JPH07112534A - Image forming device - Google Patents

Abstract

PURPOSE:To suppress the oversizing and the cost increase of a device as much as possible by splitting a plurality of nozzles to form nozzle groups not less than 2 and furthermore connecting the respective nozzle groups to the different ink tanks. CONSTITUTION:An ink jet recording head 37 is constituted of four recording head units 37a, 37b, 37c, 37d. In the case of observing the nozzle array of the respective recording head units from the side facing to a medium to be recorded, the nozzle array is divided into two in the subscanning direction and constituted of the upper nozzle array and the lower nozzle array. Two kinds of nozzle arrays are connected to ink tanks 401 of different color through feed pumps 402. In a first recording head unit 37a, the upper nozzle array is connected to the ink tank 401a of cyan C and the lower nozzle array is connected to the ink tank 401d of black K. In a second recording head 37b, the upper nozzle array is connected to the ink tank 401b of magenta M.

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 having a recording head for recording input image information on a recording medium by ejecting ink from a plurality of nozzles, and particularly not only in the forward path but also in the backward path during a recording operation. Also relates to an image forming apparatus capable of color recording.

[0002]

2. Description of the Related Art Conventionally, paper, cloth, plastic sheet, OH
An image forming apparatus that outputs input image information to a recording medium such as a P sheet (hereinafter, also referred to as recording sheet) to form an image includes a recording device as an output unit thereof as an image forming unit or a printer unit. Generally, conventional recording apparatuses have been proposed and commercialized in a form in which recording heads of various recording systems such as a wire dot system, a thermal system, a thermal transfer system, and an inkjet system are mounted.

Among such conventional recording apparatuses, a recording apparatus having an ink jet type recording head for recording on a recording sheet by ejecting ink from an ejection port (nozzle) arranged on a recording element is particularly noticeable. Has been done. This is because not only high-density and high-speed recording is possible, but also low-noise non-impact recording is achieved as compared with other methods. Therefore, information output means as one factor that determines the system value of an information processing system (image forming apparatus) required in today's information processing society, for example, a printer unit such as a copying machine, an electronic typewriter, a word processor, a workstation, etc. Printer as the output terminal of, or personal computer, host computer, optical disk device,
It is used as a handy or portable printer equipped in a video device. In such a case, the inkjet recording apparatus has a configuration corresponding to the functions and usage patterns unique to these apparatuses.

<Inkjet Recording Apparatus> Generally, an inkjet recording apparatus includes a carriage on which a recording unit (recording head) and an ink tank are mounted, a conveying unit for conveying a recording medium, and a control unit for controlling these. To have. Then, the recording head that ejects ink droplets from the plurality of ejection ports is serially scanned in a direction (main scanning direction) orthogonal to the conveyance direction (sub scanning direction) of the recording medium,
On the other hand, during non-recording, the recording medium is intermittently conveyed in an amount equal to the recording width. This recording method is one in which ink is ejected onto a recording medium according to a recording signal to perform recording, and it is widely used as a quiet recording method with low running cost. In addition, by using a recording head in which a large number of nozzles for ejecting ink are arranged in a straight line in the sub-scanning direction, the recording head scans the recording medium once so that recording with a width corresponding to the number of nozzles is performed. Done. Therefore, it is possible to speed up the recording operation.

In recent years, inkjet recording apparatuses, especially recording heads, have been manufactured by film-forming technology and micro-machining technology for semiconductor devices, and smaller and cheaper recording heads have been realized. is there. Along with this, the configuration of the recording device and the information processing system device itself including the recording device is also small and simple.

Further, in the case of a color ink jet recording apparatus, a color image is formed by superposing ink droplets ejected by recording heads of a plurality of colors. Generally, when performing color recording, yellow (Y),
There are required four types of recording heads and ink cartridges corresponding to the three primary colors of magenta (M) and cyan (C) or the four primary colors including black (B).

