JPS62113564A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To allow printing density to be variable according to a type of paper by providing a paper type identifying means, a heater and a blower and electrically controlling them on the basis of the temperature detection readings of a printing head. CONSTITUTION:If a control signal Si from a paper type identifying means 11 indicates 'paper' state (e.g. a photosensor is in 'non-operating condition' because of non-light transmission), a fan 9 and a heater 7 are set to 'low temperature L', while if the signal indicates 'OHP film' state (the photosensor is in 'operating condition' due to light transmission), the fan and heater are set to 'high temperature H'. Thus the fan and heater are controlled respectively. When controlling the heater 7, temperature data Tn from a temperature sensing means 8 are read after checking the elapse of one second to judge whether or not the temperature data thus obtained is lower than a set temperature. To control a blower 9, temperature data from the temperature sensing means 8 are read to interprete whether the data indicates a higher temperature than a set temperature. If it is higher, the blower 9 is set to 'drive ON', and if it is the blower 9 is stopped. In case the temperature is not lower, the blower 9 is left going as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording apparatus that can control print density depending on the type of paper.

[Prior art]

An inkjet recording device uses a plurality of ink l! This is a device that ejects ink from the J-exit based on a data signal and records the ink droplets on paper, and is used in printers, facsimile machines, and the like.

There are two types of inkjet recording devices: a line print type in which the print head has one line of ink ejection ports arranged and scans in the paper feeding direction, and a line print type in which the print head is mounted on a carriage that moves along the paper. There is also a serial print type that scans in the paper 1 direction. Furthermore, various arrangements of ink ejection orifices for line printing have been proposed, such as a straight line arrangement and a staggered arrangement.

Furthermore, in the case of a printer for color printing, a plurality of print heads of different colors such as yellow, magenta, cyan, and black are installed.

In such an inkjet recording device, the print head portion including the print head and head drive circuit is generally formed into a unit, and each unit can be replaced.
It is constructed.

However, in this type of inkjet recording device,
The viscosity and other properties of the ink change depending on the temperature of the apparatus, particularly the temperature of the print head, and the amount of ink ejected changes.

For example, when the temperature becomes low (for example, 5° C. or lower), the viscosity of the ink increases and the ejection becomes slow, resulting in a decrease in flight speed and a decrease in the amount of ink ejected. Also, high temperatures (e.g. 50°C)
In the above case, the ink viscosity decreases and the ink ejection amount increases.

By the way, when controlling the print density, such as making the font thinner when printing on paper or thicker when printing on OHP film, conventional temperature control of the print head is difficult, for example, in inkjet recording devices that use heat. If so, increase or decrease the driving time during the print cycle, that is, the time for energizing the heating element that is the ejection energy generator (heater), or change the energization of the heat generator (heater) for heating the head to the detected temperature of the print head. This was done in such a way as to continue based on the following.

However, with these conventional methods, it takes time to preheat and cool down, which reduces the actual printing speed, and it is difficult to maintain the optimum ejection temperature, making it difficult to control print density depending on the type of character, and paper There has been a problem in that it is difficult to control print density depending on the type of paper.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording apparatus that can solve the problems of the prior art described above and that can change print density depending on the type of paper.

〔overview〕

The present invention provides a print head unit with a heater and a temperature detection means, and also includes a blower and a paper type detection means in the apparatus, and based on a detection signal of the temperature detection means and a signal from the paper type detection means. By controlling the driving of the heater and the blower, the amount of ink ejected from the print head is controlled, thereby achieving the above object.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically explained below with reference to the drawings, taking as an example a case in which the present invention is applied to a line print type color inkjet recording apparatus.

FIG. 1 shows the internal structure of a color inkjet recording apparatus according to one embodiment, in which a print head assembly 2 is provided at the front of a case 1, that is, on the paper (not shown) side. This print head assembly includes a plurality of (four in the illustrated example) print head units 3A, 3B, 3C, and 3D arranged in the vertical direction (paper feeding direction) and installed in a replaceable manner.
Each print head unit includes a plurality of print head elements 4 and is configured to print one line (in bits) at a time. 4 print head units)
3A---3D prints different colors, and for example, cyan, magenta, yellow, and black are selected.

For example, the ■line is formed by 1792 bits (dots), and each print head unit is formed by 128 bits or 12
It has a structure in which 14 print head elements each having eight ink ejection ports are mounted above and below a base plate 5 in a staggered manner.

At the rear of case 1 are each of the print head units) 3
An ink container 6 A---6D for supplying ink to A---3D is replaceably installed.

Therefore, each print head unit (3A) is provided with a heater 7 and a temperature detection means 8. Furthermore, each print head unit h
3. A blower 9 is provided to cool the A---30.

FIGS. 2 and 3 show the print head unit 3A-
--- Take any one of the 3Ds and show its temperature control system.

