JP2930896B2 - Optical printing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical printing apparatus for irradiating a photosensitive medium with light to print images and characters.

[0002]

2. Description of the Related Art A laser printer generally used at present carries out printing by supplying toner to an electrostatic latent image formed on a photosensitive drum by a laser beam, developing the toner, and transferring the toner to a record carrier. . The method of scanning print information on the photosensitive drum with such a laser printer includes:
Rotating polygon mirrors are widely used. On the other hand, recently, an optical printing apparatus using light in a method different from a laser printer using toner has appeared. This optical printing device focuses and moves a laser beam used as printing light on a photosensitive medium, and converts the energy generated at the focal point into a photoelectric conversion (Opto-Electric conversion), a photothermal conversion (Opto-thermal conversion), etc. In this method, images and characters are transmitted to a record carrier through energy conversion by a photosensitive medium. The operation of such an optical printing apparatus is described in "High Definition Thermal Transfer Printing Usi
ng Laser Heating "(Mitsuru Irie et al, Journal of I
maging Science & Technology, Vo1.37, No.3, 1993, p
p 231-238) and "Halftone ColorImaging by Laser Dye
Transfer "(Proc. Of the 9th Int. Congress on Advanc
es in Non-impact Printing (NIP) Technologies, Yokoh
ama, Japan, Oct. 4-8, 1993, pp 362-365).

FIG. 1 shows a schematic configuration of a general optical printing apparatus. Printing information for the optical printing device is output from the computer 10. At this time, the computer 10 outputs coordinate information of the print information in addition to the print information, and these are sent to the interface unit 21.

In the illustrated optical printing apparatus, a laser driver (laser driver) 22 and a laser diode (laser diode) are used.
e) 23, optical fiber 24, beam centering unit 26, and focus system
g optics) 27, in which the print information is photoelectrically converted into a laser beam. In this case, the print head 2
5 can be composed of a beam guide 26 and an optical system 27. In addition, there is also a configuration in which print information is photoelectrically converted into a laser beam by the laser driving unit 22, the laser diode 23, and the optical system 27. In this case, the print head 25 can be configured by the laser diode 23 and the optical system 27. is there.

A process in which print information is converted into a laser beam and printing is performed by the optical printing apparatus will be described. The print information via the interface section 21 is modulated and amplified so that the laser beam can be converted by the laser drive section 22 and then output to the laser diode 23 to be converted into a laser beam. The laser beam output from the laser diode 23 based on the print information is transmitted to the beam guide 26 through the optical fiber 24. Beam guide 2
At 6, the control for positioning the laser beam transmitted via the optical fiber 24 at the center of the optical system 27 is performed. That is, the beam guide 26 has a role of aligning the optical axis of the optical fiber 24 with the optical axis of the optical system 27. The laser beam that has passed through the optical system 27 focuses on the photosensitive medium located on the drum 29. A photosensitive medium and a record carrier are located on the drum 29, and the photosensitive medium reacts with the laser beam to perform printing on the record carrier. For example, printing is performed by transferring a portion heated by laser beam irradiation to a record carrier. This thermal transfer method includes sublimation type thermal transfer (Dye D
Iffusion Thermal Transfer and Melt Thermal Transfer
al Transfer).

At the time of printing, the print head 25 is moved with respect to the X-axis relationship of the print information, and the drum 29 is rotated with respect to the Y-axis relationship. That is, the steps related to the X axis are the first step motor 33 and the lead screw (precision l).
ead screw) 31 and slide guide (precision slid)
e) Step 32 is performed, and the steps related to the Y axis are performed by the second step motor 34. The print head 25 is screwed with the lead screw 31, and when the lead screw 31 rotates by the operation of the first step motor 33, the print head 2
5 moves in the X-axis direction. And the second step motor 3
By rotating the drum 29 in the operation of 4, the record carrier becomes Y
Move in the axial direction. In many optical printing apparatuses, the slide head 32 is provided to support the print head 25, thereby improving the movement accuracy of the print head 25 moved by the lead screw 31. With such a configuration, the print head 25 slides in the X-axis direction according to the XY coordinate data output from the interface unit 21 to the first and second step motors 33 and 34 during printing, and the drum 29 Performs the rotation operation in the Y-axis direction.
Two-dimensional printing is performed.

