JPH0939268A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder capable of suppressing the change of an image density due to the influence of a heater by stabilizing an ink discharge amount irrespective of various conditions of recording of a material to be recorded. SOLUTION: The ink jet recorder comprises a heater 14 provided on a material P to be recorded to heat to dry discharged and recorded ink, temperature control means 20 for the heater, and pulse signal correcting means for the ink discharge amount, wherein the temperature and the discharge amount of the heater 14 are controlled via the control means and the correcting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus for heating and drying recording ink ejected onto a recording material by a recording head.

[0002]

2. Description of the Related Art Conventionally, as an ink jet recording apparatus of this type, there are those disclosed in Japanese Patent Publication No. 54-156536 and Japanese Patent Publication No. 55-84670, which cause unnecessary bleeding of a recorded image with ink. Also, cockling (generation of wrinkles and bulges) due to moisture absorption of the recording material is prevented. Further, as a means for heating and drying such a recording ink, the heating temperature is changed according to the type of recording material such as OHP as disclosed in Japanese Patent Publication No. 62-173259, which is suitable for the recording material used. There is one in which the recording ink is heated and dried at a temperature.

[0003]

However, the above-mentioned means for heating and drying the recording ink is to prevent the ink from bleeding and the like so that a clear image can be obtained on various general-purpose recording materials. By heating the recording material, recording is performed depending on whether the initial state of the recording head temperature T for ejecting ink is the recording head temperature T ₀ or T ′ ₀ due to the heating effect, as shown in FIG. There is a problem that the temperature of the recording head at the end is raised to T ₁ or T ′ ₁ . Therefore, as the temperature of the recording head rises, the viscosity of the ink in the head decreases and the ejection amount increases, resulting in a high image density. Further, such a temperature rise is not limited to the initial state before the recording of the recording head but is increased with each recording as shown in FIG. 8, so that the recording head temperature T ₀ or T ′ _{0 in the} initial state is recorded. Temperature difference Δ with the recording head temperature T ₁ or T ′ ₁ at the end
When T or ΔT 'becomes large and printing is performed by serial scanning, the image density of the last line becomes darker than the image density of the first line because the ejection amount changes greatly as the head temperature rises. There is a drawback that it will end up.

For the above problems, even if the above problems are solved by controlling the discharge amount or correcting the image signal, the temperature of the heating element is changed depending on the kind of the recording material. Depending on the recording material, the ink drying time,
Or because the thermal conductivity is different), the influence of the radiant heat of the heating element on the recording head also changes, which makes control difficult.
For example, when the temperature of the heating element is set higher than the conventional set temperature, the effect of radiant heat of the heating element becomes larger than the conventional effect, and the discharge amount control at the conventional set temperature or the correction of the image signal, etc. However, the correction cannot be completed, and as in the case described above, the density difference is generated by the amount that cannot be corrected, and the problem cannot be solved. Conversely, if the temperature of the heating element is set lower than the conventional set temperature, the effect of radiant heat from the heating element will be smaller than the conventional effect, and it will not be possible to control the discharge rate at the conventional set temperature or correct the image signal. The correction is overcorrected, and a density difference corresponding to the overcorrection occurs.

Further, when recording a plurality of sheets continuously, the temperature of the recording head rises as the number of recording sheets increases, so that the temperature rising conditions for the first and second recording heads change. Further, it becomes difficult to control (correction of ejection amount or image signal). For example, since the recording head starts to be affected by the radiant heat of the heating element from the initial state where the recording head is not affected by the radiant heat of the heating element on the first sheet, the heating speed of the recording head is high. Since the temperature of the head has also risen to some extent, the speed of temperature rise decreases as the number of sheets is piled up compared to the first sheet. Therefore, the control conditions change and control becomes difficult.

An object of the present invention is to pay attention to the above conventional problems, to stabilize the ink ejection amount, to minimize the density difference of the recorded image, and to control the ink ejection amount with high accuracy. To provide a recording device.

[0007]

In order to achieve such an object, the present invention comprises a recording head for discharging ink onto a recording material to perform recording, and a heating element for heating and drying the recorded ink. An ink jet recording apparatus having the above-mentioned device, further comprising: a temperature control means for the heating element; and a pulse signal correction means for correcting a pulse signal related to an ink ejection amount of the recording head, and the temperature control means controls the temperature of the heating element. In addition, the ink ejection amount is controlled via the pulse signal correction means.

