JPH11286138A - Image recorder and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a uniform image using a multi-made laser emitting laser light having a plurality of oscillation wavelengths. SOLUTION: An image processing section 32 for an image data from a diagnostic unit such as a CT or an MRI, delivers an output, signal to a binarization circuit 30 where every pixel is binarized using a threshold value from a threshold value mask section 33 and data exchange is performed between '0 (unexposed part)' and '1 (exposed part)'. A laser drive circuit 31 is controlled according to the results and a signal is delivered to a semiconductor laser 5 on a multi-laser head 21 in order to perform recording by irradiating a recording medium with a generated laser beam from the opposite side of a recording layer. A multi-mode laser emitting a laser beam having a plurality of oscillation wavelengths and halt-band width of 1.2 nm or above is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus and an image recording method, and more particularly to an exposure method of heat mode recording in which a recording medium is exposed by using heat energy of a laser beam. This is particularly effective when the recording layer needs to be irradiated with laser light through the body.

[0002]

2. Description of the Related Art As an exposure system for heat mode recording, there is an exposure system shown in FIG.
Alternatively, the recording medium 10 wound around a rotating drum 20 using a multi-laser head 21 arranged two-dimensionally
And recording is performed while moving the drum or the optical system in a direction substantially perpendicular to the rotation direction of the drum.

FIG. 5 shows a layer structure of a recording medium. This recording medium is basically composed of three layers. When the recording layer 2 is irradiated with a laser beam focused to 5 to 10 μm from the base (support) 1 side, a micro ablation phenomenon occurs on the surface of the recording layer, and the adhesive force between the base 1 and the recording layer 2 is reduced in this portion. It becomes substantially 0. By peeling the peel sheet 3 after the exposure, the recording layer 2 is removed from the base 1 only at the laser irradiation part, and minute transparent dots are formed.

[0004]

By the way, as shown in FIG. 6, when an image is recorded on a recording medium, interference occurs at the end face of the support. This varies depending on the thickness, and as a result, the recording on the recording medium is not performed uniformly, resulting in image unevenness.

When the optical path difference between the light beam L1 incident on the support and directly irradiating the recording layer and the light beam L2 irradiating the recording layer through two internal reflections is an integral multiple of the laser wavelength, the recording layer The light amount irradiated to the light source becomes maximum, and becomes minimum when the wavelength is shifted by a half wavelength from an integral multiple.

The reflectance at the interface between media having different refractive indices is 4% when the respective refractive indices are, for example, n1 = 1 and n2 = 1.5. That is, the refractive index of each medium is n
Assuming that 1, n2, the reflectance: R is R = ((n2-
n1) / (n2 + n1)) ²

[0007] Since the fluctuation in light quantity is 4R, the fluctuation in light quantity due to interference is 16%.

Further, in the recording medium used in the present invention, since reflection occurs on the surface of the recording layer, the fluctuation in the amount of light due to interference may be further increased.

[0009] The light quantity fluctuation due to the interference can be reduced by, for example, providing an anti-reflection film on the end face of the support to reduce the reflectance at the end face, and suppressing the thickness variation of the support to a fraction of the laser wavelength or less. However, it is not preferable because the cost increases. Also,
Regarding the above, it is almost impossible to suppress the variation of the medium having a thickness of 100 μm or more to the sub μm or less, although it is possible to suppress the variation of the medium having the thickness of several μm.

The present invention has been made in view of such a point, and although ordinary laser light oscillates at a single wavelength, some laser light oscillates at many wavelengths. By using this type of laser light, it is possible to provide an image recording apparatus and an image recording method which can reduce the influence of interference, constantly emit a constant amount of light, and can form an image without unevenness. The purpose is.

[0011]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention has the following constitution.

According to the first aspect of the present invention, there is provided a method of irradiating a support substantially transparent to a laser beam to be recorded and a recording medium having a recording layer on an end face thereof with a laser beam from the opposite side of the recording layer. An image recording apparatus for recording an image by using the thermal energy, wherein the laser beam is a multi-mode laser having a plurality of oscillation wavelengths. ].

According to the first aspect of the present invention, the laser light is a multi-mode laser having a plurality of oscillation wavelengths, the effect of interference can be reduced, the amount of light applied is always constant, and the Image formation is possible.

According to a second aspect of the present invention, there is provided the image recording apparatus according to the first aspect, wherein the laser beam has a half width of an oscillation wavelength of 1.2 nm or more. ].

According to the second aspect of the present invention, the laser beam has a half width of the oscillation wavelength of 1.2 nm or more, and the support of the recording medium which is a main object of the present invention has a thickness of 180 μm.
m, the refractive index is 1.5, and the wavelength of the laser light is 80
A range of 0 to 860 nm is preferable from the viewpoint of options. Under these conditions, two spectra having a wavelength difference of about 0.6 nm can cancel out the influence of interference, and the amount of irradiated light is always constant. Formation is possible.

