JPH0948144A - Thermal recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recorder wherein heat energy required for start of color development of a thermal recording material is made constant, and density in color development can be stabilized. SOLUTION: After moistening a thermal recording material S at a specific humidity higher than that of surroundings by passing the thermal recording material S through a moistening part 36, specific preheat energy is added by a preheat roller 28, and then an image or the like is recorded on the thermal recording material S with laser beams L. In that case, since the thermal recording material S is in a preheat state just before stable color development owing to constant preheat energy, an image of stable density or the like can be recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording apparatus for recording an image or the like by applying a predetermined amount of heat energy after preheating a thermal recording material.

[0002]

2. Description of the Related Art Thermal recording apparatuses for imparting thermal energy to a thermal recording material to record an image or the like have been widely used. In particular, there has emerged one that enables high-speed recording by using a laser as a heat source (Japanese Patent Laid-Open No. 50-23617,
JP-A-58-94494, JP-A-62-77983
And JP-A-62-78964.

The applicant of the present invention has applied to such a thermal recording method as a heat-sensitive recording material capable of recording a good image with high quality, and a color former, a color developer and a light absorbing dye (on a support). A material that has a photothermal conversion agent and develops a color at a concentration according to the supplied heat energy has been developed and applied for a patent (see JP-A-5-301447 and JP-A-5-24219).

The heat-sensitive recording material is prepared by dissolving at least a microcapsule containing a basic dye precursor, a color developer and a light-absorbing dye in an organic solvent which is hardly soluble or insoluble in water. And a heat-sensitive layer formed by applying a coating solution containing the emulsion.

[0005] The basic dye precursor has a property of developing a color by donating electrons or receiving a proton such as an acid, and is generally colorless, and is generally lactone, lactam, sultone, spiropyran, ester, or the like. A compound having a partial skeleton such as an amide, which opens or cleaves these partial skeletons upon contact with a developer is used. Specific examples include crystal violet lactone, benzoyl leucomethylene blue, malachite green lactone, rhodamine B lactam, 1,3,3-trimethyl-6'-ethyl-8'-butoxyindolinobenzospiropyran.

[0006] As a developer for these color formers,
Acidic substances such as phenol compounds, organic acids or metal salts thereof, and oxybenzoic acid esters are used. The developer preferably has a melting point of 50 to 250 ° C, and particularly has a melting point of 6 ° C.
Phenol or organic acid which is hardly soluble in water at 0 to 200 ° C is desirable. Specific examples of these developers are described in, for example, JP-A-61-291183.

The light-absorbing dye is preferably a dye that absorbs little light in the visible light region and has a particularly high absorptance at wavelengths in the infrared region. Examples of the dye include a cyanine dye, a phthalocyanine dye, a pyrylium / thiopyrylium dye, an azulenium dye, a squalilium dye,
Metal complex salt dyes such as i, Cr, naphthoquinone / anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium / diimmonium dyes, nitroso compounds, etc. Can be mentioned. Among these, it is preferable to use a semiconductor laser that emits near-infrared light that has a high absorptance of light in the near-infrared region having a wavelength of 700 to 900 nm from the viewpoint of practical use of a semiconductor laser that emits near-infrared light.

By the way, in order to maintain a stable storage state, such a heat-sensitive recording material is constructed so as not to develop color with low heat energy. Therefore, a considerable amount of heat energy is required to obtain the desired color development state. As a result, the dynamic range of the laser or the like is narrowed by the threshold value of the heat energy until color development, which makes it difficult to obtain a high gradation image. Further, a high output laser or the like is required, and the burden on the device side for color development becomes considerably large. Further, it has been pointed out that the sensitivity of the heat-sensitive recording material is low and it takes a considerable time to record a gradation image on the heat-sensitive recording material, so that the efficiency (throughput) of recording operation is poor.

Therefore, the applicant of the present invention uses a heat roller or the like to preheat the heat-sensitive recording material to a temperature immediately before color development, and then irradiates the heat-sensitive recording material with a laser beam modulated according to recording information. A thermal recording method capable of recording a high gradation image with high accuracy without requiring high output has been developed (see Japanese Patent Laid-Open No. 6-198924).

[0010]

Here, in the above-mentioned thermal recording method, in order to increase the sensitivity of the thermal recording material, it is necessary to make the preheating temperature as close as possible to the temperature immediately before color development.

By the way, the heat energy required for the heat-sensitive recording material to start color development depends on the humidity of the heat-sensitive recording material as shown in FIG. Therefore, if the temperature of the thermal recording material is preheated with a certain amount of preheating energy and then recording is to be performed using a laser beam, if the humidity of the thermal recording material changes due to the humidity of the surrounding environment, the color density changes with that change. As a result, stable recording of images and the like cannot be performed.

Therefore, it is conceivable to dry the heat-sensitive recording material by using warm air or a dry roll to reduce the humidity dependency of the sensitivity of the heat-sensitive recording material and stabilize the heat energy required for starting color development. .

