JP2011145153A - Foreign matter detector and droplet discharge apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foreign matter detector surely detecting foreign matters in an entire region of a workpiece surface, and also to provide a droplet discharge apparatus equipped with the same. <P>SOLUTION: The foreign matter detector is equipped with: foreign matter detection units 54, 55 which are disposed such that an optical axis A of detection light is perpendicular to a feeding direction and they stride over a work W, and detect foreign matters attached to a surface of a workpiece W by the detection light; a pair of workpiece detection sensors 56 which respectively face the workpiece W, detect an arrival of a front end a back end of the workpiece W to a position of the optical axis A, and are disposed separately from each other on a virtual line parallel to the optical axis A; and a control device 19 which starts a detection operation of the foreign matter detection units 54, 55 by using a former arrival detection as a trigger among arrival detections of the front end of the workpiece W to the position of the optical axis A by the pair of workpiece detection sensors 56, and stops the detection operation of the foreign matter detection units 54, 55 by using a latter arrival detection as a trigger among arrival detections of the back end of the workpiece W to the position of the optical axis. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a foreign matter detection device that detects foreign matter attached to the surface of a workpiece and a droplet discharge device including the foreign matter detection device.

2. Description of the Related Art Conventionally, a foreign object detection device that detects a foreign object on the surface of a CF substrate (workpiece) using a foreign object detection sensor is known (see Patent Document 1).
The foreign matter detection device includes a first foreign matter detection sensor that detects foreign matter on the surface of the CF substrate, a second foreign matter detection sensor that is arranged side by side in the moving direction of the CF substrate, and that detects foreign matter on the surface of the CF substrate, and the CF substrate. A first substrate detection sensor for detecting the CF substrate disposed on the optical axis of the first foreign matter detection sensor in the central portion, and a CF substrate disposed on the optical axis of the second foreign matter detection sensor in the central portion of the CF substrate. And a control device for controlling these constituent devices. Further, the first foreign matter detection sensor and the second foreign matter detection sensor irradiate detection light from the width of the CF substrate and detect the foreign matter for each half of the CF substrate.
In this case, when the first substrate detection sensor (second substrate detection sensor) detects the CF substrate, the control device drives the first foreign matter detection sensor (second foreign matter detection sensor) to detect foreign matter on the surface of the CF substrate. It is like that.

JP 2009-154088 A

  However, in such a foreign matter detection apparatus, since the first foreign matter detection sensor and the second foreign matter detection sensor are disposed at the center of the CF substrate, when the CF substrate is sent inclined in the θ direction (of the feed shaft) Undulation, etc.), the tip of the CF substrate is sent ahead of the first substrate detection sensor (or the second substrate detection sensor). As a result, the preceding part of the work is out of the detection area of the first foreign matter detection sensor (or second foreign matter detection sensor), and there is a problem that even if foreign matter is present in this part, it is not detected.

  An object of the present invention is to provide a foreign matter detection device that can reliably detect foreign matter over the entire surface of a workpiece surface and a droplet discharge device including the foreign matter detection device.

  The foreign matter detection apparatus of the present invention is a droplet that performs drawing on a work by driving the functional liquid droplet ejection head to discharge while feeding a rectangular work in any one feeding direction to the ink jet type functional liquid droplet ejection head. A foreign matter detection device that is provided in the discharge device and detects foreign matter adhering to the surface of the workpiece, and has a light emitting portion and a light receiving portion that are disposed across the workpiece while the optical axis of the detection light is orthogonal to the feed direction. And foreign matter detection means for detecting foreign matter adhering to the surface of the workpiece by the detection light, and each detecting the arrival of the tip and tail ends of the workpiece at the optical axis position facing the workpiece and parallel to the optical axis. Of the detection of the arrival of the tip of the workpiece at the optical axis position by the pair of workpiece detection means arranged apart from each other on the virtual line, the foreign object detection means using the previous arrival detection as a trigger A detection control unit that starts a detection operation and terminates the detection operation of the foreign matter detection unit by using a later arrival detection as a trigger of the detection of the arrival of the tail end of the workpiece at the optical axis position. .

