JP2002331687A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus in which the print speed can be increased while feeding recording sheets sheet by sheet, and a suitable ink tank is provided. SOLUTION: Recording is performed by moving any one of a first and second line head blocks 110 and 111 to a first recording position A or by moving any one of a third and forth line head blocks 112 and 113 to a second recording position B. Since respective ink tanks 201-204 are connected removably to the end part of the first through to fourth line head blocks 110-113, ink of respective colors can be fed easily from respective ink tanks 201-204 to the first through the fourth line head blocks 110-113 even if the first through to fourth line head blocks 110-113 are moved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording sheet by discharging ink toward the recording sheet.

[0002]

2. Description of the Related Art As is well known, in an ink-jet type image forming apparatus, ink is transferred from a print head to a recording sheet while a carriage on which a print head is mounted is repeatedly reciprocated in a direction perpendicular to the recording sheet conveyance direction. And an image is formed on the recording paper. Such an image forming apparatus is always required to have a higher printing speed, as with other types of apparatuses. In order to meet this demand, in the case of the ink jet system, it is general to increase the number of nozzles of the print head to increase the printing area in one scan, or to increase the moving speed of the carriage, that is, the scanning speed. Met. However, each of these methods has its limitations, and the printing speed cannot be drastically increased.

For this reason, for example, Japanese Patent Application Laid-Open No. H10-34902
In the publication, as shown in FIG. 12, print heads 91a and 91b are provided on both sides of one carriage 91, respectively.
Print heads 91 from the two paper cassettes 92a and 92b.
a, 91b, the respective recording sheets of the odd-numbered pages and the even-numbered pages are conveyed, and printing on these recording sheets is performed simultaneously.
The even-numbered recording paper is directly guided to the discharge tray 94 and discharged, and the odd-numbered recording paper is guided to the reversing path 93, and the recording paper is reversed and then discharged to the discharge tray 94. If recording is performed simultaneously on odd-numbered pages and even-numbered pages, the printing speed is greatly increased.

[0004]

However, the apparatus described in the above publication requires two paper feed cassettes and two systems of transport paths, and thus the apparatus is increased in size. In addition, in order to discharge the odd-numbered recording paper to the discharge tray 94 after turning over the recording paper, the leading and trailing ends of the even-numbered pages and the odd-numbered pages are reversed in the discharge tray 94. Furthermore, the resolution of the image on the recording paper was not changed.

For this reason, the applicant of the present invention has developed an image forming apparatus capable of increasing the printing speed and changing the resolution of an image while conveying recording paper one by one. is suggesting.

However, in this image forming apparatus, a conventional ink tank cannot be applied due to its special structure.

In view of the above, the present invention has been made in view of the above-mentioned conventional problems, and it is possible to increase the printing speed and change the resolution of an image while conveying recording sheets one by one. It is an object of the present invention to provide an image forming apparatus provided with a suitable ink tank on the premise of an image forming apparatus capable of performing such operations.

[0008]

In order to solve the above-mentioned problems, the present invention provides a plurality of line heads extending in a direction perpendicular to the direction of transport of a recording sheet, and recording on the recording sheet by each line head. In the image forming apparatus for performing the above, an ink tank for storing ink supplied to the line head is attached to an end of the line head.

According to the image forming apparatus of the present invention having such a configuration, the ink tank is attached to the end of the line head. Therefore, for example, even if the line head is moved,
Ink can be easily supplied from the ink tank to the line head. If the ink tank is provided separately from the line head and the line head is moved, it becomes difficult to supply ink from the ink tank to the line head.

In the present invention, each ink tank has the same shape and the same size.

For example, if the rectangular ink tanks are attached to the ends of the line heads arranged side by side, the ink tanks are arranged neatly, so that the space for each ink tank can be saved.

Further, in the present invention, one ink tank is attached to the ends of a plurality of line heads, and each line head shares the ink tank. Alternatively, a pair of line heads are directed in opposite directions, one ink tank is attached to an end of the pair of line heads, and the pair of line heads share the ink tank.

When one ink tank is attached to the ends of a plurality of line heads, the capacity of the ink tank can be increased. The ink tank may store ink of a frequently used color.

[0014]

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

FIG. 1 is a side view schematically showing an embodiment of the image forming apparatus of the present invention. In this image forming apparatus, the recording paper is pulled out from the paper feed tray 141 and conveyed to the first recording position A.
The recording paper is conveyed around and guided to the second recording position B, after which the recording paper is discharged to the discharge tray 160. During this conveyance, recording on a recording sheet is performed at least at one of the first recording position A and the second recording position B.