According to a third aspect of the present invention, there is provided a recording layer provided on an end face of a support by passing a multimode laser having a plurality of oscillation wavelengths through a support substantially transparent to the laser light. An image recording method in which light is condensed on the top and an image is recorded by the heat energy. ].

According to the third aspect of the present invention, a multi-mode laser having a plurality of oscillation wavelengths of a laser beam passes through a support substantially transparent to the laser beam, and is provided on an end face of the support. By condensing light on the layer and recording an image with the thermal energy, the influence of interference can be reduced, the amount of light irradiated is always constant, and an image can be formed without unevenness.

According to a fourth aspect of the present invention, there is provided a recording method comprising: providing a multimode laser having a half-width of the oscillation wavelength of 1.2 nm or more through a support substantially transparent to the laser beam and provided on an end face of the support. An image recording method in which light is condensed on a layer and an image is recorded using the heat energy. ].

According to the fourth aspect of the present invention, the laser beam has a half width of the oscillation wavelength of 1.2 nm or more, and the support of the recording medium which is a main object of the present invention has a thickness of 180 μm.
m, the refractive index is 1.5, and the wavelength of the laser light is 80
A range of 0 to 860 nm is preferable from the viewpoint of options. Under these conditions, two spectra having a wavelength difference of about 0.6 nm can cancel out the influence of interference, and the amount of irradiated light is always constant. Formation is possible.

The present invention relates to an exposure method of heat mode recording in which a recording medium is exposed by using heat energy of laser light. In an image recording process, it is necessary to irradiate a recording layer with laser light through a support. This is particularly effective in cases.

Although ordinary laser light oscillates at a single wavelength, some lasers oscillate at multiple wavelengths. By using this type of laser light, the influence of interference can be reduced.

1. In the case where the laser beam has a single wavelength (the amount of light varies due to interference) If the thickness of the support of the recording medium is 180 μm and the wavelength of the laser beam is 0.8 μm, the optical path difference δ = 2h × n2 = 54
0 μm is an integer (675) times the wavelength, and the amount of light irradiated on the recording layer becomes the maximum. Here, h is the thickness of the support.

For the convenience of explanation, the thickness of the support is set to 180.13.
μm, the optical path difference δ is 675.5 times the wavelength, and the amount of light applied to the recording layer is minimized. That is, the amount of light applied to the recording layer changes due to the thickness variation of the support.

2. When the laser beam has two wavelengths (the amount of light does not fluctuate) If the laser beam has two wavelengths of 0.8 nm and 0.8006 nm, the thickness of the support is 180 μm.
With respect to (optical path difference 540 μm), the laser light having each wavelength becomes 675 times and 674.5 times, respectively,
The amount of light applied to the recording layer is the sum of the two, that is, intermediate between the maximum and the minimum.

Here, even if the thickness of the support becomes 180.13 μm, the respective laser beams become 675.5 times and 675 times the optical path difference of 540.4 μm, respectively, and are also applied to the recording layer. The light quantity is halfway between the minimum and the maximum. That is, even if the thickness of the support changes, the amount of light applied to the recording layer does not change.

In the above description, the condition of an ideal wavelength has been described as an example. However, a similar effect can be exerted even if it is not such a laser beam as long as the distribution of the oscillation wavelength is wide.

Conventionally, when recording is performed using a laser beam of a single wavelength, the amount of light applied to the recording medium changes depending on the position of the recording medium due to interference at the end face of the support, and as a result, recording is completely performed. If it is not, or an excessive amount of light is applied, an unnecessarily large dot is formed, and the image becomes uneven and visible.

In particular, the recording medium used in the present invention is:
Since the dots recorded individually are formed in black and white binary,
A slight difference in the amount of light affects whether the threshold value is exceeded or not, and the white portion may become black. In addition, even in the case of binary recording, since each dot expresses more than 100 levels of gradation as an aggregate thereof, even a slight difference in density becomes very visually unsightly. According to the present invention, the amount of irradiated light is always constant, and an image can be formed without unevenness.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the image recording apparatus and the image recording method of the present invention will be described.

FIG. 1 shows the configuration of an image recording apparatus according to the present invention. The recording medium 10 is wound around the drum 20 with the base facing outward. The drum 20 rotates in the arrow X direction,
The two-dimensional scanning is performed by moving the multi-laser head 21 in the direction of the arrow Y in parallel with the rotation of the drum 20.