  According to this configuration, in the detection by the pair of workpiece detection means, the detection operation of the foreign matter detection means is started by using the previous arrival detection as a trigger in the detection of the arrival of the tip of the workpiece at the optical axis position. The detection operation of the foreign matter detection means is terminated using the later arrival detection as a trigger to detect the arrival of the workpiece at the optical axis position. The foreign object detection can be reliably started from the leading end part, and the foreign object detection can be surely performed up to the trailing end part. That is, foreign matter can be reliably detected over the entire work surface. If foreign matter is detected, it is preferable to immediately stop the feeding of the workpiece and notify that effect.

  In this case, it is preferable that the pair of workpiece detection means is arranged corresponding to both ends in the width direction of the workpiece.

  According to this configuration, both end portions in the width direction of the workpiece can be reliably detected, a region where no foreign matter is detected can be eliminated, and the detection accuracy of the foreign matter inspection can be improved. In an apparatus that performs drawing on a plurality of types of workpieces having different widths, it is preferable that the pair of workpiece detection means be configured to be movable in a direction orthogonal to the feeding direction.

  In this case, the pair of workpiece detection means detects the tip and tail ends of the workpiece, and at least the distance by which the workpiece is sent from the detection by each workpiece detection means to the start of the detection operation of the foreign matter detection means, with respect to the optical axis, It is preferable to be disposed on the upstream side in the feed direction.

  According to this configuration, it is possible to eliminate the time lag that occurs between the detection of the work by the work detection means and the start of the detection operation by the foreign matter detection means. That is, foreign matter on the workpiece surface can be reliably detected while considering the moving speed of the workpiece.

  In this case, it is preferable that the angle of the optical axis is set so that the detection light from the light emitting part is reflected by the work at a shallow angle and reaches the light receiving part.

  According to this configuration, it is possible to detect the presence of a workpiece in conjunction with the detection of a foreign object. Therefore, only foreign matter adhering to the surface of the workpiece can be reliably detected, and erroneous detection can be effectively prevented.

  In this case, the foreign matter detecting means detects the workpiece until the amount of light received by the light receiving portion increases and maintains the increased state, and decreases until the amount of light received by the light receiving portion increases temporarily. It is preferable to detect as a foreign object when the rate of increase in the amount of received light exceeds a predetermined threshold, and when the rate of decrease in the amount of received light exceeds a predetermined threshold.

In the configuration in which the detection light is reflected to the workpiece, the reflected light amount of the detection light increases in proportion to the workpiece feed when the workpiece is sent tilted in the θ direction due to mechanical undulation of the feed shaft. The amount of light received at the light receiving portion also increases proportionally. That is, the amount of light received by the light receiving portion increases proportionally from the predetermined light amount of the work “none” and reaches the predetermined light amount of the work “present”. For this reason, even if the threshold value for the received light amount of the workpiece “present” is set, the foreign object cannot be detected satisfactorily in a state where it is proportionally increased.
According to the above configuration, the workpiece is detected by the change in the amount of light received by the light receiving unit (the amount of reflected detection light with respect to the workpiece), and therefore exists at the leading end portion and the trailing tail end portion of the workpiece that is sent at an angle. Foreign matter can be reliably detected.

  In this case, it is preferable that the threshold corresponds to a work gap between the nozzle surface of the functional liquid droplet ejection head and the work surface.

  According to this configuration, foreign matters having a size larger than the work gap can be detected, so that the functional droplet discharge head and the work can be reliably prevented from being damaged. At the same time, it is possible to prevent color mixing of the functional fluid due to dragging of foreign matter.

  The droplet discharge device according to the present invention is a droplet that performs drawing on a work by driving the functional droplet discharge head while discharging a rectangular workpiece in any one feeding direction to the inkjet function droplet discharge head. A discharge device is provided with the foreign matter detection device described above.

  According to this configuration, it is possible to reliably prevent the functional liquid droplet ejection head and the workpiece from being damaged, so that the drawing operation can be performed stably.

It is a perspective view of a droplet discharge device. It is a side view of a droplet discharge device. It is a top view around a foreign material detection apparatus. It is a transition diagram showing movement of a work. It is a figure for demonstrating the foreign material detection of a workpiece | work. It is an enlarged view for demonstrating the foreign material detection of a workpiece | work.

  Hereinafter, a foreign object detection device and a droplet discharge device including the foreign material detection device according to an embodiment of the present invention will be described with reference to the accompanying drawings. This droplet discharge device is incorporated in a flat panel display production line, and uses, for example, a functional droplet discharge head into which a special ink or a functional liquid that is a light-emitting resin liquid is introduced. It forms (draws) a light emitting element or the like to be each pixel of the organic EL device. In addition, a plurality of types of foreign object detection devices are mounted, which detect small foreign objects on the workpiece surface immediately before drawing, and detect large foreign objects such as tools left behind during maintenance.

