Device and method

Abstract

To provide a technique that shortens an inspection time of a recording head.SOLUTION: A device, which drives a recording head having a plurality of recording elements applied with an electric voltage to discharge ink onto a recording medium, includes control means which drives the plurality of recording elements in a time sharing manner for each of multiple blocks. The control means sets an application time of the electric voltage to be applied to the recording element for each of the multiple blocks.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a driving technique for a printing element that ejects ink onto a printing medium by application of a voltage. [Background technology]

[0002] A recording device that performs recording by ejecting ink onto a recording medium such as paper uses a recording head having a plurality of recording elements that eject ink by application of a voltage. A typical recording element is an electrothermal conversion element having a heat generating resistor element. This element heats the ink and ejects ink droplets by the action of film boiling. A technique for inspecting a recording head is known in order to set driving conditions according to individual differences of the recording head. Patent Document 1 discloses a technique in which a test pattern is recorded by varying the application time of a voltage to the recording elements, and the application time of the voltage to the recording head is optimized from the recorded test pattern. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-224874 A Summary of the Invention [Problem to be solved by the invention]

[0004] The more types of application time there are in the test pattern, the more the application time can be optimized. However, if the recording length of the test pattern is long, the longer the test time will be.

[0005] The present invention provides a technique for shortening the inspection time for a print head. [Means for solving the problem]

[0006] According to the present invention, An apparatus for driving a print head having a plurality of print elements that eject ink onto a print medium by application of a voltage, comprising: a control means for driving the plurality of recording elements in a time division manner for each of a plurality of blocks, the control means sets an application time of a voltage to be applied to the recording elements for each of the plurality of blocks during inspection of the recording head. An apparatus is provided comprising: Effect of the Invention

[0007] According to the present invention, it is possible to provide a technique for shortening the inspection time for a print head. [Brief description of the drawings]

[0008] [Figure 1] 1 is an external view of a recording apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a control unit of the recording apparatus of FIG. 1. [Diagram 3] FIG. 4 is a block diagram of a circuit relating to control of the print head. [Figure 4] FIG. 4 is a block diagram of a head driving circuit. [Diagram 5] 4 is a time chart of a control signal. [Figure 6] 6 is a diagram showing an example of a test pattern recorded based on the control signal of FIG. 5; [Figure 7] FIG. 4 is a schematic diagram showing an example of a full line head. [Figure 8] FIG. 11 is a block diagram of an inspection device according to another embodiment of the present invention. [Figure 9] 11 is a flowchart showing an example of an inspection process. [Figure 10] Schematic diagram of a resistance testing circuit. [Figure 11] 4 is a time chart of a control signal. [Figure 12] 12 is a diagram showing an example of a test pattern recorded based on the control signal of FIG. 11; [Figure 13] FIG. 13 is a diagram showing a normal distribution of optimized application times. [Figure 14] FIG. 14 is a diagram showing an example of a test pattern based on the normal distribution in FIG. 13. [Figure 15]FIG. 13 is a diagram showing an example of a test pattern having a single application time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] First Embodiment 1 is an external view of a recording device 101 according to an embodiment of the present invention. The recording device 101 is an inkjet recording device that ejects ink to record on a recording medium, but the present invention is also applicable to various recording devices other than inkjet recording devices. In the figure, arrows X and Y indicate horizontal directions that are perpendicular to each other. The Y direction is the width direction (left-right direction) of the recording device 101. The X direction is the depth direction of the recording device 101.

[0011] In addition, "recording" includes not only the formation of meaningful information such as characters and figures, but also the formation of images, patterns, and the like on a recording medium, whether meaningful or insignificant, or the processing of the medium, regardless of whether it is manifested in a way that can be visually perceived by humans. In addition, although a sheet of paper is assumed as the "recording medium" in this embodiment, it may also be cloth, plastic film, etc.

[0012] The printing device 101 includes a print head 103 capable of ejecting ink. The print head 103 ejects ink onto a printing medium 105, thereby printing an image on the printing medium 105. The print head 103 is mounted on a carriage 102. The carriage 102 reciprocates in the Y direction (main scanning direction) by a moving mechanism (not shown). During the movement of the carriage 102, ink is ejected from the print head 102 onto the printing medium 105, thereby printing an image. This operation is called printing scanning.

[0013] The carriage 102 is also equipped with ink cartridges 106 that store ink to be supplied to the print head 102. The ink cartridges 106 are detachably attached to the carriage 102. In the printing device 101 of this embodiment, a plurality of ink cartridges 106 are independently detachably mounted on the carriage 102. Each ink cartridge 106 stores a different type of ink. In this embodiment, there are four types of ink: cyan, magenta, yellow, and black. The printing device 101 is capable of color printing using these multiple types of ink.