<Image Forming Apparatus Using Inkjet Recording Apparatus as Output Means> FIG. 11 shows a schematic structure of a digital color copying machine as an example of an image forming apparatus using a conventional inkjet recording apparatus as an image forming section (printer section). Show.

This figure is a vertical cross-sectional view of the device, and shows the internal structure of the device in a simplified manner. This digital copying machine comprises an upper structure and a lower structure, which are separable from each other, and can be installed at positions separated from each other, for example, by extending a connecting cable.

The upper structure is composed of a color image scanner section (scanner section) 1101 for reading a document image and outputting it as digital color image data.

The lower structure uses a color digital image signal output from the scanner section 1101 as a recording medium (recording paper).
The printer unit 1102 is configured to perform a recording operation for recording on.

The recording paper is supplied to the printer unit 1102 from the paper feed cassette 1103 or the manual insertion port 1105.
Alternatively, the roll paper 11 may be previously stored in the printer unit 1102.
It is also possible to leave it as 04. In either case, the recording sheet is sent to the position of the platen 1113 by the transport rollers 1106-1112.

The recording head 1115 is composed of recording heads corresponding to each color of yellow, cyan, magenta and black, and is mounted on the carriage 1114 so that the ejection ports (nozzles) face the recording paper. . Then, while moving the carriage 1114 in the direction perpendicular to the plane of the drawing, ink is ejected from the recording head 1114 based on the image data read by the scanner unit 1101 to print on the recording paper placed on the platen 1113. Image formation is performed. When the image is recorded, the recording sheet is conveyed by the conveying roller 1116 and is ejected to the ejection tray 1117.

[0013]

However, in the above-described image forming apparatus, the recording head is reciprocated along the main scanning direction and recording is performed by ink ejection when moving in the forward direction, as in the serial printer. Sometimes do not record. Therefore, the time required for the return trip is wasted. Therefore, when forming the entire predetermined image, as the number of scans required increases, the extra time not required for printing (time required for backward movement) increases. For example, when recording an image of a large size such as A1 size or A2 size on the recording paper, the above wasteful time further increases, and thus it takes several minutes to record just one sheet. Therefore, a method has been proposed in which recording is performed during both reciprocating movements. When simply performing reciprocal recording, for example, cyan (C), magenta (M), yellow (Y), black ( When the recording heads are arranged in the order of K), when forming another color by superimposing colors, in the case of the outward path, for example, C → M → Y → K are superposed in this order. On the reverse path, on the contrary, the order is K → Y → M → C. Therefore, even if the same color is tried to be expressed, the hue is different between the forward and backward passes. Also, to prevent this,
For example, if an attempt is made to provide forward print heads arranged in the order of C → M → Y → K and return print heads arranged in the order of K → Y → M → C, the number of print heads becomes eight. . Therefore, problems such as an increase in size of the device and an increase in cost arise. Therefore, an object of the present invention is to solve the above problems, and to provide an image forming apparatus in which the size and cost of the apparatus are suppressed as much as possible, and high-density, high-quality reciprocal recording can be performed with the same recording head. To do.

[0014]

In order to solve the above problems, an image forming apparatus according to the present invention is equipped with a recording head for ejecting ink from a plurality of nozzles to record input image information on a recording medium. In the image forming apparatus having the carriage and the means for conveying the recording medium, the plurality of nozzles are divided to form at least two nozzle groups,
Each nozzle group is connected to a different ink tank. Preferably, the ink tanks connected to at least two nozzle groups respectively contain the same color inks having different densities, or the recording heads of the recording heads compatible with color recording are connected to at least two nozzle groups of different colors. Each contains an ink. The direction of division of the plurality of nozzles of the recording head is preferably the main scanning direction (recording head moving direction) or the sub-scanning direction (recording medium conveyance direction). More preferably, the recording head has an electrothermal converter as a recording element, which uses heat net energy as energy for ejecting ink.

