Typewriting machines – Typing by other than type-face or type-die – Thermal
Reexamination Certificate
1999-03-24
2001-04-17
Hilten, John S. (Department: 2854)
Typewriting machines
Typing by other than type-face or type-die
Thermal
C400S120020, C400S120140, C347S171000, C347S172000, C347S191000, C347S194000
Reexamination Certificate
active
06217239
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a temperature control apparatus for controlling a heating temperature of a thermal head utilized in a recording apparatus, such as a high-resolution printer.
2. Description of the Related Art
An ink is known that includes fine capsules, such as micro-capsules, filled with heat-sensitive color developing dye or ink for high-resolution printing in a high resolution color printer. A recording sheet consists of a base sheet with a layer of the micro-capsules covering the base sheet. The layer of micro-capsules includes a plurality of types of micro-capsules, each type corresponding to a specific color, which seeps from the micro-capsule onto the recording sheet when the corresponding micro-capsule is heated to a predetermined temperature. The predetermined temperature varies dependent on the type of micro-capsule. Each seeped color is developed and fixed by light of a predetermined wavelength, which also varies dependent on the type of micro-capsule. Therefore, each type of micro-capsule seeps a predetermined color when heated to the predetermined temperature, and the seeped color is developed and fixed on the base sheet of the recording sheet by irradiation with the light of the specific wavelength. Thus, ink or dye of a full-color image, to be recorded on a recording sheet, can be controlled through selective breakage of the micro-capsules as seepage of the dye or ink, which occurs through control of a localized heating and irradiation with a specific wavelength of light.
The recording process utilizing the recording sheet with the layer of the micro-capsules is complicated and time-consuming as the localized heating and light irradiation must be repeatedly executed in order to develop and fix a plurality of colors.
In a printer for producing pixels via a thermal head having one or more heating elements, it is necessary to control a heating temperature of the heating elements through a time controlled application of the electric current. Usually, the heating temperature is measured by a thermistor or another type of temperature sensor. However, due to a small-size of the printer the direct measurement is difficult as the heating elements are extremely small. In this case, the temperature of the heating element cannot be directly measured and is estimated from a resistance of a thermistor disposed adjacent to the heating element within the thermal head. The temperature measured is an ambient temperature of a peripheral area around the heating element.
Due to the temperature not being directly measured, the heating temperature is inaccurate, and the printing quality of the printer, using the thermal head, is thus limited.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a temperature control apparatus for controlling the heating temperature of the thermal head when utilized in a recording apparatus.
A temperature control apparatus according to the present invention controls a heating element according to a current flowing through the heating element.
Preferably, the current flowing through the heating element is switched by a switching device, an analog signal indicative of the current is compared to a threshold value by a comparator, and the switching device is controlled according to a result of the comparison.
When a plurality of heating elements is provided, each heating element is independently and accurately controllable by the temperature control apparatus according to the present invention through a direct temperature measurement.
REFERENCES:
patent: 4399209 (1983-08-01), Sanders et al.
patent: 4440846 (1984-04-01), Sanders et al.
patent: 4644376 (1987-02-01), Usami et al.
patent: 4990931 (1991-02-01), Sato et al.
patent: 5072245 (1991-12-01), Tamura et al.
patent: 5083137 (1992-01-01), Badyal et al.
patent: 5132709 (1992-07-01), West
patent: 5223853 (1993-06-01), Wysocki et al.
patent: 5246811 (1993-09-01), Higuchi
patent: 5546112 (1996-08-01), Hunter et al.
patent: 5563635 (1996-10-01), Kneezel et al.
patent: 5736995 (1998-04-01), Bohorquez et al.
patent: 5825985 (1998-10-01), Asai et al.
patent: 5879254 (1999-04-01), Tanaka et al.
patent: 4-4960 (1992-01-01), None
Furusawa Koichi
Orita Hiroshi
Saito Hiroyuki
Suzuki Katsuyoshi
Suzuki Minoru
Asahi Kogaku Kogyo Kabushiki Kaisha
Chau Minh
Greenblum & Bernstein P.L.C.
Hilten John S.
LandOfFree
Temperature control apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temperature control apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature control apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2483315