[0014] The print head 103 has a plurality of ink ejection orifices and a plurality of printing elements. The printing elements are provided corresponding to the ink ejection orifices. The print head 103 of this embodiment employs an inkjet method that ejects ink using thermal energy. For this reason, it is provided with electrothermal converters (sometimes called heaters) as printing elements. Ink is ejected from the corresponding ink ejection orifices by applying a pulse voltage to the corresponding heater in response to a print signal.

[0015] The transport unit 107 transports the recording medium 105 fed from the feeding unit 104 in the X direction (sub-scanning direction). The feeding unit 104 includes a tray on which the recording medium is stacked and a feeding mechanism for the recording medium 105. The transport unit 107 includes a transport roller and a pinch roller that is pressed against the transport roller. While the recording medium 105 is sandwiched in a nip portion between the transport roller and the pinch roller, the recording medium 105 is transported in the X direction by the rotation of the transport roller.

[0016] A transport unit 107 intermittently transports the recording medium 105. By alternately repeating the transport operation of the recording medium 105 by the transport unit 107 and print scanning, an image can be printed on the recording medium 105 in units of pages.

[0017] Fig. 2 is a block diagram of the control unit of the recording device 101. In Fig. 2, image data to be recorded is input to an interface 201. An MPU 202 controls the entire recording device 101. A ROM 203 stores a control program executed by the MPU 202. A DRAM 204 stores various data (recording data, etc.).

[0018] The gate array 205 controls the supply of data to the printhead 103. The gate array 205 also controls data transfer between the interface 201 and the MPU 202 and DRAM 204.

[0019] A transport motor 209 is a motor that serves as a drive source for the transport unit 6, and is driven by a motor driver 207. A carriage motor 210 is a motor that serves as a drive source for a mechanism that moves the carriage 102, and is driven by a motor driver 208. A head control circuit 206 drives the printhead 103.

[0020] An outline of data processing during printing will be described below. When image data is input to the interface 201, the image data is converted to print data between the gate array 205 and the MPU 202. Then, the motor drivers 207 and 208 are driven, and the printhead 103 is driven according to the print data sent to the head control circuit 206 to perform printing. The drive circuit inside the printhead 103 selectively applies voltage to the heaters in accordance with the print data to generate ejection energy. Ink is ejected by this energy. The printhead 103 is also equipped with a drive circuit that performs divided drive control of the heaters.

[0021] Fig. 3 is a circuit diagram showing the head control circuit 206 and the head drive circuit 300 built into the print head 103, and Fig. 4 is a circuit diagram of the head drive circuit 300. A head drive circuit 300 is provided for each type of ink, and four are provided in this embodiment. The head control circuit 206 is provided on the main body side of the printing device 101, and controls each head drive circuit 300.

[0022] The head control circuit 206 outputs a reset (RESET) signal, a transfer clock (CLK) signal, and a latch (LATCH) signal as signals common to each head drive circuit 300. The head control circuit 206 also outputs data (DATA0-3) signals, block data (BDATA0-3) signals, and application time (HC0-HC3) signals as individual signals to each head drive circuit 300. The numbers 0-3 attached to the symbols of each signal correspond to the four head drive circuits 300. When there is no distinction between the output destinations of the signals or when the signals are referred to collectively, the numbers are omitted. For example, HC0-HC3 are simply written as HC. The HC signal is a signal that specifies the application time of the voltage applied to the heater when performing time-division driving.

[0023] The configuration of the head drive circuit 300 will be described. First, the recording data supply unit 301 will be described. The recording data supply unit 301 includes an M-bit shift register 302 and a latch circuit 303. The M-bit shift register 302 stores data (DATA) in synchronization with a CLK signal. The latch circuit 303 temporarily holds the same bit data (M-bit data) of the M-bit shift register 302 in response to a LATCH signal.

[0024] Next, the recording block selection unit 304 will be described. The recording block selection unit 304 includes an L-bit shift register 305 and an L-bit decoder 306. The L-bit shift register 305 stores block data (BDATA) in synchronization with the CLK signal. The L-bit decoder 306 temporarily holds the same bit data (L-bit data, where L=2 here) of the L-bit shift register 305 in response to an input LATCH signal.

[0025] In this embodiment, the block data (BDATA) is received as serial data by an L-bit shift register 305 for designating a drive block, and the output from the L-bit shift register 305 is held in an L-bit decoder 306. Therefore, by changing the data input to the L-bit shift register 305, the order of block drive during time-division drive can also be changed.

[0026] The heater group 308 includes heaters identified as 0seg to Nseg. N=2L×M-1. The AND gate group 307 is formed of N AND gates corresponding to the heaters. Each AND gate of the AND gate group 307 receives one of the block selection signals BE0 to BE(2L-1: BE3 in this embodiment) from the print block selection unit 304. Each AND gate also receives the print data selection signals HD0 to HD(M-1) corresponding to the print dots from the print data supply unit 301 and the HC signal.

