JP2729801B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording apparatus provided with a heater for promoting fixing of ink attached to a sheet such as paper or a thin plastic plate.

(Prior art)

An ink jet recording apparatus is one of recording apparatuses for recording characters, images, and the like on a sheet such as a sheet of paper or a plastic thin plate. An ink jet recording apparatus is configured to vibrate ink in an ink chamber by electrostriction or magnetostriction to cause ink droplets to fly from a nozzle toward a sheet, and to perform recording on a sheet using a dot pattern formed by attaching flying ink droplets. Has been taken.

An ink jet recording apparatus does not have a head that comes into contact with a recording sheet unlike other recording apparatuses, and thus does not generate noise during recording. Further, since there is no need to move the hammer, high-speed recording can be performed.

In addition, a heater is often provided in an ink jet recording apparatus in order to shorten the fixing time of ink on plain paper other than specific coated paper. By providing the heater, the sheet after printing is heated, the moisture of the ink evaporates, and the fixing time of the ink can be reduced. To control the heater, a temperature detecting sensor such as a thermistor is provided, and the power supply to the heater after the power is turned on is cut off in accordance with the sensor output, so that the heater surface temperature is kept constant.

However, in the conventional inkjet recording apparatus, since the surface temperature of the heater is controlled so as to be constantly maintained in a constant temperature range (for example, about 60 ° C. to 80 ° C.), such as when the printer is offline or when a print command is waited, However, if the sheet is in contact with the heater for a long time in the printing standby state, the sheet is deformed (and further discolored) by heat.

In particular, when the surrounding environment is at a high temperature, the sheet shrinks due to the rapid evaporation of moisture by the heater, causing a large deformation, causing a printing deviation in the digit direction, and further causing a paper feeding defect such as a paper jam. There was fear.

〔Purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus which can solve such problems of the prior art and can prevent deformation of a recording sheet caused by prolonged contact with a heater.

[Means for achieving the purpose]

The present invention makes the surface temperature of the heater lower than at the time of normal recording when the recording sheet is present on the print platen for a certain period of time without recording and sheet feeding, so that the recording sheet is not heated more than necessary. So that
This achieves the above object.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to FIGS.

FIG. 1 is a circuit diagram of a heater temperature control unit showing one embodiment of the present invention, FIG. 2 is an external view showing a printing unit of an ink jet recording apparatus to which the heater temperature control unit according to the present invention is applied, FIG. Is a block diagram showing a control system of the apparatus shown in FIG. 2,
FIG. 4 is a flowchart showing the heater temperature control of the embodiment of FIG.

In FIG. 2, 1 is a head for discharging ink, 2 is a carriage for reciprocating the head in the recording direction, 3 and 4 are guide shafts for movably supporting the carriage 2, and 5 is for moving the carriage 2. A carriage motor serving as a driving source, 6 is a pulley provided on the opposite side of the carriage motor 5, 7 is a pulley provided on the shaft end of the carriage motor 5, 8 is suspended between the pulleys 6 and 7, and It is a timing belt to be engaged.

Reference numeral 10 denotes a paper pan which guides the conveyance of the recording paper 9, 11 denotes a heater (heating means) provided along the paper pan 10, and 12 denotes a recording paper 9 formed by using an elastic member.
Is a paper presser plate pressed against the heater 11, 13 is a paper discharge roller for smoothly transporting the recorded recording paper 9, 14 is a wheel that rotates while abutting on 13, and 15 is a nozzle (not shown) of the head. A recovery unit 16 that supplies ink or removes foreign matter and high-viscosity ink that has adhered to the nozzles to return the ejection characteristics to a normal state. Reference numeral 16 denotes a paper feed motor for rotating the paper pan 10.

In FIG. 2, the recording paper 9 inserted from the lower rear surface of the paper pan 10 is sent out to the front surface of the head 1 as the paper pan 10 rotates. When a recording start command is issued, the carriage 2 is moved by the carriage motor 5 to an initial position in the left direction in the figure. Then, the carriage motor 5 rotates in the reverse direction, and at the same time, the head 1 is driven in accordance with the recording information.
Are sequentially performed by the ink droplets flying from the nozzles. The carriage 2 moves rightward in the figure according to the recording progress. When recording (printing) for one line is completed, the driving of the head 1 is stopped, and the carriage 2 is returned to the initial position by the reverse rotation of the motor 5. Motor at the same time
16 rotates, and the recording paper 9 is fed by one line interval.
Subsequently, recording for the next line is executed in the same manner as described above.

 Next, the configuration of FIG. 3 will be described.