[0015]

Since a plurality of nozzles are divided to form at least two nozzle groups, and each nozzle group is connected to a different ink tank, at least two different kinds of ink can be made independent by one recording head. By ejecting and changing the color of ink, it is possible to perform color recording not only in the forward path but also in the backward path during the recording operation.

[0016]

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

<Embodiment 1> FIG. 1 is a schematic view for explaining a schematic structure of an ink jet recording head included in an image forming apparatus according to the present invention.

This ink jet recording head 37 has four
Recording head units 37a, 37b, 37c, 37
It consists of d. The nozzle array (nozzle group in which a plurality of nozzles are arranged in a row) of each recording head unit is viewed from the side (ink ejection port side) facing the recording medium (recording paper) in the sub-scanning direction. The direction in which the recording medium is transported)
And an upper nozzle array and a lower nozzle array (in the figure, they are divided into upper and lower parts by dotted lines). The two types of nozzle arrays are connected to ink tanks 401 of different colors via a supply pump 402. That is, the first recording head unit 3
In 7a, the upper nozzle array is connected to the cyan (C) ink tank 401a, and the lower nozzle array is connected to the black (K) ink tank 401d. In the second recording head unit 37b, the upper nozzle array is connected to the magenta (M) ink tank 401b, and the lower nozzle array is connected to the yellow (Y) ink tank 401c. In the third recording head unit 37c,
Ink tank 40 whose upper nozzle array is yellow (Y)
1c, and the lower nozzle array is connected to the magenta (M) ink tank 401b. In the fourth recording head unit 37d, the upper nozzle array is connected to the black (K) ink tank 401d, and the lower nozzle array is connected to the cyan (C) ink tank 401a. Therefore, focusing only on the upper nozzle array, the recording head 37 has a configuration in which the recording head units are arranged in the order of K, Y, M, and C from the upstream side in the forward movement direction (arrow A in the drawing), and only the lower nozzle array is arranged. Focusing on (1), the arrangement is the exact opposite of the arrangement in the case of the upper nozzle array, that is, C, M, Y, and K.

Here, a block composed of four types of upper nozzle arrays is referred to as an upper block 301, and a block composed of four types of lower nozzle arrays is referred to as a lower block 302.

2 and 3 show a schematic structure of a digital color copying machine to which the present invention is applied, as an example of an image forming apparatus having the recording head 37 having the above structure as a recording means.

FIG. 2 is a perspective view of the digital color copying machine. This digital copying machine comprises an upper structure and a lower structure, which are separable from each other, and can be installed at positions separated from each other, for example, by extending a connecting cable.

The upper structure has a color image scanner section (scan section) 1 for reading an original image and outputting it as digital color image data, and a controller section 2 incorporated in the scan section 1 for various image processing of digital color image data. Composed of and.

The lower structure is composed of a printer section 3 which performs a recording operation for recording the color digital image signal output from the controller section 2 on a recording medium (recording paper).

FIG. 3 is a sectional view showing the internal structure of the digital color copying machine of FIG.

First, the exposure lamp 14, the lens 15, and the image sensor 16 by the CCD capable of reading a line image in full color are used to set the original glass 17
An original image placed on the image and a projected image by a projector (not shown) are read. Next, various image processing is performed by the scanner unit 1.
And the controller unit 2, and the printer unit 3 records on the recording paper. In FIG. 2, the recording paper is a small-sized standard size (A4 to A3 size in this embodiment) sheet feeding cassette 20 for storing cut paper, and a large size (A2 to A2 in this embodiment).
Paper is fed from roll paper 29 for recording up to A1 size. Further, as for paper feeding, by inserting the recording paper one by one from the manual feeding port 22 of FIG. 1 along the paper feeding unit cover 21, it is possible to feed paper from the outside of the apparatus (manual paper feeding).