[0027] The output of each AND gate turns on / off the switching transistor Tr0-TrN corresponding to that AND gate. Then, the voltage VH is applied to the heater 308 corresponding to the turned-on transistor Tr0-TrN, causing it to generate heat. This causes ink droplets to be ejected.

[0028] The printing operation in the inspection of the print head 103 will be described. The inspection is performed by printing a test pattern on the printing medium 105 for each type of ink. Fig. 5 is a time chart of each signal related to the operation of the head drive circuit 300. Fig. 6 is a diagram showing an example of the test pattern printed on the printing medium 105.

[0029] As is well known, time-division driving can be summarized as follows. The multiple printing elements (heaters) that make up each ink ejection port array are divided into multiple groups consisting of multiple adjacent printing elements, and the multiple printing elements in each group are assigned to different blocks. For example, in the example of FIG. 6, 0Seg to 3Seg form one group Gr. Similarly, 4Seg to 7Seg also form one group Gr. The same is true for 8seg to Nseg. Then, each printing element is assigned to one of the four blocks BE0 to BE3. In the example of FIG. 6, BE0 to BE3 are assigned in ascending order of Seg numbers.

[0030] One cycle of the time division driving is defined as a section in which each of the block selection signals BE0 to BE3 is output once. CY1 to CY4 respectively indicate recording pixels in one cycle. Time sections S1 to S8 in FIG. 5 show the time chart of each signal in the recording operation in cycle CY1.

[0031] First, in a time section S1, M-bit recording data (DATA) and L-bit block data (BDATA) are read into the L-bit shift register 305 and the M-bit shift register 302 in that order in synchronization with the CLK signal.

[0032] Then, when the transfer of the recording data (DATA) and block data (BDATA) is completed, the head control circuit 206 outputs a LATCH signal at the timing of time section S2. In response to this, the head drive circuit 300 holds the recording data of the first block in the latch circuit 303, and holds the block data of the first block in the L-bit decoder 306. At this timing, a block selection signal BE0 for driving the recording elements (heaters) belonging to the first block is output from the L-bit decoder 306.

[0033] When the head control circuit 206 outputs the LATCH signal, it starts transferring the next drive block in time section S3. As a result, the M-bit recording data (DATA) and L-bit block data (BDATA) of the next drive block are synchronized with the CLK signal and sequentially read into the L-bit shift register 305 and the M-bit shift register 302 of the head drive circuit 300, respectively.

[0034] The BE0 signal is output until the end of time interval S3. When the drive time for the first block ends, the head control circuit 206 outputs a LATCH signal in time interval S4, and switches drive to the next block. In time interval S4, at the timing when the block data of block BE1 is held in the latch circuit 303, the L-bit decoder 306 outputs a BE1 signal for driving the recording elements (heaters) belonging to block BE1.

[0035] In this way, the transfer of print data and block data is repeated in time intervals S5 to S9 until the drive time of the last block ends. Similarly, block selection signals BE2 and BE3 for driving the print elements belonging to blocks BE2 and BE4 are output from the L-bit decoder 306 in the timing of time intervals S6 and S8, respectively. In this way, block time-division drive is realized in response to the input of the LATCH signal, as shown in FIG. 5.

[0036] On the other hand, the head control circuit 206 can vary the length of the HC signal for each block to vary the time for applying a voltage to the recording element within one period (one column). In the example of Fig. 5, an HC signal with a pulse width HP_R and an HC signal with a pulse width HP_T are used. In the example of Fig. 5, for example, the pulse width HP_R is set as the reference time, and the pulse width HP_T is set as the measurement target time (test target time).

[0037] In the time sections S1 to S8 in FIG. 5, an HC signal with a pulse width HP_R is output in synchronization with the BE0 signal, and an HC signal with a pulse width HP_T is output in synchronization with the BE02 signal. An HC signal in synchronization with the BE01 signal and the BE03 signal is not output. In this case, as shown in the record of the cycle CY1 in FIG. 6, ink droplets with a pulse width HP_R are ejected by each heater such as 0Seg, 4Seg, and 8Seg belonging to the block BE0 to form dots. In addition, ink droplets with a pulse width HP_T are ejected by each heater such as 2Seg, 6Seg, and 10Seg belonging to the block BE2 to form dots. A dot ejected by applying a voltage with a pulse width HP_R as a reference and a dot ejected by applying a voltage with a pulse width HP_T as a measurement target are formed adjacent to each other on the recording medium 105. An inspector can visually check the density of these dots and judge whether the voltage application time is appropriate.

[0038] In the example of Fig. 5, in the time sections S0 to S8, the HC signal is as follows: block BE0: pulse width HP-R, block BE1: none, block BE2: pulse width HP_T, block BE3: none. Then, in the subsequent recording (S10 onwards), the voltage application time of the HC signal for each block is cyclically shifted within the block in a predetermined order for each period. Fig. 6 shows the recording results for four periods.

