JP5101416B2 - Image forming apparatus - Google Patents

Abstract

An image forming apparatus includes a carriage (5) which scans in a main scanning direction by being moved and includes a recording head (6) having nozzles for ejecting liquid droplets, a first mark (31) and a second mark (32) disposed at positions facing a nozzle surface (6n) of the recording head (6) by having different heights from each other, a mark reading sensor (33) attached to the carriage (5) for detecting the first mark (31) and the second mark (32), and a slant angle detecting unit which detects a slant angle of the carriage (5) in a height direction relative to the main scanning direction based on a detection result by the mark reading sensor (33).

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a carriage on which a recording head for discharging droplets is mounted.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, and a complex machine of these, for example, an ink jet recording apparatus using a recording head for discharging ink droplets is known. This ink jet recording apparatus means a sheet on which ink droplets are conveyed from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously), and a recording head A line type image using a serial type image forming apparatus that forms an image by ejecting droplets while moving in the main scanning direction, and a line type head that forms images by ejecting droplets without moving the recording head There is a forming device.

  In the present application, “image forming apparatus” means an apparatus that forms an image by ejecting ink onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, In addition, “image formation” not only applies an image having a meaning such as a character or a figure to a medium but also applies an image having no meaning such as a pattern to the medium (simply applying a droplet to the medium). It also means to land on. The “ink” is not limited to the ink, but is used as a general term for all liquids that can perform image formation, such as a recording liquid, a fixing processing liquid, and a liquid.

  In a serial type ink jet recording apparatus, a carriage on which a recording head is mounted is slidably guided by a main and subordinate guide member and moved and scanned in the main scanning direction. It is known that the carriage is inclined in the height direction with respect to the sheet conveyance surface. When such a tilt in the height direction of the carriage occurs, the distance (gap) between the nozzles having different positions in the main scanning direction and the sheet conveyance surface is different, and the flying distance from each nozzle is different. The image quality deteriorates because the position accuracy is lowered.

Therefore, for example, Patent Document 1 discloses a discharge pattern (position information) at the time of factory shipment and discharge for each number of prints set in advance in the user's use environment by a light receiving sensor fixed to a carriage that drives printing in the main scanning direction. A configuration is described in which a pattern is detected, the difference between these is calculated as a discharge accuracy difference (position shift) in the entire range of the carriage drive range, and the difference is adjusted at the discharge timing.
JP 2007-185870 A

In addition, regarding the gap variation between the carriage and the sheet conveyance surface, Patent Document 2 includes a means for measuring the distance between the print head and the recording medium for each scan to correct the droplet discharge timing. Japanese Patent Application Laid-Open No. H10-228688 discloses a method of correcting the droplet ejection timing by providing an adhesion position detection unit that detects in advance the adhesion position of the ink droplet on the recording medium when the ink droplet is ejected from the head at a predetermined timing. In this case, the distance between papers is measured by an optical paper distance sensor, and a correction value for a possible deviation amount is calculated from the obtained value to correct the droplet ejection timing.
JP 2007-044948 A JP 2000-233495 A JP 2003-334941 A

  However, in the configuration described in Patent Document 1 described above, the detection timing for reading the ejection pattern by the light receiving sensor is similarly shifted when the carriage tilts in the height direction due to secular change. There is a problem that an accurate difference from (initial position) cannot be obtained.

  In addition, there is another problem in that a sheet is wasted if a pattern is printed on the sheet in order to detect the tilt of the carriage.

  The present invention has been made in view of the above problems, and an object thereof is to accurately detect the inclination of the carriage in the height direction.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A carriage mounted with a recording head having nozzles for discharging liquid droplets and moved and scanned in the main scanning direction;
On the side facing the nozzle surface of the recording head, at different height positions, and first and second marks which are respectively disposed on different positions of the main scanning direction,
Detecting means mounted on the carriage for detecting the first and second marks;
Means for detecting an inclination in the height direction of the carriage with respect to the sheet conveying surface in the main scanning direction based on a time from when the detecting means detects the first mark to when the second mark is detected ; It was set as the structure equipped with.