  As shown in FIGS. 1 to 3, the droplet discharge device 1 is disposed on an X-axis support base 7 supported by a stone surface plate, and extends in the X-axis direction, which is the main scanning direction, to extend a workpiece W. Is moved on the X-axis table 2 that moves in the X-axis direction, and the Y-axis extending on the Y-axis direction, which is the sub-scanning direction, is disposed on the Y-axis support base 34 that spans across the X-axis table 2 The table 3, the 13 carriage units 4 suspended from the Y-axis table 3 and mounted with a plurality of functional liquid droplet ejection heads 6, and the functional liquid that supplies the functional liquid droplets to the functional liquid droplet ejection head 6 And a supply unit 5. In this droplet discharge device 1, the functional liquid supplied from the functional liquid supply unit 5 is discharged by driving the functional droplet discharge head 6 to discharge in synchronization with the driving of the X-axis table 2 and the Y-axis table 3. The ejection performance of the functional liquid droplet ejection head 6 is inspected, and a predetermined drawing pattern is drawn on the workpiece W.

  The droplet discharge device 1 also includes a discharge inspection unit 11 including an imaging camera 13 and a roll paper unit 14, a flushing unit 15, and a maintenance device 12 including a suction unit 16 and a wiping unit 17. The suction unit 16 and the wiping unit 17 are disposed in a maintenance area to be described later, and these units are used for maintenance of the functional liquid droplet ejection head 6 so as to maintain and recover the function of the functional liquid droplet ejection head 6. ing. On the other hand, the discharge inspection unit 11 (roll paper unit 14) and the flushing unit 15 are mounted on the X-axis table 2 so as to perform discharge inspection and function maintenance of the functional liquid droplet discharge head 6 when the workpiece W is discharged. It has become. The imaging camera 13 is fixedly disposed across the X-axis table 2 at a position opposite to the maintenance area across the Y-axis support base 34.

  Further, the droplet discharge device 1 includes a chamber 18 that accommodates these devices in an atmosphere in which temperature and humidity are controlled, a control device 19 (see FIG. 3) that controls these devices, and the roll described above. A foreign matter detection device 20 that detects large foreign matter around the paper unit 14 and the flushing unit 15 and detects large foreign matter and small foreign matter on the surface of the workpiece W is provided. In addition, although mentioned later for details, the foreign material detection apparatus 20 of this invention detects the small foreign material of the workpiece | work W surface.

  In the droplet discharge device 1 of the present embodiment, the workpiece W is exchanged (carrying in and out) in the discharged material area, and in parallel with the workpiece W exchange operation, the functional droplet discharge head 6 by the discharge inspection unit 11. A discharge inspection is performed. Further, the supplied work W is moved to a drawing area where the X-axis table 2 and the Y-axis table 3 intersect, and the carriage unit 4 is faced to the drawing area to perform drawing on the work W. Further, the carriage unit 4 is moved to a maintenance area where the Y-axis table 3 and the maintenance device 12 (suction unit 16 and wiping unit 17) intersect, and the function of the functional liquid droplet ejection head 6 is maintained and restored. On the other hand, by using the movement of the roll paper unit 14 and the flushing unit 15 (details will be described later) associated with the discharged material and the discharge inspection, the foreign matter detection device 20 makes a large rotation around the roll paper unit 14 and the flushing unit 15. A foreign object is detected, and a large foreign object on the set table 31 and a small foreign object on the surface of the work W are detected by the foreign object detection device 20 using the movement of the work W accompanying drawing. Note that small foreign matter detection on the surface of the workpiece W by the foreign matter detection device 20 is performed during the first main scanning in drawing. That is, drawing is performed on the detected part of the workpiece W.