According to the present invention, the temperature of the heating element is controlled by the temperature control means so as to change depending on the type of the recording material, and at the same time, the ink ejection amount from the recording head is corrected by the pulse signal correction means. As a result, it is possible to always perform stable ink heating and drying in a short time by rational power consumption to the heating element by always maintaining an appropriate relationship between the ink discharge amount and the temperature of the heating element. it can.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a structural example of an ink jet recording apparatus according to the present invention. In this example, an example of a color ink jet recording apparatus is shown, and recording heads 1C, 1M and 1Y for individually ejecting cyan (C), magenta (M), yellow (Y) and black (Bk) inks are shown. And 1Bk and the ink tanks 2C, 2M, 2Y and 2Bk that respectively store the above inks are separately mounted on the carriage. 3 is the recording heads 1C, 1M, 1Y,
Carriage 1Bk mounted in parallel, 4 is ink tank 2
A carriage in which C, 2M, 2Y, and 2Bk are mounted in parallel, and ink of a corresponding color is applied to each recording head 1 (1C to 1Bk) via a tube 5 to an ink tank 2 (2C to 2C).
Bk). 6 is a guide shaft for guiding the carriages 3 and 4 in a coupled state, 7A and 7B are timing belts connected to the carriages 3 and 4, 8
A and 8B are carriage drive motors that reciprocate the carriages 3 and 4 along the guide shaft 6 at a predetermined timing via timing belts 7A and 7B.

A recording sheet P, which is a recording material, is held at a recording position by a pair of guide rollers 9 and 10.
During one scan of the carriage 3, the recording head 1 ejects each ink onto the recording sheet P, and recording of one line is performed on the recording area 11 as indicated by the diagonal lines. Then, the sheet feed roller pair 12 feeds the sheet in the direction of the arrow S every time printing for one scan is performed. 13 is a platen for keeping the recording sheet P flat for recording, 14
Is a heating element provided along the back surface side of the platen 13, and the heating element 14 heats the recording sheet P via the platen 13 to evaporate the solvent or water of the ink ejected for recording. 15 and 16 are platen 1
A temperature sensor (temperature detection unit) for detecting the temperature of 3;
Reference numeral 17 denotes a recovery device which is in close contact with the ink ejection surface of the recording head 1 outside the recording area and ejects ink from an ink ejection port (not shown).

Reference numeral 20 is a control circuit for controlling the entire recording apparatus, 30 is a selecting means, and 40 is a material detection circuit. The control operation of these circuits 20, 30, 40 will be described later, but the control circuit 20 is The CPU functions as a CPU, and controls the carriage drive motors 8A and 8B, a sheet feed motor (not shown), and the like, and various controls according to the present invention as well as the feed of the print signal to each print head 1.

FIG. 2 shows a circuit configuration for carrying out the control of the present invention and transmission / reception of a signal to be discharged. In FIG. 2, 2
1 is an image recording signal input from the host side (not shown), 2
Reference numeral 2 is a buffer memory that temporarily stores the print signal 21 for one scan, 23 and 24 are γ conversion units and binarization processing units that perform γ conversion and binarization processing on the print signals 21, and 25 is This is a drive circuit for the recording head 1. The selection unit 30 is used by the user to specify whether to select plain paper or OHP, and is, for example, a selection switch provided in the operation unit. Further, 27 sends a sheet discrimination signal 27A to the drive circuit 25 based on the select signal 30A sent from the selecting means 30, and sends the heating element 1 to the recording sheet heating temperature control section 28.
The determination means is capable of sending the temperature control signal 27B so that the temperature of No. 4 corresponds to the type of the selected recording sheet P.
The head temperature detected by the head temperature detection unit 29 is sent to the drive circuit 25 as a temperature detection signal 29A. 25A is an ejection pulse signal supplied from the drive circuit 25 to drive the recording head 1.