[0039] In cycle CY2, block BE0: none, block BE1: pulse width HP-R, block BE2: none, block BE3: pulse width HP_T. Compared to cycle CY1, the dots ejected by voltage application of pulse width HP_R and the dots ejected by voltage application of pulse width HP_T are shifted by one pixel in the Y direction. In cycle CY3, block BE0: pulse width HP_T, block BE1: none, block BE2: pulse width HP-R, block BE3: none. Compared to cycle CY2, the dots ejected by voltage application of pulse width HP_R and the dots ejected by voltage application of pulse width HP_T are shifted by one pixel in the Y direction.

[0040] In cycle CY4, block BE0: none, block BE1: pulse width HP_T, block BE2: none, block BE3: pulse width HP-R. Compared to cycle CY3, the dots ejected by voltage application with pulse width HP_R and the dots ejected by voltage application with pulse width HP_T are shifted by one pixel in the Y direction. This means that the voltage application time of the HC signal has completed one cycle through blocks BE0 to BE3.

[0041] In the recorded test pattern, dots ejected by applying a voltage with a pulse width HP_R are arranged in a line as shown by line P1. Also, dots ejected by applying a voltage with a pulse width HP_T are arranged in a line as shown by line P2. Since the lines P1 and P2 are recorded in parallel and there is an area between them where no ink is ejected, the inspector can easily compare the density difference between the dots ejected by applying a voltage with a pulse width HP_R and the dots ejected by applying a voltage with a pulse width HP_T. Therefore, the appropriateness of the voltage application time to the heater can be visually judged more easily.

[0042] In this embodiment, the length of the HC signal is set for each block, so that the recording area of ​​the test pattern can be reduced. Therefore, the test time of the print head 103 can be shortened. FIG. 15 shows an example in which the length of the HC signal is common to all blocks as a comparative example. In order to print a test pattern similar to the example of FIG. 6, in the example of FIG. 15, four cycles are recorded with an HC signal having a pulse width HP_R, and four cycles are recorded with an HC signal having a pulse width HP_T. The example of FIG. 15 has twice the recording area compared to the example of FIG. 6, and requires a longer recording time. That is, in the example of FIG. 6, the test pattern can be recorded in half the recording time compared to the example of FIG. 15, and the test time can be shortened. Moreover, in the example of FIG. 6, dots ejected by applying voltages with different pulse widths are recorded in closer positions compared to the example of FIG. 15, so that the inspector can easily compare them.

[0043] Second Embodiment In the first embodiment, a serial type inkjet recording device 101 in which the recording head 103 is mounted on a carriage 102 and moves in the Y direction has been exemplified. However, the contents described in the first embodiment are also applicable to a recording device equipped with a full line head. FIG. 7 is a schematic diagram of a recording device 701 of this embodiment. A transport unit 703 includes a transport roller and transports the recording medium 105 in the X direction. The recording head 702 has a recording element array arranged in the Y direction for a length equivalent to the width of the recording medium 105, and the position is fixed.

[0044] In the print head 702, which is such a full-line head, the length of the HC signal can be set for each block in the same manner as in the first embodiment, so that the test pattern as shown in FIG. 6 can be printed on the print medium 105.

[0045] <Third embodiment> 8 is a block diagram of a measuring device 1000 according to an embodiment of the present invention. The measuring device 1000 is a device specialized for inspecting the print head 103 of the first embodiment, and is used, for example, before shipping of the product of the print head 103. Note that the measuring device 1000 may also be a device for inspecting the print head 702, which is a full-line head described in the second embodiment. The measuring device 1000 includes a carriage 901 that fixes the print head 103. An ink cartridge (not shown) is also mounted on the carriage 901.

[0046] For the measurement, droplets are ejected from the recording head 103 onto a recording medium 904 on a stage 903 to record a test pattern. The test pattern is imaged by a camera 905, and the imaged image data is processed to set the application time of the voltage to be applied to the recording element.

[0047] An illumination device 906 is disposed near the camera 905. The illumination device 906 uses LED illumination that can output the wavelengths R: 625 [nm], G: 528 [nm], and B: 470 [nm] and ensures durability and light quantity stability.

[0048] The recording head 103 is equipped with multiple head drive circuits 300 described in the first embodiment. The head control circuit 206 is electrically connected to the head drive circuits 300 via a contact probe unit 1002. The lighting power supply 1003 is the power supply for the lighting device 906. The lighting device 1003 has an external control terminal, and it is possible to control the amount of light of each of the RGB components of the lighting device 1003 under the control of the image capture control circuit 1004.