  As shown in FIG. 2, the X-axis table 2 includes a set table 31 that has a mechanism capable of sucking and setting the workpiece W and correcting in the θ-axis direction, and an X-axis that supports the set table 31 slidably in the X-axis direction. A first slider 32, an X-axis second slider 33 that supports the roll paper unit 14 and the flushing unit 15 slidably in the X-axis direction, and an X-axis first slider 32 and an X-axis that extend in the X-axis direction. A pair of left and right X-axis linear motors (not shown) that move the shaft second slider 33 in the X-axis direction are provided. The X-axis first slider 32 and the X-axis second slider 33 can be moved separately and independently, and the X-axis table 2 moves the set table 31 to the discharge material area when the workpiece W is discharged. The roll paper unit 14 and the flushing unit 15 are made to face the carriage unit 4 in the drawing area. When the work W is drawn, the set table 31 is made to face the carriage unit 4 in the drawing area, and the roll paper unit 14 is made to face the above-mentioned. It faces the imaging camera 13.

  As shown in FIG. 1, the Y-axis support base 34 includes a first Y-axis support base 35 on the discharge material area side, a second Y-axis support base 36 disposed in parallel to the first Y-axis support base 35, and It is composed of The first and second Y-axis support bases 35 and 36 include a first column 37 and a second column 38 disposed so as to sandwich the X-axis table 2 from the Y-axis direction, respectively, and a third column disposed in the maintenance area. The column 39 extends in the Y-axis direction so as to straddle the X-axis table 2. The foreign matter detection device 20 is supported on the first support post 37 and the second support post 38.

  The Y-axis table 3 includes 13 bridge plates 41 each having 13 carriage units 4 suspended therein, 13 sets of Y-axis sliders (not shown) that support the bridge plates 41 in both ends, and a pair of Y-axis tables. A pair of Y-axis linear motors (not shown) are provided on the shaft support base 34 and move the bridge plate 41 in the Y-axis direction. The Y-axis table 3 causes the functional liquid droplet ejection head 6 to face the suction unit 16 and the wiping unit 17 in addition to sub-scanning the functional liquid droplet ejection head 6 during drawing via each carriage unit 4. In this case, the carriage units 4 can be moved independently and individually, or the 13 carriage units 4 can be moved together.

  As shown in FIG. 2, each carriage unit 4 has a carriage body 42 suspended from a bridge plate 41 of the Y-axis table 3, and a head that is suspended from the carriage body 42 and has twelve functional liquid droplet ejection heads 6. And a unit 43. The carriage main body 42 includes a suspension member 44 supported by the bridge plate 41 and a θ rotation mechanism 27 that supports the head unit 43 supported by the suspension member 44 so as to be capable of performing θ correction (θ rotation). Yes. The head unit 43 is configured by mounting twelve functional liquid droplet ejection heads 6 on a head plate (not shown). Furthermore, each functional liquid droplet ejection head 6 is constituted by an inkjet head driven by a piezoelectric element.

  As shown in FIG. 3, the foreign object detection device 20 includes a first foreign object detection unit 51 that detects large foreign objects such as tools left on the roll paper unit 14 and the flushing unit 15, and a set table 31 (on the set table 31. A second foreign matter detection unit 52 for detecting a large foreign matter such as a tool left on the workpiece W), and a third foreign matter detection unit 53 for detecting a small foreign matter on the surface of the workpiece W set on the set table 31. . In FIG. 3, the third foreign object detection unit 53 includes a left foreign object detection unit 54 that emits detection light from right to left, a right foreign object detection unit 55 that emits detection light from left to right, and a pair of workpiece detections. Sensor 56.

  The first foreign matter detection unit 51 is disposed on the second Y-axis support base 36 side of the Y-axis support base 34 and detects foreign matter on the roll paper unit 14 and the flushing unit 15 that are moved for inspection and ejection. For example, the presence of a tool or the like that has been misplaced due to replacement or maintenance of the roll paper unit 14 is detected. Similarly, the second foreign object detection unit 52 is disposed on the supply material area side of the first Y-axis support base 35 and detects foreign objects on the set table 31 or the workpiece W mounted on the set table 31. For example, the presence of a tool or the like that is left behind in the previous process or maintenance is detected. The third foreign matter detection unit 53 detects foreign matter on the surface of the workpiece W on the set table 31 that has shifted to the drawing operation (main scanning). For example, foreign matter such as dust adhering to the surface of the workpiece W among minute dust brought in by an operator for maintenance or the like, or dust adhering to the replaced workpiece W is detected.