The pickup roller 24 is a roller for feeding cut sheets one by one from the sheet feeding cassette 20, and the fed cut sheets are conveyed to the first feeding roller 26 by the cut sheet feeding roller 25. It The roll paper 29 is sent out by the roll paper feed roller 30, cut into a standard length by the cutter 31, and conveyed to the paper feed first roller 26. Similarly, the recording paper inserted through the manual feed port 22 is conveyed to the first paper feed roller 26 by the manual feed roller 32. Pickup roller 24, cut paper feed roller 25, roll paper feed roller 30, feed first roller 2
6, the manual feed roller 32 is a paper feed motor (not shown) (for example, D
It is driven by a C servo motor), and on / off control is performed at any time by an electromagnetic clutch attached to each roller. When the printing operation is started by an instruction from the controller unit 2, the recording paper selected from any one of the above-mentioned paper feed paths is conveyed to the paper feed first roller 26. In order to remove the skew of the recording paper, the paper feed first roller 26 is turned on and the recording paper is conveyed to the paper feed second roller 27 after forming a predetermined amount of paper loop. Between the paper feed first roller 26 and the paper feed second roller 27, the recording paper is slackened by a predetermined amount in order to perform an accurate paper feed operation between the paper feed roller 28 and the paper feed second roller 27. make. The buffer amount detection sensor 33 is a sensor for detecting the buffer amount. By constantly making the above buffer during the paper conveyance, it is possible to reduce the load on the paper feed roller 28 and the second paper feed second roller 27 especially when a large-sized recording paper is conveyed, and the accurate paper feed operation is performed. It will be possible. At the time of printing by the recording head 37, the scanning carriage 34 on which the recording head 37 and the like are mounted is mounted on the carriage rail 36.
Reciprocal scanning is performed by the scanning motor 35. And
After the completion of the backward scan, the paper feed roller 28 feeds the recording paper by a predetermined amount. At this time, while the drive system is detected by the buffer amount detection sensor 33 by the sheet feeding motor, control is performed so that the buffer amount is always a predetermined value. The printed recording paper is ejected to the paper ejection tray 23 to complete the printing operation.

FIG. 4 is a diagram showing the structure around the scanning carriage 34 according to the embodiment of FIG. In FIG. 4, a paper feed motor 40 is a drive source for intermittently feeding the recording paper, and includes a paper feed roller 28 and a second paper feed roller clutch 43.
The sheet feeding second roller 27 is driven via. Scanning motor 3
Reference numeral 5 denotes a drive source for scanning the scanning carriage 34 in the A and B directions indicated by arrows via the scanning belt 34. In this embodiment, pulse motors are used as the paper feed motor 40 and the scanning motor 35 because accurate paper feed control is required. When the recording paper reaches the second paper feed roller 27, the second paper feed roller clutch 43 and the paper feed motor 40 are turned on,
The recording paper is conveyed to the paper feed roller 28 on the platen 39. The recording paper is detected by a paper detection sensor 44 provided on the platen 39, and the sensor information is used for position control and jam control. When the recording paper reaches the paper feed roller 28, the paper feed second roller clutch 43, the paper feed motor 4
0 is turned off, and a suction operation is performed from the inside of the platen 39 by a suction motor (not shown) to bring the recording paper into close contact with the platen 39. Prior to the image recording operation on the recording paper, the scanning carriage 34 is moved to the position of the home position sensor 41. After the scanner unit 1 starts the outward document reading operation, it performs forward scan in the direction of arrow A at a predetermined timing to print cyan C, magenta M, yellow Y, and black K inks from a predetermined position on the upper block 301 of the recording head. The image is recorded by discharging more. After the image recording for the predetermined length is completed, the scanning carriage 34 is moved to the position of the second home position sensor 45 and then stopped, and then the original reading operation of the scanner unit 1 on the backward path is started, and then at a predetermined timing. Performs backward scanning in the direction of arrow B, and ejects cyan C, magenta M, yellow Y, and black K ink from a predetermined position from the lower block 302 of the recording head to perform image recording. When the image recording for the length of the processing is completed, the scanning carriage 34 is moved to the position of the home position sensor 41 and then stopped, and the paper feed motor 40 drives the paper feed roller 28 to perform recording by the recording head 37. The paper feed for the length (width of the entire recording head) is directed in the direction of arrow C.