The optical printing apparatus performs optical printing using a laser beam or the like in this manner, and therefore has high resolution and high quality printing performance due to the characteristics of the optical printing.

[0008]

In the above-described optical printing apparatus, in order to achieve a high resolution of 500 dpi or more with a dot diameter of 50 μm or less, the laser focal length to the photosensitive medium must be accurately controlled. No. That is,
It is necessary to accurately maintain the distance between the print head that emits the laser beam and the photosensitive medium. Most current optical printing devices rely on mechanical mechanisms for this focal length control. Therefore, high precision is required in the assembly process, which is difficult. Also, high precision is required for each part, which leads to an increase in cost. Further, there is still room for improvement in terms of printing quality and speeding up. .

More specifically, referring to FIG. 4, since the printing quality of the optical printing apparatus is affected, the optical system 2
Of course, it must be precisely controlled that the photosensitive medium on the drum 29 is always within the depth of focus of the laser beam according to. For this purpose, the lead screw 31 and the slide guide 32 must be mechanically and precisely designed to realize smooth and accurate movement control of the print head 25. In particular, if the movement axis of the print head 25 and the rotation axis of the drum 29 do not accurately maintain parallel in one plane during the operation of the print head 25, the distance (focal length) from the optical system 27 to the photosensitive medium will increase. Since the possibility of exceeding the focal depth range (reference focal length) of the laser beam comes out,
Depending on the printing coordinates, the focus may not be adjusted, and the printing quality may be degraded. Therefore, to prevent such movement from occurring,
The lead screw 31 and slide guide 32 must be designed and assembled fairly accurately. Furthermore, because such high precision and smooth sliding operation is required,
The moving speed of the print head 25 cannot be made too high, and a satisfactory printing speed cannot be obtained.
If the surfaces of the photosensitive medium and the record carrier located on the drum 29 are wavy due to wrinkles or the like, the print head 25
However, there is also an improvement that the mechanical movement control alone cannot cope with the problem, and the focus is not focused at that portion. Therefore, realization of adaptive focus control is desired.

An object of the present invention is to provide an optical printing method capable of automatically controlling the focal length adaptively according to the focus state, focusing on the above-described prior art.

[0011]

In order to solve the above problems, the focal length of the printing light is sensed by some means to detect a deviation (error) from the reference focal length, and the focal length is corrected accordingly. I just want to be able. For this reason, in the present invention, in an optical printing method in which printing is performed by irradiating a printing medium to a photosensitive medium in contact with a record carrier by irradiating the printing light with the printing light, the reflected printing light reflected by the photosensitive medium is reflected. An optical printing method characterized by sensing and controlling a focal length from a print head to a photosensitive medium based on a state of sensing reflected light. In particular, when considering detecting a deviation of the actual focal length from the reference focal length, the reflected light of the printing light is sensed by an optical sensor in which photosensitive elements are arranged in a straight line, and in the optical sensor, If the focal length is controlled based on the reflected light sensing state by detecting how much the light sensitive element that is actually sensitive is displaced from the reference light sensitive element that is sensitive at the reference focal length, the sensing performance is excellent.

According to the present invention, as an optical printing apparatus for such an optical printing method, an optical system for outputting printing light, a sensor for sensing reflected light of the printing light, and a drive based on the output result of the sensor are provided. And an actuator for adjusting the focal length by controlling the position of the optical system. In particular, the sensor for sensing the reflected light of the printing light of the optical printing apparatus includes an optical sensor that receives the reflected light via a sensing optical system, and the optical sensor linearly arranges a number of photosensitive elements. Any one of them is determined as a reference light-sensitive element that senses at a reference focal length, and the number of light-sensitive elements that are actually sensing from the reference light-sensitive element is output as deviation distance data. Then, it is optimal for the optical printing method.

Various methods can be considered as a method of driving the actuator of the print head based on the output result of the sensor that senses the reflected light of the printing light. In particular, when the linear optical sensor as described above is used, printing is performed. The control unit that outputs print information and coordinate information for the head includes a correction table that associates the deviation distance data with the drive value of the actuator of the print head, and accesses the correction table based on the deviation distance data. It is preferable to output correction data to the actuator of the print head and drive the print head. As described above, as the correction table provided in the control unit, it is optimal to associate the deviation distance d obtained by calculating the deviation distance data with the following Expression 3 with the drive value of the actuator of the print head.