  Here, the inclination in the height direction of the carriage can be detected based on the detection time of the first and second marks by the detection means.

  The first and second marks may be arranged at a plurality of positions in the main scanning direction of the carriage.

  Further, two reference marks having the same position in the height direction at the same interval as the first and second marks may be arranged.

  Further, the first and second marks can be detected before printing starts to detect the inclination in the height direction of the carriage.

  Further, the droplet ejection timing from the recording head can be corrected according to the detection result of the inclination of the carriage in the height direction.

According to the onset bright, without wasting the paper, it is possible to accurately detect the height direction of the inclination of the carriage.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an ink jet recording apparatus as an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is an explanatory perspective view showing the entire configuration of the recording apparatus, FIG. 2 is an explanatory schematic plan view of a mechanism unit of the recording apparatus, and FIG. 3 is an explanatory schematic perspective view of the mechanism unit.

  The ink jet recording apparatus is a serial type ink jet recording apparatus, and includes a recording apparatus main body 1 and a support base 2 that supports the recording apparatus main body 1.

  Inside the recording apparatus main body 1, guide rods 3 and guide rails 4 are spanned on both side plates (not shown), and a carriage 5 can slide on these guide rods 3 and guide rails 4 in the direction of arrow A in FIG. Is held in.

  As shown in FIG. 2, the carriage 5 has eight recording heads 6k1 including liquid ejection heads that eject ink droplets of black (K), yellow (Y), magenta (M), and cyan (C). , 6k2, 6y1, 6y2, 6m1, 6m2, 6c1, and 6c2 (referred to as “recording head 6” when colors are not distinguished). The two recording heads for each color are arranged with their positions shifted in the main scanning direction and the direction orthogonal to the main scanning direction (paper feeding direction: sub-scanning direction).

  The main scanning mechanism that moves and scans the carriage 3 is disposed on one side in the main scanning direction, a driving pulley 12 that is rotationally driven by the driving motor 11, and on the other side in the main scanning direction. A driven pulley 13 and a belt member 14 wound around the drive pulley 12 and the driven pulley 13 are provided. The driven pulley 13 is tensioned outward by a tension spring 15 (in a direction away from the drive pulley 12).

  Here, the driving pulley 12 and the driven pulley 13 are arranged such that the pulley axial direction is located in a direction along the ink droplet ejection direction. The belt member 14 wound between the drive pulley 12 and the driven pulley 13 is composed of independent timing belts 14A and 14B made of two rubber toothed belts. 14A and 14B are arranged around the driving pulley 12 and the driven pulley 13 in this example without gaps in the pulley axis direction. In addition, these timing belts 14A and 14B are arranged on one side of the carriage 5 in a direction perpendicular to the main scanning direction by being partially fixed and held by a belt fixing portion 7 provided on the back side of the carriage 5, respectively. Has been.

  An encoder sheet (linear scale) 21 for detecting the main scanning position of the carriage 5 is arranged along the main scanning direction of the carriage 5, and the encoder sheet 22 provided on the carriage 5 reads the encoder sheet 21. Yes.

  In the main scanning area of the carriage 5, in the recording area, the paper 10 is guided by the platen member 20 in a direction (sub-scanning direction: arrow B direction) perpendicular to the main scanning direction of the carriage 5 by a paper feed mechanism (not shown). Are intermittently conveyed. The platen member 20 is disposed on the carriage 5 so as to face the recording head 6 at least in the recording area along the main scanning area.

  In addition, a maintenance / recovery mechanism 8 that performs maintenance / recovery of the recording head 6 is disposed in one end side region of the main scanning region. Further, a main cartridge 9 containing ink of each color to be supplied to the recording head 6 is detachably attached to the recording apparatus main body 1 outside the carriage movement area in the main scanning direction or below the other end side of the carriage movement area. Installed.

  In this ink jet recording apparatus, the carriage 5 is moved in the main scanning direction, and the recording head 6 is driven according to the image information while the paper 10 is intermittently fed in the sub scanning direction, thereby ejecting droplets. A required image is formed on 10.

