JPH10217512A - Image-recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-recording apparatus which nearly uniforms a density for the whole of a page, solves a density difference at a connection part of bands in an image astride a plurality of bands, and can obtain recorded images of good quality. SOLUTION: A recording part 6 drives a recording element 11 arranged at a recording head 1 under a set drive condition according to image data, thereby recording to a medium 9 to be recorded. When a recognizing part 5 recognizes a disconnected part of an image recorded from input image data, the recording part 6 designates a density-adjusting part 4 to determine the drive condition. The density-adjusting part 4 determines the drive condition for the recording part 6 to drive the recording element 11 in accordance with temperatures detected by a head temperature-detecting part 2 and an environment temperature-detecting part 3, etc., to make a record density constant. The recording part 6 drives the recording element 11 according to the newly determined drive condition when a next band and thereafter are to be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial type image recording apparatus for recording an image at predetermined widths (bands) according to image data, and more particularly to a function of adjusting a recording density according to a temperature. The present invention relates to an image recording device.

[0002]

2. Description of the Related Art In an image recording apparatus, it is known that the recording density changes depending on the environmental temperature and the temperature of a recording head. In particular, when recording is performed using heat, as in an image recording apparatus of a heat-sensitive, thermal transfer type, or thermal type ink jet type, this change in recording density is remarkable.

For example, in a thermal ink jet system, the recording density depends on the temperature. In general, as the environmental temperature increases, the recording density increases, and as the environmental temperature decreases, the recording density decreases. Since a normal printing apparatus sets an ink discharge amount at which an appropriate density is obtained at normal temperature (for example, 20 ° C.), the recording density is lower than the appropriate density in a low-temperature environment, and is higher in a high-temperature environment. Therefore, temperature correction such as raising the temperature of the recording head or ink is performed so that an appropriate recording density can be obtained at least even in a low temperature environment.

As a conventional image recording apparatus for performing temperature correction, for example, as described in Japanese Patent Application Laid-Open No. Sho 62-42248, there is an apparatus which performs temperature correction at one page break of continuous paper to adjust density. is there. However, in the case where the density is adjusted only at a page break, if the printing density within one page is high, the density changes at the head and the end, resulting in an unnatural image. In addition, if a pattern having a high image density is continuously printed, there is a problem that the recording head becomes too high in the last part of the page and the ejection becomes unstable.

Further, as described in Japanese Patent Application Laid-Open No. Hei 9-11463 and Japanese Patent Application No. Hei 8-286945, in a serial type image recording apparatus, a temperature is detected at the head of each band in a page and density adjustment is performed. Are doing. As described above, when the density adjustment is performed at the head of each band in the page, when recording an image with high density over a plurality of bands, the density adjustment may be performed in the middle of the image. In such a case, there is a problem that a density difference occurs at the seam of the band, resulting in an unnatural image. Such a density difference can be improved to some extent by performing fine density adjustment. However, in order to perform such fine density adjustment, it is necessary to improve the performance of the temperature detection device, and the control mechanism for the density adjustment becomes large and complicated, so that the cost and the size of the image recording apparatus increase. There is a problem that leads to the conversion.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a uniform density on the entire page and a density difference at a joint portion between bands. It is an object of the present invention to provide an image recording apparatus capable of obtaining a recorded image of high image quality.

[0007]

According to a first aspect of the present invention, there is provided an image recording apparatus for recording an image at predetermined intervals in accordance with image data, comprising: a temperature detecting means; Adjusting means for adjusting the recording density;
A recognition unit for recognizing a boundary of an image from the image data; and a recording unit for operating the adjustment unit in accordance with a recognition result of the recognition unit and recording an image for each predetermined width at the adjusted recording density. It is characterized by the following.

According to a second aspect of the present invention, there is provided an image recording apparatus for recording an image at predetermined intervals in accordance with image data, a temperature detecting means, and an adjusting means for adjusting a recording density according to a detection output of the temperature detecting means. Means, recognition means for recognizing an image segment from the image data, sub-scanning control means for controlling sub-scanning in accordance with the recognition result of the recognition means, and adjusting means in accordance with the recognition result of the recognition means. The image processing apparatus further includes a recording unit that records the image of the predetermined width in the main scanning direction at the recording density adjusted by operating.

