R, 29G, and 29B convert the digital image data input from the data buffers 28R, 28G, and 28B into analog data, respectively, and output the analog data to the AOM drivers 15R, 15G, and 15B.
The exposure control unit 30 controls the reference clock generation circuits 27R, 27G, and 27B. For example, the frequency of each pixel clock generated by the reference clock generation circuits 27R, 27G, and 27B is supplied from the synchronization sensor 21A. It is adjusted by the exposure control unit 30 so as to be synchronized with the detection signal. The exposure control unit 30 also reads image data of each color component from the R component image data storage unit 53R, the G component image data storage unit 53G, and the B component image data storage unit 53B to the data buffers 28R, 28G, and 28B ( Also controls the same timing for all colors. The overall operation of the exposure unit 6 including the exposure control unit 30 is controlled by the overall control unit 51.

  When irradiating predetermined pixels of the photographic paper P integrally with R, G, and B laser beams as in this embodiment, the refractive index of the fθ lens 20 is different between R, G, and B. If the color misalignment where the irradiation positions of the laser beams of the respective colors corresponding to the same pixel on the photographic paper P are not considered, the frequencies of the R, G and B pixel clocks are all made the same. Thus, it becomes possible to irradiate the laser light of the R, G and B colors to the same position (predetermined pixel) on the photographic paper P.

On the other hand, when considering the above-described color misregistration, the exposure control unit 30 changes, for example, the frequencies of the R, G, and B pixel clocks and makes the scanning start timings in the main scanning direction different from each other. Thus, such color misregistration can be eliminated.
In the configuration shown in FIG. 3, the R, G, and B laser beams are integrally irradiated to the predetermined pixels of the photographic paper P. For example, the R, G, and B laser beams are separately provided. It may be configured to enter the polygon mirror 18 through the optical path. In this case, since the emission angles of the laser beams from the polygon mirror 18 are different for R, G, and B, the photographic paper P is irradiated with R, G, and B laser beams at different timings at the same timing. Therefore, in this case, the exposure control unit 30 causes the R, G, B laser beams corresponding to the predetermined pixels of the photographic paper P to be emitted to the pixels at different timings. It is necessary to adjust the pixel clock.

[Detailed Configuration of Main Exposure Unit 6]
Next, a detailed configuration around the AOM driver 15 and the data supply unit 26 included in the exposure unit 6 will be described.
In the following, the AOM driver 15R and the data supply unit 26 corresponding thereto will be described. However, the AOM drivers 15G and 15B and the data supply unit 26 corresponding thereto have the same configuration. The description is omitted.

In the photographic processing apparatus 50 of the present embodiment, as shown in FIG. 5, a laser control substrate 40R is provided in front of the AOM driver 15R.
The laser control board 40R is provided in the D / A converter 29R described above, a multiplication division unit (division unit) 41R that multiplies and divides the output data from the data buffer 28R shown in FIG. 4, and the AOM driver 15R. And a magnification switching section 42R for switching the magnification in the magnification setting section 43R.

  The multiplication division unit 41R is configured to include a multiplier, and outputs two types of R component digital data, 8-bit BIAS value data and 12-bit modulation input data, from the data buffer 28R (see FIG. 4). Are multiplied by these to generate 20-bit data. Then, the multiplication division unit 41R divides the 20-bit data into upper 10-bit data and lower 10-bit data and outputs it to the D / A converter 29R.

The BIAS value data is supplementary data necessary for generating appropriate light modulation data in accordance with the color development characteristics of the paper, and the modulation input data is used to express gradation. Data including image data.
The D / A converter 29R performs digital / analog conversion on each 10-bit data that is divided into 20 bits of data and divided into upper and lower parts, and outputs analog data to the AOM driver 15R.

On the other hand, the AOM driver 15R is obtained by multiplying the magnification setting unit 43R including the two systems of processing units 43Ra and 43Rb by which the 10-bit data is multiplied, and different magnifications in the processing units 43Ra and 43Rb. And a modulation unit 44R for modulating each data.
The magnification setting unit 43R includes a low density processing unit 43Ra that sets the magnification of data corresponding to the lower 10 bits divided by the multiplication division unit 41R, and a high density processing unit 43Rb that sets the magnification of data corresponding to the upper 10 bits. And have.

The low density processing unit 43Ra has a magnification of 1/1024 (1/2 ¹⁰ ) times. When lower 10 bits of data are input, the data is multiplied by 1/1024 and sent to the modulation unit 44R. On the other hand, the low-density part of the 20-bit image data is output.
The high density processing unit 43Rb is set to a magnification of 1. When upper 10-bit data is input, the high-density portion of the 20-bit image data is used as it is for the modulation unit 44R. Output as.

  The modulation unit 44R modulates and controls the AOM 12R based on outputs from the low concentration processing unit 43Ra and the high concentration processing unit 43Rb. That is, the AOM 12R performs an exposure process for the low density region in one pixel based on the data output from the modulation unit 44R corresponding to the output from the low density processing unit 43Ra, and outputs from the high density processing unit 43Rb. The exposure processing of the high density area in one pixel is performed based on the data output from the modulation unit 44R corresponding to the above.