  Next, a first embodiment of the present invention applied to this ink jet recording apparatus will be described with reference to FIGS. 4 is an explanatory plan view of a platen member portion in the embodiment, and FIG. 5 is an explanatory front view of the same. Hereinafter, in order to simplify the description, a single recording head will be described.

  The platen member 20 is disposed in the main scanning direction of the carriage 5 so as to face the nozzle surface 6n that discharges the droplets of the recording head 6, and a groove 30 is formed at a required position to guide the paper 10. And a first surface 20b provided at a lower position in the height direction than the first surface 20b. That is, the first surface 20a and the second surface 20b have different height positions, and therefore the distance from the carriage 5 to the nozzle surface 6n of the recording head 6 is different. The groove 30 also has a function of escaping a cockling that undulates when droplets land on the paper 10, and has a depth of about 1 mm.

  A first mark 31 is disposed on the first surface 20a of the platen member 20, and a second mark 32 is disposed on the second surface 20b (note that the shape is defined by a circle in the figure). Not) Here, the first and second marks 31 and 32 are provided at a plurality of locations in the main scanning direction of the carriage 5. As a result, it is possible to detect the inclination in the height direction of the carriage 5 at a plurality of positions in the main scanning direction, and it is possible to improve the accuracy of droplet discharge timing correction, which will be described later.

  On the other hand, a reflection type photo that is a detecting means for detecting the first and second marks 31 and 32 on the surface of the carriage 5 where the recording head 6 is attached (the droplet discharge surface side of the recording head 6: the nozzle surface side). A mark reading sensor 33 composed of a sensor is provided.

Next, an outline of the control unit relating to the detection of the tilt of the carriage will be described with reference to a block diagram of FIG.
The control unit 100 includes a main control unit 101 including a microcomputer including a CPU, a ROM, a RAM, an I / F, and the like that also serves as an inclination detection unit according to the present invention that controls the entire recording apparatus, and a recording head. 6, a drive waveform storage unit 106 that stores drive waveform data applied to the recording head 6 from the head drive control unit 102, and a main scanning motor drive unit 107 that drives the main scanning motor 11. A sub-scanning motor driving unit 108 for driving the sub-scanning motor 16 for conveying the paper 10, and a communication circuit 110 for communicating with the outside.

  The main control unit 101 receives, via a cable or a network, print data from a host such as an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, etc. To do. The RAM in the main control unit 101 is used as various buffers and work memories and stores various data, and the ROM stores various control routines executed by the CPU, font data and graphic functions, various procedures, and the like.

  The head drive control unit 102 includes a drive signal generation circuit that generates a drive waveform for driving the actuator means of the recording head 6 by A / D converting the drive waveform data stored in the drive waveform storage unit 106. The print data developed in the dot pattern data (bitmap data) from the control unit 101, the generated drive waveform, and the like are sent to a head driver (not shown) provided on the carriage 5 side for driving the recording head 6.

  The main control unit 101 detects the position of the carriage 5 in the main scanning direction based on the output signal of the encoder sensor 22 and controls the movement stop position of the carriage 5. In addition, detection signals (read signals) of the first and second marks 31 and 32 from the mark reading sensor 33 of the carriage 5 are input, and the height of the carriage 5 in the main scanning direction is tilted based on the detection signals. Is detected, and the output timing of the drive waveform data from the drive waveform storage unit 106 is controlled according to the detected inclination in the height direction, thereby performing control for correcting the droplet discharge timing from the recording head 6.

Next, processing for detecting the inclination of the carriage 6 in the height direction will be described with reference to FIG. Since the position and state of the carriage 5 correspond to the position and state of the mark reading sensor 33, they are illustrated by the sensor 33 (the same applies hereinafter).
First, as shown in FIG. 7A, when the carriage 5 is not inclined, when the speed of the carriage 5 (carriage speed) is Vcrg and the distance between the first and second marks 31 and 32 is L, The time during which the carriage 5 moves from the carriage position A where the mark reading sensor 33 of the carriage 5 detects the first mark 31 to the carriage position B where the second mark 32 is detected (after the first mark 31 is detected). (Time until the second mark 32 is detected) t1 is t1 = L / Vcrg.