[0049] A recording medium 904 is placed on a stage 903, and the recording medium 904 is brought into close contact with the surface of the stage 903 by a vacuum or the like. The stage 903 is displaced by a mechanism (not shown) to constitute a transport mechanism for transporting the recording medium 904. The position of the stage 903 is detected by an encoder sensor. The position of the stage 903 is controlled by a stage controller 1005 so that an inspection pattern formed by droplets discharged from the recording head 103 on the recording medium 904 falls within the angle of view of a camera 905. The surface of the recording medium 904 is coated so that it can absorb droplets evenly when they land on the recording medium 904.

[0050] The camera 905 has an imaging sensor for capturing an image of the test pattern formed by droplets discharged from the recording head 103 and reading the image. The imaging sensor is, for example, a line sensor type CCD camera. The advantage of using a line sensor type CCD camera is that it is relatively inexpensive yet has high resolution, and furthermore, it is possible to capture only the necessary part of the test pattern as an image. This results in a high-resolution image but with a small amount of image data, and the processing speed can be improved. The image data obtained by the camera 905 is then sent to the grabber board 1013 via the image capture control circuit 1004.

[0051] The control computer 1010 has a graphics processing unit (hereinafter, GPU) 1011 for display output, and a video signal is output to a monitor 1016 via the GPU 1011. The control computer 1010 also has a network interface card (hereinafter, NIC) 1012, a grabber board 1013, and a motion control board 1014, and can collectively control each of them. Furthermore, the control computer 1010 can import image data from the grabber board 1013, and perform high-speed arithmetic processing using an arithmetic processing unit 1015.

[0052] Next, a detailed description will be given of the flow of inspection of the print head 103 in this embodiment.

[0053] First, a contact check is performed to confirm the electrical connection between the head drive circuit 300 mounted on the printhead 103 and the head control circuit 206 (S101). Next, before printing the test pattern, the electrical resistance value of the printing element (heater) is measured (S102). The head control circuit 206 of this embodiment includes a circuit for measuring the electrical resistance value of the heater. FIG. 10 is a circuit diagram showing an example. The electrical resistance value of the heater 308 of the printhead 103 is measured in the electrical circuit shown in FIG. 10. For example, a drive voltage of 5.0 V and a pulse of 5.0 μs are applied to the heater 308. The potential difference Vs between both ends of the shunt resistor Rs1201 is measured by a voltage sensor Vs, and the current Is flowing through the electrical circuit is calculated. The electrical resistance value of the heater 308 is Resistance value = (5.0-Vs) / Is Calculated from.

[0054] Returning to FIG. 9, a setting (ejection setting) is performed regarding the length (application time) of the HC signal applied to the heater 308 to eject ink droplets (S103). In this S103, a provisional application time (pulse width) of the voltage applied to the heater 308 is set. The application time is set based on the electric resistance value of the heater 308 measured in S102. The ejection energy of the ink droplets by the heater 308 is determined by the voltage value of the drive voltage VH applied to the heater 308 and the application time of the drive voltage VH. In this embodiment, the voltage value of the drive voltage VH is fixed, and the application time (length of the HC signal) is variable. Specifically, the voltage value is set to 24 V, and a provisional pulse width of the HC signal is set corresponding to the electric resistance value (average resistance value) of the heater 308. Thereby, a provisional ejection energy for ejecting ink droplets from the print head 103 is determined.

[0055] Next, the stage 903 is moved (S104) to form a test pattern on the recording medium 904. The moving speed of the stage 903 is determined by the ink ejection characteristics of the recording head 103, and is moved at, for example, 25 inches / sec.

[0056] Next, ink is ejected from the print head 103 onto the print medium 904 to print the test pattern. The conveyance of the print medium 904 and the movement of the print head 103 in printing the test pattern are basically the same as in the first embodiment. Ink ejection control uses the length of the virtual HC signal set in S103. Test patterns of different densities are printed onto the print medium 904.

[0057] When inspecting the ejection energy, it takes a lot of time to measure the entire energy setting range that is expected from the manufacturing process variations of the heater 308. By setting the length of the HC signal from the electric resistance value of the heater 308 measured in S102, it is possible to limit the range of ejection energy to be measured.

[0058] FIG. 11 is a time chart of each signal when recording a test pattern, and FIG. 12 shows an example of a test pattern recorded by the signals of FIG. 11. A pattern 1320 of FIG. 12 is recorded by a signal group 1310 of FIG. 11. Similarly, patterns 1321, 1322, and 1323 of FIG. 12 are recorded by signal groups 1311, 1312, and 1311 of FIG. 11. The signal groups 1310 to 1313 are composed of a signal train for four cycles of time-division driving, and patterns 1320 to 1323 are the recording results of four cycles of time-division driving. The signal groups 1310, 1311, 1312, and 1313 partially shown in FIG. 11 mainly show signals in the first cycle (CY1, CY11, CY21, and CY31) of time-division driving, respectively.