The image data having multi-value information is subjected to image processing such as enlargement interpolation and gradation conversion by the image processing section 32 and then to a binarization circuit with reference to the threshold mask of the threshold mask section 33. 30 is binarized. Here, one piece of image data having multi-valued information is converted into a large number of pixel data having binary information. The binarized image data is sent to the semiconductor lasers 5 mounted on the multi-laser head 21 via a plurality of semiconductor laser driving circuits 31, and each of the semiconductor lasers 5 is turned on / off based on the image data.
Perform F control.

The laser light emitted from each semiconductor laser is supplied to a collimator lens (not shown) and an imaging lens 4 (not shown).
The light is irradiated onto the recording medium 10 through the recording medium 10 and is converged into a plurality of minute beams on the surface of the recording layer of the recording medium 10. With the above scanning, it becomes possible to record an image by selectively irradiating the entire surface of the recording medium 10 with a laser based on image data.

FIG. 2 shows an example of the longitudinal mode characteristics of the semiconductor laser used in the embodiment of the present invention. FIG. 2A shows the longitudinal mode characteristics of the SLD303 series of Sony Corporation, and FIG. 2B shows the longitudinal mode characteristics of the SDL-2300 series semiconductor laser of SDL Corporation. Both semiconductor lasers oscillate at a plurality of wavelengths. As a result, interference at the end face of the support (base) was prevented, and a uniform image could be recorded without unevenness. In addition, the POL-4100 series manufactured by Polaroid, the OPC-A001 series manufactured by Optopower, and the like also oscillate at a plurality of wavelengths, and the same effect was obtained.

More preferably, as a characteristic of the semiconductor laser used in the present invention, the half width of the spectrum is 1.2 n
m or more is desirable. The recording medium that is the main object of the present invention is configured as shown in FIG.
Preferably, the wavelength is 80 μm, the refractive index is about 1.5, and the wavelength of the laser light is 800 to 860 nm from the viewpoint of options. Under these conditions, two spectra having a wavelength difference of about 0.6 nm are affected by interference. Can be canceled out, and the amount of irradiated light is always constant, so that an image can be formed without unevenness.

However, since there are few semiconductor lasers having such characteristics in reality, FIGS.
The description will be made using the characteristic (b).

In the characteristic shown in FIG. 3A, each spectrum has a wavelength difference of 0.3 nm, and the half width of the spectrum is 1.2 nm. Each spectrum was numbered from -4 to 4 with the center spectrum as 0. The spectra of -1 and 1 individually have a wavelength difference of 0.6 nm, and no interference is caused by beams having these spectra.

Next, the spectra of -2 and 2 are 1.2 nm
, And interference cannot be prevented with only a beam having these two spectra. However, the spectrum of 0 has a wavelength difference of 0.6 nm from each and has twice the amount of light, and when these three are combined, no interference occurs.

In the same manner, no interference occurs in the combination of -3 and 3 (wavelength difference 1.8 nm), and from this characteristic example, interference occurs only by the beams having the spectra of -4 and 4. . However, the proportion of the total light amount is small, and the occurrence of interference can be almost completely prevented as a whole.

FIG. 3B shows an example in which the spectrum characteristics are broad. In this case, although the interference prevention effect is slightly inferior to the ideal distribution as shown in FIG. 3A, the effect of interference can be substantially prevented for the same reason. If the half width of the spectrum is wider than 1.2 nm, the canceling effect is effective, which is effective for preventing interference.

Further, among the above-mentioned semiconductor lasers, there is a semiconductor laser having a laser emission region wider (10 to 200 nm) than that of a normal semiconductor laser (1 to 3 nm). This is called a horizontal multi mode or a broad area type. These semiconductor lasers can output much higher power than horizontal single-mode lasers (more than 2 W is possible; horizontal singles are limited to 200 to 300 mW), and are inexpensive. Very suitable as a light source for

Another advantage is that the shape of the irradiation beam on the recording medium can be made rectangular. When a normal lateral single mode semiconductor laser is used as a light source, the shape of an irradiation beam on a recording medium is close to a Gaussian shape. Therefore, when the irradiation light amount changes, the hole diameter of the recorded dot changes, which is not preferable.
On the other hand, a horizontal multi-mode semiconductor laser basically forms an image of the laser emission distribution on a recording medium as it is, so that a rectangular shape can be easily obtained. For this reason, even if the irradiation light amount changes, there is little effect on the change in the hole diameter.

When a heat fusion type (described later), a thermal sublimation type (sublimates a recording layer by laser thermal energy and transfers it to an image receiving paper) or the like is used as a recording medium, ablation is used. Because it is necessary to suppress the occurrence,
It is more preferable to use a rectangular beam that does not locally irradiate more energy than necessary (has a uniform light amount distribution).

However, since these semiconductor lasers have a wide light-emitting area, a reduction optical system is necessary to form an image on a minute spot as in the present invention, and a large amount of light is not lost on the recording medium. It is effective to use an imaging lens with a high NA (0.3 or more) to condense the light.