  On the other hand, as shown in FIG. 7B, for example, the carriage 5 is inclined at an angle θ in the height direction so that the front side in the traveling direction is relatively high and the rear side in the traveling direction is relatively low. If the difference in height between the first mark 31 and the second mark 32 (height difference) is Δh, there is no difference in height between the first mark 31 and the second mark 32. The first mark 31 is detected at a carriage position A1 earlier than the carriage position A0 (when the first mark 31 is formed at the position indicated by the phantom line).

  Accordingly, at this time, the time during which the carriage 5 moves from the carriage position A1 where the mark reading sensor 33 of the carriage 5 detects the first mark 31 to the carriage position B1 where the second mark 32 is detected (the first mark 31). T2 from the detection of the second mark 32 to the detection of the second mark 32 is t2 = (L + Δhtanθ) / Vcrg.

  That is, as shown in FIG. 8, the difference in mark detection timing is the difference Δt = (t2−t1) = Δhtanθ / Vcrg between the normal time t1 with no inclination and the time t2 with the inclination. Will occur. In FIG. 8, ta corresponds to the detection timing of the first mark 31 in the normal state, tb corresponds to the detection timing of the second mark 32, and ta1 corresponds to the detection timing of the first mark 31 when tilted.

  Accordingly, a time t1 at a predetermined carriage speed at normal time without tilt (for example, at the time of factory shipment) is stored in a memory (storage means) in the main control unit 101, and the carriage is moved at a predetermined carriage speed before printing is started. 5, the first and second marks 31 and 32 are read to obtain the time t 2, and the deviation Δt is obtained to detect the inclination θ in the height direction of the carriage 5 and correct the droplet ejection timing. By doing so, it is possible to reduce the landing position deviation due to the inclination of the carriage 5 in the height direction.

  Here, the times t1 and t2 can be calculated by counting the internal clock of the CPU in the main control unit 101. For example, as shown in FIG. 9, the count values n1 (normal time) and n2 (detection time) from the detection of the first mark 31 to the detection of the second mark 32 after counting the clock of the frequency f. ) To obtain the difference Δt (Δt = (n2−n1) / f) between the detection time (n2 / f) and the factory shipment (normal) time (n1 / f), The inclination θ of the carriage 5 can be obtained (detected) from Δt = Δhtanθ / Vcrg.

  As an example, the difference Δt between the inclination θ of the carriage 5 and the mark detection time Δt when the height difference Δh = 1 [mm], the carriage speed Vcrg = 1.185 [mm / s], and the internal clock frequency f = 80 [MHz]. The relationship is as shown in FIG. 10. For example, even when the inclination θ is 0.01 °, 12 counts can be detected with an internal clock of 80 [MHz]. By making this a table, the inclination θ of the carriage 5 can be obtained corresponding to the number of counts by the internal clock.

Here, an example of processing for detecting the inclination in the height direction of the carriage from the count value of the clock described above will be described with reference to FIG.
First, the carriage 5 is scanned in the main scanning direction to start a mark detection scan in which the first and second marks 31 and 32 are detected by the mark reading sensor 33, and the first and second marks 31 are detected by the mark reading sensor 33. , 32 are detected.

  Then, the count value n2 is obtained by counting the number of clocks from when the first mark 31 is detected to when the second mark 32 is detected. Then, a difference (n2−n1) from the factory-stored count value n1 stored in advance is calculated, and the inclination θ of the carriage 5 is obtained from the difference (n2−n1).

