JPH0531893A - Printer - Google Patents

Abstract

PURPOSE:To heat a printing medium in a short time to secure a favorable printing quality by a method wherein a heating device for heating a heating medium and a vacuum generating device for sucking a printing medium to the heating medium are controlled based on a detection temperature of the heating medium so that the heating medium is set to a predetermined temperature. CONSTITUTION:A printer of an ink jet system heats paper as a printing medium 51 to obtain a good printing quality. In this invention, the printing medium 51 is heated by a heating device 53 through a heating medium (heating platen) 52. The temperature of the heating medium 52 is detected by a temperature detection means 54. Furthermore, the printing medium 51 is sucked to the heating medium 52 by a vacuum generating device 55. The operations of the heating device 53 and the vacuum generating device 55 are respectively controlled by a controller 56 based on the temperature detected by the temperature detection means 54 so that the heating medium 52 is set to a predetermined temperature. In this manner, under control the printing medium 51 is heated by the heating medium 52 of the heat is radiated, whereby the printing medium 51 is heated in a short time to secure a high printing quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus equipped with a device for heating a paper sheet which is a printing medium.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer type or hot melt type ink jet type printing device is known which is provided with a device for heating a printing medium in order to improve printing quality. In addition, some ink jet type printers using a water-based ink are equipped with a similar device for drying the ink. Some of the printing devices provided with these heating devices are provided with a negative pressure generating device for adsorbing the printing medium to the heating medium (hereinafter referred to as the heating platen). There is one in which the heat is surely transferred to the heating medium so as to improve the print quality.

In such a printing apparatus, under special conditions, for example, when the humidity is high and the printing medium contains more water than usual, wrinkles are generated by heating the printing medium. As a result, a gap is formed between the surface of the heating platen and the heat transfer from the heating platen is deteriorated, resulting in extremely poor print quality. In addition, since there is an optimum heating temperature depending on the type and thickness of the print medium, good print quality may not be obtained if the temperature of the heating platen remains set to a predetermined value. .. Therefore, in order to obtain higher print quality, it is necessary to change the temperature of the heating platen so as to obtain the optimum temperature according to the environmental conditions and the type of print medium.

[0004]

However, when the temperature of the heating platen in the printing apparatus is changed, the thermal time constant of the heating platen itself is large, and therefore, simply controlling the electric power supply to the heating apparatus causes a short time. It was not possible to bring the heated platen to the desired temperature. The present invention is
It was made to solve the above problems,
An object of the present invention is to provide a printing apparatus that can change the temperature of a heating platen to a predetermined temperature in a short time and always obtain good printing quality.

[0005]

In order to achieve this object, the present invention is a printing apparatus for printing by heating a printing medium, as shown in FIG.
A heating device 53 for heating the sheet via a heating medium 52 (heating platen), a temperature detecting means 54 for detecting the temperature of the heating medium 52, and a negative pressure generating device 55 for adsorbing the printing medium 51 to the heating medium 52. And the temperature detecting means 54
The heating device 53 and the negative pressure generating device 5 are controlled so that the heating medium 52 reaches a predetermined temperature based on the value detected by
And a control device 56 for controlling the operation of No. 5 of FIG.

[0006]

According to the above construction, when the temperature of the heating platen is changed, the control device 56 controls the power supply to the heating device 53 and simultaneously controls the operation of the negative pressure generating device 55. For example, when the temperature is lowered, the heat of the heating platen is released to the outside of the printing device by stopping the power supply to the heating device 53 and operating the negative pressure generating device 55 at the same time. Conversely, when raising the temperature, the negative pressure generator 55
Is supplied to the heating device 53 without operating so that the heat of the heating platen does not escape. In this way, it is possible to change the temperature of the heating platen to a target temperature in a short time.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. This embodiment applies the present invention to an ink jet printer, FIG. 2 is a partially cutaway perspective view of the printing mechanism and suction mechanism, and FIG. 3 is a sectional view. The carriage 2 provided with the print head 1 is movable along the guide shaft 3 via a belt by the driving force of a motor (not shown). In front of the print head 1, there is provided a flat plate-shaped heating platen 9 (heating medium) which is supported by the frame 4 and is made of aluminum having good thermal conductivity. Below and above the heating platen 9, there are provided an upper paper feed roller 5 and a lower paper feed roller 6 rotatably supported by the frame 4, and an upper pressing roller 7 and a lower pressing roller 8. The paper feed roller 5 and the lower paper feed roller 6 are rotationally driven by a paper feed motor via a gear mechanism (not shown) to supply and discharge the print paper P (print medium).

A heater 10 (heating device) is attached to the non-printing surface of the heating platen 9, and heats the printing paper P via the heating platen 9. Further, on the heating platen 9, there is provided a temperature sensor 11 (temperature detecting means) composed of a thermistor adhered with an epoxy adhesive having good thermal conductivity, and the temperature of the heating platen 9 is converted into an electric signal. Output. On the opposite side of the heating platen 9 from the print head 1, there is provided a suction chamber 13 which communicates with the suction holes 12 and is made of synthetic resin or the like having excellent airtightness, and at the rear end of the suction chamber 13. A suction fan 14 (negative pressure generating device) is attached.
Therefore, since the suction fan 14 rotates to suck the air in the suction chamber 13, the various print sheets P fed to the heating platen 9 are adsorbed to the heating platen 9 through the plurality of adsorption holes 12. ..