However, when the humidity of the heat-sensitive recording material becomes lower than the humidity of the surrounding environment, it immediately absorbs the surrounding moisture and tries to reach an equilibrium state, so that it is difficult to further lower the humidity. On the other hand, the humidity of the surrounding environment differs depending on the place where the thermal recording material is arranged. Therefore, even if the heat-sensitive recording material is dried, its humidity easily changes depending on the humidity of the surrounding environment, and it is extremely difficult to stabilize the heat energy required to start color development.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a thermal recording apparatus capable of stabilizing the color density by keeping the thermal energy required for starting the color development of a thermal recording material constant. To aim.

[0015]

In order to achieve the above-mentioned object, the present invention supplies heat energy less than coloring heat energy to a heat-sensitive recording material that develops a color at a density according to the supplied heat energy. In the thermal recording apparatus for recording the recording information by supplying predetermined coloring heat energy according to the recording information to the thermal recording material after performing the preheating, the preheating means for preheating the thermal recording material. Is provided on the upstream side of the preheating position according to (4) above and is provided with a humidifying means for humidifying the thermosensitive recording material to a predetermined humidity.

In the thermal recording apparatus of the present invention, the humidity can be kept constant by humidifying the thermal recording material to a predetermined humidity before preheating. Therefore,
The heat-sensitive recording material can be brought into a stable preheated state immediately before color development by a constant heat energy for preheating.
By applying a predetermined amount of heat energy in this state, an image having a stable density can be recorded.

[0017]

1 shows a thermal recording apparatus 10 of this embodiment. The thermal recording apparatus 10 is for main scanning the laser beam L in the direction of arrow A and recording a gradation image or the like on the thermal recording material S which is sub-scanned and conveyed in the direction of arrow B, and outputs the laser beam L. A laser diode 12 and a collimator lens 14 for collimating the laser beam L
, The cylindrical lens 16, the reflection mirror 18,
A polygon mirror 20 for deflecting the laser beam L, fθ
A lens 22, a cylindrical mirror 24 that cooperates with the cylindrical lens 16 to correct the surface tilt of the polygon mirror 20, rollers 26a and 26b contacting the upper surface of the thermal recording material S, and a lower surface of the thermal recording material S. And a roller 26c that cooperates with the roller 26a to convey the thermosensitive recording material S in the sub-scanning direction and a lower surface of the thermosensitive recording material S to supply a predetermined preheating energy to the thermosensitive recording material S. Therefore, a preheating roller 28 for preheating is provided, and a power source 30 for supplying a current for preheating to the preheating roller 28. The power supply 30 is controlled by the control unit 32, and the laser diode 12 is controlled by the control unit 32 via the driver 34.

Further, a humidifying section 36 is provided on the upstream side in the transport direction of the thermal recording material S. The humidifying section 36 is
As shown in FIG. 2, a humidifying box 38 through which the heat sensitive recording material S passes, and a moisture supply source for applying a predetermined amount of water W to the heat sensitive recording material S passing through the humidifying box 38 through a conduit 39. 40, a heating coil 41 for setting the air temperature in the humidifying box 38 to a predetermined temperature lower than the coloring temperature of the heat-sensitive recording material S, and a power supply for supplying a predetermined current to the heating coil 41 under the control of the controller 32. And 43.

As shown in FIG. 3, the heat-sensitive recording material S has a support 42 on which a heat-sensitive layer 44 having a color-developing agent, a color-developing agent and a photothermal conversion agent is formed, and the heat-sensitive layer 44 is protected. The layer 46 is formed and configured. As a material for forming the heat sensitive layer 44, as described above, JP-A-5-301 is used.
No. 447, JP-A-5-24219 and the like can be used.

The thermal recording apparatus 10 of this embodiment is basically constructed as described above. Next, the operation and effect of the thermal recording apparatus 10 will be described.

The thermal recording material S is conveyed in the direction of arrow B,
First, it is introduced into the humidifying box 38 that constitutes the humidifying section 36. The inside of the humidification box 38 is heated by a current supplied from a power source 43 to a predetermined temperature at which the thermosensitive recording material S is not colored by the heating coil 41. Then, in this state, the moisture W is supplied from the moisture supply source 40 into the humidification box 38 through the conduit 39, whereby a predetermined humidity is realized. The humidity can be further stabilized by setting it to the saturated humidity of the space inside the humidification box 38. Therefore, the thermosensitive recording material S introduced into the humidifying box 38 is humidified by the water W to a constant humidity.

Next, the thermosensitive recording material S humidified to a constant humidity in the humidifying box 38 is sub-scanned in the direction of arrow B while being sandwiched between the roller 26b and the preheating roller 28 and between the rollers 26a and 26c. Preheat while transporting. That is, by supplying a predetermined current from the power supply 30 to the preheating roller 28, the thermosensitive recording material S is preheated to the temperature immediately before the color development.

Therefore, after the heat-sensitive recording material S humidified to have a constant humidity as described above is preheated by the preheating roller 28, the controller 32 drives the laser diode 12 via the driver 34. The laser diode 12 outputs a laser beam L modulated according to the gradation of an image or the like recorded on the thermosensitive recording material S. The laser beam L is collimated by the collimator lens 14 and then guided to the polygon mirror 20 through the cylindrical lens 16 and the reflection mirror 18. The polygon mirror 20 is rotating at a high speed, and the laser beam L reflected by the reflecting surface thereof and deflected in the direction of the arrow A is the fθ lens 2
2 and the cylindrical mirror 24, the roller 2
The thermosensitive recording material S, which is guided to the thermosensitive recording material S from between 6a and 26b and is sub-scanned and conveyed in the direction of the arrow B, is main-scanned.