  Then, it is determined whether or not the inclination [theta] of the carriage 5 is [theta] = 0. If [theta] = 0, there is no inclination in the height direction of the carriage 5, and the process is directly exited. On the other hand, if θ = 0, it is determined whether θ> 0. At this time, if θ> 0, the carriage 5 is inclined in a direction in which the front side in the carriage traveling direction is relatively higher than the rear side. If θ> 0 is not satisfied (θ <0). Since the carriage 5 is inclined in a direction in which the rear side in the carriage traveling direction is relatively higher than the front side, a correction value for correcting the droplet discharge timing from each nozzle row is calculated. And stored in an internal register of the main control unit 101.

  For example, as shown in FIG. 12, when ejecting liquid droplets from two nozzle rows 6na and 6nb arranged in the main scanning direction of the recording head 6, the carriage 5 is relatively rearward in the carriage traveling direction relative to the front side. When tilted in the increasing direction, the gap Ga between the nozzle row 6Na on the rear side in the carriage traveling direction and the paper surface is shorter than the gap G when there is no tilt, and the nozzle row 6Nb on the rear side in the carriage traveling direction and the paper surface. Since the gap Gb is longer than the gap G when there is no inclination, the droplet discharge timing of the nozzle row 6Na is relatively earlier than when there is no inclination, and the droplet discharge timing of the nozzle row 6Nb is higher than when there is no inclination. Also, a correction that makes it relatively slow is performed. Note that. It is also possible to correct the droplet discharge timing of the nozzle row 6Nb (and vice versa) based on the droplet discharge timing of the nozzle row 6Na. Further, the correction of the droplet discharge timing between the plurality of recording heads 6 can be performed in the same manner. Further, correction that makes the droplet ejection timing of one nozzle the same when it is normal and when it is tilted will be described later.

  In the above-described embodiment, the scanning in one direction of the carriage (for example, the forward path) is described. However, when the detection is performed in the scanning in the other direction (for example, the backward path), detection of the first and second marks is performed. Just by reversing the order, tilt detection can be performed in the same manner.

  As described above, the first and second marks arranged at different height positions on the side facing the nozzle surface of the recording head are provided, and the height of the carriage is determined based on the detection results of the first and second marks. Since the inclination in the vertical direction is detected, it is possible to accurately detect the inclination in the height direction of the carriage without wasting paper.

  Next, another embodiment of the present invention will be described with reference to FIGS. 13 is an explanatory plan view of a platen member portion in the embodiment, and FIG. 14 is an explanatory front view of the same.

  Here, the first and second reference marks 41 and 42 are provided on the second surface 20 b of the platen member 20 at the same interval L as the attachment interval (distance L) of the first and second marks 31 and 32. The first and second reference marks 41 and 42 can also be provided on the first surface 20a. That is, the first and second reference marks 41 and 42 are two marks having no height difference.

A method for detecting the inclination of the carriage with this configuration will be described with reference to FIG.
First, as shown in FIG. 15B, the first and second reference marks 41 and 42 applied to the platen member 20 where there is no difference in height do not have the inclination of the carriage 5 in the height direction. However, the time from the detection of the first reference mark 41 to the detection of the second reference mark 42 (clock count value) is constant.

  On the other hand, as shown in FIG. 15A, the first and second marks 31 and 32 applied to the platen member 20 at different heights are, as described above, the height direction of the carriage 5. As a result, the time from when the first reference mark 41 is detected until the second reference mark 42 is detected (clock count value) changes according to the inclination θ. The distance in the main scanning direction when the carriage 5 has an inclination θ is (L + Δh tan θ).

  Thus, by comparing the interval between the first and second reference marks 41 and 42 (distance, time, count value, etc.) with the interval between the first and second marks 31 and 32, the factory shipment time can be obtained. Even if the initial value such as is not stored, or even if the initial value disappears, the inclination θ in the height direction of the carriage 5 can be detected.

Here, an example of processing for detecting the inclination in the height direction of the carriage in this embodiment will be described with reference to FIG.
First, a mark detection scan in which the carriage 5 is scanned in the main scanning direction to detect the first and second marks 31 and 32 and the first and second reference marks 41 and 42 by the mark reading sensor 33 is started.