D = n × δ × Z ₀ / [s × sin (α ± θ)] θ = tan ⁻¹ (n × δ / s) Z ₀ : Reference focal length, α: Reference focal length Z ₀ , The deviation angle of the reflected light at the actual focal length with respect to the reference reflected light, n: the number of photosensitive elements that are actually sensitive from the reference photosensitive element, and δ: the number of photosensitive elements pitch,
s: Length from sensing optical system to reference light sensitive element

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The same components in the drawings are denoted by common reference numerals. In the following description, many specific details such as laser beam width, focal radius, focal diameter, focal depth, etc. are provided for a more general understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details.

FIG. 1 shows a schematic configuration of a main part of an optical printing apparatus according to this embodiment. When the print information and the coordinate information are output from the computer 40 to the interface unit 51, the interface unit 51 outputs the print information and the coordinate information to the control unit 52. The control unit 52 outputs dot data to be printed from the received print information. Further, based on the received coordinate information, X coordinate data for moving the print head 58 in the X axis direction and Y coordinate data for rotating the drum 61 in the Y axis direction are used.
Generate coordinate data.

The controller 52 has a correction table for correcting the focal length at which the deviation has occurred. That is,
Receiving deviation distance data indicating the deviation between the reference focal length and the actual focal length, and accessing the correction table corresponding to the deviation distance from the reference focal length to the focal position deviating from the reference focal length,
The corresponding correction data is output.

The laser drive unit 53 receives the dot data output from the control unit 52, modulates and amplifies the dot data for conversion into a laser beam used as printing light, and outputs the modulated laser beam. A laser source 54, which is a printing light source, photoelectrically converts dot data output from the laser driving unit 53 and generates a laser beam as printing light. A first optical fiber connector 55 is provided at an output end of the laser source 54, and a laser beam is output to the optical fiber 56 via the first optical fiber connector 55. The optical fiber 56 is a second optical fiber connector.
nector) 57 via a printing head 58
Optics (focusing optics) 71 and transmits the laser beam to the optical system 71 by total internal reflection. As a result, the laser beam generated by the laser source 54 is input to the optical system 71 and irradiated on the photosensitive medium 63.

The print head 58 includes an optical system 71 and a sensor (d
instance sensor) 72 and actuator (actuator)
73. The optical system 71 is adjusted so that the laser beam is focused on the photosensitive medium 63 at the reference focal length. The sensor 72 detects the reflected light (focal image) from the laser focal point and converts it into an electric signal, thereby generating deviation distance data indicating the deviation distance of the actual focal length from the reference focal length, and outputs the deviation distance data to the control unit 52. I do. Actuator 7
3 is driven based on the correction data output from the control unit 52, and adjusts the position of the optical system 71. The print head 58 may be configured without using the optical fiber 56. The laser source 54, the optical system 71, the sensor 72,
And the actuator 73.

The means for moving the print head 58 in the X-axis direction includes a first step motor 67, a lead screw 6
5 and a slide guide 66. The first step motor 67 operates according to the X coordinate data output from the control unit 52. When the lead screw 65 is rotated by the operation of the first step motor 67, the print head 58 screwed to the lead screw 65 is supported and guided by the slide guide 66 and slides. The means for moving the record carrier 62 in the Y-axis direction includes a drum 61 and a second step motor 68. The second step motor 68 operates according to the Y coordinate data output from the control unit 52. The drum 61 is rotated by the operation of the second step motor 68, and the recording medium (receiving layer) 62 lightly adhered to the drum 61 and the photosensitive medium (reactio
n layer) 63 moves in the Y-axis direction. Therefore, the movement of the print head 58 in the X-axis direction and the recording
In response to the movement of the photosensitive medium 63 in the Y-axis direction and the photosensitive medium 63, the photosensitive medium 63 reacts with the laser beam emitted from the optical system 71, and printing is performed on the record carrier 62.

The optical printing apparatus of this example is a computer 40
In this method, printing is performed on the record carrier 62 by thermal transfer of the photosensitive medium 63 based on print information and coordinate information output from the printer. The print information and the coordinate information output from the computer 40 are sent to the control unit 52 via the interface unit 51. The control unit 52 controls the overall operation of the optical printing apparatus according to the print information and the coordinate information.