According to a third aspect of the present invention, in the image recording apparatus according to the first or second aspect, the recording means applies an electric pulse to a heater to generate heat, thereby causing bubbles to grow in the ink to generate the ink. The image is recorded by a thermal ink-jet method in which the image is made to fly from a nozzle, and the adjusting means adjusts a pulse width of the electric pulse.

According to a fourth aspect of the present invention, in the image recording apparatus according to the third aspect, the electric pulse comprises a pre-pulse and a main pulse, and the adjusting means adjusts a pulse width of the pre-pulse. It is assumed that.

According to a fifth aspect of the present invention, in the image recording apparatus according to the first or second aspect, the adjusting means adjusts a pause time before the recording means performs recording of the predetermined width. It is a feature.

According to a sixth aspect of the present invention, in the image recording apparatus according to the first or second aspect, the adjusting means adjusts a speed at which the recording means performs the recording of the predetermined width. It is assumed that.

[0013]

FIG. 1 is a system configuration diagram showing an embodiment of an image recording apparatus according to the present invention. In the drawing, 1 is a recording head, 2 is a head temperature detecting unit, 3 is an environmental temperature detecting unit, 4 is a density adjusting unit, 5 is a recognizing unit, 6 is a recording unit, 7 is a sub-scanning control unit, 8 is a driving motor, 9 is a recording medium, 10 is a guide rail, 11 is a recording element, 12 is a main scanning direction, 1
3 is a sub-scanning direction.

The recording head 1 is provided with a large number of recording elements 11. The recording elements 11 are provided in one or a plurality of rows at a slight angle from a direction substantially perpendicular to the main scanning direction 12 or a direction perpendicular thereto. The recording elements 11 are provided according to the recording density, and for example, 256 elements are arranged so as to have a resolution of 24 dots / mm. For example, the recording element 11 is a heater in the thermal or thermal transfer method, and is a nozzle having a built-in heater in the thermal inkjet method. FIG. 1 shows only a few pieces. Recording element 1
1 is driven by application of a predetermined electric pulse from the recording unit 6 to perform recording on the recording medium 9.

The recording head 1 is provided with a head temperature detector 2 for detecting the temperature of the recording head 1.
Further, an environmental temperature detector 3 for detecting the environmental temperature is separately provided. Of course, the configuration may be such that only one of the head temperature detecting unit 3 and the environmental temperature detecting unit 4 is provided. The density adjusting unit 4 obtains the temperature of the recording head 1 and the environmental temperature detected by the head temperature detecting unit 2 and the environmental temperature detecting unit 3, and performs recording at an appropriate density at that temperature. , The driving condition of the recording element 11 is set.

For example, image data sent from the outside is input to the recognition unit 5 and the recording unit 6. Recognition unit 5
Recognizes a break in an image to be recorded from input image data. For example, when there is a line on which nothing is recorded in the main scanning direction 12, it is recognized. At this time, it may be recognized that there is a line in which nothing is recorded for one band, or it may be recognized that a line in which nothing is recorded exists at the upper end or the lower end of one band. If a line where nothing is recorded exists at the upper end of one band, it indicates that a new image to be recorded appears from the band. If it exists at the lower end, one of the images to be recorded in the band is displayed. Indicates termination. Each is a break in the image to be recorded. The recognition result in the recognition unit 5 is sent to the recording unit 6 and the sub-scanning control unit 7.

The recording section 6 sends an electric pulse to the recording element 11 of the recording head 1 under the set driving conditions in accordance with the input image data, and drives the recording element 11 to perform recording. At this time, when the recognizing unit 5 recognizes a break in the image, before or after recording of the band, the density adjusting unit 4 sets driving conditions for obtaining an appropriate recording density at the temperature at that time. When the recording density is adjusted after recording of the band, it is desirable to perform the adjustment immediately before recording of the band to be recorded next. Also,
The drive conditions can be set in consideration of, for example, the number of simultaneously driven printing elements 11 described in JP-A-8-11463, in addition to the temperature.