In this image forming apparatus, the first line head block 110 and the second line head block 1
11 and the third line head block 1
The twelfth and fourth head blocks 113 are integrated.
As shown in FIG. 2, the first and second line head blocks 11
0 and 111 are movably supported by two shafts 171 and are moved up and down by a drive source (not shown).
Similarly, the third and fourth line head blocks 112 and 11
3 is also movably supported by two shafts 172 and is moved up and down by a drive source (not shown).

Further, as shown in FIG. 3, the tips of the ink pipes 211 protrude from both ends of the first and second line head blocks 110 and 111, and as shown in FIG. Ink tank 201, 2
02, 203 and 204 are detachably connected.
Similarly, the third and fourth line head blocks 112, 1
The end of each of the ink pipes 211 protrudes from both ends of the ink pipe 13, and four ink tanks 201, 202, 203, and 204 are detachably connected to the end of each of the ink pipes 211.

Each of the ink tanks 201, 202, 203,
And 204 store yellow, magenta, cyan, and black inks, respectively. Ink tanks 201, 2 of the first and second line head blocks 110, 111
02, 203, and 204 supply the respective color inks to the respective line head blocks through the respective ink pipes 211. Similarly, the ink tanks 201 and 202 of the third and fourth line head blocks 112 and 113,
203 and 204 supply the respective color inks to the respective line head blocks through the respective ink pipes 211.

As shown in FIG. 2, the first to fourth line head blocks 110 to 113 include four rows of line heads 11.
5, 116, 117, and 118. Each of the line heads 115, 116, 117, and 118 has a plurality of nozzle orifices 122 arranged therein. The numbers and arrangement intervals of the nozzle orifices 122 of the line head are equal between the first to fourth line head blocks 110 to 113.

Each of the line heads 115, 116, 117,
And 118, yellow, magenta, cyan, and black inks are supplied from respective ink tanks 201, 202, 203, and 204 through respective ink pipes 211, and the respective color inks are supplied to the respective nozzle orifices 12 and 12.
Discharge from 2. First to fourth line head blocks 1
The diameter of each nozzle orifice 122 differs between 10 and 113. As shown in FIG. 4, the nozzle orifices 122a of the first line head block 110 have the largest diameter, the nozzle orifices 122b of the second line head block 111 have the second largest diameter, and the nozzle orifices 122b of the third line head block 112 have the second largest diameter. The nozzle orifice 122c has the third largest diameter and the fourth line head block 11
The diameter of each nozzle orifice 122d of No. 3 is the smallest.
The smaller the diameter of the nozzle orifice 122, the smaller the particle size of the ejected ink. Also, the larger the diameter of the nozzle orifice 122, the greater the amount of ink discharged per unit time. Conversely, if the same amount of ink is ejected, the larger the diameter of the nozzle orifice 122, the shorter the ink ejection time.

Each nozzle of the line head has a known structure. That is, a piezo element is provided adjacent to the ink chamber of the nozzle, and a voltage is applied to the piezo element,
The piezo element is deformed, thereby generating a pressure wave in the ink chamber and discharging ink from the ink chamber through the nozzle orifice (see, for example, JP-A-6-23979).

Further, as shown in FIG. 1, the first to fourth line head blocks 110 to 113 are provided with sensors 102, 103, 104 and 105, respectively. Each of the sensors 102 to 105 detects the pitch mark 101 fixed at a predetermined position on the apparatus main body side as the respective line head blocks move up and down. When the pitch mark 101 is detected by the sensor 102, the first line head block 110 moves to the first recording position A on the recording paper.
Placed in Further, when the pitch mark 101 is detected by the sensor 103, the second line head block 111 is arranged at the first recording position A of the recording paper.
Similarly, when detected by the sensor 104, the third line head block 112 is arranged at the second recording position B, and when detected by the sensor 105,
The line head block 113 is arranged at the second recording position B.

As shown in FIG. 5, each of the sensors 102 to 105
Is a light emitting element 221, a light receiving element 222, and a lens 22
3 is provided. The light emitting element 221 emits light to the outside of the line head block. When the light of the light emitting element 221 is reflected by the pitch mark 101 at a predetermined position as the line head block moves up and down, the reflected light enters the light receiving element 222. The pitch mark 101 can be detected based on the light receiving output of the light receiving element 222 at this time.