In the recording head 37 on the scanning carriage 34, the width of each of the upper block 301 and the lower block 302 is the same as the original reading width of the scanner section 1, and the scanning carriage 34 is indicated by an arrow A (see FIG. 1). When performing the forward scan in the direction, the upper block 301 is used to eject ink in the order of C, M, Y, K at a predetermined timing.
When the scanning carriage 34 performs the backward scan in the direction of arrow B (see FIG. 1), the lower block 302 is used to eject ink in the order of C, M, Y, and K at a predetermined timing to change the tint. No image is recorded.

The scanning carriage 34 is at the home position.
When the recording head 37 is stopped at the home position detected by the sensor 41, the recovery operation of the recording head 37 is performed. This is a process for performing a stable recording operation, and in order to prevent unevenness at the start of ejection, which is caused by a change in the viscosity of the ink remaining in the nozzles of the recording head 37, the paper feeding time, the temperature inside the apparatus, and the like. , A process of performing a pressurizing operation on the recording head 37, an idle ejection operation of ink, and the like according to pre-programmed conditions such as ejection time. Image recording is performed on the entire surface of the recording paper by repeating the operation described above.

Next, the operation of the scanner section 1 will be described. Figure 5
FIG. 3 is a diagram showing a mechanism inside the scanner unit 1 according to the first embodiment. The CCD unit 18 includes a CCD 16 and a lens 15.
Is a unit configured by a main scanning motor 50 fixed on the rail 54, a pulley 51, a pulley 52, and a wire 53 in the main scanning direction.
It moves up, and the image on the platen glass 17 is read in the main scanning direction. Light shield 55, home position sensor 56
Is used for position control when the CCD unit 18 is moved to the home position for main scanning in the correction area 68 in the figure, and the light shielding plate 77 and the first home position sensor 78 are used for position control during backward scanning. It Rails 65,6
9, the sub-scanning motor 60, the pulleys 67, 7
1, 78, 76, shafts 72, 73, and wires 66, 70 are moved by a drive system in the sub-scanning direction. Light shield 5
7. The home position sensor 58 is the platen glass 17
It is used for position control when moving the rail 54 to each sub-scanning home position when reading a document such as a book placed on it.

FIG. 5 is a diagram for explaining the document reading operation according to the first embodiment. First, the CCD unit 18 is moved to the illustrated home position (indicated by HP in the figure) in the correction area indicated by 68 in FIG. 6, and the reading operation of the entire original placed on the original glass 17 is performed from here. Start. Prior to scanning the document, parameters necessary for shading correction, black level correction, color correction, etc. are set in the correction area 68. After that, the main scanning motor 50 starts scanning in the main scanning direction in the direction of arrow A in the figure. When the reading operation of the area shown by is finished and the light shielding plate 77 shields the second home position sensor, the sub scanning motor 6
0 is driven, and the area is moved in the sub-scanning direction. Subsequently, the main scanning motor 50 is rotated in the reverse direction to start the backward scanning in the direction of arrow B. Then, the area after moving to the correction area 68 of the area is moved in the sub-scanning direction, and processing such as shading correction, black level correction, and color correction is performed as necessary, and the area is scanned in the direction of arrow A. Read operation. By repeating the above scanning ~
The reading operation of the entire area of is performed, and after the reading operation of the area of is completed, the CCD unit 18 is returned to the home position again. In the present embodiment, since the document table glass 17 can read a document of maximum A2 size, it is necessary to actually scan a larger number of times, but in the present embodiment, it is simplified for easy understanding of the operation. ing.