By adjusting the recording density at a break in the image in this way, even if an image covers a plurality of bands, the density difference at the seam between the bands in the image is eliminated. In general, it is rare that all images in one page are high-density images. Since the recording density is adjusted at the breaks of some images, the density difference between the beginning and end of a page is reduced. In this way, a recorded image with good image quality can be obtained.

The recording head 1 is mounted on a carriage (not shown), for example, in a main scanning direction 1 along a guide rail 10.
While moving to 2, recording for one band is performed. At this time, an electric pulse is sent from the recording unit 6 to the recording head 1 in accordance with the set driving conditions according to the image data from the outside as described above, and the recording element 11 is driven by the electric pulse to perform recording. Recording is performed on the medium 9.

When the recording for one band is completed or before the recording for one band is started, the sub-scanning control unit 7 drives the driving motor 8 and normally, the sub-scanning direction is shifted by one band in the sub-scanning direction.
The recording medium 9 is moved to 3. When the recognizing unit 5 recognizes that there is a line in which nothing is recorded for one band, the recording operation of the sub-scanning control unit 7 only moves the recording medium 9 without performing the one-band recording operation. Also,
If the number of unrecorded lines is known by the recognition unit 5, the recording medium 9 may be moved by the number of lines. Note that, in this example, a configuration example in which the recording medium 9 is moved in the sub scanning is shown, but a configuration in which the recording head 1 is also moved in the sub scanning direction may be employed.

FIG. 2 is a flowchart showing an example of the operation of the image recording apparatus according to the embodiment of the present invention.
When a recording command is input from outside, prior to recording an image, first, in S21, a process of determining driving conditions by the density adjusting unit 4 is performed. The drive condition determination process will be described later. When the driving conditions are determined, the sub-scanning control unit 7 moves the recording medium 9 to start recording, and adjusts the position of the recording head 1 to the position on the recording medium 9 to be recorded.

In S23, image data for one band is received. Then, in S24, the recognizing unit 5 recognizes from the received image data whether there is a line for recording nothing for one band. As a result, if there is data to be recorded in the image data for one band, in S25, the recording unit 6 records the received image data for one band in accordance with the set driving conditions.

On the other hand, in the case of an empty band in which no data to be recorded exists in the received image data of one band, the recording unit 6 instructs the density adjusting unit 4 to recognize the empty band in S26. To determine the recording conditions. The density adjusting section 4 determines the recording condition based on the temperatures detected by the head temperature detecting section 2 and the environmental temperature detecting section 3 accordingly. If there is data to be recorded in the next band, the determined recording condition is used at the time of recording after that band.

After the recording of one band in S25 or the determination of the recording condition in S26, the recording medium 9 is moved by the sub-scanning control unit 7 in S27. At this time, if this band is an empty band,
The recording operation is not performed, and only the movement of the recording medium 9 by the sub-scanning control unit 7 is performed.

In step S28, it is determined whether or not the last line of the image data to be received has been reached. If the last line has not been reached, the flow returns to step S23 to perform the recording operation of the image data for the next one band. repeat. At the time when the recording operation up to the last line is performed,
End the job for one recording instruction.

FIG. 3 is a flowchart showing an example of the drive condition determining process in the embodiment of the image recording apparatus of the present invention. Here, the temperature of the recording head 1 is 22 ° C.
It is assumed that the recording density can be properly adjusted in the range of 50 ° C.

First, in step S31, the density controller 4 takes in the head temperature from the head temperature detector 2 attached to the recording head 1. If the temperature of the recording head 1 is 22
If the temperature is equal to or lower than C, it is determined whether or not the page is within the page in S33. . As the temperature raising operation, for example, a so-called half-pulse drive in which an electric pulse that does not perform recording is applied to the recording element 11 to generate only heat is performed. After the temperature raising drive in S34, the process returns to S31 and the temperature of the recording head 1 is measured again, and this temperature raising driving is repeated until the temperature of the recording head 1 exceeds 22 ° C.

