JP3253105B2 - Ink jet recording apparatus and ink jet recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid jet recording apparatus and, more particularly, to a recording apparatus in which a liquid is heated by using an electrothermal energy converter to discharge liquid droplets.

[0002]

2. Description of the Related Art The liquid jet recording method is a recording method in which ejection droplets of a recording liquid (ink) are formed by various methods, and these are adhered to a recording material such as paper to perform recording.

[0003] Among the printing apparatuses to which such a printing method is applied, an apparatus having a structure suitable for forming a high density multi-orifice of a printing head is a liquid jet printing type utilizing heat as energy for forming a droplet to be ejected. Devices can be mentioned.

A liquid jet recording apparatus utilizing heat as the droplet discharge energy usually heats the recording liquid to give the recording liquid a displacement accompanied by a sudden increase in volume, and discharges the recording liquid from an orifice of a nozzle portion to perform recording. The recording head includes a liquid droplet forming means for forming liquid droplets, that is, a recording head having an electric-thermal energy converter that generates heat by applying an electric signal and can heat the recording liquid.

In the liquid jet recording apparatus, the liquid jet characteristics, particularly the droplet diameter, are affected by the temperature of the recording head, and the print density changes with the temperature. Therefore, temperature control such as keeping the temperature of the recording head constant is performed. Done.

FIG. 8 shows an ink jet printer head for heating and bubbling a liquid by a heater as described above to discharge droplets, and particularly shows details of a discharge element 18 as a main part thereof.

Here, the heaters H ₁ and H ₁ for heating and maintaining the temperature of the head are used.
H ₂ , 25 and 26 are made of the same material as the heater 23 for discharging, and
i formed on the substrate 21, by the head temperature information from the on-board temperature detecting means (thermistor 19) on the base plate 13, heated heater H _1, H _2, the energization of the 25, 26 are ON-OFF control This controls the head temperature. Reference numeral 22 denotes an orifice from which ink is ejected, 24 denotes a nozzle communicating with the orifice 22, 2
Reference numeral 8 denotes a liquid chamber for supplying ink from an ink tank (not shown) to the nozzle 24, and reference numeral 29 denotes a filter. Each heater 23,
The wires 25 and 26 are connected to the electric wiring board 14 via the Al wiring 27 by wire bonding 30.

[0008]

However, in a liquid jet recording head that ejects liquid droplets by using thermal energy, the recording head itself generates heat by performing recording, so that the ink in the nozzle having the ejection heater is heated. During recording, the temperature is higher than the temperature detected by the temperature detecting means, and the degree differs depending on the recording pattern and recording density. Therefore, in general, during printing at a high printing density such as an image pattern, the ink temperature in the nozzle is high and the printing density is high. On the other hand, at the time of recording having a relatively low recording density such as character printing, the printing density is low, and the same printing density cannot always be obtained.

In the case of printing an image pattern, multi-pass printing is sometimes performed in which one-line printing is divided into a plurality of carriage scans in order to improve image quality (color boundary blur, blur, etc.). Also in this case, a difference in print density may occur due to a difference in head temperature rise due to a difference in print density during each scan. Furthermore, if the print density at each scan is different, the state of penetration of the recording liquid onto the recording medium will be different, and in general, when printing is performed a plurality of times at a low print density, compared to printing at a high print density in one pass. However, since the lateral spread of the individual droplets on the recording material is smaller, the apparent print density is lower.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to provide a liquid jet recording apparatus capable of eliminating a difference in print density due to a difference in recording mode.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an ink jet recording apparatus which performs recording on a recording medium using a recording head for discharging ink. Discriminating means for discriminating whether to record or to record an image; and when the discriminating means determines that the image is to be recorded, the same line on the recording medium is recorded by one scan of the recording head. Selecting means for selecting which of the one-pass print mode and the multi-line print mode for printing the same line by scanning the print head a plurality of times, the print mode, and the selecting means Ejection amount control means for controlling an ink ejection amount per droplet ejected from the recording head according to the recording mode selected by The ejection amount control means increases an ink ejection amount per droplet when printing an image in the multi-pass printing mode, as compared to when printing an image in the one-pass printing mode. Things.
Further, the present invention is an ink jet recording method for performing recording on a recording medium using a recording head for discharging ink, and a determination step of determining whether to record a character or an image, When it is determined in the determining step that an image is to be printed, a one-pass print mode in which the same line on the print medium is printed by one scan of the print head, and the same line is printed by a plurality of scans of the print head. A selection step of selecting which of the multi-pass printing modes for printing the image is to be printed, and a droplet ejected from the print head according to the printing mode selected in the selection step. And a discharge amount control step for controlling the ink discharge amount of the ink. Te, the ink discharge amount per droplet in the case of recording an image in the multi-pass recording mode is characterized in that large. According to the above configuration, since the ink ejection amount per droplet is made different depending on the printing mode (one-pass printing mode or multi-pass printing mode), it is possible to reduce a difference in print density due to a difference in printing mode.