The spot diameter converged by the imaging lens is generally determined by the ratio of the focal length of the collimator lens and the imaging lens (imaging magnification).
By blocking a part of the collimated beam with an aperture as in the above, it is possible to converge on a smaller spot. In this case, the light amount is lost, but it is effective for obtaining a small spot.

Further, it is preferable that the direction having a rectangular spread is set to a direction perpendicular to the rotation of the drum. Even when the thickness of the support is thinner than 180 μm, a spectral half width of 1.2 nm or more is effective. In this case, the effect is exhibited from a region where the half width is smaller.

As a heat mode recording medium, a heat fusible recording medium is also applicable. When this type of recording medium is used, the laser is irradiated from the peel sheet side of the recording medium shown in FIG. Since the recording layer is fused to the peel sheet by the thermal energy in the laser irradiation section, if the peel sheet is peeled off after exposure, transparent dots are formed in the laser irradiation section. The same effect can be obtained by using a heat-fusible recording medium,
Since this type of recording medium is irradiated with laser from the side of the peel sheet, the support that causes interference is thin (10 to 50 μm).
m). Therefore, if the spectral half width is 0.2 nm or more, the effect of preventing interference is exhibited.

[0047]

As described above, according to the first aspect of the present invention, the laser light is a multi-mode laser having a plurality of oscillation wavelengths, the influence of interference can be reduced, and the amount of irradiated light is always constant. , And an image can be formed without unevenness.

According to the second aspect of the present invention, the laser beam has a half width of the oscillation wavelength of 1.2 nm or more, and the support of the recording medium which is a main object of the present invention has a thickness of 180 μm and a refractive index of 1.5. And the wavelength of the laser light is 800 to 86
0 nm is preferable in terms of options. Under these conditions, two spectra having a wavelength difference of about 0.6 nm can offset the influence of interference, the amount of irradiated light is always constant, and image formation without unevenness can be achieved. It becomes possible.

According to the third aspect of the present invention, a multi-mode laser having a plurality of oscillation wavelengths of a laser beam is passed through a support substantially transparent to the laser beam and onto a recording layer provided on an end face of the support. By condensing the light and recording an image using the thermal energy, the influence of interference can be reduced, the amount of light irradiated is always constant, and an image can be formed without unevenness.

According to the fourth aspect of the present invention, the half width of the oscillation wavelength of the laser light is 1.2 nm or more, and the support of the recording medium which is the main object of the present invention has a thickness of 180 μm and a refractive index of 1.5. And the wavelength of the laser light is 800 to 86
0 nm is preferable in terms of options. Under these conditions, two spectra having a wavelength difference of about 0.6 nm can offset the influence of interference, the amount of irradiated light is always constant, and image formation without unevenness can be achieved. It becomes possible.

[Brief description of the drawings]

FIG. 1 shows the configuration of an image recording apparatus according to the present invention.

FIG. 2 shows an example of longitudinal mode characteristics of a semiconductor laser used in an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing that each spectrum has a wavelength difference of 0.3 nm and the half width of the spectrum is 1.2 nm.

FIG. 4 is a diagram illustrating an exposure method of heat mode recording.

FIG. 5 shows a layer configuration of a recording medium.

FIG. 6 is a diagram illustrating that interference occurs at an end face of a support when an image is recorded on a recording medium.

FIG. 7 is a diagram illustrating a spot diameter converged by an imaging lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base (support) 2 Recording layer 3 Peel sheet 10 Recording medium 20 Drum 21 Multi-laser head 30 Binarization circuit 31 Laser drive circuit 32 Image processing part 33 Threshold mask part

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H04N 1/23 103 B41M 5/26 V

Claims (4)

[Claims] 1. A recording medium having a recording layer having a recording layer on an end face thereof, which is substantially transparent to a laser beam to be recorded, is irradiated with a laser beam from the side opposite to the recording layer, and an image is formed by the thermal energy. An image recording apparatus for recording, wherein the laser light is a multi-mode laser having a plurality of oscillation wavelengths. 2. The laser beam according to claim 1, wherein said laser beam has an oscillation wavelength half width of 1.
2. The image recording apparatus according to claim 1, wherein the thickness is 2 nm or more. 3. A multi-mode laser whose laser light has a plurality of oscillation wavelengths is focused on a recording layer provided on an end face of the support through a support substantially transparent to the laser light. An image recording method for recording an image using thermal energy. 4. A multi-mode laser having a half-width of the oscillation wavelength of 1.2 nm or more through a support substantially transparent to the laser beam, and condensed on a recording layer provided on an end face of the support. An image recording method for recording an image using the heat energy.