In FIG. 3, reference numeral 20 denotes a host computer for overall control of the printing apparatus and other terminal devices, 21 is a CPU for controlling the ink jet printing apparatus of the present invention, and 22 is print data for transmitting print data from the host computer 20 to the CPU 21. Receiving unit, 23 is a head control unit that controls ink ejection of head 1, and 24 is a head control unit that controls the electrostrictive element or magnetostrictive element of the head.
A head drive unit that drives according to the output of 23, 25 is a timer connected to the CPU 21, 26 is a character generator ROM for image processing, 27 is a control ROM for causing the CPU 21 to execute control of each unit, and 28 is received data and processing. RAM for storing the result, 29 is an input port to which an operation switch or a temperature detection sensor is connected, 30 is an output port connected to the CPU 21, and 31 is connected to the output port 30 to control the energization of the heater 11. This is a heater temperature control circuit. In the configuration shown in FIG. 3, data to be recorded on the recording paper 9 is stored in the host computer 20.
Is transferred to the CPU 21 through the receiving unit 22. The CPU 21 drives the head 1 via a head control unit 23 and a head drive unit 24 based on the transferred data. The drive timing of the head 1 is controlled by the set time of the timer 25.

When the recording data transmitted from the host computer 20 is a character or a symbol, the data is transferred in the form of a character code, and is converted into dot image data so that the recording apparatus can record the data using a dot matrix type head. . The program for this is a character generator ROM (CGRO
M) 26. The CPU 21 is connected to the input port 29
The heater temperature control circuit 31 controls the energization of the heater 11 so that the heater temperature detection information is always taken in and the temperature value becomes the set temperature.

Next, an embodiment of the present invention shown in FIG. 1 corresponding to the heater temperature control circuit 31 having the configuration shown in FIG. 3 will be described.

In FIG. 1, a thermistor 40 for measuring the surface temperature of the heater 11 and a resistor 41 (R1) are provided between the DC power supply and the ground.
Are connected in series, and the comparator 42 and the
43 positive input terminals are connected. Comparator 42 and
Reference power supplies 44 and 45 for outputting reference voltages Vref1 and Vref2 are connected to each of the negative input terminals 43. Each of the output terminals of the comparators 42 and 43 has an AND circuit 46 and
One input terminal of the AND circuit 46 is connected to the other input terminal of the AND circuit 46, and a heater temperature switching signal is input to the AND circuit 46.
The other input terminal of the AND circuit 47 is connected to the output terminal of the inverter 48, and the input terminal of the inverter 48 is supplied with a heater temperature switching signal provided from the output port 30 shown in FIG. This signal is normally at "H" level, and becomes "L" level when the recording paper 9 is on the heater 11 for a certain time or more.

The output terminals of the AND circuits 46 and 47 have a two-input NOR gate 4
9 is connected and the output terminal of NOR gate 49 is a photocoupler.
50 is connected. The photocoupler 50 is a NOR gate 49
The light emitting device 50a is formed by an LED or the like generated when the LED is turned on, and the light receiving device 50b is formed by a phototransistor or the like for supplying a photoelectric conversion current according to the light intensity of the light emitting device 50a. One end of the light emitting element 50a is connected to the DC power supply via the resistor 51 (R2), and the other end is connected to the output terminal of the NOR gate 49. One end of the light receiving element 50b is connected to a capacitor 52 (C
1), it is connected to one side of an AC power supply 54 via a resistor 53 (R3), and the other end is connected to the other side of the AC power supply 54. Further, a series circuit of the heater 11 and a thyristor 55 for controlling the energization of the heater 11 is connected between the terminals of the AC power supply 54, and the gate of the thyristor 55 is connected to the output terminal of the light receiving element 50b. Thyristor 55 between terminal and ground
Is connected to a resistor 56 (R4) for preventing malfunction of the circuit.

In the configuration shown in FIG. 1, the internal resistance of the thermistor 40 changes according to the heat-sensitive temperature, and the voltage division ratio with the resistor 41 changes. The terminal voltage VIN of the resistor 41 generated according to the heater temperature becomes the input voltage of the comparators 42 and 43, and is compared with the reference voltages Vref1 and Vref2 of the reference power supplies 44 and 45. Reference voltage
Vref1 is set so that VIN = Vref1 at the heater setting temperature T1 at the time of normal printing, and the reference voltage Vref2 is V at the heater setting temperature T2 when the recording paper is on the printing platen for a certain time or more.
It is set so that IN = Vref2 (however, T1> T
2 and Vref1> Vref2).

