JP2006319240A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device by which state of deterioration of a laser diode can be recognized when image formation is performed by using the laser diode. <P>SOLUTION: The image forming device for performing image formation by using a laser beam irradiated from the laser diode comprises a photo diode 37 for detecting output intensity of the laser beam, a current control means 49e which so controls a current value made to flow to the laser diode 30 that the detected output intensity is in a specified range, a current variation detecting means 50a for detecting variation of the current value in a specified time, and a deterioration degree indicating means 50c for indicating deterioration degree. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image using laser light emitted from a laser diode.

  In a photographic processing system for forming an image on an image forming medium such as a photographic material, a photographic processing system provided with an image forming apparatus for forming an image using laser light is known. As an example of an element for outputting laser light, a laser diode is used, and in order to form a color image, laser light of each color of R (red) G (green) B (blue) is output. A laser diode is required. Laser diodes that output R laser light are relatively inexpensive and are available with desired wavelength characteristics, but laser diodes that output G laser light and B laser light are not only expensive, It is difficult to obtain one that outputs a wavelength that matches the photosensitive characteristics of the photographic material.

  Therefore, a laser generator as shown in Patent Document 1 below is known, and a laser diode that outputs a near-infrared laser beam is used, and this laser beam is incident on a QPM-SHG element, so that the laser beam is emitted. By generating the second high frequency, G laser light and B laser light are output. For example, by using a near infrared laser diode having a wavelength of 1060 nm, a G laser beam having a wavelength of 530 nm (second high frequency) can be generated. Thereby, it is possible to generate laser beams of respective colors that match the characteristics of the photographic photosensitive material. Incidentally, QPM is Quasi Phase Matching (pseudo phase matching), and SHG is Second Harmonic Generation (second high frequency generation).

The QPM-SHG element is composed of PPLN (Periodically-Poled LiNbO ₃ : Periodically Polarized Inverted Lithium Niobate), and generates a second high frequency by quasi-phase matching the laser light emitted from the laser diode. By quasi-phase matching, cancellation of the second high frequencies inside the SHG element is prevented and conversion efficiency is increased, and high power G laser light and B laser light are output from the SHG element.

  Further, in order to stabilize the power of the laser beam output from the SHG element, it is necessary to stabilize the wavelength characteristics of the laser beam output from the laser diode. This is because if the wavelength characteristic is changed, the color of the image formed on the photographic light-sensitive material is affected and the image quality may be deteriorated. Therefore, in Patent Document 1, a fiber Bragg grating (FBG) is arranged between the laser diode and the SHG element. The FBG can reflect the laser beam in the main longitudinal mode to the laser diode side. Therefore, only the main longitudinal mode laser light is incident on the laser diode by the FBG, the FBG acts like an external resonator, and only the main longitudinal mode laser light is amplified and introduced into the SHG element. Therefore, since the laser beam in the main longitudinal mode is greatly amplified as compared with other modes, the wavelength characteristics of the laser diode are stabilized. As a result, stable laser light is output from the SHG element.

JP 2005-50843 A

  As described above, the output intensity of the laser light output from the SHG element can be stabilized, but the fluctuation factor of the output intensity of the laser light is not only that, but also depending on the temperature of the environment where the laser diode and the SHG element are installed. It can vary. Such a variation factor can be removed by adjusting the temperature so that the environmental temperature falls within a predetermined range.

  Although various configurations are employed in which the output intensity is constant, the output intensity still varies. For this reason, there is a method of detecting the output intensity of the output laser light and controlling the current flowing through the laser diode so that it falls within a predetermined range. As a characteristic of the laser diode, if the current is increased, the output intensity can be controlled to increase, and if the current is decreased, the output intensity can be decreased.

  As a factor of fluctuation of the output intensity described above, there is a laser diode failure. The failure includes a sudden failure and a deterioration failure, and causes of the deterioration failure include a shift of the optical system with time and a deterioration of the laser diode with time. In the case of a deterioration failure, it is a phenomenon in which the output intensity gradually changes, but the current value hardly changes in one day. On the other hand, in the case of sudden failure, most of them are sudden deterioration of the laser diode. For example, the end face of a laser diode chip generates heat due to an increase in light density, and the laser deteriorates instantaneously due to end face destruction caused by the heat. It is impossible to predict when such a sudden failure will occur.

