Typewriting machines – Typing by other than type-face or type-die – Thermal
Reexamination Certificate
2002-08-30
2004-06-29
Nolan, Jr., Charles H. (Department: 2854)
Typewriting machines
Typing by other than type-face or type-die
Thermal
C400S124010
Reexamination Certificate
active
06755580
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a printing head, a head cartridge having the printing head, a printing apparatus using the printing head and a printing head substrate, and more particularly, to data transmission/reception between a printing head and a printing apparatus using the printing head.
DESCRIPTION OF RELATED ART
Electrothermal transducers (heaters) of a printing head mounted on a printing apparatus according to a conventional ink-jet method and a driver which drives the electrothermal transducers in accordance with an input image signal are formed on one substrate by using a semiconductor process technique, as disclosed in Japanese Published Unexamined Patent Application No. Hei 5-185594. Further, it has been proposed to form a device to detect condition of the substrate such as temperature of the substrate, distribution of resistance values and variation of characteristic of the driver, on the same substrate.
FIG. 8
is a block diagram conceptually showing a method for detecting the condition of a substrate in a conventional ink-jet printing head.
In
FIG. 8
, reference numeral
101
denotes a semiconductor substrate or a base plate (hereinbelow referred to as “substrate”) constructing a printing head;
102
, a heater array having a plurality of electrothermal transducers (heaters) to generate thermal energy necessary for discharging ink;
103
, a heater of the heater array
102
;
104
, a power transistor block to drive the heater by supplying a desired current to the heater;
105
, a logic circuit comprising a latch circuit, a shift register and the like, for ON/OFF controlling the respective heaters in accordance with data transfer from the outside of the printing head;
106
, a power source line for applying a predetermined voltage to the heaters, thus supplying the current to the heaters;
107
, a GND line which the current that flowed through the heaters and the power transistor enters; and
108
and
109
, a GND terminal and a power source terminal for leading the power source line to the outside of the printing head.
Further, numeral
410
denotes a temperature detection device for detecting the temperature of the substrate
101
;
411
, wiring for transmitting a signal from the temperature detection device
410
;
412
, a terminal for leading the signal from the temperature detection device
410
to the outside of the printing head;
420
, a resistor for monitoring a resistance value of the electrothermal transducers formed on the substrate;
421
, wiring for applying a voltage to the resistor
420
to measure a resistance value of the resistor;
422
, a terminal for leading the wiring
421
to the outside of the printing head;
430
, a signal processor block for processing an output from the temperature detection device and that from the resistance value monitor resistor;
413
and
423
, wiring for connecting the temperature detection device
410
and the resistor
420
with the signal processor block
430
;
440
, a judgment circuit block for receiving an output from the signal processor block
430
to detect the condition of the substrate and feeding back appropriate control in accordance with the detected condition to the substrate;
450
, wiring connecting the signal processor block
430
with the judgment circuit block
440
; and
460
, wiring connecting the judgment circuit block
440
with the logic circuit
105
in the substrate.
Next, the conception of control in accordance with substrate temperature detection and a detected temperature in the conventional printing head will be described with reference to FIG.
8
.
The power transistor supplies a current for generating thermal energy necessary for ink discharge to the heater array
102
. The timing of current supply is as follows. The judgment circuit block
440
determines an optimum driving method and the like corresponding to the condition of the substrate at that time, then a control signal according to the determined driving method is sent to the logic circuit
105
, and the logic circuit
105
supplies the control signal to a control terminal of the power transistor.
At this time, the amount and period of heat generation by the heater are determined by the timing of current that flows through the heater, and ink corresponding to the amount is discharged for the period. However, as the heat generation energy by the heater is supplied not only to the ink but also to the substrate
101
, the temperature of the substrate
101
rises. Accordingly, ink discharge cannot be performed on a constant condition. That is, it is difficult to maintain the same ink discharge condition in a wide temperature range at constant drive timing. For this reason, there is a need to drive the heaters while detecting the substrate temperature and selecting an optimum ink discharge condition.
Preferably, the device to monitor a temperature change in the substrate has a known temperature characteristic. For example, a P-n junction diode is employed and its forward voltage-current characteristic or the like is utilized. Stable ink discharge can be maintained in a wide temperature range by providing the diode on the substrate, detecting the change of characteristic of the device at predetermined intervals from an external position, and supplying optimum drive timing corresponding to each detected result.
That is, in
FIG. 8
, a predetermined voltage is applied to the power source terminal
109
in advance, then if a timing pulse based on print information and driving condition is inputted from the logic circuit
105
into the power transistor block
104
, a corresponding heater
103
in the heater array
102
is driven, and a nozzle at a specific position corresponding to the driven heater discharges ink.
At this time, if heat generation operation with respect to the heater is continuously repeated, the temperature of the substrate rises corresponding to the heat generation operation. The temperature detection device
410
sends an output signal corresponding to the temperature of the substrate, via the substrate internal wiring
411
and the terminal
412
and the substrate external wiring
413
, to the signal processor block
430
on the printing apparatus side. Generally, the output from the temperature detection device
410
is an analog signal. The signal processor block
430
amplifies the analog signal, converts the output into a digital value, and sends the digital vale via the wiring
450
to the judgment circuit block
440
.
The judgment circuit block
440
detects the temperature rise of the substrate
101
by the digital value, and sends a driving signal indicative of an optimum driving condition at the temperature via the wiring
460
to the logic circuit
105
. The logic circuit
105
supplies a timing pulse corresponding to the substrate temperature to the power transistor, and as a result, the heater is driven and ink is discharged.
In this manner, even if the substrate temperature changes, a stable ink discharge condition can be maintained by detecting the substrate temperature at predetermined intervals.
Next, the conception of monitoring of resistance value of the electrothermal transducer (heater) formed on the substrate in the conventional printing head and control in accordance with the result of monitoring will be described.
In the ink-jet printing head, upon printing, heat generated by the heater
103
boils ink, and the ink is discharged by a pressure of bubble generated by boiling. The quantity of heat (Q) generated at this time is expressed by Q=I
2
R with the current (I) which flows the heater and the resistance value (R) of the heater. According to the relation between the quantity of heat (Q) and the resistance value (R), the quantity of heat (Q) changes based on the resistance value (R) of the heater itself, and the formation of bubble changes in correspondence with the change of the quantity of heat (Q).
When the printing head is exchanged for a new one, the quantity of heat (Q) depends on the resistance value of the heater of the new printing head. Howe
Furukawa Tatsuo
Maru Hiroyuki
Ohta Kazuki
Yoshida Takashi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nolan, Jr. Charles H.
LandOfFree
Ink-jet printing head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink-jet printing head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink-jet printing head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3350273