Ink jet recording method and ink jet recording apparatus

Abstract: When the color printing is performed using a recording head arranged such that the number of nozzles for discharging the black ink is greater than the nozzles for discharging the inks of other colors, the use frequency of some nozzles among all the nozzles for discharging the black ink is higher, so that image unevenness may arise when transferred to the black printing. The present invention provides an ink jet recording method and an ink jet recording apparatus in which the image unevenness often seen in the black printing involving the use of more nozzles than other colors, and the blur of recorded image seen in the image having black image and color image located adjacent are reduced.

Description: The present invention relates to an ink jet recording method for recording a multi-color image by using the inks of a plurality of colors and a recording head having a plurality of nozzles corresponding to such colors, and particularly to an ink jet recording method of using a recording head in which the number of nozzles for a specific color is greater than the number of nozzles for other colors. Conventionally, methods of recording color image using four colors of yellow (Y), magenta (M), cyan (C) and black (Bk) have been well known and applied to printers or copying machines. As one technique for such methods, an ink jet recording method of using four ink jet recording heads corresponding to four colors to permit independent discharging of four colors has been put to practical use. This method has the merits that the recording heads can be used in common when the amount of discharging the ink for each color is equal, and the driving method of each recording head can be simple, because the recording heads are independent for each color. On the other hand, this method has the drawback that it is unsuitable for the smaller apparatus in the recent trend, since four recording heads are mounted, resulting in higher costs and complicated assembling. Also, since the four recording heads are used, this method is suitable for the higher speed, but if the printing is made on the recording sheet on which the ink is less liable to fix, such as a plain paper, the blur of color inks, may easily occur, resulting in the image quality remarkably degraded. Therefore, a recording head has been proposed in which nozzle (discharge unit) groups for discharging the inks of four colors of yellow, magenta, cyan and black are arranged not to be overlapped in a scan direction, as shown in Fig. 1. This recording head allows the use of single recording head to provide a multi-color image, and is very suitable for inexpensive and small-sized apparatuses. Also, this recording head hardly produces the blur of inks, resulting in higher quality of image, although it takes longer time to perform the printing, as compared with the use of the four recording heads. However, the use of this recording head in which the nozzle groups for four colors are not overlapped, as shown in Fig. 1, can not completely prevent the blur of color inks from occurring. Also, it is naturally required that the color printers or color copying machines produce the black image of high quality, comparable to that of conventional white and black apparatuses. To meet that requirement, an attempt has been made to make the discharge amount of black ink greater than that of color inks. However, in this case, there was a problem that the blur of inks was remarkable at the boundaries between black image and color image, resulting in the quite bad print quality. Also, various proposals for recording the color image using plural color inks have been made to achieve the higher quality recording and higher speed recording. In Japanese Laid-Open Patent Application No. 58-138656 (hereinafter referred to as conventional example 1), the present applicant has proposed a method of arranging an increased number of ink jet nozzles corresponding to only a main color K among CMYK to attain a recording speed in the recording mode of only color K faster than in the color recording mode. Also, the present applicant has proposed a method for improving the image quality in Japanese Laid-Open Patent Application No. 58-173669 (hereinafter referred to as conventional example 2) and Japanese Laid-Open Patent Application No. 3-146355 (hereinafter referred to as conventional example 3). According to conventional example 3, a proposal has been made to achieve the overall improvement by discharging a greater amount of K ink than that of other inks. Also, according to this conventional example 3, another proposal has been made to prevent the blur of K in such a manner that other colors than K are not recorded around the K. Also, according to USP 4,967,203 (hereinafter referred to as conventional example 4), a proposal has been made to suppress the blur as a whole in such a manner as to record all colors in either a cross pattern or a counter-cross pattern at the forward recording. However, in the above method of conventional example 1, the number of nozzles used for K is equal to the number of nozzles for CMY at the color recording, which means that no improvement in the recording speed or recording quality is expected at the color recording. Also, in the above proposal of conventional example 2, the overall image quality may be enhanced, but in some cases, the blur of K may spread over CMY at the color recording, resulting in degraded image quality. Also, in the above proposal of conventional example 3, unrecorded pixels around K may exposed the underlying color, for example, white on the white paper, resulting in degraded image quality. Also, in the above proposal of conventional example 4, the substantial recording may slow down to one-half thereof. The same recording speed can be attained by doubling the number of nozzles for the recording head, but there is the disadvantage of increasing the costs of an expensive recording head or a control or drive circuit section. Suppose now an instance wherein an ink jet head (recording head) has discharge nozzle groups for yellow (Y), magenta (M), cyan (C) and black (Bk), and the number of black nozzles is greater than the number of nozzles for each color, or wherein the longitudinal length of black nozzle group is equal to greater than the longitudinal length of font data, or the longitudinal length of color nozzle groups is equal to or greater than the longitudinal length of font data. The color recording with such recording head is accomplished by using all the nozzles of the heads for yellow, magenta and cyan, and only predetermined nozzles of black head, while reciprocating the recording head in a main scan direction by multiple times. Also, the recording of monochrome image is performed by discharging the ink onto the recording sheet, using all the nozzles of black head. Therefore, conventionally, in performing the recording with such recording head, when control is transferred from the color recording to the monochrome recording, the recording operation of using all the nozzles including other nozzles than the predetermined nozzles of black head as described above which are not used during the color recording is started. However, the other nozzles which are not used before may not be fully activated, and therefore it is apprehended that the discharged ink causes an unevenness at the initiation of the recording. Such black unevenness may arise not only when switching is made from the color recording to the monochrome recording, but also when font data with its width exceeding the longitudinal length of nozzle group for the recording head is recorded in monochrome, because different section of the nozzles of the black head is used by each scan of the recording head, causing a problem that the recorded image has degraded quality. US-A-4750009 describes an ink jet system printer which comprises a number of parallel arrays of ink ejection orifices with the black array containing a larger number of orifices than the cyan, magenta and yellow arrays. DE-UM-G8906890 describes an ink jet head which comprises an array of ink ejection nozzles divided into respective groups for ejecting, black, cyan, magenta and yellow inks. The groups are spaced apart from one another and the black ink ejection nozzle group has more nozzles than the other groups. JP-A-61-104856 describes an ink jet colour print head with parallel arrays of nozzles for ejecting cyan, magenta and yellow inks. The head also comprises two parallel but staggered arrays of nozzles for ejecting black ink. According to one aspect of the present invention, there is provided an ink jet recording method in accordance with claim 1. The present invention also provides an ink jet recording apparatus in accordance with claim 12. The colour inks may be yellow, magenta and cyan. In an embodiment, the number m of black ink discharge portions and the number n of colour ink discharge portions satisfies the inequality m ≤ 2n. Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic view for explaining a recording head used in example 1. Fig. 2 is a view for explaining a process of printing only black image. Figs. 3A to 3F are views for explaining a process of printing an image consisting of a black image and a color image which are mixed. Figs. 4A to 4G are views for explaining a process of printing an image in which the adjacent boundary exists between black image portion and color image portion. Fig. 5 is a schematic view for explaining a recording head used in example 2. Fig. 6 is a view for explaining a process of printing only black image. Figs. 7A to 7H are views for explaining a process of printing the image of Fig. 4 by a method of example 2. Fig. 8A and 8B are views for explaining the kind of image and the feeding of recording paper. Fig. 9 is a perspective view of an ink jet recording apparatus to which the present invention is applicable. Fig. 10 is a view of a head mechanism for the ink jet recording apparatus to which the present invention is applicable. Fig. 11 is a block diagram of a control circuit for the ink jet recording apparatus to which the present invention is applicable. Fig. 12 is an enlarged view of a recording head unit applicable to the present invention on the front side. Fig. 13 is a block diagram showing the schematic configuration of an ink jet printer applicable to an embodiment of the present invention. Fig. 14 is a detailed view showing the internal structure of an ink jet head which is mounted on the ink jet recording apparatus applicable to the present invention. Figs. 15A to 15E are views for explaining the discharge principle of an ink jet head. The preferred embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) Fig. 1 shows schematically a recording head for use with an ink jet recording method of the present invention. 1 is a recording head, and 10 is a nozzle (discharge unit), wherein 10a is a nozzle for discharging the yellow ink, 10b is a nozzle for discharging the magenta ink, 10c is a nozzle for discharging the cyan ink and 10d is a nozzle for discharging the black ink. A nozzle group of each color is configured not to be overlapped in a scan direction, with a space 10e, 10f, 10g provided between such nozzle group of each color. Each of a nozzle group 10a, a nozzle group 10b, and a nozzle group 10c has twenty four nozzles, and a nozzle group 10d has forty eight nozzles arranged at a density of 360 per inch (360 dpi). The discharge amount of nozzle 10d is about 80ng, and the discharge amount of each of nozzles 10a, 10b and 10c is about 40ng. A print method for printing various images with the recording head as shown in Fig. 1 will be described below. Fig. 2 shows an instance of printing only black image using the nozzle group 10d for the discharge of black ink, wherein forty eight nozzles for the nozzle group 10d are all used, and recording sheet is fed by the amount of forty eight nozzles to print the next line when the scan of the recording head is ended. This method is effective particularly when one page has only black image, as shown in Fig. 8A, or in printing the black image