JPH07164622A - Transfer-type ink jet recording device - Google Patents

Abstract

PURPOSE:To prevent an image on a transfer medium from qualitatively deteriorating by providing a means for detecting the total ink quantity of ink droplets sticking to a transfer medium and a means for controlling the drive speed of an ink jet recording head and a transfer medium based on the total ink quantity. CONSTITUTION:Image data originating from a host computer is sent to a printer controller, and a total dot quantity which constitutes the image data calculated by a dot counting circuit is returned to the printer controller side. The total ink quantity for constituting a single image is determined based on the total dot quantity and the previously entered weight of the ink which forms a single dot. In addition, the time required for printing is previously entered, so that the thermal energy required for drying an ink solvent for each unit time is determined and the electric energy sent to a heater lamp is calculated. If the required electric energy exceeds the rated power consumption, the amount of signals sent to a motor and a head drive circuit from the print controller per unit time is reduced to reduce a printing speed.

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 which forms an ink image on a transfer medium and then transfers it to the recording medium to obtain the ink image on the recording medium.

[0002]

2. Description of the Related Art A recording device (inkjet printer) for generating ink droplets in conformity with image data by a recording head having a plurality of nozzles communicating with a pressure generating chamber, and ejecting the ink droplets onto recording paper for printing is known. As compared with the wire impact type printer, the number of moving parts is small, so that it has low noise and is small and lightweight.
However, since an image is formed on the recording sheet using the liquid ink, there is a disadvantage that bleeding occurs depending on the quality of the recording sheet and the print quality deteriorates. Further, in the inkjet printer, clogging of the inkjet head may occur due to unintentional contact between the recording paper and paper dust and the recording head.

In order to solve such a problem, for example, as shown in US Pat. No. 4,538,156, ink droplets ejected in accordance with image data from an ink jet recording head are once formed in a drum shape or a band shape. There is also proposed a so-called transfer type ink jet printer which is configured to be received by a transferred transfer medium, volatilize the ink solvent to some extent, and then transfer to a recording sheet.

The use of such a transfer system is characterized in that the occurrence of bleeding can be prevented regardless of the quality of the ink or the recording paper and a high quality printed matter can be obtained.

[0005]

A transfer medium that receives ink droplets is usually made of a material having a peeling property for easily transferring a dried ink image onto a recording sheet, for example, a material such as silicone rubber. ing. Therefore, the ink droplets held on the transfer medium are initially in a liquid state and are in a very unstable state. Therefore, it is necessary to evaporate the solvent of the ink before the ink flows and the image is disturbed. In order to quickly dry the solvent of the ink, it is common to have a device that raises the temperature of the transfer medium to promote evaporation of the solvent.

However, when the ink droplets are held on the transfer medium, if the amount of ink to be held on the transfer medium is large, the amount of heat required to evaporate the ink solvent also becomes large. When the amount of heat per unit time that needs to be supplied to the entire transfer medium exceeds the limit of the amount of heat per unit time that can be supplied to the transfer medium, the ink drying rate decreases. Then, since the ink images on the transfer medium are overprinted while the ink images are not sufficiently dried or fixed, the ink flows on the transfer medium and the image on the transfer medium is disturbed.

[0007]

Therefore, the transfer type ink jet recording apparatus of the present invention comprises a pressure generating chamber communicating with the nozzle opening, and a pressure generating element for giving a pressure change to fly an ink droplet in the pressure generating chamber. An ink jet recording head, a transfer medium that receives the ink droplets from the ink jet recording head, a backup roller that presses a recording sheet against the transfer medium, drive means that gives a drive signal to the pressure generating element, and the transfer. Means for detecting the printing state of the total ink amount of the ink droplets deposited on the medium, and means for controlling the driving speed of the inkjet recording head and the transfer medium according to the printing state of the total ink amount and the like It is characterized by having.

[0008]

With the above structure, when outputting by the transfer type ink jet recording apparatus, the driving speed of the ink jet type recording head and the transfer medium is controlled according to the printing condition such as the total amount of ink printed on the transfer medium. As a result, the flow of the ink image is suppressed, deterioration of the image on the transfer medium is eliminated, and an output with good print quality is obtained.

[0009]

EXAMPLES The transfer type ink jet recording apparatus of the present invention will be described below with reference to Examples.

FIG. 1 is a schematic view of a transfer type ink jet recording apparatus of the present invention. A recording head 2 which is an inkjet recording head, a backup roller 3, a heater lamp 4 which is a heating unit, and a temperature sensor 6 which is a temperature detection unit are sequentially arranged around a transfer drum 1 which is a transfer medium. The heater lamp 4 includes an output signal processing circuit 7,
It is controlled by a heating control means including a heating drive circuit 8 for turning on the heater lamp 4. The directions of rotation and movement of each member are indicated by arrows A, B, and C.