FIG. 7 is a block diagram showing the arrangement of a digital full-color copying machine according to the first embodiment. In the figure, control units 701, 702 and 703 are control circuits for controlling the scanner unit 1, the controller unit 2 and the printer unit 3, respectively, and a microcomputer 70 (not shown).
2a, a ROM 702b storing a program, a data memory and a RAM 702c which is a work area, a communication circuit and the like. Control units 701 to 702 and control unit 702
˜703 are connected by a communication line, and the control unit 7
02, the control units 701 and 703 operate.
That is, the master / slave control mode is adopted.
When operating as a color copying machine, the control unit 702 operates according to an input instruction from the operation unit 10. Operation part 1
0 uses a liquid crystal (LCD), for example, as a display unit, and has a touch panel made of a transparent electrode on the surface thereof, so that selection instructions such as color designation and editing operation designation can be performed. Also, keys related to the operation, such as a start key for instructing the start of the copying operation, a stop key for instructing to stop the copying operation, a reset key for returning the operation mode to the standard state, a projector key for selecting a projector (not shown), etc. Keys that are frequently used are provided independently. The control unit 702 also controls the image processing unit 704, the binarization processing unit 705, and the like that perform various types of processing related to the image. The control unit 701 controls the mechanical drive unit 706 that controls the drive of the mechanism of the scanner unit 1 described above, the exposure control unit 707 that controls the exposure of the reflection original reading lamp, and the halogen lamp when the projector is used. The exposure control unit 708 that controls the exposure is controlled. In addition, the control unit 70
The control unit 1 also controls an analog signal processing unit 709 and an input image processing unit 710 that perform various types of processing related to images. The control unit 703 synchronizes with the mechanical driving unit 711 that controls the driving of the mechanical unit of the printer unit 3 described above and the variation correction of the mechanical operation time of the printer unit 3 and the delay correction due to the arrangement of the recording heads 37 on the mechanism. The delay memory 716 and the head driver for driving the head are controlled.

Next, FIG. 7 will be described based on a series of copying operations. The image formed on the CCD 16 is converted into an analog electric signal by the CCD 16. The converted image information is serially processed like red, green, and blue and input to the analog signal processing unit 709. Analog signal processing unit 70
In No. 9, analog-digital conversion (A / D conversion) is performed after sample-and-hold, dark level correction, dynamic range control, etc. for each color of red, green, and blue, and serial multi-value (in this embodiment, is used). It is converted into a digital image signal of 8 bits for each color and output to the input image processing unit 710. In the input image processing unit 710, correction processing necessary for the reading system such as shading correction, color correction, and γ correction is similarly performed with the serial multivalued digital image signal. The image processing unit 704 of the control unit 2 is a circuit that performs smoothing processing, edge enhancement, black extraction, masking processing for color correction of recording ink used in the recording head 37, and the like. The serial multi-value digital image signal output is output by the binarization processing unit 70.
Input to 5. The binarization processing unit 705 is a circuit for binarizing a serial multi-valued digital image signal, and can select simple binary with fixed slice level and pseudo halftone processing with dither method. Here, the serial multivalued digital image signal is converted into a binary parallel image signal of four colors. Synchronous delay memory 716 of printer unit 3
Is a circuit for absorbing variations in mechanical operation time of the printer unit 3 and correcting delay due to the mechanical arrangement of the recording head 37, and also internally generates timing required for driving the recording head 37. The head driver 717 is an analog drive circuit for driving the recording head 37, and internally generates a signal that can directly drive the recording head 37. The selectors 718 to 721 are portions that select the upper block and the lower block of the recording head 37 according to reciprocal scanning and backward scanning, and are controlled by the control unit 703 via the head driver 717. The recording head 37 ejects cyan, magenta, yellow, and black inks, respectively, and records an image on recording paper.