In this embodiment, when the user selects the type of the recording sheet P to be recorded through the selecting means 30, the determining means 27 selects the recording sheet P based on the select signal 30A, for example, plain paper. It is determined whether there is or OHP. If it is determined that the sheet is plain paper, the temperature of the heating element 14 may be such that ink bleeding can be prevented. Therefore, the recording sheet heating temperature control unit 28 controls the temperature of the sheet P to maintain such a temperature. A signal 27B is sent to control the temperature of the heating element 14, and a sheet discrimination signal 27A indicating that the sheet is plain paper is output to the drive circuit 25. On the other hand, since the recording temperature detection signal 29A of the recording head, which is the result of detection by the head temperature detection unit 29 (not shown in FIG. 1), is input to the drive circuit 25, it is assumed that the drive circuit 25 is plain paper. Then, the discharge pulse signal 2 corresponding to the temperature detected by the signal 29A
5A is fed to the recording head 1 to perform recording. In addition,
In the case of this example, since the color recording is performed, the recording heads 1C to 1C
The ejection pulse signal 25 corresponding to each of Bk
A is output.

When the type of the recording sheet P selected by the selecting means 30 is OHP, the OHP absorbs ink more slowly than plain paper, and the OHP itself is hard to heat up. The case requires heating the OHP at a temperature. However, if the heating temperature is too high, the OHP may be deformed, so
As a result of experiments, the present inventor set such a sheet heating temperature as a predetermined temperature of 140 ° C. or lower. That is, the temperature of the heating element 14 is controlled via the temperature control unit 28 so that such a sheet temperature is obtained, and the sheet discriminating signal 2 indicating that the sheet P is OHP is given to the drive circuit 25.
Send 7A. Therefore, on the assumption that the driving circuit 25 is OHP, the ejection pulse signal 25A corresponding to the temperature detected by the temperature signal 29A is supplied to the recording head 1 to perform recording.

Now, for example, when the recording sheet P is plain paper due to heating by the heating element 14 of the recording head P, the head temperature changes from T ₀ to T in FIG. 3 from the start to the end of recording.
_The temperature is raised to 1 A, and in the case of OHP, the temperature is raised from T ₀ to T _1B . The head initial temperature at the start of recording is heated to _1A or T _'1B' T on plain paper or OHP For ₀ 'T. Therefore, the ink ejection amount Q from the recording head 1 is represented by T ₀ , T _1A , and T _1B at the start of recording and at the end of recording in both cases due to the temperature changes ΔT ₁ and ΔT ₂ , for example. It becomes different and is not stable, and the stabilization is required. Therefore, in this embodiment, the ejection energy of the ejection pulse signal 25 supplied to the recording head 1, for example, the ejection pulse width is changed so that the ink ejection amount is appropriate without being affected by the temperature change of the recording head 1. Control.

That is, the ink ejection amount Q from the recording head 1 is Q ₀ depending on whether the recording sheet P is plain paper (curve A) or OHP (curve B) as shown by curves A and B in FIG. , Q _1A , and Q _1B follow different upward trends, it is necessary to control the ejection pulse width in order to secure a stable ejection amount in each case. It should be noted that the temperature rising tendency of the recording head 1 due to the radiant heat of the heating element 14 shown in FIG. 3 or the temperature rising tendency shown as the curves A and B in FIG. 4 can be predicted in advance based on experiments and the like. The change of the ejection amount due to the tendency of temperature rise is used as a data table, and the ejection pulse signal output via the drive circuit 25 is controlled based on the data table.

Such control of the ejection pulse signal can be performed, for example, by changing the pulse width PW to PW1 to PW2 as shown in FIG. 5, and the temperature change of the recording head 1 as shown in FIG. In the case of prediction, as shown in FIG. 6, when the recording sheet P is plain paper, the correction table for the discharge amount change follows the curve A ′, and when the recording sheet P is the OHP, the correction table for changing the discharge amount is shown. Each drive circuit 25
The discharge pulse width PW is controlled by the look-up of such a correction table from the recording start time t ₀ to the recording end time t _P.
It is possible to perform recording with a stable ejection amount regardless of the temperature change due to.

Next, a second embodiment will be described.