portion (area a and area c in Fig. 8B) when one page has a black image and a color image mixed, as shown in Fig. 8B but the black image and the color image are separated in a feed direction of recording sheet, and has the advantage that the recording speed is high. Note that when this type of recording head is used, the feed pitch of recording sheet in the color image portion (area b in Fig. 8B) is basically twenty four nozzles. Figs. 3A to 3F show an instance of printing a color image using the color ink discharging nozzles 10a, 10b, 10c and the black ink discharging nozzle 10d of the recording head as shown in Fig. 1, wherein twenty four nozzles are used for each color (same figure F). In the same figure, the nozzles for discharging the black ink are those arranged on the side of the cyan ink discharging nozzle 10c. In the figure, Y is printed with yellow ink, M is printed with magenta ink, C is printed with cyan ink, and B is printed with black ink. A process of forming a color image will be described using Figs. 3A to 3E, Fig. 3A shows an instance of scanning the recording head 1 at a position as shown, where the upper part of a black character "B" corresponding to twenty four nozzles is printed. Subsequently, the recording sheet is fed by the amount of twenty four nozzles, and the remaining lower part of black character "B" and the upper part of a cyan character "C" corresponding to twenty four nozzles are printed from a state of Fig. 3B. Further, the recording sheet is fed by the amount of twenty four nozzles, the lower part of cyan character "C" corresponding to twenty four nozzles, as well as the upper part of a magenta character "M" corresponding to twenty four nozzles, are printed as shown in Fig. 3C. The above operation is further performed as shown in Figs. 3D and 3E until the printing of four colors is ended. By the way, the image as shown in Figs. 3A to 3F consists of color images which are not adjoining, so that there is particularly no decrease of the print quality due to the blur of colors. However, in the case of an image as shown in Figs. 4A to 4G, a black character "B" exists in the background of yellow, magenta and cyan, so that the blur of color is likely to occur at the boundaries between black and color. In particular, it is preferable that the discharge amount of black ink per dot is designed to be greater than that of color inks from the aspect of print quality, though the blur is likely to occur at the boundaries between black image and color image. Therefore, a recording method according to the embodiment 1 of the present invention is to record an image consisting of adjoining black image and color image as shown in Fig. 4G, using a recording head as shown in Fig. 1, wherein the nozzles used for printing the black image are twenty four nozzles on the lower part thereof, as will be described in Figs. 4A to 4F. First, as shown in Fig. 4A, the portions corresponding to the upper part of a black character "B" is printed using, nozzles on the lower part of the black ink discharging nozzles 10d. Subsequently, a recording sheet is fed by the amount of twenty four nozzles, and then the remainig lower part of black character "B" is printed, using the lower part of the black ink discharging nozzles 10d (B in the same figure). After the recording sheet is further fed, the upper part of a cyan background portion is printed using the cyan ink discharging nozzles 10c (C in the same figure). After the recording sheet is fed, the lower part of cyan background portion is printed by the nozzles 10c, and the upper part of a magenta background is printed by the nozzles 10d (D in the same figure). The same operation is repeated until the printing is ended in Fig. 4F. Herein, comparing the process of printing the image of Fig. 3F in accordance with the procedure of Figs. 3A to 3E with the process of printing the image of Fig. 4G in accordance with the procedure of Figs. 4A to 4F, the latter process has one greater number of scanning the recording head required to record a color image corresponding to the amount of forty eight nozzles in a paper feed direction. That is, the latter process uses the lower part of nozzles for discharging the black ink, which are separated by one scan or the amount of twenty four nozzles from the cyan ink discharging nozzles 10c, so that the number of scans in the latter process is one greater than in the former process. Therefore, the latter method takes a longer time from printing black image to printing color image than the former method, even though black image and color image are adjoining, so that it produces less blur at the adjoining portion than the former. As described above, with the recording method of the present invention, the print timing of black image and color image can be delayed from normal timing by appropriately setting the nozzles for printing the black image when there are adjoining black image and color image, so that a high quality color image without blur between colors can be obtained. Also, the number of scans for the recording head in reciprocatory motion is one greater for each printing of one page of recording sheet, so that the substantial recording time is hardly affected. In the embodiment as described above, the image of Figs. 4A to 4G was printed at a discharge frequency of 6 kHz, with the time from the start of one scan to the start of next scan for the recording head being about one second, so that a high quality image without blur at the boundaries between black image and color image could be obtained. (Embodiment 2) A recording head as shown in Fig. 5 is comprised of a yellow ink discharging nozzle 10a, a magenta ink discharging nozzle 10b, a cyan ink discharging nozzle 10c and a black ink discharging nozzle 10d, like the embodiment 1, the black ink discharging nozzle has sixty four nozzles arranged, and each of other color ink discharging nozzles has twenty four nozzles arranged. Also, a space of eight nozzles 10e, 10f is provided between the yellow ink discharging nozzle 10a and the magenta ink discharging nozzle 