The input to the low concentration processing unit 43Ra and the input to the high concentration processing unit 43Rb are included in the low concentration processing unit 43Ra and the high concentration processing unit 43Rb by the magnification switching unit 42R included in the laser control substrate 40R. It can be switched by switching the front and rear switching elements.
In the photographic processing apparatus 50 of the present embodiment, gradation is expressed in one pixel by scanning twice (see FIG. 6). In the exposure unit 6, as described above, the laser control substrate 40R of the exposure unit 6 has 20 bits. Are divided into high-order and low-order 10-bit data, and these are separately D / A converted by the D / A converter 29R, and then output to the AOM driver 15R. Then, the AOM driver 15R multiplies each data with a different magnification (1/1024 times, 1 time) and outputs the data.

  As a result, gradation expression in a wide area becomes possible by dividing gradation within one pixel into a high density region and a low density region and expressing the gradation by scanning twice. For example, as compared with the conventional exposure unit in which the BIAS value is adjusted in 100 steps, the exposure unit 6 of the present embodiment only needs two steps of adjustment on the low density side and the high density side. Control can be greatly simplified. Furthermore, the exposure unit 6 that can operate stably can be obtained without complicating the circuit configuration of the AOM driver 15R.

[Characteristics of the main exposure unit 6]
(1)
In the photographic processing apparatus 50 of the present embodiment, gradation is expressed in one pixel by a plurality of scans (see FIG. 6). In the exposure unit 6, as shown in FIG. Is output to the D / A converter 29R. The D / A converter 29R performs D / A conversion on the input 10-bit data, and outputs it to the AOM driver 15R. In the AOM driver 15R, the 10-bit data is input to the low density processing unit 43Ra and the high density processing unit 43Rb in which different magnifications are set. Then, the respective data multiplied by 1/1024 times and 1 times in each processing unit 43R are output as they are via the modulation unit 44R. In the AOM 12R, the exposure process is performed by the first scanning (low density region) and the second scanning (high density region) within one pixel based on each output data.

  Thereby, since the setting of the magnification in the AOM driver 15R can be performed in two stages, the modulation control of the AOM 12R can be greatly simplified. Since each 10-bit data is output separately corresponding to the first scan and the second scan, there is no need to use a multiplier or the like at the time of output, so the circuit configuration is simplified and stable. An exposure unit 6 capable of operation can be obtained.

Furthermore, as described above, since 20-bit data is divided into upper and lower 10-bit data and output to the D / A converter 29R, the processing capacity of the D / A converter 29R can be reduced and an inexpensive D / A converter can be provided. An A converter 29R can be used.
Since the laser control boards 40G and 40B and the AOM drivers 15G and 15B included in the exposure unit 6 have the same configuration, the same effect can be obtained.

(2)
In the photographic processing apparatus 50 of this embodiment, as shown in FIG. 5, the exposure unit 6 multiplies 8-bit BIAS value data by 12-bit modulation input data before D / A conversion. The data is further provided with a multiplication and division unit 41R that divides the data into upper 10 bits and lower 10 bits and outputs the data.

As a result, modulation control can be performed by setting different magnifications to the respective data, with the upper 10 bits of data corresponding to the high density portion and the lower 10 bits of data corresponding to the low density portion. As a result, it is possible to obtain the exposure unit 6 capable of expressing a wide range of gradations even when the gradation is expressed by two scans by dividing one pixel into a low density region and a high density region.
Further, since the BIAS value data and the modulation input data are multiplied at the digital data stage, errors due to individual differences are reduced, and more accurate modulation control can be performed.

Since the laser control boards 40G and 40B and the AOM drivers 15G and 15B included in the exposure unit 6 have the same configuration, the same effect can be obtained.
(3)
In the photographic processing apparatus 50 of the present embodiment, as shown in FIG. 5, the exposure unit 6 uses BIAS value data and modulation input data as data input to the D / A converter 29R.

As a result, 8-bit BIAS value data and 12-bit modulation input data are multiplied at the digital data stage to obtain 20 bits, which can be divided into 10-bit data for D / A conversion. . As a result, errors due to individual differences are reduced, and more accurate modulation control can be performed.
[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

(A)
In the above embodiment, as shown in FIG. 5, 20-bit data obtained by multiplying an 8-bit bias value and a 12-bit modulation input is divided into upper 10 bits and lower 10 bits separately and separately. An example of inputting to one D / A converter 29R has been described. However, the present invention is not limited to this.

  For example, as shown in FIG. 7, a laser control board 140R that inputs 8-bit bias value data and 12-bit modulation input data to independent D / A converters (D / A converters 29Ra and 29Rb), respectively. It may be an exposure part provided with. Thus, even when two systems of D / A converters are provided, the same effects as described above can be obtained by outputting the outputs with different magnifications.

(B)
In the above embodiment, the example in which the magnification setting in the AOM driver 15R is set in two stages has been described. However, the present invention is not limited to this.
For example, the exposure unit that scans one pixel three times or more may have an AOM driver 150R including a magnification setting unit 143R that performs magnification setting of three or more levels in accordance with each scan, as shown in FIG. . In this case, as shown in FIG. 8, different magnifications of 1 / x, 1 / y, and 1 are set for the low concentration processing unit 143Ra, the medium concentration processing unit 143Rb, and the high concentration processing unit 143Rc, respectively. The same effects as those of the exposure unit 6 according to the above embodiment can be obtained.