Since the heat-sensitive recording material S is humidified to a constant humidity in the humidification box 38, the heat energy required to start color development can be kept constant regardless of the humidity fluctuation of the surrounding environment. it can. Therefore, when a predetermined heat energy is supplied to the heat sensitive layer 44 of the heat sensitive recording material S by the laser beam L, a gradation image or the like is recorded with high accuracy. Further, since the preheating energy can be kept constant, it becomes extremely easy to control the temperature of the preheating roller 28 and the conveyance speed of the heat-sensitive recording material S.

The color development characteristics of the heat-sensitive recording material S depend not only on the humidity but also on the time during which the preheating is continued. FIG. 4 shows the color developing characteristics of the heat-sensitive recording material S depending on the humidity and the preheating time. ○ and ● represent color development characteristics when the preheating time is shortened by setting the transport speed high, and the humidity of the thermal recording material S is set high and low, and Δ and ▲ are transport speeds. Shows the color development characteristics when the humidity of the heat-sensitive recording material S is set high and low when the preheating time is lengthened by delaying. In this case, if the preheating time is long, the change in the color development characteristic with respect to humidity is small, but the sensitivity is low, and high heat energy is required before the start of color development. On the other hand, when the preheating time is short, the variation of the color development characteristic with respect to humidity becomes large, but the sensitivity is also high, and the color can be developed with low heat energy. On the other hand, if the humidity of the heat-sensitive recording material S is higher than the humidity of the surrounding environment, it is extremely easy to keep the humidity in the humidification box 38 constant, and if the preheating time is short, the fluctuation of humidity due to the heat energy also occurs. Extremely low.

Therefore, the heat-sensitive recording material S can be kept at a constant humidity to record an image or the like in a state where the preheating time is set to be short. As a result, the thermal energy at the start of color development can be kept constant and a highly accurate image or the like can be recorded on the thermosensitive recording material S having a high sensitivity in a stable state. Moreover,
Since the heat-sensitive recording material S has high sensitivity, the heat-sensitive recording material S
The conveyance speed of can be set high, which enables efficient recording of gradation images.

The heat-sensitive recording material S is provided with a humidifying roller 48 to which the water W is supplied, as shown in FIG. 5, instead of being humidified by the water W in the humidifying section 36 as shown in FIG. Humidification may be performed by directly contacting the thermal recording material S.

Further, in the above-mentioned embodiment, the laser beam L is used for recording an image or the like, but it is also possible to use a heating means such as a thermal head.

[0029]

According to the thermal recording apparatus of the present invention, the following effects can be obtained.

That is, by humidifying the thermosensitive recording material to a predetermined humidity before preheating, the humidity can be kept constant regardless of the surrounding environment. If the humidity is constant, the color development characteristics of the heat-sensitive recording material can be stabilized, and thus the heat-sensitive recording material can be brought into a stable preheating state immediately before color development with a constant preheating energy. By applying a predetermined amount of heat energy in this state, it is possible to record a highly accurate image having a stable density.

Further, since the humidity of the heat-sensitive recording material can be kept constant, stable recording of images and the like can be performed even when the preheating time is shortened, thereby improving the conveying speed and increasing the efficiency. Processing can be performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the configuration of a thermal recording apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of a configuration in the vicinity of a recording portion of the thermal recording device shown in FIG.

FIG. 3 is a structural explanatory view of a thermal recording material.

FIG. 4 is a color development sensitivity characteristic diagram depending on preheating time or humidity of the heat-sensitive recording material.

FIG. 5 is a configuration explanatory diagram of another embodiment near a recording portion of the thermal recording apparatus.

FIG. 6 is a color development sensitivity characteristic diagram depending on humidity of a thermal recording material.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Thermal recording device 12 ... Laser diode 20 ... Polygon mirror 26a-26c
... Roller 28 ... Preheating roller 30 ... Power supply 32 ... Control part 36 ... Humidification part 38 ... Humidification box 40 ... Moisture supply source 41 ... Heating coil 48 ... Humidification roller L ... Laser beam S ... Thermal recording material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B41J 3/20 117Z

Claims (2)

[Claims] 1. A heat-sensitive recording material that develops a color at a density according to the supplied heat energy is preheated by supplying heat energy that is less than the color-developing heat energy, and then recorded information on the heat-sensitive recording material. In a thermal recording device for recording the recording information by supplying a predetermined coloring heat energy corresponding thereto, the thermal recording material is arranged at an upstream side of a preheating position by a preheating means for preheating the thermosensitive recording material, and the thermosensitive recording material is predetermined. A thermal recording device comprising a humidifying means for humidifying the humidity. 2. The thermal recording apparatus according to claim 1, wherein the humidifying means humidifies the humidity of the thermosensitive recording material to saturated humidity.