AND circuit when the heater temperature switching signal is "H" level
46 becomes operable, and when it is at the “L” level, the AND circuit 47 becomes operable. When the heater temperature is equal to or lower than the set temperature T1 at the time of normal application, the relationship of Vref1> VIN is satisfied, and the outputs of the comparators 42 and 43 are both at the “L” level. Therefore, the AND of the AND circuits 46 and 47 does not hold regardless of the polarity of the heater temperature switching signal, and the respective outputs are at the "L" level. Therefore, the output of the NOR gate 49 is at “H” level, and the NOR gate 49 is non-conductive and the light emitting element 50a
Current does not flow through the thyristor 55, and the gate circuit of the thyristor 55 does not close.

At this time, since a phase shift circuit composed of the resistor 53 and the capacitor 52 is connected to the gate of the thyristor 55, a current whose phase has advanced beyond the power supply voltage is applied to the gate, and the thyristor 55 The conduction is performed only for a half cycle, and the heater 11 is energized. As a result, the temperature of the heater 11 rises, and the resistance of the thermistor 40 decreases with this rise.

When the temperature of the heater 11 exceeds the set temperature T1, VIN> Vref
1 occurs, and the output of the comparator 42 changes to “H” level (at this time, the output level of the comparator 43 becomes “L”
Level). At this time, if the heater temperature switching signal is at the “H” level, the AND circuit 46 establishes a logical product, and the output thereof becomes the “H” level. The NOR circuit 49 receiving this output voltage changes its output from “H” level to “L” level. As a result, the NOR circuit 49 becomes conductive and causes the light emitting element 50a to emit light. The light from the light emitting element 50a is received by the light receiving element 50b, and the state between the gate of the thyristor 55 and the ground is short-circuited, the operation of the thyristor 55 is stopped, and the power supply to the heater 11 is cut off. As a result, the temperature of the heater 11 starts to decrease. VIN according to heater temperature
Each time is increased or decreased, comparison with Vref1 is performed, the output level of the comparator 42 is changed according to the level state, and the above control is repeated so that the temperature of the heater 11 is maintained at the set temperature.

Next, when printing and paper feeding are not performed, such as during printing standby, and the recording paper 9 is present on the heater 11 for a predetermined time or longer, the CPU 21 determines this and switches the heater temperature switching signal to the “L” level. As a result, the AND circuit 46 is set in an operable state, and an “H” level signal is supplied to the AND circuit 47 via the inverter 48 to set the operable state. In this state, the comparison target for VIN is Vref2, and when the temperature of the heater 11 is equal to or higher than the set temperature T2, VIN> Vr
Because of ef2, the output of the comparator 43 is at "H" level. As a result, the output of the AND circuit 47 becomes “H” level, and the output of the NOR gate 49 becomes “L” level. As a result, the light emitting element 50a emits light to make the light receiving element 50b conductive, and the gate of the thyristor 55 The circuit is closed, and the power supply to the heater 11 is completely cut off. Therefore, the temperature of the heater 11 gradually decreases.

When the temperature of the heater 11 falls below the set temperature T2, Vref2> VI
The relationship of N is established, the output of the comparator 43 changes from the “H” level to the “L” level, the output of the AND circuit 47 is set to the “L” level, and the NOR gate 49 is set to the “H” level. Thereby, the energization of the light emitting element 50a is cut off, the light emitting element 50a is turned off,
The internal resistance of the light receiving element 50b becomes infinite, and a firing signal is given to the gate of the thyristor 55 via the phase shift circuit,
The thyristor 55 is turned on in the positive half cycle, and the heater 11 is energized. In this way, the thyristor 55 is activated or deactivated according to the comparison result between VIN and Vref2, and the control is performed so that the temperature of the heater 11 is maintained at the set value T2.
Therefore, even if the recording paper 9 is on the heater 11, the temperature is lowered, so that the deformation of the recording paper 9 can be minimized.

FIG. 4 is a flowchart showing the heater temperature control according to the present invention.

When the power of the recording apparatus is turned on, the CPU 21 writes the "H" level to the corresponding bit of the output port 30 so that the heater temperature switching signal is set to the "H" level (step 101). Next, start the timer 25 (step 1
02), it is checked whether a print start command is issued within the time set by the timer 25 (step 103). If the print start command is issued within the time, the timer 25 is reset (step 104), and it is checked whether printing has been completed (step 105). When printing is completed, the process returns to the timer start, and the above-described processing is repeated thereafter.