[0059] The patterns 1320 to 1323 are recorded such that droplets that are discharged from the ink discharge ports and land on the recording medium 904 form one dot without overlapping each other.

[0060] In the signal group 1310 for recording the pattern 1320, two types of pulse width HP_0 and pulse width HP_1 are set as the length (application time) of the HC signal. The pulse width HP_0 is set as the length of the temporary HC signal in S103. The pulse width HP_1 is set to a length obtained by reducing the pulse width HP_0 by a predetermined time (here, 0.02 μs).

[0061] In the signal group 1311 for recording the pattern 1321, two types of pulse widths HP_2 and HP_3 are set as the length (application time) of the HC signal. The pulse width HP_2 is set to a length obtained by reducing the pulse width HP_1 by 0.02 μs, and the pulse width HP_3 is set to a length obtained by reducing the pulse width HP_2 by 0.02 μs.

[0062] In the signal group 1312 for recording the pattern 1322, two types of pulse widths, namely, pulse width HP_4 and pulse width HP_5, are set as the length (application time) of the HC signal. The pulse width HP_4 is set to a length obtained by reducing the pulse width HP_3 by 0.02 μs, and the pulse width HP_5 is set to a length obtained by reducing the pulse width HP_4 by 0.02 μs.

[0063] In the signal group 1313 for recording the pattern 1323, two types of pulse widths HP_6 and HP_7 are set as the length (application time) of the HC signal. The pulse width HP_6 is set to a length obtained by reducing the pulse width HP_5 by 0.02 μs, and the pulse width HP_7 is set to a length obtained by reducing the pulse width HP_6 by 0.02 μs.

[0064] By repeating this method, the pulse width of the HC signal is set for each pattern, and a large number of patterns are recorded. In the example of Fig. 10 and Fig. 11, the test pattern is composed of four patterns 1320 to 1323, but it may be five or more patterns (for example, nine patterns).

[0065] As in the first embodiment, in four periods of time-division driving, the blocks to which each pulse width of the HC signal is applied are cyclically shifted. As a result, for example, in pattern 1320, as shown in Fig. 12, dots ejected by applying a voltage with a pulse width HP_0 are arranged in a line, and in parallel with this, dots ejected by applying a voltage with a pulse width HP_1 are arranged in a line.

[0066] 9, when the recording of the inspection pattern is completed, the stage 903 carrying the recording medium 904 is moved to the measurement area of ​​the camera 905, and the inspection pattern is captured by the camera 905 (S106). The captured inspection pattern is input to the control computer 1010 as one image. Next, the pattern within the allowable range is determined from the captured image of the inspection pattern (S107). For example, the determination can be made by calculating the landing ratio of the ink droplets and based on the calculation result. The landing ratio can be specified from the area SA0 of the pattern recording region and the landing area of ​​the ink droplets for each pulse width. The area SA0 is a known value that is determined in advance. In the determination of S107, the total area of ​​the ink droplet dots for each pulse width can be obtained as the landing area by image processing. For example, the landing ratio of the ink droplets ejected by applying a voltage with a pulse width HP_0 is calculated by landing ratio=(total area of ​​the ink droplet dots ejected by applying a voltage with a pulse width HP_0) / area SA0. Similarly, the landing ratios are calculated for each of the other pulse widths HP_1 to HP7.

[0067] 11 and 12, the relationship is as follows: pulse widths HP_0>HP_1...>HP_7. Therefore, the droplet landing ratio of the pulse width HP_0 in the pattern 1320 is the highest, and the ejection energy is the strongest. Since the value of the ejection energy is proportional to the application time of the voltage to the heater 308, the ink density decreases as the pulse width becomes shorter. If the density is within the allowable range, that is, the pulse width whose landing ratio falls within a predetermined allowable range, can be set as the pulse width to be used in printing after inspection. The allowable range may be varied depending on the conditions under which the print head 103 is used.

[0068] As an allowable range, the minimum value of the landing ratio may be, for example, 1.0%. Then, for example, if the landing ratio falls below the allowable minimum value at the pulse width HC_6, the pulse width HC_5 having the second strongest ejection energy after the pulse width HC_6 may be set as the pulse width to be used in recording after the inspection.

[0069] In S108, the application time of the voltage to the recording element (the pulse width of the HC signal) is set according to the determination result in S107. The setting may be performed by writing information on the application time to a ROM (not shown) mounted on the recording head 103. In addition to the application time, the ID of the recording head 103, the date of manufacture, etc. can also be written to this ROM.

[0070] In this embodiment, it is possible to automate the inspection of the print head 103. Furthermore, by setting the application time of the voltage to the printing elements based on the landing ratio, the inspection can be completed in a relatively short time.

[0071] <Fourth embodiment> In each of the above embodiments, two types of time (pulse width HP of HC signal) are used in one cycle of time-division driving for the voltage application time to the recording element. However, the number of types of application time in one cycle of time-division driving may be three or more, and the number of types may be changed depending on the pattern.