Next, the third foreign object detection unit 53 will be described in detail. However, the left foreign object detection unit 54 and the right foreign object detection unit 55 are the same, and the description will proceed mainly with the left foreign object detection unit 54 as an example. .
As shown in FIG. 3, the left foreign object detection unit 54 includes a left light emitting unit 61 that irradiates (emits) detection light, and a left light receiving unit 62 that receives the detection light emitted from the left light emitting unit 61. ing. The left light emitting unit 61 and the left light receiving unit 62 are arranged so as to straddle the workpiece W and so that the optical axis 63 of the detection light is orthogonal to the feeding direction of the workpiece W. The left light emitting unit 61 is disposed at a height at which the detection light can be irradiated onto the workpiece W on the side surface on the drawing area side of the first support column 37. On the other hand, the left light receiving unit 62 is disposed at a height at which the detection light can be received on the side surface of the second support column 38 on the drawing area side. That is, the left foreign object detection unit 54 emits detection light from the left to the right in FIG. 3 to mainly detect the foreign object on the surface in the left half of the workpiece W in the width direction.

  The left light-emitting unit 61 has a left light-emitting element 63 made of a semiconductor laser or the like serving as a light-emitting light source, and emits laser light that is detection light based on the light emission signal from the control device 19. The left light receiving unit 62 includes a left light receiving element 64 that photoelectrically converts the received detection light, and outputs an electric signal as a detection result to the control device 19. Then, the control device 19 calculates the received light amount of the detection light in time series based on the electrical signal.

  The left light emitting unit 61 adjusts the angle of the optical axis 63 slightly obliquely downward toward the work W so that the detection light is reflected mainly at the left half of the work W at a shallow angle and received by the left light receiving unit 62. Has been. As a result, when the workpiece W has not reached the position of the optical axis 63 of the left foreign object detection unit 54, the left light receiving unit 62 receives a small amount of detection light, and the workpiece W receives the optical axis 63 of the left foreign object detection unit 54. When the position has been reached, the left light receiving unit 62 receives detection light corresponding to the amount of reflection to the workpiece W. Thereby, the presence or absence of the workpiece W on the optical axis 63 is detected.

Similarly, the right foreign object detection unit 55 includes a right light emitting unit 65 and a right light receiving unit 66. The right light emitting unit 65 and the right light receiving unit 66 are disposed so as to straddle the workpiece W and so that the optical axis 63 of the detection light is orthogonal to the feeding direction of the workpiece W. The right light emitting unit 65 is disposed at a height at which the detection light can be irradiated on the workpiece W in the second support column 38, and the right light receiving unit 66 is configured at a height at which the first support column 37 can receive the detection light. It is arranged. That is, the right foreign object detection unit 55 mainly detects the foreign object on the surface in the right half of the workpiece W in the width direction. Also in this case, the right light emitting unit 65 includes a right light emitting element 67 made of a semiconductor laser or the like. Then, the right light emitting unit 65 has the optical axis 63 slightly inclined downward toward the work W so that the detection light is reflected mainly at a shallow angle on the right half of the work W and received by the right light receiving unit 66. The angle is adjusted.
As described above, in the third foreign object detection unit 53 in the present embodiment, the left foreign object detection unit 54 and the right foreign object detection unit 55 are irradiated so that the respective detection lights face each other, and the respective optical axes. 63 is arranged so as to be located on the same line (in a plane orthogonal to the feeding direction).

  On the other hand, the pair of workpiece detection sensors 56 are respectively disposed downward on the lower surface of the first Y-axis support base 35. Each workpiece detection sensor 56 is constituted by, for example, a reflection type optical sensor, and detects whether or not the workpiece W has reached the position of the optical axis 63 as a result. In other words, the pair of workpiece detection sensors 56 are disposed so as to be separated from each other on the imaginary line parallel to the optical axis 63 of both foreign matter detection units 54 and 55 and to correspond to both ends in the width direction of the workpiece W. . Specifically, the left workpiece detection sensor 56 is disposed on the movement locus of the left end portion in the width direction of the workpiece W, and the right workpiece detection sensor 56 is disposed on the movement locus of the right end portion in the width direction of the workpiece W. It is arranged. The pair of workpiece detection sensors 56 (virtual line positions) are relative to the optical axis 63 by the distance that the workpiece W is sent from the detection by each workpiece detection sensor 56 to the start of the detection operation of each foreign matter detection unit 54, 55. The work W is disposed on the upstream side in the feed direction. Note that the two workpiece detection sensors 56 in the present embodiment are disposed on the upstream side in the feed direction of the workpiece W with respect to the optical axis 63 by more than the above distance (details will be described later).