In the embodiments described so far, the heating element 14
Change in the ejection amount due to the temperature rise of the recording head 1 (see FIG.
The pulse width of the ejection pulse signal is changed by using a table shown by curves A'and B'in FIG. However, since the initial temperature itself of the recording head 1 after the continuous recording is made is accidentally raised, as shown as T _'0 in FIG. 3, when raising the temperature trend of the recording head 1 is plain paper T _'0 → T' _1A, also discharge amount Q by the case of OHP differs with T _'0 → T' _1B
Also, Q in FIG 4 _'0 → Q' _1A changes, Q _'0 → Q' _1B
The curves C and D are different from each other. Therefore, the correction of the ejection pulse width PW with respect to the ejection amount Q is also shown in FIG.
It becomes necessary to use a different table as indicated by D '. Therefore, in this embodiment, a plurality of tables for changing the pulse width are prepared for plain paper and OHP for a plurality of different initial temperatures T ₀ , T ′ ₀ , ... Of the recording head 1, In the drive circuit 25, the head temperature detection unit 2
The pulse width is changed according to the initial temperature of the recording head obtained via 9.

Next, a third embodiment of the present invention will be described.

In this example, even when recording is performed on one recording sheet P, the initial temperature of the recording head 1 is already raised if the time interval after the previously performed recording operation is short. It is in consideration of being in a fixed state.

That is, in this example, the initial temperature of the recording head 1 is set to a value such as T ₀ shown in FIG. 3, and the initial temperature of the recording head 1 detected by the head temperature detector is set to the above-mentioned value. When the value is equal to or greater than the value T ₀ , instead of using the table, the pulse width of the ejection pulse signal is changed from the actual temperature of the recording head 1 and the temperature of the heating element 14 at that time.

A fourth embodiment of the present invention will be described with reference to FIG.

In this example, the material detection circuit 4 shown in FIG. 1 is used.
According to the detection signal 40A from 0, the ejection pulse signal control for driving the recording head 1 as described above is performed. The material detection circuit 40 is configured to detect the type of the recording sheet P, and the level of the reflected light amount of the recording sheet P varies depending on the type. Therefore, the detection circuit having such a known configuration is used. May be The control operation performed based on the detection signal 40A from the material detection circuit 40 is the same as that described in FIG. 2, and the description thereof will be omitted.
According to the present invention, as in the first embodiment, the selection means 30
Therefore, the type of the recording sheet P can be automatically notified to the discriminating means 27 by the apparatus itself without bothering the user, and the operation procedure can be simplified.

In each of the embodiments described above, the temperature of the heating element 14 is changed depending on the type of the recording sheet P so that the ink dries easily. However, not only the type of the recording sheet P, but also other types. Conditions, such as the amount of ink ejection,
Alternatively, an example of the case where it is necessary to control the temperature of the heating element 14 to appropriately change depending on the environmental temperature will be described as a fifth embodiment.

For example, when the image density of the entire image is judged from the original document and the recording is performed by ejecting the ink corresponding to the density, the temperature of the heating element 14 is adjusted so that the ink is easily dried according to the magnitude of the ink ejection amount. Need to control.
Therefore, when it is determined that the ink ejection amount is large, the heating element 14 is drive-controlled so as to be kept at a temperature corresponding to it, and when it is determined that the ink ejection amount is small, it is kept at a low temperature corresponding thereto. The temperature of the heating element 14 may be drive-controlled as described above. Thus, the drying acceleration effect of drying the ink can be obtained in an appropriate time.

Although not shown, the environmental temperature at which the recording apparatus is installed is detected, and the temperature of the heating element 14 is controlled in accordance with the environmental temperature to affect the recording sheet and the ink. The effect of suppressing the influence and promoting the drying with an appropriate drying time can be obtained.

In the fourth and fifth embodiments described above, the basic control operation is the same as the control operation described in the first embodiment, and the temperature of the heating element 14 is as described above. Controlling can also contribute to saving power consumption. Further, the temperature control of the heating element 14 is not limited to the above-described independent conditions such as the type of recording sheet, the ink ejection amount, and the environment, but may be a combination of these conditions or other conditions related to recording. But well,
Needless to say, in any case, the above-described effects can be obtained. INDUSTRIAL APPLICABILITY The present invention is widely applied to an inkjet recording apparatus that includes a heating element for drying ink and the temperature of the recording head may rise due to the influence of the heating element. It can also be applied to a recording device. Furthermore, the present invention is not limited to the case where the recording is performed using the binarized signal, and is applicable to an inkjet recording apparatus in which the recording is performed using the multi-valued signal.

