JPH03263057A - Recording method - Google Patents

Abstract

PURPOSE:To perform recording with a thermal head having experience in making cost low and miniaturizing a device by performing development as soon as or just after thermal write is performed to a specified dielectric with the thermal head. CONSTITUTION:A recording medium 1 whose volume resistivity is >=1X10<12> OMEGAcm at 25 deg.C, and <=1X10<15> OMEGAcm at 120 deg.C is obtained by forming a conductive layer 12 such as an Al vacuum-deposited layer on the dielectric layer 11 having the volume resistivity smaller than the value at 25 deg.C. As soon as heat energy equivalent to an image signal is inputted in the recording medium 1 from the thermal head 2, an alternating current biased to be negative is impressed on the side of a developing roller 4 which carries two-component developer 3 consisting of carrier 32 and negative charged toner 31 between the developing roller 4 and the recording medium 1. Therefore, an electrostatic latent image on the dielectric is developed with the negative toner. Thus, the inexpensive dielectric and the thermal head 2 are used, thereby accomplishing the recording by the use of a small-sized device and at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording method (chargeless electrostatic thermal recording method) in which primary charging is omitted in electrostatic thermal recording.

[Prior Art] Several recording methods have been proposed in which primary charging in electrostatic recording is omitted. An overview of these methods is as follows: (1) Japanese Patent Laid-Open No. 58-98746 A method in which the back side of a photoreceptor is exposed (laser flash, CRT) and development is performed from the front side with a conductive magnetic toner at the same time.

(2) JP-A No. 58-158957 Same as (1) above, but a method in which exposure is performed using an LED array; (3) Electrophotography Society, Jal) an Hard Cop
y'88. This is a method in which optical writing is performed from the back side of the NIP-23 photoreceptor using an LED, and development is simultaneously performed using a two-component developer (conductive carrier and insulating toner).

The LED array used as a light source in the above-mentioned conventional technology is expensive, and the uneven brightness of each LED has not yet been sufficiently resolved.

Furthermore, since a photoreceptor is used to form an image, it is not only expensive, but also has the disadvantage that it is difficult to achieve both latent image retention for repeated use and an initialization step by uniform conductivity.

Furthermore, the method (3) above requires primary charging, which makes it somewhat difficult to reduce the size and cost of the device.

In addition, even if the entire recording medium is exposed for initialization or a reverse electric field is applied while exposing the entire surface, the trapped holes do not easily return, making initialization difficult and therefore difficult to use repeatedly. It is.

[Problems to be Solved by the Invention] It is an object of the present invention to provide a recording method using a thermal head that has a proven track record of high reliability, low cost, and miniaturization in contrast to the above-mentioned conventional technology.

[Means for Solving the Problems] The configuration of the present invention for solving the above problems is as follows.

(1) Volume resistivity is 1×1O12Ωe at 25℃
1 or more, LX 10''Ω1 or less at 120°C, and smaller than the value at 25°C, a recording method in which development is performed simultaneously with thermal writing with a thermal head or immediately after thermal writing.

(2) The recording method according to item (1) above, wherein a developing roller is provided facing the dielectric material, and development is performed while applying a positively or negatively biased alternating current to the developing roller.

(3) The recording method described in item (1) or (2) above, using a (one-component) magnetic toner as a developer.

(4) The recording method described in item (1) or (2) above, using a two-component developer as the developer.

The structure of the above invention will be explained in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the structure of a recording medium used in the invention. The recording medium 1 has a volume resistivity of 1×1OL2Ωcm or more at 25°C, and a volume resistance of 1×1OL2Ωcm or more at 120°C.
The basic configuration is that a conductive layer 12 such as an Al vapor deposited layer is formed on a dielectric layer 11 that is less than

If necessary, the conductive layer may be replaced with an organic conductor, or a base layer may be provided under the conductive layer.

The volume resistance of the above dielectric layer is 1xlOI2ΩC1 at 25℃
If it is less than 1×10'Ω at 120℃, the image will have background stains.
If it exceeds C■, the density (ID) of the image area is insufficient.

Further, if the volume resistivity at 120° C. is not sufficiently smaller than the volume resistivity at 25° C., the S/N will be insufficient.

Specific examples of materials suitable for forming such a dielectric layer include polyvinyl chloride, cellulose acetate, polyacetal, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, acrylic polymer, and styrene. Polymers include polyester, polyamide, polyethylene, polypropylene, polypropylene polymers, fluorinated acrylic-acrylic copolymers, styrene-acrylic copolymers, etc.