FIG. 8 is a timing chart of signals between the circuit blocks shown in FIG. The signal BVE is a signal indicating the image effective section for each scan of the main scanning reading operation described in FIG. By outputting the signal BVE a plurality of times, the image output of the entire screen is performed. Signal VE is CCD1
6 is a signal indicating the effective section of the image for each line read in 6. Only the VE when the signal BVE is valid is valid.
The signal SLCT is the upper block 301 of the head shown in FIG.
And a signal for selecting the lower block 302, for example, 80
Section 1 indicates selection of an upper block in forward scanning, and section 802 indicates selection of a lower block in backward scanning. That is, this signal switches each time the signal BVE is output. The signal VCK is a clock signal for sending out the image data VD, and the signals BVE, VE, and SLCT also change in synchronization with the signal VCK. Signal R
EG1 is a signal output from the home position sensor 41 when the printer unit 3 starts forward scanning, and is a signal that is a trigger for starting the forward printing operation.
The signal HS is a signal that is output based on the signal REG1 after a certain period of time, and is a signal indicating the start of image output for one line. Further, the signal REG2 is a signal output from the home position sensor 45 when the printer unit 3 starts the backward scanning, and is a signal which is a trigger for starting the backward printing operation. When these signals are output from the head driver 717 to the recording head 37 via the selectors 718 to 721 at the timing shown in FIG.
Reference numeral 21 switches blocks for outputting the signals BVE, VE, VCR, and image data VD based on the signal SLCT. Desired reciprocal printing can be performed on the selected block by ejecting ink onto the recording paper according to the image data VD.

<Embodiment 2> In Embodiment 1, as shown in FIG. 1, the nozzles of the print head are divided into upper and lower parts, and the width of each block is the same as the original reading width of the scanner section. However, the width of the entire head is the same as the original reading width of the scanner unit, and the nozzles are arranged in two rows in a staggered pattern as shown in FIG. 9A or in two rows in parallel as shown in FIG. The same effect as that of the first embodiment can be obtained by using a head in which the chamber is divided into left and right. In FIG. 9, when the scanning carriage 34 performs forward scanning in the direction of arrow A, printing is performed using the right block 901, and when the image recording for a predetermined length is completed, the second home position sensor 45
After moving the scanning carriage 34 to the position, the scanning carriage 34 is stopped and the paper is fed by the width of the recording head 37 in the direction of arrow C in FIG. Subsequently, when performing the backward scan in the direction of arrow B, printing is performed using the left block 902, and when the image recording for a predetermined length is completed, the scanning carriage 34 is moved to the position of the first home position sensor 41. After that, the process is stopped, and the paper is fed by the width of the recording head 37 in the direction of arrow C in FIG. However, when the nozzles are arranged in a staggered pattern as shown in FIG. 9A, the distance between the nozzles of the right block and the left block is X.
Therefore, it is necessary to reduce the paper feed amount after the backward scan by the distance indicated by X.

<Embodiment 3> By applying the above embodiment, FIG.
2 sets of ink tanks as shown in FIG.
If the ink supplied to one block of No. 7 has a normal density and the ink supplied to the other block has a low density, multiple gradations can be achieved. For example, the image processing unit 704 generates a signal for selecting one of the blocks according to the density of the read document, and the signal is generated by the control unit 702.
Input to the head driver 717 via 703. When the scanner unit 1 performs the outward document reading operation and outputs a signal for selecting the low-density side block, the printer unit 3 switches to the low-density ink side 1003 in the outward scan to print only the low-density portion, and the scanner unit The unit 1 reads the same portion read on the outward path again on the return path, and this time outputs a signal for selecting a block on the normal density side. The printer unit is switched to the normal density ink side 1004, and the same portion is printed at the normal density on the return path without performing the paper feeding operation. By repeating this, multi-tone printing becomes possible.

The image forming apparatus based on the above embodiment is
One recording head is divided into a plurality of nozzles to form at least two nozzle groups, and inks of different colors are filled in the recording heads. Since the arrangement is such that the color order according to one combination is the same on the forward and return paths, the color tone of the recorded image does not change, and reciprocal printing is possible without increasing the cost and increasing the size of the device.

