JPH0672030A - Method and apparatus for forming image - Google Patents

Abstract

PURPOSE:To provide a method and an apparatus for forming an image on an image forming medium with a laser beam. CONSTITUTION:A method for forming an image comprises the steps of so winding an image forming medium 14 having a thermal color developing layer containing a thermal color developing material on a transparent or a translucent support that the developing layer is brought into contact with a surface of a drum, and irradiating it with a laser beam from the support side. An image forming apparatus comprises a drum 11 for supporting an image forming medium having a thermal color developing layer, and a laser light source 13 in such a manner that the drum 11 absorbs the laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image forming apparatus using a laser beam.

[0002]

2. Description of the Related Art A thermosensitive recording paper having a thermosensitive coloring layer on a support has been conventionally used as a recording paper for facsimiles, and its existence and use are well known. In the image forming method using such a thermal recording sheet, since the thermal head is closely contacted with the thermal color forming layer, abrasion of the thermal head, contamination of the thermal head may occur, and an image abnormality may occur due to the abrasion. Further, since the resolution of the thermal head determines the resolution of the image, there is a problem that an image with high resolution cannot be obtained.

On the other hand, attempts have been made to form a high-resolution image in a non-contact manner using a laser beam, and such a method is disclosed in, for example, Japanese Patent Laid-Open No. 58-568.
No. 90, No. 58-94494, etc.

However, in such a method, the absorption of the laser beam is weak, and therefore a high-density image cannot be formed. In particular, when using a He-Ne laser, a semiconductor laser, or the like that oscillates light having a wavelength of 500 nm or more and 1200 nm or less, there is a problem that an image with high contrast cannot be obtained due to absorption of the light absorbing material used.

[0005]

SUMMARY OF THE INVENTION The present invention provides an image forming method and an image forming apparatus which solve the above problems, and in particular, it is possible to form an image on an image forming medium having no light absorbing layer by laser light. It is a method and a device.

[0006]

According to the present invention, an image-forming medium having a thermosensitive coloring layer containing a thermosensitive coloring material on a transparent or translucent support is wound so that the thermosensitive coloring layer faces the drum surface, and the support side is wound. The image forming method is characterized by irradiating more laser light. The present invention is also an image forming apparatus having a drum capable of carrying an image forming medium having a thermosensitive coloring layer and a laser light source, wherein the drum absorbs laser light. Especially on the drum surface, the reflection optical density is 1.0 for the laser light wavelength.
The above is preferably 1.2 or more, and the drum surface is preferably smooth. Since the drum surface is smooth, an image is formed with high sensitivity to heat generated during laser light irradiation, and therefore high-speed recording is possible.
It has an advantage that a clear image can be obtained.

In the image forming method of the present invention, a transparent or semi-transparent support is wound around the drum having the above-mentioned characteristics so that the support is on the laser light source side, and the laser is irradiated in accordance with the image information, whereby the irradiation portion is colored. This is a method of forming an image.

The image forming medium may have a protective layer on the thermosensitive color developing layer, and depending on the thickness and thermal conductivity of the protective layer,
A clear image with sufficiently high color density can be obtained.

The Beck's smoothness of the surface of the medium is preferably 2
When the time is 50 seconds or more and is less than 50 seconds, an image having a sufficiently high density cannot be formed.

The heat-sensitive color-developing layer may be a conventionally known light-fixing type heat-sensitive layer.

In order to absorb the laser efficiently on the drum surface, carbon black, metal oxide, metal hydroxide,
In addition to inorganic compounds such as sulfates, organic pigments such as polymethine dyes, phthalocyanines, naphthalocyanines, naphthoquinone dyes, cyanine dyes, merocyanine dyes, chalcogen dyes, and light absorbing materials such as organic dyes are used.

Such light absorbing materials may be used alone or in combination of two or more kinds. The drum surface may be formed by coating or may be formed by a method such as vapor deposition. When prepared by coating, a binder, a lubricant, a surfactant, a cross-linking agent, etc. may be used in addition to the light absorbing material.

When the heat conversion efficiency of the drum is sufficiently high (for example, when the reflection optical density is 1.5 or more), heat fusion between the image forming medium and the drum is apt to occur, and therefore the smoothness of the drum is moderated. It is preferable to lower it. Such a method can be achieved by appropriately forming irregularities on the drum surface, or by appropriately distributing fine particles (for example, plastic beads) on the drum surface. The drum surface is measured by a surface roughness meter Ra (JIS
The standard value of B0601) is preferably 0.1 to 9.0 μm, and more preferably 0.3 to 6.0. It can be appropriately set within this range by the numerical value of the laser power. On the contrary, when the surface roughness is 9.1 μm or more, the thermal conductivity becomes poor, the sharpness becomes poor, and the image density becomes low.