Next, referring to FIG. 4, the heater 10 and the suction fan 14 are based on the electric signal from the temperature sensor 11.
The signal processing circuit 20 for controlling the signal will be described. The signal processing circuit 20 mainly includes an electronic control unit 26 including a CPU 21, a ROM 22, a RAM 23, an input interface 24, and an output interface 25. In the input side circuit of the signal processing circuit 20, an A / D converter 27 for converting an electric signal from the temperature sensor 11 into a digital signal processable by a computer, and an analog signal from a trimmer 28 are converted into a digital signal. A / D converter 29
Is provided. The trimmer 28 is for manually adjusting the target temperature of the heating platen 9, and by adjusting the resistance value, an analog signal corresponding to the resistance value is output.
Further, the output side circuit includes a timer circuit 30 for the heater 10.
Further, a heater drive circuit 31 that drives the heater 10 is provided, and a suction fan drive circuit 32 that drives the suction fan 14 and the suction fan 14 is further provided. The heater drive circuit 31 is a switch element that turns on and off the operation of the heater 10 according to the duty signal from the timer circuit 30, and is composed of a transistor or a solid state relay.

Next, the heater control executed by the electronic control unit 26 will be described with reference to the flowchart of FIG. This control is repeatedly executed at predetermined time intervals based on a command from the CPU 21 and a command from a built-in timer according to a control program stored in the ROM 22. In addition,
In the following description, step is abbreviated as S. First, S
1, the detected temperature T of the heating platen 9 converted into a digital signal by the A / D converter 27, and the A / D converter 2
The target temperature T similarly set by the trimmer 28 at 9
s is read. In the next S2, the detected temperature T and the target temperature Ts are compared and calculated. As a result, when it is determined that the detected temperature T is lower than the target temperature Ts, the process proceeds to S7, and the suction fan 14 is turned off. Then, in subsequent S8, S2
The duty ratio is obtained based on the calculation result of the above, and this signal is transferred to the timer circuit 30. The timer circuit 30 sends the set duty signal to the heater drive circuit 31, and S9
The heater drive circuit 31 controls the energization of the heater 10 according to the duty signal.

On the other hand, at S2, the detected temperature T is the target temperature Ts.
When it is determined that the above is the case, the process proceeds to S3, and the reference temperature difference Td is read as the reference temperature difference data stored in the ROM 22 in advance. At S4, the reference temperature difference Td and S
The difference between the detected temperature T obtained as a result of the comparison calculation in 2 and the target temperature Ts is compared, and the difference is the reference temperature difference Td.
If it is determined that it is smaller than the above, the process returns to S3.
On the other hand, if it is determined in S4 that the difference between the detected temperature T and the target temperature Ts is not less than the reference temperature difference Td, the process proceeds to S5, and the suction fan 14 is turned on. Then, in subsequent S6, the heater 10 is turned off by transferring data representing 0% as the duty ratio to the timer circuit 30.

According to the present embodiment described above, the temperature of the heating platen 9 is higher than the target temperature, and the temperature difference is
When the temperature difference is equal to or more than the preset temperature difference, the heat of the heating platen 9 can be released to the outside by cutting off the power supply to the heater 10 and operating the suction fan 14. When the temperature of the heating platen 9 is lower than the target temperature, the suction fan 14 is not operated and the heater 1
By supplying power to 0, it is possible to prevent the heat of the heated heating platen 9 from escaping, so it is possible to reach the target temperature in a shorter time than when the power supply to the heater 10 is simply controlled. Become.

The present invention is not limited to the embodiments described in detail above, and various changes can be made without departing from the spirit of the invention. For example, in the present embodiment, when setting the target temperature Ts of the heating platen 9, the resistance value of the trimmer 28 is manually changed and the analog signal thereof is converted into a digital signal by the A / D converter 29. , This is the target temperature Ts directly from the host computer
It is also possible to send the data of the above, and it is also possible to detect the type of paper and the like in advance by an appropriate sensor and set the most suitable target temperature Ts for the paper from the prepared table. The present invention can also be applied to the case where the temperature of the heating platen 9 is lowered to the target temperature in a short time when the printer cover or the like is opened.

[0014]

As is apparent from the above description, according to the present invention, in the printing apparatus of the type that heats the print medium, the heater is controlled in order to control the temperature of the heating medium, for example, the heating platen. Since a negative pressure generating device for adsorbing the print medium to the heating platen, for example, a suction fan is also controlled to be turned on and off, it is possible to change the heating platen to a target predetermined temperature in a short time. Become. Therefore, good print quality can always be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a printer of the present invention.

FIG. 2 is a partially cutaway perspective view of a printing mechanism and a suction mechanism according to an embodiment of the present invention.

FIG. 3 is a sectional view of a printing mechanism and a suction mechanism according to an embodiment of the present invention.

FIG. 4 is a block diagram of a control device according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a temperature control process according to an embodiment of the present invention.

[Explanation of Codes] P printing paper (printing medium) 9 heating platen (heating medium) 10 heater (heating device) 11 temperature sensor (temperature detecting means) 14 suction fan (negative pressure generating device) 26 electronic control device 51 printing medium 52 Heating medium 53 Heating device 54 Temperature detecting means 55 Negative pressure generating device 56 Control device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B41J 29/13 8804-2C B41J 29/12 C

Claims (1)

Claim: What is claimed is: 1. A printing device for printing by heating a printing medium, a heating device for heating the printing medium via the heating medium, and a temperature detecting means for detecting the temperature of the heating medium. A negative pressure generating device for adsorbing the print medium to the heating medium, and a heating device and a negative pressure generating device for causing the heating medium to reach a predetermined temperature based on the value detected by the temperature detecting means. A printing device characterized by comprising a control device for controlling the operation.