As shown in FIG. 1, a large number of recording papers P are stacked and stored in a paper supply tray 141, and the uppermost recording paper is pulled out by a paper supply roller 125 and guided to a transport path. The recording paper is transported to the first recording position A by the transport rollers 130, and is transported to the suction drum 150 by the transport rollers 6. Furthermore, the recording paper is
While being sucked by the suction drum 150 and being pressed against the outer periphery of the suction drum 150 by the respective conveying rollers 8, 9, and 10, it is conveyed by the suction drum 150 rotating in the direction of the arrow. Subsequently, the recording paper is transported to each transport roller 1.
The sheet is conveyed to the second recording position B by the sheet 31 and finally discharged to the sheet discharge tray 160 by the respective conveying rollers 132.

As shown in FIG. 6, the suction drum 150 is cylindrical and has a number of small holes 150a formed on the outer periphery thereof, and an exhaust fan 151 is provided at an opening 150b at one end. . The air in the suction drum 150 is exhausted by the exhaust fan 151, and the air is sucked into the suction drum 150 through the small holes 150 a, thereby sucking the recording paper to the outer periphery of the suction drum 150.

Further, on the recording paper transport path, respective paper detection sensors 120 and 121 are provided immediately before each transport roller 130 and immediately before each transport roller 131, respectively.
The sheet detection sensors 120 and 121 detect the leading edge of the recording sheet.

The first recording position A to the second recording position B
The transport distance up to is set according to the length of the A4 recording sheet, where the maximum recording sheet size is A4. First
When the transport distance from the recording position A to the second recording position B is longer than the recording paper of A4, the recording at the second recording position B is performed after the recording at the first recording position A is completed.
If the transport distance from the first recording position A to the second recording position B is shorter than the recording paper of A4, the first recording position A
In the middle of the recording, the recording at the second recording position B is started, and the respective recording time zones partially overlap.
The recording time is reduced.

FIG. 7 shows a configuration of a drive control system of the image forming apparatus according to the present embodiment. The control unit 231 controls the block driving unit 232 while detecting the positions of the first to fourth line head blocks 110 to 113 based on the detection outputs of the sensors 102 to 105, thereby performing the first
And the second and fourth line head blocks 110 and 111 are moved up and down.
2 and 113 are moved up and down to control the positions of the first to fourth line head blocks 110 to 113, respectively. The control unit 231 controls the transport driving unit 233 to rotate the paper feed roller 125, each transport roller, and the suction drum 150 to rotate the recording paper and feed the recording paper to the paper feed tray 14.
Pull out from 1 and transport. Further, the control unit 231 performs the following based on the detection output of each of the sheet detection sensors 120 and 121.
The leading edge of the recording sheet is detected, and the transport speed of the recording sheet is determined based on the rotation speed of each transport roller and the suction drum 150. The control unit 231 then determines the timing of detecting the leading edge of the recording sheet and the transport speed of the recording sheet based on
The position of the leading edge of the recording paper in the transport path is detected. In addition, the control unit 231 drives the first to fourth line head blocks 110 to 113 by controlling the line head drive control unit 234 to eject ink from at least one line head block to recording paper. .

Next, a process of recording an image on a recording sheet by the image forming apparatus of this embodiment will be described with reference to a flowchart shown in FIG.

First, when the power supply of the image forming apparatus is turned on, the first line head block 1 having the nozzle orifices 122 having the largest diameter is in an initial state.
10 is disposed at a first recording position A, and a third line head block 112 having nozzle orifices 122 having the third largest diameter is disposed at a second recording position B. When the second line head block 111 is arranged at the first recording position A or the fourth line head block 113 is arranged at the second recording position B, the second line head block is operated by operating the operation key of the image forming apparatus. The block 111 or the fourth line head block 113 is selected. In response, the control unit 231 moves the first and second line head blocks 110 and 111 up and down through the block driving unit 232, and moves the second line head block 111 to the first recording position based on the detection output of the sensor 103. A, or move the third and fourth line head blocks 112 and 113 up and down through the block drive unit 232, and move the fourth line head block 113 to the second recording position B based on the detection output of the sensor 105. .

Thereafter, when an image recording is requested by operating an operation key or the like of the image forming apparatus or by an external computer, the control unit 231 controls the transport driving unit 233 to supply the paper feed roller 125 and each transport roller. By rotating the suction drum 150, the recording paper is pulled out from the paper feed tray 141 and transported (step S1).
Then, when the leading end of the recording sheet is detected by the sheet detection sensor 120 ("Ye" in step S2).
s "), the detection of the leading edge position of the recording sheet in the transport path is started based on the detection timing of the leading edge of the recording sheet and the transport speed of the recording sheet (step S3). Subsequently, when the leading end of the recording sheet moves to the preset position after passing the first recording position A, the control unit 231 controls the start of image recording and the line head drive control of the line head block at the first recording position A. Instruct the unit 234. In response, the line head drive control unit 234 drives the line head block at the first recording position A to start recording an image on recording paper (step S4). Further, the control unit 2
31 is that when the leading edge of the recording paper moves by the length of the image,
The end of the image recording is instructed to the line head drive control unit 234, and the recording of the image by the line head block at the first recording position A is terminated (step S5).