[0012]

FIG. 5 is a schematic diagram showing an example of the configuration of a liquid jet recording apparatus to which the present invention can be applied.

The liquid jet recording head 2 is mounted on a carriage 3 that is scanned left and right by a carriage driving motor (CR motor) (not shown) and a carriage driving belt 11 on a sliding shaft 10. An electric signal from the main board 7 is supplied via a flexible printed circuit (FPC) 6. The recording liquid is supplied from the ink cartridge in the main body of the liquid jet recording apparatus 1 (not shown) to the liquid jet recording head 2 via the sub ink tank 4 on the carriage 3 via the ink supply suction tube 5. In addition, the liquid jet recording head 2 rarely causes a discharge failure due to the incorporation of air bubbles and the adhesion of the recording liquid to the orifice surface.
At the home position of the carriage 3 of the liquid jet recording apparatus 1, a suction recovery device is provided. The recording medium is sent upward by a paper feed motor (LF motor) (not shown) on the platen 9, and the recording head 2 is scanned left and right to perform recording on the recording medium.

FIG. 6 is a block diagram showing an example of the configuration of the control section (main board 7) of the liquid jet recording apparatus 1. The control unit receives print data from, for example, a host computer, stores print data for one line, and performs printing by controlling the recording head 2 by the head controller 31 of the recording head 2.

First, a PPI (Programmable Peripheral Interface) 32 receives print data sent from the host computer of the recording apparatus according to the present embodiment in parallel and sends print data to the CPU 33. CPU
33 executes various processing procedures of the recording apparatus according to the contents of the control ROM 34. RAM 35 is a line buffer memory for storing print data received by PPI 32 for several lines,
The font generating ROM 36 is a memory that stores fonts of print output characters, and the control ROM 34 is a memory that stores processing procedures executed by the CPU 33. These are connected via an address bus and a data bus.

The I / O controller 37 includes a paper feed motor (LF motor) 38, a carriage drive motor (CR motor) 39, and a suction recovery device drive motor (pump motor) 4.
0, control of data input / output to and from the panel switch 41, control of the heat retention heater in the print head 2, print head 2
This is an IC for exclusively controlling the input of temperature information from a temperature detecting means (thermistor) in the apparatus based on a command from the CPU 33. The head controller 31 is a dedicated IC that latches print data and print output time, and sends a print output to the recording head 2 in response to a command from the CPU 33. The recording head 2 discharges a recording liquid and performs recording on a recording medium in accordance with print data and print output time data from the head controller 31.

FIG. 7 is a schematic diagram showing an example of the configuration of a liquid jet recording head, particularly an ink jet head utilizing heat as ejection energy. On a base plate 13, an electric wiring board (PCB) 14, a thermistor 19, and a discharge element 18 composed of a nozzle, a heater, and a liquid chamber for discharging a recording liquid are joined. This discharge element 1
8, the print data from the FPC 6 (FIG. 3) is transmitted through the electric wiring board 14 by the engagement of the head connector 12 (FIG. 3) on the FPC 6 and the connector portion 15 of the electric wiring board 14 on the recording head 2. Is transmitted.

The recording liquid is supplied to the ejection element 18 via a holder 16 for protecting a main part of the recording head integrated with the ink supply pipe 17 and the liquid reservoir 20. The details of the ejection element 18 are the same as those shown in FIG.

The temperature of the recording head is controlled by the discharge heater 23.
This is performed in order to maintain the print head 2 at a temperature suitable for a predetermined ink discharge amount using the heat retention heaters 25 and 26 provided separately, and is performed at the time of printing and in a predetermined standby state. FIG. 9 shows an example of the ejection amount obtained according to the head warming temperature. About 34 pl / drop at 32 ° C, 4
At 0 ° C., the amount of ejection becomes about 42 pl / drop, and there is a substantially proportional relationship in this temperature range. (First Embodiment) FIG. 1 shows a first embodiment of the present invention, in which temperature control of a print head during printing is performed. It is a flowchart regarding. When the power of the recording apparatus is turned on, first, in step S1, the CPU 33 maintains the head temperature at 25 ° C. via the I / O controller 37, and enters a print signal input standby state. Step S2
When a print signal is input via the PPI 32 in step S3, the CPU 33 determines in step S3 whether the record is a character (text) or an image based on a control signal in the print signal. If it is a character, the CPU 33 proceeds to step S
In step 4, the head warming temperature is set to 38 ° C., and printing is performed in step S5. On the other hand, if the input print signal is an image, printing is performed in step S6 by setting the head warming temperature to 32 ° C.