  When such a sudden failure occurs and the output intensity decreases, control is performed to increase the current of the laser diode in order to keep the output intensity constant. However, the current value to be passed through the laser diode needs to be within a predetermined range in order to perform appropriate control (this point will be described later with reference to FIG. 7). Therefore, the range of the current value to be controlled is also limited, and when the range is exceeded, an error is displayed to notify the operator. The operator performs maintenance such as output adjustment and parts replacement by viewing the error display. However, if the current increases but stays within the range to be controlled, no error is displayed.

  However, even if the current value fluctuates to such an extent that no error is displayed, it is possible that some abnormality has occurred in the laser diode, and after a while, there may be a transition to deterioration that causes an error display. . When an error display occurs, the work time is taken for the maintenance, and the photo processing work is interrupted. Therefore, if it is possible to know the occurrence of an error display in advance, it can be considered that maintenance can be handled smoothly.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus capable of recognizing a deterioration state of a laser diode when image formation is performed using the laser diode.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
An image forming apparatus that forms an image using laser light emitted from a laser diode,
Laser light detection means for detecting the output intensity of the laser light;
Current control means for controlling the current value flowing through the laser diode so that the detected output intensity falls within a predetermined range;
Current change detecting means for detecting a change of the current value within a predetermined time; and
A deterioration degree display means for displaying a deterioration degree when the change of the current value exceeds a predetermined level is provided.

  The operation and effect of the image forming apparatus having this configuration will be described. The output intensity of the laser beam output from the laser diode is detected by a laser beam detection means. The current flowing through the laser diode is controlled so that the detected output intensity falls within a predetermined range. Further, the current change detection means detects a change in the current value within a predetermined time. As a result, it is possible to detect how much current change has occurred and to detect the occurrence of sudden deterioration. When the change in the current value exceeds a predetermined level, it can be displayed as a degree of deterioration. The operator can perform maintenance smoothly even if a failure that causes an error display in the future occurs by looking at the degree of deterioration. As a result, it is possible to provide an image forming apparatus capable of recognizing the deterioration state of the laser diode when performing image formation using the laser diode.

In the present invention, an SHG element that outputs a second high frequency of laser light emitted from a laser diode;
A fiber Bragg grating that is disposed between the laser diode and the SHG element and defines a wavelength range of the laser light emitted from the laser diode;
It is preferable that the output intensity of the laser beam output from the SHG element is detected by the laser beam detection means.

  According to such a configuration, the laser light output from the laser diode becomes laser light having a stable wavelength characteristic by the fiber Bragg grating (FBG), and further, a second high frequency having a desired wavelength is generated by the SHG element. By detecting the output intensity of the laser beam output from the SHG element and controlling the current of the laser diode, a laser beam having an output intensity within a predetermined range can be obtained.

In the present invention, temperature adjusting means for adjusting the environmental temperature of the laser diode to be a set temperature,
When the set temperature is changed in connection with the adjustment of the output intensity of the laser beam, it is preferable to display the deterioration degree by the deterioration degree display means.

  The output intensity of the laser beam can be adjusted by controlling the current passed through the laser diode as described above, but can also be controlled by changing the ambient temperature of the laser diode. Therefore, for example, when the output intensity cannot be controlled only by controlling the current, further adjustment can be performed by changing the environmental temperature. As a result, the laser diode can be used as long as possible, and the cost required for maintenance can be reduced.

  A preferred embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a configuration of a photographic processing system in which an image forming apparatus is used.

<Photo processing system configuration>
In FIG. 1, an image input unit 1 has a function of acquiring image data from various media. The film scanner 1a can capture image data of each frame image into the system by scanning the frame image formed on the developed negative film (photographic film). A storage medium used for a digital camera and other storage media such as an MO disk and a CD-R can be mounted on the medium mounting unit 1b, and image data stored in these storage media is stored in the system. Can be captured.