On the other hand, if the head temperature exceeds 50 ° C., it is determined whether or not the page is within the page in S35. If the head is at the beginning of the page, the recording is suspended for a predetermined period in S36. Wait for the to cool down naturally. Then, the process returns to S31. In step S31, the temperature of the print head is measured again, and the process is continued until the temperature of the print head 1 becomes 50 ° C. or less.
The recording pause at 36 will continue.

The branch due to the temperature detected by the recording head 1 is 1
Applies only to the beginning of the page. If the temperature within one page is 22 ° C or less or exceeds 50 ° C, 1
In order to suppress the density change in the page, the same adjustment as the adjustment of the recording density in the normal temperature range is performed.

If the temperature of the recording head 1 exceeds 22 ° C. and is 50 ° C. or lower, or if printing is being performed within one page outside this temperature range, the density adjusting unit 4 controls the recording element 11 in step S37. , For example, the pulse width of the electric pulse is determined according to the head temperature. The determined driving conditions are passed to the recording unit 6, and when the recording element 11 is driven thereafter, an electric pulse corresponding to the determined driving conditions is applied to the recording element 11.
Will be driven.

The above temperature setting of 22 ° C. to 50 ° C. is merely an example, and can be set to an optimum temperature at the time of design. Further, the driving conditions may be determined in the same manner in all temperature bands without changing the operation according to the temperature. For example, drive conditions may be set such that the period of the recording suspension performed in S36 is changed depending on the temperature. Further, as described above, the driving condition may be determined in consideration of the position of the recording element 11 and the number of the recording elements 11 driven simultaneously. Further, the driving condition may be determined by utilizing the environmental temperature detection unit 3 and also taking the environmental temperature into consideration.

FIG. 4 is a waveform diagram showing an example of an electric pulse for driving the recording element 11. For example, in a thermal inkjet type image recording apparatus, the recording element 1
As a first configuration, the ink is heated by a heater, bubbles are generated in the ink, and the ink is caused to fly from the nozzles by the pressure at which the bubbles grow. The electric pulse from the recording unit 6 is given to the heater. As the electric pulse given to the heater, for example, FIG.
A single pulse as shown in FIG. 4 and a double pulse composed of a pre-pulse and a main pulse as shown in FIG. 4B are used.

In the case of the single pulse shown in FIG. 4A, the amount of energy applied to the heater changes according to the pulse width, so that the amount of ink droplets flying can be controlled by controlling the amount of heat generated by the heater. Therefore, the density adjusting unit 4 determines the pulse width from the detected temperature and transmits the pulse width to the recording unit 6 as driving conditions. In the recording unit 6, the heater may be driven with a pulse width determined according to the temperature. In general, the viscosity of ink decreases as the temperature increases, so that the amount of ink droplets that fly when given energy is applied increases as the temperature increases, and the recording density increases. Therefore, in the density adjusting unit 4, when the temperature is high, the pulse width is relatively reduced,
When the temperature is low, the pulse width is determined so that the pulse width is relatively large. If the recording is performed by the recording unit 6 based on the determined pulse width, the ink droplet amount becomes substantially constant even when the temperature differs, and the density can be kept substantially constant.

In the case of the double pulse shown in FIG. 4B, the pre-pulse does not fly the ink but only heats the ink. The ink is actually caused to fly by the main pulse. When controlling the amount of flying ink droplets, the pulse width of the pre-pulse is controlled. By controlling the pulse width of the pre-pulse, rather than controlling the pulse width of the main pulse, fine control of the ink droplet amount can be easily performed. For example, when the temperature is high, the pulse width of the pre-pulse is relatively small, and when the temperature is low, the pulse width of the pre-pulse is relatively large. By transmitting a pre-pulse from the recording unit 6 to the heater based on the determined pulse width of the pre-pulse, the ink is locally heated at the nozzle where the heater is disposed, and the temperature of the ink is controlled by the recording head. It is almost constant irrespective of the temperature and the environmental temperature.
Therefore, even if the pulse width of the next main pulse is constant irrespective of the temperature, the amount of flying ink droplets becomes almost constant, and the recording density can be kept almost constant.

When using the double pulse, when the pulse width of the pre-pulse is changed, the interval between the pre-pulse and the main pulse is also changed so that the time from the rise of the pre-pulse to the fall of the main pulse is set to be constant. Good. As a result, it is not necessary to lower the driving frequency even if the pre-pulse becomes longer, and high-speed recording can be maintained.