[0030]

As described above, according to the present invention, the ink jet recording having the recording head for ejecting the ink onto the recording material for recording and the heating element for heating and drying the recorded ink. In the apparatus, the temperature control means for the heating element, and a pulse signal correction means for correcting a pulse signal relating to the ink ejection amount of the recording head, and controlling the temperature of the heating element by the temperature control means, Since the ink ejection amount is controlled via the pulse signal correction means, stable high-quality image recording can be always performed without being affected by the heating element.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration example of a color inkjet recording apparatus to which the present invention is applied.

FIG. 2 is a block diagram showing a control circuit configuration according to the first embodiment of the present invention together with output signals from respective units.

FIG. 3 is a characteristic curve diagram showing the relationship between print head temperature and print duration analyzed for control according to the present invention.

FIG. 4 is a characteristic curve diagram showing the relationship between the ink ejection amount and the print duration analyzed for the control according to the present invention.

FIG. 5 is a pulse waveform diagram for explaining a relationship between an ink ejection amount and a pulse width of an ejection pulse signal.

FIG. 6 is a characteristic curve diagram showing an example of a pulse width correction table according to the present invention.

FIG. 7 is a block diagram showing a control circuit configuration according to a fourth embodiment of the present invention together with output signals from respective units.

FIG. 8 is a characteristic curve diagram showing an example of a temperature rise of a recording head which is heated by the influence of a heating element.

[Explanation of symbols]

1, 1C, 1M, 1Y, 1Bk recording head 2, 2C, 2M, 2Y, 2Bk ink tank 3, 4 carriage 8A, 8B carriage drive motor 14 heating element 15, 16 temperature sensor 20 control circuit 21 image recording signal 22 buffer memory 25 head drive circuit 27 discriminating means 28 recording sheet heating temperature control section 29 head temperature detecting section 30 selecting means 40 material detecting circuit P recording sheet T ₀ , T ' ₀ initial temperature of recording head T _1A , _T'1A in case of plain paper Recording head recording end temperature T _1B , T ′ _1B OHP recording end temperature Q ₀ , Q ′ ₀ Initial ejection amount of recording head Q _1A , Q ′ _1A Ejection amount Q _1B , Q ′ _1B Ejection amount at the end of head recording for OHP A ′, B ′, C ′, D ′ From the beginning of recording to the end of recording Of the pulse width changing table according to the present invention

Claims (9)

[Claims] 1. An ink jet recording apparatus having a recording head for ejecting ink onto a recording material to perform recording, and a heating element for heating and drying the recorded ink, the temperature controlling means for the heating element, A pulse signal correction means for correcting a pulse signal relating to the ink ejection amount of the recording head, the temperature control means controls the temperature of the heating element, and the ink ejection amount is controlled via the pulse signal correction means. An ink jet recording apparatus characterized by being controlled. 2. The ink jet recording apparatus according to claim 1, wherein the heating element is a unit that heats the recording material at a position facing the recording head. 3. The heating temperature of the heating element is controlled according to the type of the recording material.
Or the inkjet recording device according to 2. 4. The ink jet recording apparatus according to claim 3, wherein the type of the recording material is selectable from an external selection unit. 5. The ink jet recording apparatus according to claim 3, further comprising a detection unit that detects the type of the recording material. 6. The ink jet recording apparatus according to claim 1, wherein the temperature of the heating element can be controlled according to a change in the ink ejection amount. 7. The ink jet recording apparatus according to claim 1, wherein the temperature of the heating element can be controlled according to environmental conditions. 8. A head temperature detecting means for detecting the temperature of the recording head is provided, and the ink ejection amount of the ink is determined based on the temperature detected by the head temperature detecting means and the temperature controlled by the heating element. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is changeable. 9. The ink jet recording apparatus is a serial type recording apparatus, and the heating element is provided along a platen that holds the recording material at a recording position. The ink jet recording apparatus according to the item.