The print information is received as coded data. The control unit 52 converts the coded print information into dot data and outputs the dot data. Also, X coordinate data and Y coordinate data for determining the transfer position of the dot data are generated from the coordinate information. X coordinate data is the first
The print head 58 is input to the step motor 67, and the first step motor 67 operates in response to the rotation of the lead screw 65 to move the print head 58 in the X-axis direction. During this movement, the generation of vibration is suppressed by the support of the slide guide 66, and the movement can be performed smoothly. On the other hand, the Y coordinate data is input to the second step motor 68, and the second step motor 68 operates to rotate the drum 61 accordingly. Due to the rotation of the drum 61, the record carrier 62 and the photosensitive medium 63 mounted on the drum 61 move in the Y-axis direction. In this way, the transfer position of the dot data is determined by the XY coordinate data.

The dot data output from the control unit 52 is output to a laser drive unit 53, where it is modulated and amplified so that it can be converted into a laser beam. Then, the laser driving unit 5
The dot data output from 3 is converted into a laser beam by the laser source 54 and transmitted to the optical system 71 of the print head 58 via the first optical fiber connector 55-optical fiber 56-second optical fiber connector 57. The transmitted laser beam is output from the optical system 71 and focuses on the photosensitive medium 63. In the photosensitive medium 63, thermal transfer occurs on the irradiated portion in response to the laser beam, and dot data is printed on the record carrier 62.

At this time, the focus of the laser by the optical system 71 needs to be accurately set on the photosensitive medium 63. If the focus is out of focus, the dot data is blurred, and high resolution cannot be obtained. Therefore, the correction is performed by detecting the actual focal length by receiving the reflected light from the laser focal point of the photosensitive medium 63 and obtaining the deviation distance from the reference focal length from the optical system 71 to the photosensitive medium 63 set in advance. The sensor 72 generates deviation distance data for obtaining the deviation distance. That is, the sensor 72
It is a detecting unit that receives the reflected light (focal image of the printing light) reflected from the photosensitive medium 63 and detects a deviation between the reference focal length and the actual focal length. In this example, the sensor 72
PS, a one-dimensional image sensor in which photosensitive elements are arranged in a straight line
D (Position Sensitive Detector) or linear CCD (Lin
ear Charge Coupled Device).

The control unit 52 has a correction table corresponding to the deviation distance data from the sensor 72, and outputs correction data based on the correction table, corrects the deviation, and corrects the deviation.
The focal length between the optical system 3 and the optical system 71 is controlled so as to maintain the reference focal length. When the control unit 52 that has received the deviation distance data from the sensor 72 accesses and outputs the correction data corresponding to the deviation distance data from the correction table, the data is input to an actuator 73 that controls the position of the optical system 71. Actuator 73 receiving correction data
Performs a focusing servo function of adjusting the focal length by moving the optical system 71 in the Z-axis direction according to the value. Thus, the laser beam is accurately focused on the photosensitive medium 63. As the actuator 73, an electromagnetic induction linear actuator (linear actuator)
And a piezoelectric actuator can be used.

FIG. 2 is a diagram for explaining the relationship between the print head 58 and the photosensitive medium 63. In FIG.
Represents the value indicated by.

Dapt: Aperture Diameter of optical system 71 L: Plane on which output end of optical system 71 is located Z ₀ : Reference focal length from plane L to photosensitive medium 63 O: Reference focal length Z ₀ Reference focal position M: Deviation focal position when deviated from reference focal distance Z ₀ d: Deviation distance from reference focal position O to deviation focal position M H: Main plane on which sensing optical system 81 of sensor 72 is located R: Sensor The reference focus position O in the optical sensor 82 of 72
Reference position N at which the reference reflected light reflected by the light source N is deviated focal position M in the optical sensor 82 of the sensor 72
Α: Reference reflected light angle 基準 LOH at reference focal length Z ₀ θ: Deviation angle 反射 OHM of the reflected light at deviation focal position M with respect to the reference reflected light

FIG. 3 shows an optical sensor 82 using a PSD.
The symbols in the figure represent the values shown in Table 2 below. In this case, each cell of the PSD is a photosensitive element.