[0072] Here, we will explain an example of an inspection method that takes into account manufacturing variations (individual differences) in the print head 103. The manufacturing variations mentioned here include, for example, variations in resistance values ​​that change depending on the material, line width, and length of the wiring in the circuit of the print head 103. The manufacturing variations affect the variations in the ejection energy.

[0073] Even if there is manufacturing variation, it is known from experience that the optimum value of the application time of the voltage to the recording element falls within a certain range. Fig. 13 shows a normal distribution showing an example of this. The horizontal axis shows the type of pulse width HP, and as exemplified in the third embodiment, 24 types of pulse widths are shown, which are decreased by 0.02 μs from HP_0. The vertical axis shows the frequency with which the pulse width was determined to be the optimum value in past inspections. The example of Fig. 13 shows that there is a high possibility that the optimum value exists within the range of pulse widths HP_8 to HP_11.

[0074] Therefore, in the time domain of the application time where the probability of obtaining the optimum ejection energy is low (for example, the pulse widths HP_0 to HP_7 and HP_12 to HP_23 in FIG. 13), the number of types of application time in one cycle of the time-division driving may be increased.

[0075] 14 is a diagram showing an example of a test pattern. In the illustrated example, for a time region of application time where the probability of obtaining optimal ejection energy is low, the number of types of application time in one cycle of time-division driving is relatively increased. Conversely, for a time region of application time where the probability of obtaining optimal ejection energy is high, the number of types of application time in one cycle of time-division driving is relatively decreased to improve the pattern recognition rate.

[0076] Specifically, since the pulse widths HP_0 to HP_6 have a low probability of becoming the optimal ejection energy, four types of application time are set in one cycle of the time-division driving. For example, in the pattern 1502, the pulse widths HP_0 to HP_3 are set in one cycle of the time-division driving. In four cycles of the time-division driving, one of the pulse widths HP_0 to HP_3 is set cyclically to each of the four blocks BE0 to BE3.

[0077] Similarly, in pattern 1503, pulse widths HP_4 to HP_7 are set in one cycle of time-division driving. In four cycles of time-division driving, any of pulse widths HP_4 to HP_7 is set cyclically to four blocks BE0 to BE3. The same is true for pulse widths HP_12 to HP_23, which are less likely to result in optimal ejection energy, although not shown.

[0078] On the other hand, since pulse widths HP_7 to HP_11 have a high probability of being optimal ejection energy, two types of application time are set in one cycle of the time-division driving. For example, in pattern 1504, pulse widths HP_8 and HP_9 are set in one cycle of the time-division driving. In four cycles of the time-division driving, one of pulse widths HP_8, none, pulse width HP_9, none is set cyclically to four blocks BE0 to BE3.

[0079] Similarly, pulse widths HP_10 and HP_11 are set in one cycle of the time-division driving in pattern 1505. In four cycles of the time-division driving, one of pulse widths HP_10, none, pulse width HP_11, none is cyclically set in four blocks BE0 to BE3.

[0080] According to this embodiment, since it is possible to form an ejection energy inspection pattern weighted according to the probability of obtaining the optimum ejection energy, it is possible to improve the inspection accuracy while shortening the inspection time.

[0081] <Other embodiments> The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0082] <Disclosure of the embodiment> The above embodiment discloses the following inventions.

[0083] Item 1. An apparatus for driving a print head having a plurality of print elements that eject ink onto a print medium by application of a voltage, comprising: a control means for driving the plurality of recording elements in a time division manner for each of a plurality of blocks, the control means sets an application time of a voltage to be applied to the recording elements for each of the plurality of blocks during inspection of the recording head. An apparatus comprising:

[0084] Item 2. The device according to item 1, The control means, when inspecting the recording head, The application time for each of the plurality of blocks is cyclically shifted within the plurality of blocks in a predetermined order. An apparatus comprising:

[0085] Item 3. The device according to item 1, The control means, when inspecting the recording head, the application time for each of the plurality of blocks is cyclically shifted within the plurality of blocks in a predetermined order for each period of the time division driving; An apparatus comprising:

[0086] Item 4. The device according to item 2 or 3, The control means, when inspecting the recording head, a first application time is set as the application time in one block of the plurality of blocks; a second application time different from the first application time is set as the application time in another block; An apparatus comprising:

[0087] Item 5. The device according to item 2 or 3, The control means, when inspecting the recording head, a first application time is set as the application time in a first block of the plurality of blocks; The application time is not set so that ink is not ejected from a second block that is next to the first block in the order. setting a second application time different from the first application time as the application time for a block next to the second block in the order; An apparatus comprising:

[0088] Item 6. Item 1, the device according to The control means, when inspecting the recording head, In a first time region of the application time, the number of types of the application time for each of the plurality of blocks in one cycle of the time division driving is set to a first number of types; In a second time region of the application time, the number of types of the application time for each of the plurality of blocks in one cycle of the time-division driving is set to a second number different from the first number of types. An apparatus comprising:

[0089] Item 7. Item 1, the device according to an imaging unit that images an image recorded on the recording medium by ink ejected from the plurality of recording elements during inspection of the recording head; A setting means for setting the application time to be applied after the inspection based on the captured image of the imaging means. An apparatus comprising:

[0090] Item 8. Item 7. The device according to item 7, a calculation means for calculating a ratio between a predetermined area and an ink landing area from the captured image, The setting means sets the application time to be applied after the inspection based on the calculation result of the calculation means. An apparatus comprising:

[0091] Item 9. The device according to any one of items 1 to 6, The apparatus is a recording apparatus including a carriage that carries the recording head and moves. An apparatus comprising:

[0092] Item 10. The device according to any one of items 1 to 6, the device is a recording device equipped with a full-line head as the recording head, An apparatus comprising:

[0093] Item 11. The device according to any one of claims 1 to 8, the device is an inspection device that inspects the recording head; An apparatus comprising:

[0094] Item 12. The device according to any one of items 1 to 11, A conveying means for conveying the recording medium is provided. An apparatus comprising:

[0095] Item 13. A method for driving a print head having a plurality of print elements that eject ink onto a print medium by application of a voltage, comprising: a conveying step of conveying the recording medium; a control step of driving the plurality of recording elements in a time division manner for each of a plurality of blocks, In the control step, a duration of application of a voltage to be applied to the recording elements is set for each of the plurality of blocks during inspection of the recording head. A method comprising:

[0096] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0097] 101 recording device, 103 recording head, 107 transport unit, 1000 inspection device

Claims

1. An apparatus for driving a print head having a plurality of print elements that eject ink onto a print medium by application of a voltage, comprising: a control means for driving the plurality of recording elements in a time division manner for each of a plurality of blocks, the control means sets an application time of a voltage to be applied to the recording elements for each of the plurality of blocks during inspection of the recording head. An apparatus comprising:

2. 2. The apparatus of claim 1, The control means, when inspecting the recording head, The application time for each of the plurality of blocks is cyclically shifted within the plurality of blocks in a predetermined order. An apparatus comprising:

3. 2. The apparatus of claim 1, The control means, when inspecting the recording head, the application time for each of the plurality of blocks is cyclically shifted within the plurality of blocks in a predetermined order for each period of the time division driving; An apparatus comprising:

4. 4. An apparatus according to claim 2 or claim 3, comprising: The control means, when inspecting the recording head, a first application time is set as the application time in one block of the plurality of blocks; a second application time different from the first application time is set as the application time in another block; An apparatus comprising:

5. 4. An apparatus according to claim 2 or claim 3, comprising: The control means, when inspecting the recording head, a first application time is set as the application time in a first block of the plurality of blocks; The application time is not set so that ink is not ejected from a second block that is next to the first block in the order. setting a second application time different from the first application time as the application time for a block next to the second block in the order; An apparatus comprising:

6. 2. The apparatus of claim 1, The control means, when inspecting the recording head, In a first time region of the application time, the number of types of the application time for each of the plurality of blocks in one cycle of the time division driving is set to a first number of types; In a second time region of the application time, the number of types of the application time for each of the plurality of blocks in one cycle of the time-division driving is set to a second number different from the first number of types. An apparatus comprising:

7. 2. The apparatus of claim 1, an imaging unit that images an image recorded on the recording medium by ink ejected from the plurality of recording elements during inspection of the recording head; A setting means for setting the application time to be applied after the inspection based on the captured image of the imaging means. An apparatus comprising:

8. 8. The apparatus of claim 7, a calculation means for calculating a ratio between a predetermined area and an ink landing area from the captured image, The setting means sets the application time to be applied after the inspection based on the calculation result of the calculation means. An apparatus comprising:

9. 2. The apparatus of claim 1, The apparatus is a recording apparatus including a carriage that carries the recording head and moves. An apparatus comprising:

10. 2. The apparatus of claim 1, the device is a recording device equipped with a full-line head as the recording head, An apparatus comprising:

11. 2. The apparatus of claim 1, the device is an inspection device that inspects the recording head; An apparatus comprising:

12. 2. The apparatus of claim 1, A conveying means for conveying the recording medium is provided. An apparatus comprising:

13. A method for driving a print head having a plurality of print elements that eject ink onto a print medium by application of a voltage, comprising: a conveying step of conveying the recording medium; a control step of driving the plurality of recording elements in a time division manner for each of a plurality of blocks, In the control step, a duration of application of a voltage to be applied to the recording elements is set for each of the plurality of blocks during inspection of the recording head. A method comprising:

Images