Subsequently, the recording paper is sequentially conveyed by the respective conveying rollers 6, the suction drum 150, and the respective conveying rollers 131, and is guided to the second recording position B. And
When the leading edge of the recording paper is detected by the paper detection sensor 121 (“Yes” in step S6), the paper detection sensor 1
Based on the detection timing of the leading edge of the recording paper by the recording paper 21 and the transport speed of the recording paper, the detection of the leading edge position of the recording paper in the transport path is started (step S7). After passing through and moving to a preset position, the line head drive control unit 234 drives the line head block at the second recording position B to start recording an image on recording paper (step S).
8) When the leading edge of the recording paper is transported by the length of the image,
The recording of the image ends (step S9).

The recording paper on which the image has been recorded at the first and second recording positions A and B in this manner is transferred to each of the transport rollers 132.
And is discharged to the paper discharge tray 160.

Here, the same image is recorded on the same recording paper at both the first recording position A and the second recording position B. In this case, the first recording position A and the second recording position B
Since the respective inks ejected from the two line head blocks overlap on the recording paper, it can be considered that the amount of ink ejected per unit time has increased, and the transport speed of the recording paper has been increased. , The recording speed can be increased. In other words, since the amount of ink ejected per unit time is increased, the time for ejecting the amount of ink per dot is shortened. Therefore, the ink ejection interval is shortened, and the recording time for one line is shortened. However, as the recording time for one line is reduced, the transport speed of the recording paper is increased. As described above, the number and arrangement intervals of the nozzle orifices 122 of the line head are equal between the first to fourth line head blocks 110 to 113. For this reason, the images formed by the two line head blocks of the first recording position A and the second recording position B just overlap on the recording paper, and the quality of the image can be kept good.

The first recording position A and the second recording position B
The image may be recorded on the recording paper only in any one of the above. That is, the first and second line head blocks 11
0 or 111 is moved to the first recording position A, and recording is performed only by the line head block positioned at the first recording position A, or one of the third and fourth line head blocks 112 and 113 is performed. Is moved to the second recording position B, and recording is performed only by the line head block positioned at the second recording position B. Here, the first to fourth
The nozzle orifices 122 have different diameters between the line head blocks 110 to 113. In the first line head block 110 having the largest nozzle orifice 122, the nozzle orifice 12
2 to the largest amount of ink ejected per unit time. Therefore, when only the first line head block 110 is selected, the control of the line head drive control unit 234 shortens the ink discharge time per dot and also shortens the ink discharge interval. To shorten the recording time for one line. Accordingly, the transport speed of the recording paper by the transport drive unit 233,
That is, the recording speed can be increased. Further, as the diameter of each nozzle orifice 122 of the line head block becomes smaller, the amount of ink ejected from each nozzle orifice 122 per unit time becomes smaller, so that the diameter of each nozzle orifice 122 of the selected line head block becomes smaller. Accordingly, the ejection time and the ejection interval of the ink per dot are increased, and the transport speed of the recording paper is decreased to decrease the recording speed. However, the smaller the diameter of each nozzle orifice 122, the smaller the particle size of the ejected ink, so that a high-resolution image can be recorded on recording paper.

Alternatively, as shown in FIG.
Then, the ink 241 having a large particle diameter is superimposed on the dot, and then the ink 242 having a small particle diameter is superimposed on the same dot at the second recording position B, so that the colors of the inks 241 and 242 are different from each other. , More diverse colors can be expressed.

Further, in the image forming apparatus of this embodiment, the recording paper is conveyed one by one and discharged, so that the leading and trailing ends of the even and odd pages are reversed as in the conventional apparatus. There is no. Further, unlike the conventional apparatus, two paper feed cassettes and two transport paths are not required, so that the apparatus can be downsized.

By the way, in the image forming apparatus of this embodiment, the first and second line head blocks 110, 1
11, ink tanks 201 to 204 are arranged at both ends. Therefore, the first and second line head blocks 1
Each of the ink tanks 201 to 2
04 to the first and second line head blocks 110, 1
11 can be easily supplied with ink of each color. Similarly, the third and fourth line head blocks 1
Since the ink tanks 201 to 204 are arranged at both ends of the ink tanks 201 and 113, even if the third and fourth line head blocks 112 and 113 are moved, the ink tanks 201 to 204 are moved.
204 to the third and fourth line head blocks 112,
113 can be easily supplied with the inks of the respective colors.