  First, the mark reading sensor 33 detects the first and second marks 31 and 32 having a height difference, and counts the number of clocks from when the first mark 31 is detected until the second mark 32 is detected. Thus, the count value n2 is obtained.

  Next, the first and second reference marks 41 and 42 having no height difference are detected by the mark reading sensor 33, and the number of clocks from when the first reference mark 41 is detected until the second reference mark 42 is detected. To obtain a count value n1.

  Thereafter, a difference (n2−n1) between the count value n2 and the count value n1 is calculated, and the inclination θ of the carriage 5 is obtained from the difference (n2−n1).

  Then, it is determined whether or not the inclination [theta] of the carriage 5 is [theta] = 0. If [theta] = 0, there is no inclination in the height direction of the carriage 5, and the process is directly exited. On the other hand, if θ = 0, it is determined whether θ> 0. At this time, if θ> 0, the carriage 5 is inclined in a direction in which the front side in the carriage traveling direction is relatively higher than the rear side. If θ> 0 is not satisfied (θ <0). In other words, the carriage 5 is inclined in a direction in which the rear side of the carriage traveling direction is relatively higher than the front side, and therefore, a correction value for correcting the droplet discharge timing from each nozzle row is calculated. .

  If the direction of the mark detection scan of the carriage 5 is reversed, the detection starts from the second reference mark 42, so that only the count value n1 is obtained and then the count value n2 is obtained. Therefore, explanation is omitted.

  Next, the detection in the forward path and the detection in the backward path described above will be described with reference to FIG. The first mark 31 shown in the phantom line in FIG. 17 is a position when there is no height difference from the second mark 32, and the mark reading sensor 33 shown in the phantom line shows a height difference from the second mark 32. The position when the first mark 31 that is not present is read is shown.

  First, as described above in the forward path, as shown in FIG. 17A, when the carriage 5 has an inclination θ, the first mark 31 is detected earlier than the second mark 32, and the first Is detected at an earlier timing than when the carriage 5 is not inclined, the distance corresponding to the time from detection of the first mark 31 to detection of the second mark 32 is inclined. The distance (L + Δhtanθ) with respect to the distance L when there is not.

  On the other hand, on the return path, as shown in FIG. 17B, when the carriage 5 has an inclination θ, the second mark 32 is detected before the first mark 31, and the first mark When the distance 31 corresponding to the time from when the second mark 32 is detected to when the first mark 31 is detected is not tilted, because 31 is detected at a timing earlier than when the carriage 5 is not tilted. The distance (L−Δhtan θ) with respect to the distance L.

  In any case, the deviation Δt is obtained by Δhtanθ / Vcrg, so that the inclination θ of the carriage 5 can be detected.

  Thus, even when bidirectional printing is performed, the inclination of the carriage 5 can be detected separately for the forward path and the backward path, and the droplet ejection timing can be corrected.

Next, correction of droplet discharge timing will be described with reference to FIG.
Ink velocity (droplet velocity) is Vjet, head-paper gap is h, droplet flight time is T1 when the carriage is not tilted (tilt θ = 0 °), and droplet flight is when the carriage is tilted (tilt θ) Assuming that the time is T2, as shown in FIG. 10 (c), when the carriage is tilted, the speed of Vjetsin θ is obtained in the horizontal direction, so that the droplet flight distance is extended.

  That is, when there is no inclination of the carriage, h = Vjet × T1, x1 = Vcrg × T1, so that x1 = Vcrg / Vjet × h, and when the carriage is inclined at an angle θ, h = Vjet cos θ × T2, x2 = ( From Vcrgsin θ + Vcrg) × T2, x2 = (Vcrgsin θ + Vcrg) × Vjet cos θ / h.

  Therefore, even if the droplet is ejected at the same position when the carriage 5 is tilted at an angle θ and when there is no tilt, the landing position error Δx = x2−x1 = h {tan θ + Vcrg / Vjet (1 / cos θ−1)} Will occur.

  Therefore, when the carriage 5 is tilted, printing can be performed by shifting the droplet discharge timing earlier by Δx / Vcrg, so that the droplet landing position can be adjusted.