Thus, by increasing the ink ejection amount in the case of character printing with a low print density, a print density equivalent to image printing with a high print density can be obtained.

(Second Embodiment) In this embodiment, when an image is printed, it is classified into one-pass printing and multi-pass printing. FIG. 2 is an explanatory diagram of one-pass printing and multi-pass printing.

FIG. 2A shows one-pass image printing, in which solid printing is constituted by one carriage scan.

FIG. 2B shows two-pass image printing, in which two carriage scans are performed and overprinting is performed at a position where interpolation is performed at a printing density of 1/2. This is an effective recording method for preventing boundary bleeding.

In this case, the image obtained by the sum of the first scanning and the second scanning is the same as the one-pass printing shown in FIG. 2A, but the printing density in one scanning printing is low. The temperature rise in the nozzle portion of the head is reduced, and the volume of the discharged droplet is reduced. Furthermore, since the printing density is low,
Since the lateral bleeding on the recording medium is smaller than that in one pass, the print density of an image obtained by two scans as a result is lower than that in one pass printing.

Similarly, FIG. 2C shows a multi-pass printing method capable of obtaining high-definition printing. In this method, the paper feed amount is set to 送 り line between each scan, and the printing is performed. Is a printing method that can be made inconspicuous in visual observation. In this case as well,
The print density is lower than one-pass printing.

FIG. 3 is a flow chart showing a second embodiment of the present invention, in which step S7 is added to FIG. In this embodiment, if the recording mode is image, it is determined in step S7 whether the image mode is one pass or multi-pass. In the case of one pass, the head warming temperature is set to 3
The temperature is set to 2 ° C., and in the case of multi-pass printing, the temperature is set to 38 ° C. which is the same as that for characters in step S4.

Thus, one pass during image recording,
Multi-pass print density can be eliminated.

(Third Embodiment) FIG. 4 is a flow chart showing a third embodiment, in which the head heat retaining temperature can be set more precisely. That is, step S8 in FIG. 3 is added. In the case of the character mode (text mode), 38 ° C. in step S4, in the case of a one-pass image, 32 ° C. in step S6, and in the case of a multi-pass image, 35 ° C. Set to ° C.

As a result, the printing density difference between the printing modes can be further reduced.

In each of the above embodiments, the print density is controlled to be uniform in each print mode.
The present invention can also be applied when it is necessary to make the print density in a specific mode particularly high or low as compared with other modes.

In the present embodiment, the temperature of the recording head is controlled to control the ink discharge amount. However, the present invention is not limited to this.

The present invention provides an excellent effect particularly in a recording head and a recording apparatus of a type utilizing thermal energy among ink jet recording types.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or liquid path in which , Heat energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head.
As a result, air bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal, which is effective. The growth of this bubble,
The liquid (ink) is discharged through the discharge opening by contraction to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. The drive signal in the form of a pulse is disclosed in U.S. Pat.
Suitable are those described in 345262. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

[0034]

As described above, according to the present invention, the recording mode of the input print signal is identified, and the recording head warming temperature is set for each mode, so that the difference in print density between the recording modes can be reduced. Can be smaller.

The present invention is also effective when it is necessary to make the print density in a specific mode particularly high or low as compared with other modes.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating head temperature control according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an image recording method.

FIG. 3 is a flowchart illustrating head temperature control according to a second embodiment.

FIG. 4 is a flowchart illustrating head temperature control according to a third embodiment.

FIG. 5 is a schematic diagram of a liquid jet recording apparatus to which the present invention can be applied.

FIG. 6 is a block diagram of a control unit of the liquid jet recording apparatus to which the present invention can be applied.

FIG. 7 is a schematic diagram of a liquid jet recording head to which the present invention can be applied.

FIG. 8 is a sectional view of a main part of a liquid jet recording head to which the present invention can be applied.