10b and between the magenta ink discharging nozzle 10b and the cyan ink discharging nozzle 10c, and a space of sixteen nozzles 10g is provided between the cyan ink discharging nozzle 10c and the black ink discharging nozzle 10d. The discharge amount of each nozzle is equal to that of the embodiment 1. Also, this recording head, owing to the spaces provided, is easily formed with a liquid chamber for supplying the ink to the nozzles of each color, and has the advantage that a temperature detecting sensor for the recording head can be provided in such spaces, with its effects easily drawn by applying the present invention. Fig. 6 shows a printing method for printing the black image portion among black image and color image separated in a feed direction of recording sheet, when the image within one page is all black, or when the black and color images are mixed in one page, using this recording head. That is, the black image is printed using all sixty four nozzles, while the feed pitch of recording sheet is equal to the amount of 64 nozzles. Next, a printing method for printing an image as shown in Fig. 4G using this recording head will be described with reference to Figs. 7A to 7H. As will be clear from the figure, the nozzles located at predetermined positions from the uppermost in the figure among the black ink discharging nozzles 10d are used in printing the black image. Specifically, twenty four nozzles from the twenty-fifth nozzle to forth-eighth nozzle from the uppermost in the figure are used. First, the upper part of a black character "B" is printed using the twenty fifth to forth-eighth nozzles, as shown in Fig. 7A. Subsequently, the recording sheet is fed by the amount of twenty four nozzles, and the lower part of black character "B" is printed using the same nozzles as shown in Fig. 7B. In this case, the color printing is not performed. Then, after the recording sheet is fed by the amount of twenty four nozzles, part of a cyan background portion is printed using the cyan ink discharging nozzles 10c. Thereinafter, the printing of a background portion of each color is performed each time by the amount of twenty four nozzles, the details being the same as those of the embodiment 1 and omitted. Owing to the use of the recording head provided with a predetermined space between adjacent nozzle groups, the total of eight scans is required to print the image as shown in Fig. 4G in this embodiment. As described above, owing to the use of the twenty-fifth to forty-eighth nozzles among the black ink discharging nozzles, there occurs an idle time amounting to one scan in reciprocatory motion until the color ink getting contiguous to black character most early after the black character is printed, specifically, the cyan ink, is printed, there occurs no blur at the adjoining portion. The image of Fig. 4G was printed under the same conditions as those of the embodiment 1, so that a high quality equivalent to that of the embodiment 1 was obtained. (Embodiment 3) When printing an image having the contiguous boundaries between black image and color image, using the same recording head as in the embodiment 2, the forty-first to sixty-fourth nozzles among the black ink discharging nozzles were used. The feed pitch of recording sheet is equal to the amount of twenty four nozzles, like the embodiment 2, there is a time difference amounting to two scans in reciprocatory motion from the printing of black image at the continuous boundaries to the printing of color image (cyan) to be performed at the earliest time. Thus, the same image was printed as that of Fig. 4G, so that a higher quality image without any blur could be obtained than the image of the embodiment 2. Fig. 9 is a perspective view of an ink jet printer with an ink cartridge and a carriage mounted thereon, to which the present invention is applicable. Carriage 101 has a print head 102 and a cartridge guide 103 mounted, and can scan over a guide shaft 104 and a guide shaft 105. A recording sheet 106 is fed into a main device by a sheet supply roller 107 to be carried between a sheet feed roller 108 and a pinch roller (not shown) and passed under a sheet presser plate 109 on to the front face of the sheet feed roller 108 for the printing. An ink cartridge has two kinds of a color ink cartridge 110 for three colors of yellow, magenta and cyan, and a black ink cartridge 111, each inserted into a cartridge 103, separately, to communicate with the print head 102. The inks of yellow, magenta and cyan accommodated within the color ink cartridge 110 have a higher permeating rate into the recording sheet not to produce the blur of ink at the color boundaries in forming the color image. On the other hand, the black ink accommodated in the black ink cartridge 111 has a relatively slower permeating rate into the recording sheet than the three kinds of color inks so that the black image may be of high quality having a high density and less blur of ink. The constituents of the inks for use in this embodiment are as follows. (Yellow) C.I. direct yellow 86 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetynol EH (Kawaken Chemical) 1 part Water remaining parts (Magenta) C.I. acid red 289 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetynol EH (Kawaken Chemical) 1 part Water remaining parts (Cyan) C.I. direct blue 199 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetynol EH (Kawaken Chemical) 1 part Water remaining parts (Black) C.I. direct black 154 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetynol EH (Kawaken Chemical) 1 part Water remaining parts Referring now to Fig. 10 in detail, the print head 102 has the groups of discharge orifices for yellow, magenta, cyan and black, arranged in a line on the front surface of the print head 102. One group comprises twenty four discharge orifices for each of yellow, magenta and cyan, or sixty four discharge orifices for black, and a space amounting to eight nozzles between adjacent nozzle groups, or sixteen nozzles between black and color nozzle groups is provided. Further, these nozzles are