  The image storage unit 2 stores image data captured from the image input unit 1 in a predetermined unit (for example, an order unit). The image processing unit 3 provides a function of performing image processing on the captured image data. The image processing unit 3 can also perform image processing other than data enlargement / reduction processing, for example, color / density correction, red-eye correction, backlight correction, trimming, and the like. Data (color / density correction data, etc.) for performing these image processes can be input by the input operation unit 6. The input operation unit 6 includes a keyboard, a mouse, and the like. The monitor 5 displays information necessary for the operator to perform image processing work.

  Print image data generated by the image processing unit 3 is transferred to the laser control unit 8 of the image forming apparatus A via the image transfer unit 4. The laser control unit 8 controls the laser engine 12 and has a function of creating a photographic print based on the transferred print image data. In the paper magazine 10, paper (corresponding to an image forming medium and a photographic photosensitive material) is accommodated in the form of a roll. The long paper drawn from the paper magazine 10 is transported along a predetermined transport path, and is cut into a predetermined print size by the paper cutter 11.

  The laser engine 12 receives the print image data transferred from the image transfer unit 4, scans the laser beam, and prints and exposes the image on the paper surface. The paper on which the image is printed and exposed is subsequently transported along the transport path, subjected to predetermined development processing in the development processing unit 13, and then subjected to drying processing in the drying processing unit 14, and the paper discharge unit 15. Is output to the outside as a finished photographic print.

<Configuration of image forming apparatus>
Next, the configuration of the image forming apparatus A (laser engine 12) will be described with reference to FIG. In order to form a color image, an R laser light source unit 20R (20), a G laser light source unit 20G (20), and a B laser light source unit 20B (20) that output laser beams of R, G, and B colors are provided. The R laser light source unit 20R is configured by a laser diode that generates R (red) laser light having a wavelength of 685 nm, for example. The configurations of the G laser light source unit 20G and the B laser light source unit 20B will be described later.

  A collimator lens 21R is disposed on the output side of the R laser light source unit 20, and an acousto-optic element (hereinafter referred to as “a”) is provided on the output side of the G laser light source unit 20G and the B laser light source unit 20B via the collimator lenses 21G and 21B. AOM (Acousto-Optic Modulator) 22G and 22B are arranged. That is, the R laser beam does not use an AOM, and a direct modulation method is employed in which the drive current of a laser diode that outputs the R laser beam is modulated based on print image data. On the other hand, the G laser beam and the B laser beam employ an external modulation method in which they are modulated by the AOMs 22G and 22B.

  On the output side of the collimator lens 21R and the output side of the AOMs 22G and 22B, an opening 23 for shaping the laser light and a reflection mirror 24 are arranged in this order. A spherical lens 25 and a cylindrical lens 26 are reflected at the reflection destination of the reflection mirror 24. Polygon mirrors 27 are arranged in order. The laser beam reflected by the polygon mirror 27 reaches the emulsion surface of the photographic material P through the fθ lens 28 and the imaging lens 29.

  The polygon mirror 27 is driven to rotate counterclockwise in FIG. 2, and the combined laser light of each color is repeatedly scanned on the emulsion surface of the photographic material P in the direction of arrow C (main scanning direction). The photographic photosensitive material P is driven in a direction (sub-scanning direction) perpendicular to the paper surface of FIG. 5, and the light-modulated laser light is moved along the main scanning direction while the photographic photosensitive material P is transferred in the sub-scanning direction. By repeating scanning, an image (latent image) is formed on the emulsion surface of the photographic material P.