FIG. 9 is a diagram illustrating a correlation between a head temperature control temperature of a recording head and a discharge amount.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid ejection recording apparatus 2 Liquid ejection recording head 3 Carriage 13 Base plate 18 Discharge element 19 Thermist 22 Orifice 23 Discharge heater 24 Nozzle 25 Head heat retaining heater H ₁ 26 Head heat retaining heater H ₂ 32 PPI 33 CPU 34 Control ROM 35 RAM

Claims (12)

(57) [Claims] An ink jet recording apparatus that performs recording on a recording medium using a recording head for discharging ink, comprising: a determination unit configured to determine whether to record a character or an image. When it is determined that the image is to be printed by the determining means, the same line on the recording medium is
A selection for selecting which printing mode to print the image from among a one-pass printing mode for printing by one scan and a multi-pass printing mode for printing the same line by multiple scans of the print head. Means, according to the recording mode selected by the selecting means,
An ejection amount control unit for controlling an ink ejection amount per droplet ejected from the recording head, wherein the ejection amount control unit is compared with a case where an image is recorded in the one-pass recording mode. An ink jet recording apparatus for increasing an ink ejection amount per droplet when recording an image in the multi-pass recording mode. 2. The ink jet recording apparatus according to claim 1, wherein the discharge amount control means controls the ink discharge amount per droplet by controlling a heat retaining temperature of the recording head. 3. The discharge amount control means sets a higher heat retaining temperature of the print head when printing an image in the multi-pass printing mode than when printing an image in the one-pass printing mode. 3. An ink jet recording apparatus according to claim 2, wherein the ink ejection amount per droplet is increased. 4. When printing an image in the one-pass printing mode, the heating temperature of the print head is set to a first temperature, and when printing the characters and printing the image in the multi-pass printing mode. In this case, by setting the heat retaining temperature of the recording head to a second temperature higher than the first temperature, compared with the case of recording an image in the one-pass recording mode,
4. The ink jet printer according to claim 2, wherein the ink ejection amount per droplet is increased when the character is printed and when the image is printed in the multi-pass printing mode. Recording device. 5. When recording an image in the one-pass recording mode, the heat-retention temperature of the recording head is set to a first temperature, and when recording an image in the multi-pass recording mode, the recording head is set to a first temperature. In the case where the heat retaining temperature is set to a second temperature higher than the first temperature and the characters are recorded, the heat retaining temperature of the recording head is set to a third temperature higher than the second temperature.
By setting the temperature of the above, compared with the case of printing an image in the multi-pass printing mode and the case of printing an image in the one-pass printing mode,
4. The method according to claim 2, wherein when printing the character, the ink ejection amount per droplet is increased.
3. The ink jet recording apparatus according to claim 1. 6. The ink jet recording apparatus according to claim 1, wherein the recording head has at least an electrothermal transducer for discharging ink. 7. An ink jet recording method for performing recording on a recording medium by using a recording head for discharging ink, comprising: a discriminating step of discriminating whether to record a character or an image; If it is determined in the determining step that the image is to be printed, the same line on the printing medium is
A selection step of selecting which print mode to print the image from among a one-pass print mode in which printing is performed by one scan and a multi-pass print mode in which the same line is printed by performing multiple scans of the print head. According to the recording mode selected in the selecting step,
An ejection amount control step for controlling an ink ejection amount per droplet ejected from the print head, wherein the ejection amount control step is performed in comparison with a case where an image is printed in the one-pass printing mode. An ink jet recording method, wherein an ink ejection amount per droplet is increased when an image is recorded in the multi-pass recording mode. 8. The ink jet recording method according to claim 7, wherein in the ejection amount control step, the ink ejection amount per droplet is controlled by controlling a heat retaining temperature of the recording head. 9. In the discharge amount control step, a heat retaining temperature of the print head is set higher when printing an image in the multi-pass printing mode than when printing an image in the one-pass printing mode. 9. The ink jet recording method according to claim 8, wherein the ink ejection amount per droplet is increased. 10. When printing an image in the one-pass printing mode, the heating temperature of the print head is set to a first temperature, and when printing the characters and printing the image in the multi-pass printing mode. In this case, by setting the heat retaining temperature of the recording head to a second temperature higher than the first temperature, compared with the case of recording an image in the one-pass recording mode,
10. The ink-jet apparatus according to claim 8, wherein the ink ejection amount per droplet is increased when the character is printed and when the image is printed in the multi-pass printing mode. Recording method. 11. When printing an image in the one-pass printing mode, the heat-retention temperature of the printing head is set to a first temperature. When printing an image in the multi-pass printing mode, the printing head is controlled by the printing head. In the case where the heat retaining temperature is set to a second temperature higher than the first temperature and the characters are recorded, the heat retaining temperature of the recording head is set to a third temperature higher than the second temperature.
By setting the temperature of the above, compared with the case of printing an image in the multi-pass printing mode and the case of printing an image in the one-pass printing mode,
10. The method according to claim 8, wherein the ink ejection amount per droplet is increased when the character is recorded.
3. The inkjet recording method according to item 1. 12. The ink jet recording method according to claim 7, wherein said recording head has at least an electrothermal transducer for discharging ink.