The recording head 2 is an ink jet recording head, and has a plurality of nozzles which are separated from each other by a predetermined distance in the axial direction of the transfer drum 1. Each nozzle includes a pressure generating chamber that communicates with the nozzle opening, and a pressure generating element that applies a pressure change that causes ink droplets to fly. The recording head 2 is supplied with ink from the ink container 21 and ejects ink droplets.

The transfer drum 1, which is a transfer medium, has a surface layer 12 around a raw tube 11 made of aluminum which is a good conductor of heat.
Is laminated with silicone rubber. Surface layer 1
The material 2 is not limited to silicone rubber, and any material having a property of easily peeling off an ink image can be used.

The shaft end portion of the transfer drum 1 is supported by a support shaft 14 via an insulating bearing 15. Bearing 15
Is fixed to the frame 17 by being electrically insulated from the frame 17 by an insulating bush 16.

The heater lamp 4 is composed of a rod-shaped halogen heater, is housed inside the transfer drum 1, and has a support shaft 14
Electric power is supplied through the contact 18 built in the. The transfer drum 1 is heated from inside by a heater lamp 4. A part of the transfer drum 1 does not have a surface layer, and the temperature sensor 6 directly contacts the raw tube 11 to detect the temperature. The output of the temperature sensor 6 is input to the heating drive circuit 8 via the output signal processing circuit 7. Here, the energization state of the heater lamp 4 is changed in accordance with the temperature of the transfer drum 1, so that the transfer drum 1 is controlled to be maintained at a predetermined temperature.

The backup roller 3 is a metal roller made of aluminum and is configured to be pressed against the transfer drum 1 by a pressure generating mechanism (not shown). In the transfer step, the transfer drum 1 is pressed via the recording paper 5. The transfer load is about 10 kg in this embodiment.

As the ink, one that can obtain an appropriate ink film strength by evaporation of the solvent is used. In this example, an ink composed of emulsion resin dispersion 37.5% carbon black dispersion 9.8% maltitol 20.0% diethylene glycol 6.0% surfactant 3.0% pure water 23.7%. Is used. Not limited to this configuration, the ink film after the solvent of the ink is evaporated is not broken, and the physical strength is such that sufficient adhesive force with the recording paper can be obtained.
It is necessary to use one having chemical properties.

Next, the operation will be described.

While the apparatus is on standby, the transfer drum 1 is stopped,
The heater lamp 4 is also kept off. At the start of the printing operation, the heater lamp 4 is turned on and the transfer drum 1 is heated to a predetermined temperature by the control operation described above.

When the transfer drum 1 reaches a predetermined temperature, the transfer drum 1 is started to rotate by the driving means 19. The rotation direction and movement direction of each member are indicated by arrows in the figure.

Ink is supplied from the ink container 21 to the plurality of nozzles of the recording head 2, and a driving signal (not shown) is applied to the pressure generating element of the recording head 2 by a drive means to selectively eject ink droplets to transfer the transfer drum 1. An ink image is recorded on top.

The transfer drum 1 carrying the ink image is kept at a predetermined temperature by the heater lamp 4 and the control means for driving and controlling the heater lamp 4. As a result, the water, which is the main component of the ink solvent, is removed from the ink image on the transfer drum 1 to obtain a dry ink image, and the transfer process is started.

In the transfer step, the recording paper 5 is fed by a recording paper conveying means (not shown), brought into contact with the transfer drum 1, and pressure is applied by the backup roller 3, and the ink image on the transfer drum 1 is applied by the pressure. Transfer to 5. When the recording operation is completed, the heater lamp 4 is turned off.

The recording paper 5 that has undergone the transfer process is pressed and heated by a thermal fixing mechanism (not shown) to thermally fix the ink image. By heat fixing, abrasion resistance and water resistance are improved. With the above, all steps are completed.

FIG. 2 is a flow chart showing a means for controlling the driving speed of the ink jet recording head and the transfer medium based on the total ink amount. The dot counting circuit and printer controller in the figure constitute a unit for detecting the total amount of ink to be printed. First, the image data output from the host computer is sent to the printer controller. The image data from the printer controller is sent to the dot counting circuit, and the total dot amount forming the calculated image data is returned to the printer controller side. From the total dot amount and the weight of the ink forming one dot that has been input in advance, the total ink amount forming one image is found. Here, when an image is formed by dots having different weights or dots of different types, the ink amount is calculated for each. There are dots with different weights in one image when giving a gradation by changing the discharge amount of a single ink drop, and when forming a full-color image, four colors of yellow, magenta, cyan, and black are used. Different types of ink are usually needed.