R: Reference cell (center cell) for sensing reference reflected light (reference focal image) at reference focal position O BIS: Range of reflected light at deviation focal position M (deviation focal image) N: Reflection Center deviation cell at the center of the light range BIS (nTH c
ell) n: Number of center deviation cells N from reference cell R (cell number) n _s : Number of deviation cells closest to reference cell R in reflected light range BIS from reference cell R (cell number) n _e : number of deviation cells located farthest from the reference cell R in the reflected light range BIS from the reference cell R (cell number) δ: pitch of each cell of the optical sensor 82

The laser beam is transmitted through the optical system 71 to the photosensitive medium.
When the surface of the body 63 is irradiated, light → heat energy conversion
Recording by the phase transfer of the photosensitive medium 63
Transcription to body 62 occurs. At this time, the laser irradiation diameter
Is the reference focal length Z at which ₀ The photosensitive medium 63 is located at
If so, as shown in FIG.
To the reference cell R of the optical sensor 82 through the sensing optical system 81 of
The focus is on. Optical system 71 in this case
And the main optical axis (OH) of the sensing optical system 81
Is the reference reflected light angle α. In this state, the laser beam
A state in which the photosensitive medium 63 is accurately focused,
This is a state where correction is unnecessary.

On the other hand, when the distance between the optical system 71 and the photosensitive medium 63 is shorter or longer than the reference focal length Z ₀ , the reflected light input to the optical sensor 82 shifts from the reference cell R. That is, the angle between the main optical axis of the optical system 71 and the main optical axis of the sensing optical system 81 changes by the deviation angle θ. FIG. 2 shows an optical system 71.
The distance between the photosensitive medium 63 is shown to be longer than the reference focal length Z _0. In this case, the reflected light input to the optical sensor 82 has the highest sensitivity in the center deviation cell N, and shifts from the reference cell R to one side (the left side in the drawing) by n × δ as shown in FIG. Can be sensed. The main optical axis (LM) of the optical system 71 and the main optical axis (M
H) is α-θ obtained by subtracting the deviation angle θ from the reference reflected light angle α.

At this deviation focal position M, various aberrations and diffraction effects in the optical system 71 and the sensing optical system 81 cause
The reflected light input to the optical sensor 82 is blurred and the reflected light range B
You will have IS. Therefore for the sake of completeness, cell number n _s of both cells endmost sensitive to the reflected light in the optical sensor 82, with n _e, determine the cell number n of the center deviation cell N of the reflected light range BIS . That is, n = (n
_s + _ne ) / 2. Using this n, the deviation angle θ with respect to the reference reflected light angle α can be obtained by the following equation 4.

## EQU4 ## θ = tan ⁻¹ (n × δ / s)

S in Equation 4 represents the length (HR) from the main plane H of the sensing optical system 81 to the reference cell R of the optical sensor 82.

If the distance between the optical system 71 and the photosensitive medium 63 changes due to some influence, the deviation distance d can be obtained from Expression 4 for obtaining the deviation angle θ as in the following Expression 5.

D = n × δ × Z ₀ / [s × sin (α ± θ)]

In the equation (5), + indicates that the focal length is the reference focal length Z.
_When shorter than ₀ ,-corresponds to longer. The deviation distance d determined by Expression 5 can be used as information for adjusting the position of the optical system 71 to accurately focus on the photosensitive medium 63.

The control unit 52 controls the optical sensor 8 that has received the reflected light.
2 is received as deviation distance data, and based on this, the corresponding correction data is stored in a correction table (lookup tabl).
e) Access from The accessed correction data is output to drive the actuator 73. The drive value of the actuator 73 output as the correction data is a current value for a linear actuator and a voltage value for a piezo actuator. Tables 3 and 4 show examples of the correction table in this case. These relationships can be easily obtained by measuring the characteristics of the actuator 73 in advance. Alternatively, in addition to those shown in these tables, the control unit 52 is provided with a correction table in which the deviation distance d and the drive value of the actuator 73 are associated, and the control unit 52 that has received the deviation distance data uses The deviation distance d
Is calculated, and correction data corresponding to the deviation distance d is output from the correction table. Since it is easier to make the correspondence between the deviation distance d and the drive value of the actuator 73, this is preferable.