arranged at a density of 360 per inch (360 dpi). Normally, for printing only black image, all sixty four nozzles within a black discharge orifice group, while for printing color image including black image, twenty four nozzles for each of yellow, magenta, cyan and black are used. Each of these discharge orifices is provided with an ink liquid channel communicating thereto, a common liquid chamber or supplying the ink to ink liquid channels is provided rearward of the ink liquid channels disposed. An ink liquid channel corresponding to each of the discharge orifices has an electricity-heat converter for generating a heat energy for use in discharging an ink droplet through the discharge orifice, and an electrode wiring for supplying the electric power to such electricity-heat converter. These electricity-heat converters and electrical wirings are formed by film formation technique on a substrate 201 made of silicon. Further, by laminating partition walls and a ceiling plate made of resin and glass material on this substrate, the discharge orifices, the ink liquid channels and the common liquid chamber are made. Further rearwardly thereof, a drive circuit for driving the electricity-heat converters based on a recording signal is provided in the form of a printed board. In parallel to silicon substrate 201 and printed board 202 is disposed an aluminum plate 203, and projection pipes 204 to 208, extending in parallel to the aluminum plate 203, project outward from a plastic member 208 called a distributor extending in a direction perpendicular to the silicone substrate 201, and communicate to liquid channels provided further inward thereof, which in turn communicate to the common liquid chamber. Within the distributor, four liquid channels for yellow, magenta, cyan and black are provided to connect the pipes to respective common liquid chambers. Each discharge orifice for yellow, magenta and cyan provided on the print head 102 discharges an ink of about 40ng, and a discharge orifice for black discharges an ink of about 80ng. Fig. 11 is an electrical control block diagram of a color ink jet printer as described above. Reference numeral 301 represents a system controller for controlling the overall apparatus, which is internally provided with a microprocessor, a storage element (ROM) for storing control programs, a storage element (RAM) for use when the microprocessor operates. Reference numeral 302 represents a driver for driving the print head in a main scan direction, and reference numeral 303 represents a driver for moving the print head in a sub-scan direction. Reference numerals 304, 305 represent respective motors for the above-described drivers, which operate by receiving the information of speed and movement distance. Reference numeral 306 represents a host computer which is an equipment for transferring the printing information to the printer of the present invention. Reference numeral 307 represents a reception buffer for temporarily storing data from the host computer, or storing data until the data is read through the system controller. Reference numeral 308 represents a frame memory for expanding print data to image data, the frame memory having a memory size necessary for the printing. In this embodiment, a frame memory capable of memorizing one print sheet will be described, but the present invention is not limited in the size of frame memory. Reference numeral 309 represents a storage element for temporarily storing the data to be printed, wherein the storage capacity varies depending on the number of nozzles provided for the recording head. Reference numeral 310 represents a print control section for appropriately controlling the print head in accordance with an instruction from the system controller in terms of the discharge rate and the print data number. Reference numeral 311 represents a driver for driving the heads 312Y, 312M, 312C, 312Bk, which is controlled by a signal issued from the print control section 310. Note that using the first to twenty-fourth nozzles among the black ink discharging nozzles, the same image as in the embodiment 2 was printed, the blur occurred particularly at the boundaries between cyan and black of the image in which black character exists in the cyan background. Thus, experimentally, the printing was performed by gradually prolonging the time from the start of one scan of the recording head to the start of next scan, beginning from 1 second. As a result, barely near 2 seconds as doubled, a print quality equivalent to that of the embodiment 2 could be obtained. As described above with respect to the embodiments 1 to 3, when the black image for printing with the black ink and color image for printing with the color ink are contiguous, there occurs no blur at the contiguous boundaries between the black image and the color image by selectively using the black ink discharging nozzles so that the scan of forming the black image is not continuously followed by the scan of forming the color image, resulting in a high quality recorded image. Also, since the blur does not occur at the contiguous bondaries between black image and color image, the discharge amount of black ink can be greater than the discharge amount of color inks, so that a high quality image can be obtained with high density of black image. Moreover, these effects can be attained without substantially increasing the printing time for one page. Note that in the above embodiments, in printing the portion in which the black image and the color image are contiguous, the black ink discharging nozzles are set so that the time from the printing of black image to the printing of color image contiguous there to may be at least one scan or more, but these can be also set when the contiguous portion between the black image and the color image does not exist as shown in Fig. 3F. Next, an ink jet recording method which can improve the recorded quality without decreasing the recording speed will be described below in detail with reference to the drawings. As a further example, a color ink jet recording