On the other hand, if the print start command is not issued within the timer set time in step 103, it is checked whether or not the timer has timed out (step 106). If it is before the time-out, the process returns to step 103. If the time-out occurs, the process proceeds to step 107, in which the heater temperature switching signal is set to the "L" level (low temperature side), and temperature control is performed so that the heater surface temperature is maintained at the set temperature. . In this state, it is determined whether or not a print start command is present (step 108). If the print start command is received, the heater temperature switching signal “H” is set so that the heater 11 is heated to a high temperature.
The level is set (step 109). Next, it is determined in step 110 whether or not printing has been completed.
And the subsequent processing is repeatedly executed.

FIG. 5 is a circuit diagram of a heater temperature control section showing another embodiment of the present invention. This embodiment is different from the configuration of FIG. 1 in that the comparator 43, the reference power supply 44, the AND circuit 47, and the inverter 48 are removed from FIG.
The configuration is such that a connection is made to one input terminal of the NOR gate 49 and a heater on / off (ON / OFF) signal is applied to the other input terminal of the NOR gate 49.

FIG. 6 is a flowchart showing the control contents of the embodiment of FIG.

After the power of the recording apparatus is turned on, the heater ON / OFF signal is set to "L" level (step 201), and the timer 25 is started (step 202). Steps 203 to 205 are the same as steps 103 to 105 in FIG. 4, and thus description thereof is omitted here.

If the printing start command has not been issued in step 203, it is determined whether or not the time set by the timer 25 has expired (step 206). The ON / OFF signal is set to "H" level (step 207). As a result, the power supply to the heater 11 is cut off, the temperature of the heater 11 is reduced, and the deformation of the recording paper 9 is prevented.

In this state, when a print start command is issued (step 208), the heater ON / OFF signal is set to the “L” level (step 209), and energization of the heater 11 is started. As the temperature of the heater 11 rises, the ink on the recording paper 9 dries quickly. When the end of printing is confirmed (step 210), the process returns to step 202, and the subsequent steps are repeatedly executed.

As described above, in the embodiment shown in FIG. 5, the power supply to the heater 11 is turned off when the recording paper 9 remains on the heater 11 for a certain period of time or longer, and this off state is continued until a print start command is issued. It was made. In the embodiment shown in FIG. 1, the energized state and the off state are alternately generated so as to maintain the low set temperature, and the temperature is set near the set temperature. The feature is that it remains off until you leave.

As described above, according to the present invention, when recording paper is on the heater for a certain period of time without recording and sheet feeding, the surface temperature of the heater is set to be lower than that during normal recording. Therefore, the recording paper can be prevented from being deformed or discolored without impairing the fixing ability of the heater during recording.
It is possible to prevent print misalignment and jams caused by deformation of the recording paper.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a heater temperature control unit according to an embodiment of the present invention. FIG. 2 is an external view showing a printing unit of an ink jet recording apparatus to which the heater temperature control unit according to the present invention is applied.
FIG. 3 is a block diagram showing a control system of the apparatus shown in FIG.
FIG. 5 is a flowchart showing the control contents of the heater temperature control unit of FIG. 1, FIG. 5 is a circuit diagram showing another example of the heater temperature control unit according to the present invention, and FIG. 6 is a heater temperature control unit of FIG. 5 is a flowchart showing the control contents of FIG. 1 ... head, 2 ... carriage, 9 ... recording paper, 10 ...
... Paper pan, 11 ... Heater, 21 ... CPU, 40 ... Thermistor, 42, 43 ... Comparator, 44, 45 ... Reference power supply, 46, 47 ... And circuit, 49 ... NOR gate, 50a ... …
Light-emitting element, 50b …… Light-receiving element, 52 …… Capacitor, 53…
… Resistance, 54 …… AC power supply, 55 …… Thyristor.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoji Ara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Takanori Mukai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Masaaki Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuyuki Yokoi 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-62-138249 (JP, A)

Claims (4)

(57) [Claims] 1. An ink jet recording apparatus comprising: heating means for recording ink by flying ink droplets from a nozzle onto a recording sheet in accordance with recording information, and promoting the fixing of ink on a recording surface. An ink jet recording apparatus, comprising: a control unit for lowering the surface temperature of the heating unit from that at the time of normal recording, provided that the recording sheet has been present for a certain period of time without performing recording and sheet feeding. 2. An ink jet recording apparatus according to claim 1, wherein said control means performs temperature control using a second set temperature lower than a set temperature during normal printing as a reference. 3. An ink jet recording apparatus according to claim 1, wherein said control means performs temperature control by stopping energization to said heating means under said condition. 4. An ink jet recording apparatus according to claim 1, wherein said control means raises the temperature of said heating means to the surface temperature of said heating means during said normal recording in response to the start of recording.