If the ink tank is provided apart from the line head, it becomes extremely difficult to supply ink from the ink tank to the line head block.

Further, the ink tanks can be replaced for each of the ink tanks 201 to 204, or the ink in the ink tanks can be refilled. Generally, the consumption amount of black ink is much larger than that of other color inks, and the ink tank 204 for black ink is likely to be empty. By replacing only the ink tank 204 or replenishing the ink tank 204 with black ink, maintenance management becomes easy and the maintenance cost can be reduced.

Furthermore, since the ink tanks 201 to 204 have the same shape and size, the color of the ink can be easily changed. For example, when the consumption amount of black ink is large, instead of the ink tanks 201, 202, and 203 of yellow, magenta, and cyan inks, each ink tank 204 of black ink is attached, and black ink is attached. The amount of ink may be increased.

As shown in FIGS. 10A and 10B, one ink tank 205 containing black ink is detachably attached to one end of the first and second line head blocks 110 and 111. One ink tank 206 storing black ink may be detachably attached to one end of the third and fourth line head blocks 112 and 113.

Further, as shown in FIGS. 11A and 11B, one ink tank 207 containing black ink is detachably attached to one end of the first to fourth line head blocks 110 to 113. Is also good. However, in this case, the movement of the first and second line head blocks 110 and 111 and the movement of the third and fourth line head blocks 112 and 113 need to be linked.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
By increasing the number of ink tanks, more types of ink may be stored in the respective ink tanks, and various types of ink may be supplied from the respective ink tanks to the respective line heads. Alternatively, the shape of the ink tank may be changed.
Also, the color combinations of each ink are different between each line head block, each line head block expresses a different color, and each color is superimposed on the recording paper to express more colors. May be.

[0045]

As described above, according to the present invention, the ink tank is attached to the end of the line head. Therefore, for example, even if the line head is moved, the ink can be easily supplied from the ink tank to the line head.

According to the present invention, each ink tank has the same shape and the same size. For example, if each rectangular ink tank is attached to the end of each line head arranged side by side, the ink tanks are arranged in an orderly manner.
The space of each ink tank can be saved.

Further, according to the present invention, since one ink tank is attached to the ends of the plurality of line heads, the capacity of the ink tank can be increased. The ink tank may store ink of a frequently used color.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a perspective view schematically showing first to fourth line head blocks in the image forming apparatus of FIG. 1;

FIG. 3 is a perspective view showing an ink tank detachably mounted on first to fourth line head blocks in the image forming apparatus of FIG. 1;

FIG. 4 is a view used to explain the diameter of nozzle orifices of first to fourth line head blocks in the image forming apparatus of FIG. 1;

FIG. 5 is a diagram schematically illustrating a configuration of a sensor in the image forming apparatus of FIG. 1;

FIG. 6 is a perspective view schematically showing a suction drum in the image forming apparatus of FIG. 1;

FIG. 7 is a block diagram illustrating a configuration of a drive control system of the image forming apparatus of FIG. 1;

FIG. 8 is a flowchart illustrating a process performed by the image forming apparatus of FIG. 1;

FIG. 9 is a side view showing a state in which two ink particles are overlapped.

FIGS. 10A and 10B are perspective views showing a modification of the ink tank in the image forming apparatus of FIG. 1;

FIGS. 11A and 11B are perspective views showing another modified example of the ink tank in the image forming apparatus of FIG. 1;

FIG. 12 is a side view schematically showing a conventional device.

[Explanation of symbols]

8, 9, 10 Driving rollers 102, 103, 104, 105 Sensor 110 First line head block 111 Second line head block 112 Third line head block 113 Fourth line head block 115, 116, 117, 118 Line head 120 , 121 Paper detection sensor 122, 122a, 122b, 122c, 122d Nozzle orifice 125 Feed roller 201, 202, 203, 204, 205, 206, 2
07 Ink tank

Claims (4)

[Claims] 1. An image forming apparatus in which a plurality of line heads extending in a direction orthogonal to a recording paper conveyance direction are arranged in parallel, and each line head performs recording on the recording paper, and stores ink supplied to the line heads. An image forming apparatus, wherein an ink tank to be mounted is attached to an end of a line head. 2. The image forming apparatus according to claim 1, wherein each ink tank has the same shape and the same size. 3. The image forming apparatus according to claim 1, wherein one ink tank is attached to an end of the plurality of line heads, and the line head shares the ink tank. 4. A pair of line heads are oriented in opposite directions, one ink tank is attached to an end of the pair of line heads, and the pair of line heads share the ink tank. 2. The image forming apparatus according to 1.