apparatus to which the present invention is applicable is the same as shown in Fig. 9, and the detailed explanation has been described before and thus is omitted. An ink cartridge is comprised of a color ink cartridge 110 accommodating three colors of yellow, magenta and cyan, and a black ink cartridge 111 accommodating only the black ink, each of which is separately inserted into a cartridge guide 103. On the front face of the recording head 102, the nozzle groups for yellow, magenta, cyan and black are linearly arranged, the number of nozzles in each nozzle group being N for yellow, magenta and cyan, and M for black, which is greater than that for yellow, magenta and cyan. And the space between adjacent nozzle groups is equal to or greater than a nozzle pitch (see Fig. 10). Note that in the following embodiment, the number of nozzles for yellow, magenta and cyan is twenty four, and the number of nozzles for black is 64. The details of recording head unit are the same as shown in Fig. 10. The nozzles which form the ink discharge orifices of recording head 102 are connected with ink liquid channels for supplying the ink from the cartridge to the nozzles, the ink cartridge for supplying the ink is disposed rearward of those ink liquid channels disposed. The ink liquid channels corresponding to the nozzles are provided with electricity-heat converters for generating the heat energy which ink droplets are discharged through the nozzles, and electric wirings for supplying the electric power to the electricity-heat converters. If the ink is supplied into the ink liquid channels, the electricity is supplied to the electricity-heat converters, in accordance with an image data, for generating the heat within the ink liquid channels. When the ink expands, ink droplets are discharged via each nozzle onto the recording sheet 106 such as paper or cloth, whereby an image in accordance with the image data is recorded on the recording sheet which is recording medium. Herein, 204 is a pipe for yellow, 205 is a pipe for magenta, 206 is a pipe for cyan, and 207 is pipe for black. There are four flow passages for a distributor 208 corresponding to yellow, magenta, cyan and black, each of which connects a common liquid chamber to each pipe as above described. In Fig. 10 and Fig. 12, 2Y is a yellow ink jet head having twenty four nozzles, 2M is a magenta ink jet head having twenty four nozzles, 2C is a cyan ink jet head having twenty four nozzles, and 2Bk is a black ink jet head having sixty four nozzles. Fig. 13 is a block diagram showing the schematic configuration of an ink jet printer in this embodiment, the common parts to those of previous drawings are given the same numbers, and their explanation is omitted. In Fig. 13, 620 is a control unit, comprising a CPU 710, such as for example a microprocessor, a ROM 711 for storing the control programs for the CPU and various data, and a RAM 713 for use as the work area of the CPU 710. 621 is a head driver for driving the recording head corresponding to each color in accordance with record data by inputting the record data from the control unit 620. 624 is a carriage motor for conveying and driving the carriage 101. 625 is a sheet feed motor for feeding the recording sheet 106 by driving a sheet supply roller 107 or a sheet feed roller 108 in rotation. Each of 622, 623 is a motor driver for driving a corresponding motor in accordance with an instruction of the control unit 620. 626 is a recording sheet sensor for sensing the presence of recording sheet 106, and 627 is an ink sensor for sensing the presence of an ink cartridge mounted and the ink remaining amount. 628 is an input unit for receiving the recording data input from an external equipment such as a host computer, in which it informs the control unit 620 that the recording data has been received. Then, the control unit 620 stores the recording data in one of the buffers 714 to 717 of the RAM 713 in accordance with the color. That is, the recording yellow data as input is stored in a yellow buffer 714, magenta data in a magenta buffer 715, cyan data in a cyan buffer 716, and black data in a black buffer 717. Herein, if the received data from the host computer contains the data of at least two colors of yellow, magenta, cyan and black, the color mode is determined, while if only the black data is input, the monochrome mode is determined. Thus, the recording data stored in the buffer corresponding to each color is read synchronously with the scan in the main scan direction by the carriage 1, and sent out to the head driver 21, which distributes and outputs each color data to each of yellow head 2Y, cyan head 2M, magenta head 2C and black head 2Bk. Fig. 14 shows the details of the inside of the nozzles 2Y, 2M, 2C and 2Bk. On a silicone substrate 221 are formed electricity-heat energy conversion elements (heaters) 223 and wirings at equal intervals through the same process as that for semiconductors, wherein a resin layer is laid between heaters 223 to form a partition wall 228, on to which a liquid channel forming member 227 is joined, and a ceiling plate 225 made of glass is joined thereon, whereby nozzles 222, liquid channels 226 and a common liquid chamber 224 are formed. Figs. 15A to 15E show the ink discharge principle through one nozzle of print head 102. Figs. 15A to 15E show the discharge process. (a) Discharge wait state. 