[Table 3]

[0034]

[Table 4]

When the control unit 52 accesses the correction table according to the deviation distance data and outputs the correction data, the actuator 73 operates in accordance with the access and the position of the optical system 71 is adjusted. Accordingly, the laser beam is corrected to the reference focal length Z ₀ , so that the laser beam is focused on the photosensitive medium 63. That is, when the focal length changes and the focus becomes out of focus, the position of the optical system 71 in the Z-axis direction is adjusted by using a linear actuator or a piezo actuator using electromagnetic induction, and the reference focal length is always maintained. ing.

As a specific example, the width ω of the collimated laser beam entering the optical system 71 is ω = 0.8.
mm (1 / e ² Gaussian Beam width), reference focal length f of optical system 71 = 26 mm (Z ₀ ), wavelength λ = 700 m
m, aperture Dapt of the optical system 71 = 1.2 mm, various aberrations such as spherical aberration, and blurring factors (blurr) caused by diffraction effects.
ing factor) Under the condition of γ = 1.35 (generally 1.3 <γ <2), the following equation is obtained.

[0037] Diffraction limited system
laser beam width (1 / e ² Gaussia
n beam width) is as follows.

(Equation 6)

Airy disk by diffraction
The spot radius is as follows:

(Equation 7)

A reference plane (reference surfa)
The spot diameter occurring at ce) is as follows:

## EQU8 ## φ = 2r ₀ × γ = 50 μ

The distance in the Z-axis direction at which the laser beam width ω ₀ changes by ± 5%, that is, the depth of focus is as follows.

[Equation 9] ΔZ = ± 0.32πω ₀ ² /λ=±75.3μ

In this example, a resolution equivalent to 500 dpi can be obtained despite the fact that the system is constructed with considerable margin. The use of an optical system of a level commonly used at present can easily realize a resolution of 4,000 dpi or more and a high print head moving speed of 2 m / sec or more in the X-axis direction.

According to the print head constructed as in this embodiment, the reflected light (focal image) interlocked with the change in the focal length
Is detected by the optical sensor 82, so that the edges of the record carrier 62 and the photosensitive medium 63 can be detected by using this. That is, when passing through the edge of the record carrier 62 or the photosensitive medium 63, the movement of the focal image becomes discontinuous due to the step. Since the optical sensor 82 can detect this, accurate edge detection can be realized. Therefore,
A separate edge detection sensor becomes unnecessary.

Even if the record carrier 62 or the photosensitive medium 63 has a slight curvature such as wrinkles, it can be adaptively corrected so as to maintain the reference focal length. High resolution printing can be performed within the range.

[0044]

As described above, according to the present invention, the mechanical accuracy of the print head can be supplemented by using a method of adaptively and automatically controlling the focal length by detecting the reflected light (focal image). Therefore, there is no need for the mechanical accuracy required in the related art. Therefore, the assembling process can be made easier and the cost can be reduced. In addition, since the focal length is adaptively and automatically controlled, it is possible to cope with slight rattling, thereby enabling the print head to move at a higher speed.

In addition, there is a limit in increasing the size of the optical printing apparatus due to an increase in error in the conventional mechanical method. However, according to the present invention, the error can be absorbed and the size of the optical printing apparatus increases. And printing can be performed even on a record carrier of a larger size. In addition, the distance between the optical system of the print head and the photosensitive medium is detected by detecting the reflected light (focal image) of the printing light applied to the photosensitive medium. Laser focus diameter (spot diam
eter) can be servo-controlled to the desired size,
It is also useful for multi-tone print control such as halftone expression corresponding to a photograph.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an optical printing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a print head shown in FIG.

FIG. 3 is an explanatory diagram of an optical sensor used for the sensor shown in FIG.

FIG. 4 is a schematic configuration diagram of a conventional optical printing apparatus.

[Explanation of symbols]

 Reference Signs List 50 optical printing device 51 interface unit 52 control unit 53 laser driving unit 54 laser source (print light source) 55 first optical fiber connector 56 optical fiber 57 second optical fiber connector 58 print head 61 drum 62 record carrier 63 photosensitive medium 64 engine frame 65 Lead Screw 66 Slide Guide 67 First Step Motor 68 Second Step Motor 71 Optical System 72 Sensor 73 Actuator 81 Sensing Optical System 82 Optical Sensor

Claims (9)