In FIG. 2, the heater 7 and the temperature detecting means 8 are provided at a desired position on the base plate 5 of the print head unit 3, that is, at a position close to each print head element 4 or at a position that indicates a temperature corresponding to the temperature thereof. There is. This print head unit can be cooled by the common blower 9 provided within the apparatus. As the heater 7, for example, a power transistor or a heating element can be used.

The detection signal of the temperature detection means 8 is input to the control unit (microcomputer) of the apparatus, and the control unit controls the driving of the heater 7 and the air blower 419 based on this temperature signal, thereby controlling the temperature of the print head portion. properly control.

FIG. 3 shows this control system, in which the paper type detection signal Si from the paper type detection means 11 (for example, a photocoupler configured as shown in FIG. 4) is input to the control section 10, and the temperature detection means 8 The detected temperature signal S is input to the control unit (CPU) 10, and the control unit 10 issues a drive signal DH to the heater 7 when the print head is at a low temperature and requires heating. When doing so, a drive signal DF is issued to the blower 9.

Next, an example of the control operation will be explained with reference to FIGS. 5 to 7.

For example, when printing on paper, the head temperature is lowered to reduce the amount of ink ejected to make the print sharper.
When printing on HP film, the temperature is raised and the amount of ink ejected is increased to make the dots darker.

FIG. 5 shows the control procedure. First, if the control signal St from the paper type detection means 11 is in the "paper" state in step 71 (for example, the photosensor is in an inactive state because no light passes through), the low temperature L (for example, 5° C.) is set in step 72. When the film is set to OHP film in step 73 (the photo sensor is in operation because light passes through it), the temperature is set to high temperature H (for example, 50°C) in step 74.
The fan is controlled in step 75, the heater is controlled in step 76, and printing is performed in step 77.

FIG. 6 shows the procedure for controlling the heater 7. In step 102, the timer is activated for 1 second, and after confirming that 1 second has elapsed in step 103, in step 104 temperature data Tn ( n=o~3).

From this temperature data Tn, it is determined in step 105 whether or not the temperature of the print head portion is lower than the set temperature. If it is lower, the process proceeds to step 106, where the heater 7 is turned on and heated.

When it is determined in step 105 that the temperature is not lower than the set temperature, the process proceeds to step 107 and it is determined whether or not the temperature is higher than the set temperature.If it is higher, the heater 7 is turned off in step 108, and if it is not higher, it is left as it is. .

FIG. 7 shows the procedure for controlling the blower 9. At step 102, temperature data from the temperature detection means 8 is read.

In step 103, it is determined whether the temperature data is higher than the set temperature, and if it is higher, the blower 9 is turned on in step 104. If the temperature is not higher than the set temperature, step 105
Proceed to and determine whether the temperature is lower than the set temperature. If the temperature is lower than the set temperature, the blower 9 is stopped in step 106, and if it is not lower than the set temperature, it is left as it is.

According to the embodiment described above, when the temperature of the print head becomes low or high, the heater 7 or the blower 9 is operated based on the detection signal to actively heat or cool the print head. The temperature of the area could be controlled quickly and accurately, and the print density could be controlled by controlling the amount of ink discharged.

In the illustrated embodiment, the print head unit 3 is provided with one heater 7 and one temperature detection means 8, but a plurality of heaters 7 and temperature detection means 8 may be provided as required, and the temperature may also be controlled for each divided area. can.

Further, the present invention can be similarly applied regardless of the number and structure of print head units, and can be similarly applied to a serial print type in which print heads are mounted on a carriage.

〔effect〕

As is clear from the above description, according to the present invention, a means for detecting the paper type, a heater, and a blower are provided, and these are electrically controlled based on the detected temperature value of the print head. The temperature can be quickly and accurately controlled to control the amount of ink ejected from the print head, and the print density can be controlled depending on the paper type, resulting in good print quality depending on the paper type. is obtained.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing the inside of an embodiment of an inkjet recording apparatus according to the present invention, and FIG. 2 is an explanatory diagram showing the temperature HIliI means of the print head unit in FIG. 1.
FIG. 3 is a schematic block diagram showing the control system of the temperature control means in FIG. 2, FIG. 4 is a schematic diagram showing an example of the paper type detection means, and FIGS. 3 is a flowchart illustrating a control operation procedure for a heater and a blower in the temperature control shown in the figure. 3, 3 A---3D: Print head unit, 4
: Print head element, 7: Heater, 8: Temperature detection means, 9: Air blower, 10: Control unit (CPU), 11: Paper type detection means, 12 Paper or OHP film.

Claims (1)

[Claims] (1) A heater and temperature detection means are provided in the print head unit, and a blower and means for detecting the paper type are provided in the apparatus, and the signal from the paper type detection means and the detection signal from the temperature detection means are An inkjet recording apparatus characterized in that the amount of ink ejected from a print head is controlled by controlling the drive of the heater and the blower based on the amount of ink ejected from the print head.