223a is the ink and 223b is a liquid channel. (b) State where a bubble 223c grows when an electric signal is applied to an ink discharging heater 223. (c) State where the bubble is growing when the electric signal is continuously applied to the heater 223. (d) State where a liquid droplet of the ink 223a is discharged. (e) State where the heater 223 is electrically disconnected, and the ink 223a is refilled to a discharge orifice of nozzle. In the above process, it is desired that the temperature elevation of the heater 223 is rapidly made and followed by the temperature elevation of the ink near the heater 223 to exhibit its function excellently, but it is necessarily difficult to realize the ideal discharge state only by applying a single phase electric pulse due to the outside air temperature and the ink characteristic. Therefore, a measure can be taken in which before heating by the heater, the temperature of the surroundings of nozzles 223b is retained, or a preheat pulse is applied immediately before an electric pulse for the generation of bubbles. The present invention brings about excellent effects particularly in a recording apparatus using a recording head of the ink jet recording system of forming fine liquid droplets by the use of heat energy for the recording among the various ink jet recording systems. As to its representative constitution and principle, for example, one practiced by use of the basic principle disclosed in, for example, U.S. Patents 4,723,129 and 4,740,796 is preferred. This system is applicable to either of the so-called on-demand type and the continuous type. Particularly, the case of the on-demand type is effective because, by applying at least one driving signal which gives rapid temperature elevation exceeding nucleus boiling corresponding to the recording information on electricity-heat converters arranged corresponding to the sheets or liquid channels holding a liquid (ink), heat energy is generated at the electricity-heat converters to effect film boiling at the heat acting surface of the recording head, and the consequently the bubbles within the liquid (ink) can be formed corresponding one by one to the driving signals. By discharging the liquid (ink) through an opening for discharging by growth and shrinkage of the bubble, at least one droplet is formed. By making the driving signals into the pulse shapes, growth and shrinkage of the bubbles can be effected instantly and adequately to accomplish more preferably discharging of the liquid (ink) particularly excellent in response characteristic. As the driving signals of such pulse shape, those as disclosed in U.S. Patents 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employment of the conditions described in U.S. Patent 4,313,124 of the invention concerning the temperature elevation rate of the above-mentioned heat acting surface. As the constitution of the recording head, in addition to the combination of the discharging orifice, liquid channel, and electricity-heat converter (linear liquid channel or right-angled liquid channel) as disclosed in the above-mentioned respective specifications, the constitution by use of U.S. Patent 4,558,333 or 4,459,600 disclosing the constitution having the heat acting portion arranged in the flexed region is also included in the present invention. In addition, the present invention can be also effectively made the constitution as disclosed in Japanese Laid-Open Patent Application No. 59-123670 which discloses the constitution using a slit common to a plurality of electricity-heat converters as the discharging portion of the electricity-heat converter or Japanese Laid-Open Patent Application No. 59-138461 which discloses the constitution having the opening for absorbing pressure wave of heat energy correspondent to the discharging portion. That is, the present invention makes it possible to realize the secure and efficient recording in whatever form the recording head may be configured. In addition, among the serial-type recording heads as above described, the present invention is effective for a recording head fixed to the main device, a recording head of the freely exchangeable chip type which enables electrical connection to the main device or supply of ink from the main device by being mounted on the main device, or a recording head of the cartridge type having an ink tank integrally provided on the recording head itself. Also, addition of a restoration means for the recording head, a preliminary auxiliary means, etc., provided as the constitution of the recording device of the present invention is preferable, because the effect of the present invention can be further stabilized. Specific examples of these may include, for the recording head, capping means, cleaning means, pressurization or suction means, electricity-heat converters or another type of heating elements, or preliminary heating means according to a combination of these, and predischarging means for performing discharging separate from recording. In addition, though the ink is considered as the liquid in the embodiments as above described, another ink may be also usable which is solid below room temperature and will soften or liquefy at or above room temperature, or liquefy when a recording signal is issued as it is common with the ink jet device to control the viscosity of ink to be maintained within a certain range of the stable discharge by adjusting the temperature of ink in a range from 30 to 70°C. In addition, in order to avoid the temperature elevation due to heat energy by positively utilizing the heat energy as the energy for the change of state from solid to liquid, or to prevent the evaporation of ink, the use of the ink which will stiffen in the shelf state and liquefy by heating is also possible. In any way, the ink that will liquefy only with the application of heat energy, such as liquefying with the application of heat energy in accordance with a recording signal so that liquid ink is discharged, or may be already solidifying prior to reaching the recording medium, is also applicable in the present invention. In such a case, the ink may be held as liquid or solid in recesses or through holes of a porous sheet, which is placed opposed to electricity-heat converters, as described in Japanese Laid-Open Patent Application No. 54-56847 or No. 60-71260. The most effective method for the ink as above described in the present invention is based on the film boiling. Further, an ink jet recording apparatus according to the present invention may be used as an image output terminal for the information processing equipment such as a computer, a copying machine in combination with a reader, or a facsimile terminal equipment having the transmission and reception feature.