<Configuration of laser light source>
Next, the configuration of the laser light source units 20G and 20B will be described with reference to FIG. The basic configuration of the laser light source 20G for G laser light and the laser light source 20B for B laser light are the same. Laser light output from a laser diode 30 (hereinafter referred to as LD) passes through the optical fiber 31 and reaches the FBG 32. When the laser light passes through the FBG 32, it again passes through the optical fiber 33 to the PPLN (corresponding to a QPM-SHG element) 34. be introduced. The laser light output from the PPLN 34 passes through an IR (infrared) cut filter 35 and a splitter 36 and is output. The output laser light is directed toward the collimator lens 21 and the AOM 22. Further, a part of the laser light output by the splitter 36 is directed to the photodiode 37 (corresponding to laser light detection means), and the output intensity of the laser light is detected. Based on the detected output intensity, control is performed so that the intensity of the laser beam to be output falls within a predetermined range. This control will be described later.

  As a laser diode for generating the G and B laser beams, a laser diode that outputs a near infrared laser beam is used, and the laser beam is incident on the PPLN 34 to generate a second high frequency of the laser beam. And B laser light is output. For example, a G laser beam having a wavelength of 530 nm (second high frequency) is generated by using a near infrared laser diode having a wavelength of 1060 nm, and a wavelength of 473 nm (second high frequency) is generated by using a near infrared laser diode having a wavelength of 946 nm. B laser light can be generated. Thereby, it is possible to generate laser beams of respective colors that match the color development characteristics of the photographic photosensitive material P.

  The FBG 32 is a member that causes a refractive index change at a constant interval in the core of the optical fiber and acts as a mirror for only a specific wavelength. By irradiating the optical fiber with periodically changing ultraviolet rays, a diffraction grating is formed, and has a function of reflecting light having a wavelength (Bragg wavelength) twice the period of the diffraction grating. Therefore, the FBG 32 is designed to reflect 1060 nm laser light (main longitudinal mode) in the case of G laser light and to reflect 946 nm laser light (main longitudinal mode) in the case of B laser light. .

  Thus, since the main longitudinal mode laser beam is reflected by the FBG 32 to the LD 30 side, only the main longitudinal mode laser beam is incident on the LD 30 by the FBG 32, and the FBG 32 acts like an external resonator. Are amplified and introduced into the PPLN 34. For this reason, the laser beam in the main longitudinal mode is greatly amplified as compared with the other modes, so that the wavelength characteristics of the LD 30 are stabilized. As a result, stable laser light is output from the PPLN 34.

<Circuit block configuration diagram>
Next, the control circuit of the laser light source unit 20 will be described with reference to the block diagram of FIG. The PPLN folder 40 is a folder for attaching and supporting the PPLN 34, and is attached to the circuit board via a Peltier element 41 (an example of a temperature control element). The thermistor 42 (an example of a temperature sensor) is attached to the PPLN folder 40 and detects the temperature. With this configuration, the temperature control is performed so that the PPLN 34 reaches the set temperature.

  The LD folder 43 is a folder for attaching and supporting the LD 30 and the FBG 32, and is attached to the circuit board via a Peltier element 44 (an example of a temperature control element). The thermistor 45 (an example of a temperature sensor) is attached to the LD folder 43, detects the temperature, and is controlled so that the LD 30 and the FBG 32 have a set temperature.

  The temperature adjustment substrate 46 (corresponding to temperature adjustment means) includes a temperature adjustment IC 46a for adjusting the temperature of the PPLN 34 and a temperature adjustment IC 46b for adjusting the temperature of the LD 30 and the FBG 32. Temperature control by the temperature control board 46 is performed by a temperature control ON command signal from the CPU board 49. The driver board 47 is a circuit board for driving the LD 30 and the photodiode 37. The voltage-current (V-I) converter 47a converts the voltage value into a current value and drives the LD 30. The current-voltage (IV) converter 47b converts the current value detected by the photodiode 37 into a voltage value, and detects the output intensity of the laser beam.

  The LD control board 48 includes a DA converter 48a and an AD converter 48b. The DA converter 48 a performs serial communication with the CPU board 49, converts the transmitted digital data of the temperature setting value and the current setting value into analog data, and transmits the data to the temperature control board 46 and the driver board 47. The AD converter 48b performs serial communication with the CPU board 49, converts the analog temperature detection value detected by the temperature control board 46 and the analog output intensity value detected by the driver board 47 into digital data, and converts the CPU board to the CPU board 49. 49.