Although the above embodiment has been made by paying attention to an image forming apparatus compatible with color recording, a new recording head provided in the image forming apparatus according to the present invention, a structure around the head, and control of recording operation. The means and the like are applicable to other information processing systems, and such application can be easily achieved by those skilled in the art.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating heat energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the apparatus main body or the electrical connection to the apparatus main body or the ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add the ejection recovery means of the recording head, the auxiliary auxiliary means, etc. because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or below and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus of the present invention, other than the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function can be used. It may be a form or the like.

[0048]

As described above, in the image forming apparatus according to the present invention, the carriage and the recording medium on which the recording head for ejecting the ink from the plurality of nozzles to record the input image information on the recording medium and the recording head are mounted. In the image forming apparatus, the plurality of nozzles are divided to form at least two nozzle groups, and each nozzle group is connected to a different ink tank, preferably at least two. The ink tanks connected to the two nozzle groups contain different concentrations of the same color ink, or
Alternatively, the recording head is a recording head compatible with color recording, and the ink tanks connected to at least two nozzle groups respectively contain inks of different colors, and the dividing direction of the plurality of nozzles of the recording head is preferably the main scanning direction. Or in the sub-scanning direction, and more preferably, the recording head has an electrothermal converter that uses thermal energy as energy for ejecting ink, as a recording element, so that at least two different types of ink can be formed by one recording head. Can be independently ejected, and color recording can be performed not only in the forward path but also in the backward path during the recording operation by changing the color of the ink.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a schematic configuration of a recording head included in an image forming apparatus according to the present invention.

FIG. 2 is a perspective view of an image forming apparatus provided with the recording head shown in FIG.

FIG. 3 is a sectional view for explaining a schematic configuration of the image forming apparatus shown in FIG.

FIG. 4 is a diagram for explaining a schematic configuration of a carriage unit of the image forming apparatus shown in FIG.

5 is a diagram for explaining a schematic configuration of a scanner unit of the image forming apparatus shown in FIG.

FIG. 6 is a schematic diagram for explaining a document reading operation by the image forming apparatus shown in FIG.

7 is a block diagram for explaining image processing and recording operation by the image forming apparatus shown in FIG.

FIG. 8 is a timing chart of signals between circuit blocks in FIG.

FIG. 9 is a schematic diagram for explaining a schematic configuration of a recording head (second embodiment) included in the image forming apparatus according to the present invention.

FIG. 10 is a schematic diagram for explaining a schematic configuration of a recording head (third embodiment) included in the image forming apparatus according to the present invention.

FIG. 11 is a sectional view for explaining a schematic configuration of a conventional image forming apparatus (digital color copying machine).

[Explanation of symbols]

 34 carriage 37 recording head 301 upper block consisting of upper nozzle group 302 lower block consisting of lower nozzle group 401 ink tank

Claims (7)

[Claims] 1. An image forming apparatus comprising: a carriage having a recording head for ejecting ink from a plurality of nozzles to output input image information on a recording medium; an ink tank; and a carriage for conveying the recording medium. In the image forming apparatus, the plurality of nozzles are divided to form at least two nozzle groups, and each nozzle group is connected to a different ink tank. 2. The image forming apparatus according to claim 1, wherein the ink tanks connected to the at least two nozzle groups contain different color inks of the same color. 3. The apparatus according to claim 1, wherein the recording head is a recording head compatible with color recording, and the ink tanks connected to the at least two nozzle groups respectively contain inks of different colors. A characteristic image forming apparatus. 4. The image forming apparatus according to claim 1, wherein the division direction of the plurality of nozzles of the recording head is a moving direction of the recording head. 5. The image forming apparatus according to claim 1, wherein a direction in which the plurality of nozzles of the recording head are divided is a direction in which the recording medium is conveyed. 6. The image forming apparatus according to claim 1, wherein a direction in which the plurality of nozzles of the recording head are divided is a sub-scanning direction. 7. The image forming apparatus according to claim 1, wherein the recording head includes an electrothermal converter that uses thermal energy as energy for ejecting the ink, as a recording element.