Claims: An ink jet recording method for recording a multi-color image on a recording medium using a recording head having an array of discharge portions consisting of a group (10d) of m discharge portions for discharging black ink and a plurality of groups (10a, 10b, 10c) of n, where m ≥ n, discharge portions for discharging respective color inks, which method comprises plural recording steps of scanning the recording head relative to the recording medium in a main scan direction so as to permit the discharge portions to discharge ink across the recording medium during each main scan; and moving the recording medium relative to the recording head in a sub-scan direction between recording steps, characterized by forming a black image area adjacent a colour image area by selecting the discharge portions of the black ink discharge portion group for forming the black image area so that there is at least one main scan of the recording head between the scan for forming the black image area and the scan for forming the colour image area adjacent said black image area. A method according to claim 1, which comprises using yellow, magenta and cyan inks as the color inks. A method according to claim 1 or 2, which comprises using a recording head in which the group of black ink discharging portions (10d) are disposed at an end portion of said recording head. A method according to claim 1, 2 or 3, which comprises using as the recording head a recording head wherein a space is provided between said groups (10a to 10d) of discharge portions. A method according to any one of the preceding claims, which comprises using as the recording head a recording head wherein m ≤ 2n. A method according to any one of the preceding claims, which comprises using as the selected discharge portions a number 1 of black ink discharge portions where l ≤ n. A method according to claim 6, which comprises using as the selected discharge portions a number l of black ink discharge portions where l=n. A method according to claim 6 or claim 7, which comprises feeding the recording medium by a pitch corresponding to the number l of predetermined discharge portions between recording of the black and color images. A method according to any one of the preceding claims, which comprises using as the recording head a recording head which discharges ink using heat energy. A method according to claim 1, wherein said recording medium is moved in the sub-scan direction between recording steps by a distance which is less than the distance between the set of selected discharge portions for discharging black ink and the set consisting of the groups of discharge portions for discharging colour ink. A method according to claim 1, wherein the black ink discharge portion group is located at one end of said array of discharge portions and said selected discharge portions of the black ink discharge group are located at the end of the group of black ink discharge portions away from the colour ink discharge portions. An ink jet recording apparatus for recording a multi-color image on a recording medium comprising: a recording head having a group (10d) of m discharge portions for discharging black ink and a plurality of groups (10a, 10b, 10c) of n, where m ≥ n, discharge portions for discharging the respective color inks, with the groups of black ink and color ink discharge portions being arranged one after another in the direction in which the discharge portions are arranged; scan means (303) for effecting relative scanning between the recording medium and the recording head; control means (301) for causing an image to be recorded by carrying out a number of recording steps each recording step consisting of a main scan of the recording head during which at least some of the discharge portions are driven to record an image along a recording path across the width of the recording medium; and means (305) for effecting relative movement between the recording medium and the recording head between recording steps in a sub-scan direction, characterised by selecting means (310) for selecting predetermined black ink discharge portions for recording from amongst said group of m discharge portions (10d) for forming the black image area so that there is at least one main scan of the recording head between the scan for forming the black image area and the scan for forming the colour image area adjacent said black image area. An ink jet recording apparatus according to claim 12, wherein said color inks are yellow, magenta and cyan. An apparatus according to claim 13, wherein said group of black ink discharge portions (10d) are arranged at an end portion of said recording head. An apparatus according to any one of claims 12 to 14, wherein a respective space is provided between each group of discharge portions (10a, 10b, 10c, 10d). An apparatus according to any one of claims 12 to 15, wherein the number of discharge portions m and n satisfy the inequality m ≤ 2n. An apparatus according to any one of claims 12 to 16, wherein the selecting means (310) is adapted to select a number l of predetermined discharge portions which satisfies the inequality 1 ≤ n. An apparatus according to claim 17, wherein the selecting means (310) is adapted to select a number l of predetermined discharge portions where l=n. An apparatus according to either claim 17 or claim 18, wherein the scan means (303) is arranged to convey the recording medium by a pitch corresponding to the number l of predetermined discharge portions. An apparatus according to any one of claims 12 to 19, wherein said discharge portion groups have heat energy generating means for applying heat to the ink to cause a state change resulting in ink being discharged through said discharge portions. An apparatus according to any of claims 12 to 20, wherein said selecting means (310) is arranged to select the discharge portions for discharging black ink such that the distance between the set of selected discharge portions for discharging black ink and the set consisting of the groups of discharge portions for discharging colour inks is greater than the distance by which said relative movement means (305) effects relative movement between the recording medium and the recording head between recording steps. An apparatus according to any of claims 12 to 21, wherein the black ink discharge portion group is located at one end of said array of discharge portions and said selecting means (310) is arranged to select discharge portions of the black ink discharge group at the end of the group of black ink discharge portions away from the colour ink discharge portion.

Inventors: EBISAWA ISAO, INUI, ISHINO TAKAYOSHI, KITAZAWA HIROAKI, MORIYAMA JIRO, NUMATA YASUHIRO, YAEGASHI HISAO, EBISAWA, ISAO, ISHINO, TAKAYOSHI, KITAZAWA, HIROAKI, MORIYAMA, JIRO, NUMATA, YASUHIRO, YAEGASHI, HISAO, EBISAWA, ISAO, C/O CANON K. K., INUI, TOSHIHARU, C/O CANON K. K., ISHINO, TAKAYOSHI, C/O CANON K. K., KITAZAWA, HIROAKI, C/O CANON K. K., MORIYAMA, JIRO, C/O CANON K. K., NUMATA, YASUHIRO, C/O CANON K. K., YAEGASHI, HISAO, C/O CANON K. K.
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: B41J2
IPC codes: B41J2