(C)
In the above embodiment, an example in which the magnification setting in the AOM driver 15R is set to 1 × and 1/1024 has been described. However, the present invention is not limited to this.
For example, the same effect as described above can be obtained even when the magnification is changed to another magnification according to the number of bits of input data.

Therefore, it is more preferable that the AOM driver can automatically change the magnification according to the number of input data bits. In this case, since an appropriate magnification is automatically set according to the size of the input data, the modulation process can be performed efficiently.
(D)
In the above embodiment, an example in which data (BIAS value and modulation input) input to the laser control board 40R is 8 bits and 12 bits has been described. However, the present invention is not limited to this.

For example, each data size may be 10 bits. In this case, it can be input to the magnification setting unit 43R as it is, or it can be once input to the multiplication division unit 41R and again divided into 10-bit data and input to the magnification setting unit 43R.
(E)
In the above embodiment, an example in which an AOM (acousto-optic modulation element) is used as the light modulation element that modulates the laser light of each color has been described. However, the present invention is not limited to this.

  For example, even when other light modulation elements such as an electro-optic modulation element (EOM) and a magneto-optic modulation element (MOM) are used, the same effect as described above can be obtained.

  The exposure apparatus of the present invention is an exposure apparatus that expresses gradation by scanning a predetermined number of times in one pixel, and outputs image data divided into the same number of data as the predetermined number of times, thereby performing stable operation with a simple configuration. Since the apparatus can be obtained, the present invention can be widely applied to an exposure apparatus that modulates laser light using various optical modulation elements and performs gradation expression by scanning a plurality of times for each pixel.

1 is a perspective view showing a schematic configuration of a photographic processing apparatus equipped with an exposure unit according to an embodiment of the present invention. The figure which shows schematic structure of the printing part with which the photographic processing apparatus of FIG. 1 is provided. The figure which shows schematic structure of the light source part in the exposure part of FIG. 1, a scanning part, and a conveyance part. FIG. 2 is a block diagram showing a schematic configuration of an exposure unit installed in the photographic processing apparatus of FIG. 1. FIG. 2 is a diagram showing a schematic configuration around an AOM driver included in an exposure unit installed in the photo processing apparatus of FIG. 1. The figure which shows the structure of 1 pixel scanned twice by the exposure part which the photographic processing apparatus of FIG. 1 is mounted. The block diagram which shows the schematic structure of the exposure part with which the photographic processing apparatus which concerns on other embodiment of this invention is provided. The block diagram which shows the schematic structure of the exposure part with which the photographic processing apparatus which concerns on further another embodiment of this invention is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing part 2 Photographic paper storage part 3 Developing part 4 Drying part 5 PC
6 Exposure unit (exposure device)
7 Light source unit 7R Light source unit 8 Scanning unit 9 Transport unit 10R Red LD (light source)
12R AOM (light modulation element)
15R AOM driver (modulation circuit)
16 Reflective mirror 17 Cylindrical lens 18 Polygon mirror 19 Polygon driver 20 fθ lens 21A Sync sensor 21B Mirror 22 Carrying roller 23 Microstep motor 24 Microstep driver 26 Data supply unit 27R Reference clock generation circuit 28R Data buffer 29R D / A converter (D / A converter)
29Ra D / A converter (D / A converter)
29Rb D / A converter (D / A converter)
30 Exposure control unit 40R Laser control substrate 41R Multiplication division unit (division unit)
42R Magnification Switching Unit 43R Magnification Setting Unit 43Ra Low Density Processing Unit 43Rb High Density Processing Unit 44R Modulation Unit 50 Photo Processing Device 140R Laser Control Board 143R Magnification Setting Unit 143Ra Low Density Processing Unit 143Rb Medium Density Processing Unit 143Rc High Density Processing Unit P Printing Paper (photosensitive material)
R1 to R5 transport rollers

Claims (5)

An exposure apparatus that performs exposure processing based on image data and performs gradation expression by scanning a predetermined number of times for one pixel,
A D / A converter for converting the image data divided every predetermined number of times from digital data to analog data;
A modulation circuit that outputs a modulation signal of a light beam obtained by processing the converted analog data at a different number of magnifications equal to the predetermined number of times set in advance;
A light modulation element that receives the output from the modulation circuit and modulates the light beam;
An exposure apparatus comprising: A division unit that divides the image data input to the D / A conversion unit into the same number of data as the predetermined number of times;
The exposure apparatus according to claim 1. The dividing unit divides the image data having a certain number of bits expressing the gradation of one pixel into a plurality of stages and outputs the divided data to the modulation circuit.
The exposure apparatus according to claim 2. The D / A converter is provided with two or more systems,
The exposure apparatus according to claim 1. The D / A converter is supplied with the image data and supplementary data for supplementing the image data.
The exposure apparatus according to any one of claims 1 to 4.

Images