As a method of determining the pulse width from the temperature in the density controller 4, a table is prepared in advance in which the correspondence between the temperature and the pulse width is obtained, and the pulse width is obtained by referring to the table according to the measured temperature. can do. In this case, according to the present invention, since the density adjustment is not performed in a continuous portion of the image, it is possible to sufficiently cope with a table having a coarse temperature interval. Alternatively, the pulse width may be obtained by calculation from the measured temperature according to a predetermined function.

The above-described method for determining the driving conditions is merely an example, and another method for determining, for example, changing the pulse voltage may be used. In addition, the driving method of the recording element is also the same as these two.
The present invention is not limited to one driving method, and various driving methods can be used, and a density adjusting method suitable for the driving method can be used.

Further, for example, the moving speed and the driving frequency of the recording head 1 in the main scanning direction 12 are changed. For example, when the temperature is high, the recording operation is performed slowly, thereby suppressing the heat generation per unit time and increasing the ink droplet amount. And the recording density can be kept almost constant. As described above, in addition to the method of changing the electric pulse, various methods of adjusting the concentration can be applied.

[0039]

As is apparent from the above description, according to the present invention, the density adjustment is performed at the boundary between the images, so that the apparatus is not increased in cost, complicated or enlarged. Even if the image extends over a plurality of bands, no density difference occurs at the seam of the band,
In addition, when the entire page is viewed, the temperature is adjusted at the boundaries between the images, so that the recording density is substantially uniform at the beginning and the end of the page, and there is an effect that a recorded image with good image quality can be obtained. .

[Brief description of the drawings]

FIG. 1 is a system configuration diagram illustrating an embodiment of an image recording apparatus according to the present invention.

FIG. 2 is a flowchart illustrating an example of an operation of the image recording apparatus according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating an example of a drive condition determining process according to the embodiment of the image recording apparatus of the present invention.

FIG. 4 is a waveform diagram showing an example of an electric pulse for driving the recording element 11.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording head, 2 ... Head temperature detection part, 3 ... Environmental temperature detection part, 4 ... Density adjustment part, 5 ... Recognition part, 6 ... Recording part, 7
... a sub-scanning control unit, 8 ... a drive motor, 9 ... a recording medium, 1
0: guide rail, 11: recording element, 12: main scanning direction, 13: sub-scanning direction.

Claims (6)

[Claims] 1. An image recording apparatus for recording an image at predetermined intervals according to image data, comprising: a temperature detecting means; an adjusting means for adjusting a recording density according to a detection output of the temperature detecting means; A recognition unit for recognizing a boundary between images; and a recording unit for operating the adjustment unit in accordance with the recognition result of the recognition unit and recording an image for each of the predetermined widths at the adjusted recording density. Image recording device. 2. An image recording apparatus for recording an image at predetermined intervals according to image data, comprising: a temperature detecting unit; an adjusting unit for adjusting a recording density according to a detection output of the temperature detecting unit; Recognizing means for recognizing a segment of an image, sub-scanning control means for controlling sub-scanning in accordance with the recognition result of the recognizing means, and the recording adjusted by operating the adjusting means in accordance with the recognition result of the recognizing means An image recording apparatus, comprising: recording means for recording the image having the predetermined width in the main scanning direction at a density. 3. The recording means for recording an image by a thermal ink jet system in which an electric pulse is applied to a heater to generate heat, a bubble is grown in the ink, and the ink flies from a nozzle. The adjustment means
The image recording apparatus according to claim 1, wherein a pulse width of the electric pulse is adjusted. 4. The image recording apparatus according to claim 3, wherein said electric pulse comprises a pre-pulse and a main pulse, and said adjusting means adjusts a pulse width of said pre-pulse. 5. The image recording apparatus according to claim 1, wherein the adjusting unit adjusts a pause time before the recording unit performs recording of the predetermined width. 6. The image recording apparatus according to claim 1, wherein the adjusting unit adjusts a speed at which the recording unit performs the recording of the predetermined width.