  The CPU board 49 includes a CPU that is the center of the control unit and its peripheral circuits. Further, a program for performing temperature control, current control, etc., a memory for storing necessary data, and the like are also provided.

  In the temperature setting value setting unit 49a, a temperature setting value for setting the PPLN 34 and the LD 30 to a predetermined environmental temperature is set. For the PPLN 34 and the LD 30, temperature setting values are set separately. The temperature set value can be arbitrarily set depending on circumstances such as the environment in which the image forming apparatus is placed. The temperature comparison determination means 49b compares and determines the temperature value detected by the thermistors 42 and 45 and the temperature setting value set in the temperature setting value setting unit 49a, and adjusts the temperature to the set temperature. A command is given to 46.

  The output intensity setting unit 49c has a preset output intensity of laser light. The output intensity comparison / determination means 49d compares and determines the output intensity detected by the photodiode 37 and the output intensity set by the output intensity setting unit 49c, and sets the drive current of the LD 30 so as to obtain a predetermined output intensity. Control. Here, the relationship between the LD current and the visible output intensity is shown in FIG. As shown in FIG. 5, when the current exceeds a certain level, a visible output (output intensity) can be obtained, and when the current increases beyond that level, the output intensity increases proportionally. Therefore, by controlling the current value, the LD 30 can be controlled so that a desired laser output intensity can be obtained. The current control unit 49e controls the drive current of the LD 30 so that the set output intensity can be obtained based on the determination result by the output intensity comparison / determination unit 49d.

  The current change detecting means 50a detects the degree of change in current when the current control means 49e controls the current. In particular, when any failure occurs in the LD 30, the output intensity changes. In the case of a deterioration failure, the output intensity gradually changes, and there is almost no change in the current value in one day. On the other hand, in the case of a sudden failure, it is conceivable that the visible output of the LD 30 largely fluctuates (decreases). When such a sudden failure occurs and the output intensity decreases, the current of the LD 30 is controlled to increase in order to keep the output intensity constant. However, the current value to be passed through the LD 30 needs to be within a predetermined range in order to perform appropriate control. Accordingly, when the predetermined range is exceeded, an error is displayed to notify the operator. The operator performs maintenance such as output adjustment and parts replacement by viewing the error display.

  Further, even if the current value fluctuates to such an extent that no error is displayed, this means that some abnormality has occurred in the LD 30, and after a while there may be a transition to a deterioration in which an error is displayed. When an error display occurs, the work time is taken for the maintenance, and the photo processing work is interrupted. Therefore, a function that can predict the occurrence of an error display in advance is installed.

  Therefore, a change level setting unit 50b is provided, and a change level of the current value is set. Not only one change level but also a plurality of levels can be set in stages. The change level indicates, for example, a case where “a change of 10 mA (corresponding to a change amount) or more in one minute (corresponding to a predetermined time)” occurs. In the case where a plurality of levels are set stepwise, for example, in addition to the above-described example, the case where “a fluctuation of 5 mA or more per minute” is further set is set. In addition, a change level for displaying an error is also set. Note that the predetermined time and the amount of change can be set as appropriate.

  When the change in the current value exceeds a predetermined change level, the deterioration degree display means 50c displays the deterioration degree corresponding to the change level. The error display means 50d displays an error when the change in the current value exceeds a predetermined change level. The display circuit board 51 has a function of displaying a predetermined display on the display screen of the monitor 5.

  FIG. 6 shows a display example when the degree of deterioration is displayed on a monitor. When displaying the deterioration degree in two stages (the same applies to three or more stages), as shown in the figure, both the deterioration degrees A and B can be displayed on the monitor, and the corresponding one can be surrounded by a frame. In this case, comments such as “LD life is approaching” and “LD life is expected to be XX hours” are also displayed. Thereby, the operator can predict the life of the LD 30 and can smoothly perform future maintenance work. It is also possible to take measures such as contacting the service person in advance. Various display examples for displaying the degree of deterioration are conceivable and are not limited to those shown in FIG. For example, the date and time when the current increase occurred may be displayed together. The color display may be changed according to the progress of the degree of deterioration. Moreover, you may make it display only one applicable thing among several deterioration degrees.