The time required for printing is also entered in advance, and the thermal energy per unit time required to quickly dry the solvent of the ink so that the ink image does not flow can be known, and the electricity to be sent to the heater lamp 4 can be known. Energy can be calculated. If the required electric energy exceeds the rated power consumption of the heater lamp 4, the amount of signals sent from the printer controller to the motor drive circuit and the head drive circuit per unit time is reduced to print. Reduce speed. By doing so, the number of dots adhering to the transfer drum 1 per unit time is reduced, and therefore the thermal energy per unit time required to sufficiently dry the ink drops is reduced, and the unit time to be sent to the heater lamp 4 is reduced. Image deterioration on the transfer medium can be suppressed in a state in which the electric energy per hit is kept below the rated power consumption.

In this embodiment, the ink 0.035 described above is used.
One dot is formed by microgram, and the dot is printed on the transfer drum 1 at a pitch of 600 dpi. Since the recording paper 5 is A4 size, when printing on the entire surface of the recording paper 5,

[0027]

[Equation 1]

[0028] The weight composition ratio of water in the ink is 6
Since it is 0.5%, the total water content when printing is performed on the entire A4 surface is 1.22 × 0.605 = 0.74 g. Since the heat of vaporization of water is 2267.2 joules per gram, the energy required to vaporize water when printing on A4 size paper at 100% duty is 2267.2 x 0.74 = 1678 joules. Become. The weight of the recording paper 5 used is 4.58.
Gram, heat capacity is 1.2 joules per gram.
Since the temperature of the transfer drum 1 is 80 ° C, the room temperature is 20 ° C.
Then, the energy of (80-20) × 4.58 × 1.2 = 330 joules will be lost to the recording paper 5. The heat conversion efficiency of the heater lamp 4 is 40%. Further, in this embodiment, since the recording paper 5 is output at a speed of 6 ppm, it takes 10 seconds to output one sheet. Therefore, the required capacity of the heater lamp 4 is (1678 + 330) ÷ 10 ÷ 0.4 = 502 watts at 100% duty. The print duty here means the recording paper 5
The ratio of the amount of ink printed on the transfer drum 1 to the total amount of ink when the entire surface is covered with one type of ink is expressed in percent. Also, with the same calculation, 40 watts gives 250 watts and 5% duty gives 103 watts.
Will be watts.

In this embodiment, although not shown in FIG. 1, there is a fixing step using a heat fixing roller. The temperature required for heat fixing is 140 ° C. in the ink of this embodiment.
At the time of transfer, the recording paper 5 and the transferred ink image have a temperature of 80 ° C., and when a fixing process is started from there, there is a temperature difference of 60 ° C. The ink of this example has a nonvolatile content of 3 by weight.
Since it is 9.5%, when the entire surface of A4 is printed and dried, the weight of the ink is 1.22 × 0.395 = 0.482 g, and the specific heat at that time is 1.34 joules / g · ° C.
Is. Therefore, the energy required to raise the temperature is 60 × 1.34 × 0.482 = 38.8 Joules. The amount of heat required to raise the temperature of the recording paper 5 at the time of fixing is 60 × 4.58 × 1.2 = 330 joules. Since it takes 10 seconds to output one sheet, the amount of heat required for heat fixing is 1000% duty.

[0030]

[Equation 2]

It becomes Further, by the same calculation, it is 86 W at 40% duty and 83 W at 5% duty.

In this embodiment, in order to suppress the power consumption of the entire apparatus, the upper limit of the power consumption of the heater is set to 500 W, the maximum power consumption of the mechanical drive section is 100 W, and the maximum power consumption of the head drive section is 100 W. The maximum power consumption is 700 W. When using the printer as a personal use at home, it is not common to use a printer that consumes a large amount of power;
Is set to. 2 at a print duty of 40%
The sum of the required power consumption of the two heaters is 326W. Further, the sum of heat radiation from each heater is approximately 170W. Therefore, the print duty is 40%
At this time, the power consumption of the heater is about 500 W, and if the print duty exceeds 40%, the drying speed of the ink will decrease.

FIG. 3 shows the relationship between the print duty in this embodiment and the minimum power consumption of the heater for suppressing the deterioration of the print quality due to the fluidity of the ink. The power consumption is the sum of the power consumptions of the heater for the transfer drum (heater lamp 4) and the heater for thermal fixing. As described above, when the print duty is 40% or more, the drying speed of the ink on the transfer drum decreases under the preset printer conditions (the driving frequency of the head for printing and the rotation speed of the drum), Distortion of the image such as ruled balls and flipping occurs due to the fluidity of the image. This is shown in FIG. FIG. 4a shows a ruled line ball generated when a ruled line is printed on a transfer medium. A thick line width due to the ink flow is seen in the portion indicated by E. Further, FIG. 4B is a repelling of ink when printing is performed so that the entire area of a limited plane on the transfer medium is covered with ink. The portion indicated by F is a portion where the ink has run out due to the flow of the ink. Since such a phenomenon does not occur, when the print duty calculated by the printer controller from the number of dots counted by the dot counting circuit exceeds 40%, the print speed is reduced according to the duty, The ink image on the transfer medium can be fixed before flow occurs, and the required print quality can be maintained.