(57) [Claims] 1. An optical printing method in which printing is performed by irradiating a printing medium onto a photosensitive medium in contact with a record carrier by irradiating the printing light with a printing light, wherein the printing light reflected by the photosensitive medium is reflected by the light. Sensing elements are arranged in a straight line and sensed by an optical sensor that operates together with the print head. In this optical sensor, the photosensitive element that is actually sensing is changed from the reference photosensitive element that senses at the reference focal length. An optical printing apparatus which enables an optical printing method, wherein a focal length from a print head to a photosensitive medium is controlled based on a state of sensing reflected light by detecting how much deviation has occurred. An optical system that outputs the printing light, and an optical sensor that receives the reflected printing light via the sensing optical system. The optical sensor is composed of a number of light-sensitive elements arranged in a straight line and any one of them. And a sensor that outputs the number of light-sensitive elements that are actually sensing from the reference light-sensitive element as deviation distance data, and an output of the sensor. An actuator that is driven based on the result and adjusts the focal length by controlling the position of the optical system; and a control unit that outputs print information and coordinate information for the print head. A correction table in which data and a drive value of the actuator of the print head are associated with each other, and the correction table is accessed based on the deviation distance data to output correction data to the actuator and drive the actuator. The correction table provided in the control unit includes a deviation distance d obtained by calculating the deviation distance data by the following equation 1 and the printing head. An optical printing apparatus, wherein a driving value of an actuator of the actuator is associated with the driving value. ## EQU1 ## d = n.times..delta..times.Z0 /[s.times.sin (.alpha .. ± ..theta.)]. Theta. = Tan-1 (n.times..delta. / S) Z0: Reference focal length, .alpha .: Reference reflection at reference focal length Z0. Light angle, θ: deviation angle of the reflected light at the actual focal length with respect to the reference reflected light, n: the number of photosensitive elements that are actually sensitive from the reference photosensitive element, δ: pitch of the photosensitive elements,
s: Length from sensing optical system to reference light sensitive element 2. A method in which a recording medium and a photosensitive medium are brought into close contact with each other on a drum, and the photosensitive medium is focused and irradiated with printing light so that the photosensitive medium is reacted and transferred to the recording medium to perform printing. In the optical printing apparatus, the printing information is output as dot data, and a correction table for storing correction data for correcting the deviation distance is provided.
A control unit that accesses and outputs correction data corresponding to the deviation distance from the correction table, a printing light source that converts the dot data into printing light, an optical system that focuses the printing light on a photosensitive medium, and a printing light. A large number of light-sensitive elements that receive reflected light through a sensing optical system are arranged in a line, and one of them is determined as a reference light-sensitive element that senses at a reference focal length. A sensor configured using an optical sensor that detects a focal length between the photosensitive medium and a sensor that outputs the number of photosensitive elements that are actually sensing from the reference photosensitive element as the deviation distance data, and
A print head having an actuator driven by the correction data to control the position of the optical system, wherein the control unit calculates the deviation distance d using the following equation (2). Printing device. ## EQU2 ## d = n.times..delta..times.Z0 /[s.times.sin (.alpha .. ± ..theta.)] .Theta. = Tan @ -1 (n.times..delta. / S) Z0: Reference focal length, .alpha .: Reference reflection at reference focal length Z0. Light angle, θ: deviation angle of the reflected light at the actual focal length with respect to the reference reflected light, n: the number of photosensitive elements that are actually sensitive from the reference photosensitive element, δ: pitch of the photosensitive elements,
s: Length from sensing optical system to reference light sensitive element 3. The optical printing apparatus according to claim 2, wherein the optical sensor constituting the sensor of the print head is a linear position detector (PSD). 4. The optical printing apparatus according to claim 3, wherein the actuator of the print head is a linear actuator. 5. The optical printing apparatus according to claim 3, wherein the actuator of the print head is a piezo actuator. 6. The optical printing apparatus according to claim 2, wherein the optical sensor constituting the sensor of the print head is a one-dimensional charge-coupled device (Linear CCD). 7. The optical printing apparatus according to claim 6, wherein the actuator of the print head is a linear actuator. 8. The optical printing apparatus according to claim 6, wherein the actuator of the print head is a piezo actuator. 9. An optical fiber is connected between a print light source and an optical system of a print head via an optical fiber connector, and the print light is transmitted from the print light source to the optical system via the optical fiber. An optical printing apparatus according to any one of claims 2 to 8.