  For example, when the head-paper gap h = 1.13 [mm], the carriage speed Vcrg = 1,185 [mm / s], and the ink speed Vjet = 8,000 [mm / s], the carriage tilt angle θ. The relationship between the landing error Δx and the discharge delay amount is as shown in FIG.

  If this is tabulated, the delay time can be obtained from the inclination θ of the carriage 5.

  The above-described inclination detection processing of the carriage 5 is performed every time before printing is started, so that the droplet ejection timing in each printing can be accurately corrected and the image quality can be improved. Also, the image quality can be improved by performing it at a predetermined timing or every time the apparatus is activated.

1 is an explanatory perspective view illustrating an overall configuration of an example of an ink jet recording apparatus according to the present invention. It is a typical plane explanatory view of a mechanism part similarly. It is an outline perspective explanatory view of the mechanism part similarly. It is plane explanatory drawing of the platen member part in 1st Embodiment of this invention. It is front explanatory drawing similarly. It is a block explanatory view explaining the outline of a control part similarly. It is explanatory drawing with which it uses for description of the inclination detection of a carriage. It is explanatory drawing explaining the detection of a 1st, 2nd mark similarly. It is explanatory drawing explaining the relationship between detection of a 1st, 2nd mark, and a clock similarly. It is explanatory drawing which shows an example of the relationship between the inclination of a carriage, a time deviation, and the count number of a clock. FIG. 10 is a flowchart illustrating an example of a carriage tilt detection process. It is explanatory drawing with which it uses for description of correction | amendment of droplet discharge timing. It is plane explanatory drawing of the platen member part in 2nd Embodiment of this invention. It is front explanatory drawing similarly. It is explanatory drawing similarly provided to description of the inclination detection of a carriage. FIG. 10 is a flowchart illustrating an example of a carriage tilt detection process. It is explanatory drawing with which it uses for description of the inclination detection of the carriage in an outward path and a return path. It is explanatory drawing with which it uses for description of the correction | amendment of the inclination of a carriage, a droplet landing position shift, and droplet discharge timing. It is explanatory drawing explaining an example of the relationship between the inclination of a carriage, a landing error, and the delay time of a droplet discharge timing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording device main body 2 ... Support stand 5 ... Carriage 6k1, 6k2, 6y1, 6y2, 6m1, 6m2, 6c1, 6c2 ... Recording head 7 ... Belt fixing part 11 ... Drive motor 12 ... Drive pulley 13 ... Drive pulley 14 ... Belt Member 20 ... Platen member 30 ... Groove 31 ... First mark 32 ... Second mark 33 ... Mark reading sensor 41 ... First reference mark 42 ... Second reference mark

Claims (6)

A carriage mounted with a recording head having nozzles for discharging liquid droplets and moved and scanned in the main scanning direction;
On the side facing the nozzle surface of the recording head, at different height positions, and first and second marks which are respectively disposed on different positions of the main scanning direction,
Detecting means mounted on the carriage for detecting the first and second marks;
Means for detecting an inclination in the height direction of the carriage with respect to the sheet conveying surface in the main scanning direction based on a time from when the detecting means detects the first mark to when the second mark is detected ; an image forming apparatus characterized in that it comprises.   The image forming apparatus according to claim 1, wherein an inclination in the height direction of the carriage is detected based on detection times of the first and second marks by the detection unit.   3. The image forming apparatus according to claim 1, wherein the first and second marks are arranged at a plurality of locations in the main scanning direction of the carriage.   4. The image forming apparatus according to claim 1, wherein two reference marks having the same position in the height direction are arranged at the same interval as the first and second marks. Forming equipment.   5. The image forming apparatus according to claim 1, wherein the first and second marks are detected before the start of printing to detect the inclination in the height direction of the carriage. apparatus.   6. The image forming apparatus according to claim 1, wherein the droplet discharge timing from the recording head is corrected in accordance with a detection result of the inclination of the carriage in the height direction.

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