The image forming apparatus of the present invention has the above-mentioned drum and an exposure unit of a drum scan type or a polygon scan type. The schematic views are shown in FIGS. 1 to 3. 1 and 3 are of the drum scan type, of which the internal diagram 3 is shown.
Is an apparatus for exposing from the inner surface of the drum. In these figures, 13 is a light source laser, 12 is a lens, 11 is a drum, 14 is an image forming medium carried on the drum,
Reference numeral 15 denotes an optical path of the laser, and 31 is an optical deflector.

FIG. 2 is a schematic view of a polygon scan type exposure unit. Reference numeral 21 is a collimator lens, 22 is a polygon, and 23 and 24 are scanning lens systems.

Ar laser and He are used as the light source laser.
A —Ne laser, a semiconductor laser, a He—Ca laser, or the like is used, and an oscillation intensity of 10 mW or more, preferably 20 mW or more is used.

Although a single laser light source is shown in FIGS. 1 to 3, there may be two or more laser light sources, in which case the laser light may be condensed through an optical system. Alternatively, each optical system may be provided so as to be simultaneously exposed to different places. Further, a shutter unit may be provided in the middle of the optical system to continuously oscillate the laser, and the image formation may be performed by distinguishing between exposure and non-exposure by opening and closing the shutter.

[0018]

EXAMPLES Next, the present invention will be described with reference to examples. <Example> As the image forming apparatus, the drum scan type apparatus shown in FIG. 1 was used. The drum has a carbon black layer on the surface, has a reflection density of 1.6, and has a surface roughness Ra (SE-30H, manufactured by Kosaka Laboratory) of 1.0 μm to 1.2 μm. A semiconductor laser having a laser wavelength of 830 nm and an oscillation intensity of 100 mW was used.

A transparent thermosensitive coloring layer and a protective layer are provided on a polyethylene terephthalate (PET) film on the drum, and an image forming medium having a surface Beck smoothness of 400 seconds is formed on the drum.
It was wrapped so that the ET film was on the outside. Dot diameter is about 30μm × 30μm, 3.5 × 10 ^-6 sec
It was exposed at a speed of / dot. The exposed portion of the image forming medium was colored black and vividly, and the transmission optical density was 1.50 to 1.55. Further, the optical density of the color-developed portion where only one line was isolated and exposed under the above conditions was measured by a spectrophotometer, and the result is shown in FIG.

The horizontal axis of this figure indicates length, and its unit is μ
m, and the vertical axis represents the transmission optical density. This clearly shows that a clear image is formed. <Comparative Example 1> The surface roughness of the drum used in Example 1 was set to 0.
Image formation was performed in the same manner as in Example 1 except that the thickness was set to 09 μm. The transmitted optical density of the formed image area is 1.52
However, when the area of the coloring portion was large, heat fusion with the drum occurred and the image was distorted. Further, there was a portion where a crack was generated at the boundary between the colored portion and the non-colored portion. <Comparative Example 2> The surface roughness of the drum used in Example 1 was set to 9.
Image formation was performed in the same manner as in Example 1 except that the thickness was set to 1 μm. The color density of the exposed portion of the image forming medium was low and unclear. Comparative Example 3 An image was formed in the same manner as in Example 1 except that an image forming medium having a transparent thermosensitive coloring layer and a protective layer provided on a PET film and having a Bekk smoothness of 200 seconds was used. As the components of the thermosensitive coloring layer, the same composition ratio and film thickness of the leuco dye, the developer and the sensitizer as in Example 1 were used. At a speed of 3.5 × 10 ⁻⁶ sec / dot, sufficient color density was not obtained. Even when the exposure time is increased by 10 times, the transmission optical density of the color-developed portion is 0.
The value was from 61 to 0.64, which was inferior to the sharpness of the image.

[0021]

As described above, the present invention is a novel method and an apparatus capable of forming an image by using a laser beam, and the image obtained by the present invention is a high-definition image sufficiently corresponding to exposure. Is.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a drum scan type image forming apparatus of the present invention.

FIG. 2 is a schematic diagram of a polygon scan type image forming apparatus of the present invention.

FIG. 3 is a schematic view of an inner surface exposure drum scan type image forming apparatus of the present invention.

FIG. 4 is a graph showing the relationship between the optical density and the distance of the color-developing portion of the present invention.

[Explanation of symbols]

 11 Drum 12 Lens 13 Laser 14 Image Forming Medium 15 Laser Optical Path 21 Collimator Lens 22 Polygon 31 Optical Deflection Device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical indication location H04N 1/23 103 Z 9186-5C 8907-2C B41J 3/20 109 A

Claims (2)

[Claims] 1. A thermosensitive coloring layer is wound on an image forming medium having a thermosensitive coloring layer on a transparent or semitransparent support so that the thermosensitive coloring layer absorbs laser light, and the thermosensitive coloring layer is irradiated with laser light from the support side. An image forming method characterized by forming an image by coloring a color forming layer. 2. An image forming apparatus having a drum around which an image forming medium is wound and a laser light source, wherein the drum absorbs laser light.