An example of the characteristics of the recording medium is as shown in FIG.

Polyethylene 11, polypropylene 2, and polyethylene terephthalate (PET) 3 are suitable for the temperature dependence of volume resistivity (logPv), and vinyl chloride 4 with antistatic agent has a Pv of 8 x 1011 Ωel at 25°C, and the no signal part of the thermal head ( Even at 120°C, the resistance of tetrafluoroethylene 5 remains as high as IX 1016 Ωel, and a sufficient electric field is not applied to the signal area (image area) of the thermal head, resulting in low image density and S/ N (
The image area/background area) also becomes small and unclear.

Since the electrostatic latent image on this recording medium is formed only during heating, it is necessary to develop it simultaneously with or immediately after thermal writing.

Furthermore, the developer can be either a one-component developer or a two-component developer.

FIG. 2 is an explanatory diagram showing the principle of the recording method of the present invention using a two-component developer as an example.

Thermal energy corresponding to the image signal is input to the recording medium 1 from the thermal head 2, and at the same time the carrier 32 (about 100 mm in diameter
μ intestine, conductive, magnetic) and theta charged toner 31 (diameter 1
The developing roller side is e between the developing roller 4 carrying the two-component developer 3 made of
Apply an alternating current biased to . In this case, the thermally written part on the dielectric layer side is biased to Φ, and Φ carriers (holes) move to the vicinity of the dielectric surface, and the unwritten part (background part) Since the carriers (holes) are not activated, they cannot move and remain on the conductive layer. The θ toner is developed according to the electrostatic latent image thus generated on the dielectric material.

Among the dielectric materials used in the present invention, particularly in polymer films with low polarity such as polyethylene and polypropylene, the difference in the movement of holes and electrons is small, and both Φ charging and e charging have almost the same charging and heat The potential attenuation characteristics are shown. Therefore, an electrostatic latent image exists only during thermal writing,
It can be developed and is easily initialized by alternating current biased at Φ, which is opposite to that during development.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Using a recording apparatus arranged as shown in FIG.
Thermal writing is performed from a 1g+ thermal head with a recording energy of 0.5mJ/dot, and at the same time e500V.

Development was performed while applying a 1 kHz alternating current biased at Φ200v and θ.

The image was developed using a developer for 2-color 5000 (e-polar cyan toner). When the toner on this PP film was transferred onto Ricoh PPC paper (type 8000) using a transfer roller 7 to which Φ500V was applied and fixed with a heat roller, an extremely clear and highly saturated cyan image with an ID of 1.4 was obtained. Ta.

Similarly, a full-color image was obtained by overlapping magenta and yellow toners.

The residual toner was removed and the electrostatic latent image was initialized by the AC-applied roller 8 biased toward the recording medium Φ.

Example 2 Using the same device as in Example 1, the developing unit was changed to a one-component developing unit, a bias voltage of e500V DC voltage was applied to the developing roller, and conductive magnetic toner (60% magnetic material, styrene acrylic resin) was used. An image was formed under the same conditions as in Example 1, except that 40% of the sample was used. As a result, similar to Example 1, a clear image was obtained.

[Effects of the Invention] As explained above, since the recording medium used in the method of the present invention can use an inexpensive dielectric material and a thermal head, low-cost recording is possible with a small device.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of the recording medium used in the present invention. Figure 2 is a schematic diagram showing the principle of the present invention. Figure 3 is a graph showing the relationship between the volume resistivity and temperature of each dielectric. FIG. 2 is an explanatory diagram of an apparatus used in Examples. ■... Recording medium, 11... Dielectric layer, 12... Conductive layer, 2... Thermal head, 3... Developer, 31...
Toner 32...Carrier, 4...Developing roller, 4
1... Magnet, 42... Sleeve, 5... AC power source biased to θ, 6... Paper, 7
...Transfer roller 8...AC power source biased to Φ.

Claims (4)

[Claims] (1) Volume resistivity is 1×10^1^2 at 25℃
Ωcm or more, 1×10^1^5 at 120℃
A recording method characterized by performing thermal writing on a dielectric material having a resistance of Ωm or less and a value smaller than 25° C. at the same time as or immediately after thermal writing with a thermal head. (2) A recording method according to claim (1), characterized in that a developing roller is provided opposite to the dielectric material, and development is performed while applying a positively or negatively biased alternating current to the developing roller. (3) The recording method according to claim (1) or (2), characterized in that a (one-component) magnetic toner is used as the developer. (4) The recording method according to claim (1) or (2), characterized in that a two-component developer is used as the developer.