Usually, the behavior of the hardware may be changed in the printer depending on the print quality of the image data. For example, in the monochrome mode, since the image data is monochrome, the output is black ink 1
Do by type. Therefore, since it is not necessary to repeatedly eject ink droplets at the same position on the recording paper, the amount of ink per unit area can be small. However, in the case of the full color mode, it is necessary to express the intermediate color with Y, M, and C types of ink. That is, there is a case where ink drops adhere to the same position. Therefore, full-color images generally take longer to dry. Therefore, when the print mode is sent as data from the beginning to the recording device side, the information reduces the amount of signals sent from the printer controller to the motor drive circuit and head drive circuit per unit time. Reduce the printing speed. That is, the portion of the dot counting circuit in the flowchart of FIG. 2 is replaced with a circuit having a mode discrimination function. By switching the printing speed according to such a printing mode, it is possible to obtain an output image as fast as possible while preventing the image from being disturbed due to the flow of the ink image in each mode.

If one type of ink has different resolutions, for example, a mode with a large dot interval (draft mode) and a mode with a small dot interval (fine mode), the ink image is dried depending on each mode. Since the required energy is different, the printing speed can be set for each mode by having the mode discrimination function as described above, and the image disturbance due to the flow of the ink image can be prevented. In this case, when changing the ink amount of a single dot according to each mode, the printing speed is determined in consideration of both the ink amount of the single dot and the dot interval.

[0036]

According to the present invention, an ink jet type recording head comprising a pressure generating chamber communicating with a nozzle opening and a pressure generating element for giving a pressure change to fly an ink droplet in the pressure generating chamber, and the ink jet type Transfer-type inkjet recording comprising: a transfer medium that receives the ink droplets from the recording head; a backup roller that presses a recording sheet against the transfer medium; and drive means that applies a drive signal to the pressure generating element. In the apparatus, means for detecting a printing state such as a total ink amount of the ink droplets deposited on the transfer medium, and means for controlling a driving speed of the ink jet recording head and the transfer medium according to the total ink amount. By suppressing the deterioration of the image on the transfer medium, the final output with good print quality can be obtained. It can be.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a means for controlling the driving speed of the inkjet recording head and the transfer medium according to the total ink amount in the inkjet recording apparatus of the present invention.

FIG. 3 is a diagram showing a relationship between the print duty and the power consumption of the heater in one embodiment of the inkjet recording apparatus of the present invention.

FIG. 4 is a diagram showing image disturbance due to fluidity of an ink image.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 2: Recording head 3: Backup roller 4: Heater lamp (heating means) 5: Recording paper (recording medium) 6: Temperature sensor (temperature detection means) 7: Output signal processing circuit (heating control) Means) 8: Heating drive circuit (heating control means) 11: Element tube 12: Surface layer 14: Support shaft 15: Bearing 16: Bushing 17: Frame 18: Contact point 19: Driving means A: Rotation direction B: Rotation direction C: Moving direction E: Thick ruled line ball with line width F: Ink-free area

Claims (4)

[Claims] 1. An ink jet recording head comprising a pressure generating chamber communicating with a nozzle opening, and a pressure generating element for giving a pressure change to fly an ink droplet in the pressure generating chamber, and the ink from the ink jet recording head. A transfer medium that receives drops, a backup roller that presses a recording sheet against the transfer medium, a drive unit that applies a drive signal to the pressure generating element, and a total ink amount of the ink drops that are attached to the transfer medium are detected. A transfer type ink jet recording apparatus comprising: a means and a means for controlling a driving speed of the ink jet recording head and the transfer medium according to the total ink amount. 2. The ink jet recording head comprising: the pressure generating chamber communicating with the nozzle opening; and the pressure generating element that gives a pressure change that causes the ink droplet to fly to the pressure generating chamber, and the ink jet recording. The transfer medium that receives the ink droplets from the head, the backup roller that presses the recording sheet against the transfer medium, the drive unit that applies a drive signal to the pressure generating element, the print mode, and the print mode according to the print mode. A transfer-type inkjet recording apparatus comprising: the inkjet recording head; and means for controlling a driving speed of the transfer medium. 3. The transfer type ink jet recording apparatus according to claim 2, wherein the print modes are distinguished by a difference in resolution when the ink droplets are deposited on the transfer medium. 4. The printing mode according to claim 2, wherein the printing mode is distinguished by how many kinds of ink droplets the ink image formed by the ink droplets attached to the transfer medium is composed of. Transfer type inkjet recording device.