  When displaying an error, a specific maintenance operation such as “Please replace the LD” is displayed. Even if the degree of deterioration is displayed in this way, the life of the LD 30 has not reached the point in time, so that the image formation can be performed using the LD 30 continuously, but the life of the LD 30 can be predicted. it can.

<Another Embodiment of Deterioration Degree Display>
Next, another embodiment for displaying the degree of deterioration will be described. The LD 30 has temperature characteristics, and when the temperature is changed, the intensity of the output laser light also changes proportionally. Therefore, the output can be adjusted by changing the environmental temperature of the LD 30. In this case, the output intensity is usually controlled by changing the drive current of the LD 30. However, since the wavelength size is defined by the FBG 32, the relationship between the output intensity of the laser light detected by the photodiode 37 and the drive current of the LD 30 changes in a sawtooth shape as shown in FIG. The current control range is set so as not to include the intermittent point. Therefore, the output intensity can be adjusted by increasing or decreasing the current within this range, but cannot be controlled beyond this range. In this case, the output intensity can be further adjusted by changing the environmental temperature of the LD 30. However, in such a case, since it is considered that the degradation of the LD 30 is progressing, the degradation degree display is performed.

<Another embodiment>
In the present embodiment, a photodiode is used as the laser light detection means, but the present invention is not limited to this, and other types of optical sensors may be used. For controlling the LD drive current, either digital control or analog control may be used.

  About R laser light source part 20R, you may employ | adopt the structure similar to the other G and B laser light source parts 20G and 20B.

Schematic diagram showing the configuration of the photo processing system Schematic diagram showing the configuration of the image forming device (laser engine) Schematic diagram showing the configuration of the laser light source Circuit block diagram of laser light source Graph showing accounting of laser diode current and visible output intensity The figure which shows the example of a display when displaying a deterioration degree on a monitor Graph showing the relationship between LD drive current and output laser light

Explanation of symbols

12 Laser Engine 20 Laser Light Source 20R R Laser Light Source 20G G Laser Light Source 20B B Laser Light Source 30 Laser Diode 31 Optical Fiber 32 FBG (Fiber Bragg Grating)
33 Optical fiber 34 PPLN
37 Photodiode 40 PPLN folder 41 Peltier element 42 Thermistor 43 LD folder 44 Peltier element 45 Thermistor 46 Temperature control board 47 Driver board 48 LD control board 48a DA converter 48b AD converter 49 CPU board 49a Temperature set value setting unit 49b Temperature comparison / determination means 49c Output intensity setting unit 49d Output intensity comparison / determination unit 49e Current control unit 50a Current change detection unit 50b Change level setting unit 50c Degradation degree display unit 50d Error display unit A Image forming apparatus P Photosensitive material

Claims (3)

An image forming apparatus that forms an image using laser light emitted from a laser diode,
Laser light detection means for detecting the output intensity of the laser light;
Current control means for controlling the current value flowing through the laser diode so that the detected output intensity falls within a predetermined range;
Current change detecting means for detecting a change of the current value within a predetermined time; and
An image forming apparatus comprising: a deterioration degree display means for displaying a deterioration degree when the change in the current value exceeds a predetermined level. An SHG element that outputs the second high frequency of the laser light emitted from the laser diode;
A fiber Bragg grating that is disposed between the laser diode and the SHG element and defines a wavelength range of the laser light emitted from the laser diode;
2. The image forming apparatus according to claim 1, wherein an output intensity of the laser beam output from the SHG element is detected by the laser beam detecting means. Temperature adjusting means for adjusting the environmental temperature of the laser diode to be a set temperature;
3. The image forming apparatus according to claim 1, wherein when the set temperature is changed in relation to the adjustment of the output intensity of the laser beam, the deterioration degree is displayed by the deterioration degree display means.

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