  Although details will be described later, in contrast to the right foreign object detection unit 55, the left foreign object detection unit 54, and the pair of work detection sensors 56 configured as described above, the control device 19 performs one work of the pair of work detection sensors 56. The left and right foreign matter detection units 54 and 55 are driven (validated) with the detection of the tip of the first (previous) workpiece W detected by the detection sensor 56 as a trigger. Further, the control device 19 uses both the left and right foreign object detection units 54 as a trigger triggered by detection of the tail end of the last (rear) work W detected by one work detection sensor 56 of the pair of work detection sensors 56. , 55 are stopped (invalidated).

  In addition, both the workpiece | work detection sensors 56 and 56 may be comprised so that a movement in the Y-axis direction is possible according to the width | variety magnitude | size of the multiple types of workpiece | work W from which width differs (both are not shown in figure).

  With reference to FIG. 4 and FIG. 5, a method for detecting the workpiece W by the foreign object detection units 54 and 55 based on the detection results of the pair of workpiece detection sensors 56 will be described. Here, the control device 19 calculates the workpiece W from the distance (Ld) from the workpiece detection sensors 56, 56 to the optical axis 63 of the foreign object detection units 54, 55 and the moving speed (V) of the workpiece W. The time (td) required to move Ld is stored, and the received light amounts of the left foreign object detection unit 54 and the right foreign object detection unit 55 are acquired and combined to determine the presence or absence of foreign objects. It shall be determined. This detection is performed in parallel with the drawing operation. In the droplet discharge device 1 of the embodiment, drawing is performed on one work W in a plurality of passes, but this inspection is performed in parallel with the drawing in the first pass.

  When the workpiece W is sent in a posture inclined with the left end as the leading end in the plane, first, the left workpiece detection sensor 56 detects the left tip of the workpiece W (see FIG. 4A). Subsequently, the right workpiece detection sensor 56 detects the right tip of the workpiece W (see FIG. 4B). In parallel with this, the control device 19 drives the left foreign object detection unit 54 after the elapse of td from the detection time (t1s) of the left tip by the work detection sensor 56 on the left side, and from the detection time (t2s) of the right tip. After the elapse of td, the right foreign object detection unit 55 is driven. At this time, the combined received light amount of both the light receiving portions 62 and 66 increases at a constant rate from the time when the left tip passes through the optical axis 63 (t1s + td) until the right tip passes through the optical axis 63 (t2s + td) (FIG. 5). reference). That is, the foreign matter detection units 54 and 55 start the detection operation using the previous tip detection as a trigger among the tip detection of the workpiece W, and also detect the presence of the workpiece W.

  Then, after the right tip passes through the optical axis 63, the left and right light receiving units 62 and 66 receive a certain amount of light for a predetermined time. Here, the predetermined time refers to the detection of the left tail end (t1e) by the left work detection sensor 56 after the right tip passes the optical axis 63 (t2s + td) (see FIG. 4C), and td. This is the time (t1e + td) until the elapsed time.

  Further, after a lapse of a certain time, the left work detection sensor 56 detects the left tail end (t2e) (see FIG. 4D). Almost parallel to this, the combined light reception amount decreases at a constant rate from the time when the left tail end is detected by the left work detection sensor 56 until td elapses until the right tail end passes through the optical axis 63 (t2e + td). (See FIG. 5). That is, the third foreign object detection device 53 terminates the detection operation using the subsequent tail end detection as a trigger in the detection of the tail end of the workpiece W, and detects the workpiece W as “none”. Therefore, the third foreign object detection device 53 detects the amount of light received by both the light receiving units 62 and 66 from the increase to the decrease as the workpiece W.

  Next, with reference to FIGS. 5 and 6, detection of foreign matter on the surface of the workpiece W by both foreign matter detection units 54 and 55 will be described. Here, the increase rate of the combined received light amount when the received light amount increases and the decrease rate of the combined received light amount when the received light amount decreases vary depending on the tilt angle of the workpiece W. Therefore, the control device 19 calculates the tilt angle of the workpiece W by Equation 1 until the rear end of the workpiece W passes through the optical axis 63 of the foreign object detection unit 54 (55), and stores the tilt of the workpiece W stored in advance. An increase rate standard line L1 (increase standard received light amount) and a decrease rate standard line L3 (decrease standard received light amount) corresponding to the angle are determined. Note that the increase rate standard line L1 and the decrease rate standard line L3 have a relationship in which the signs of the slopes are opposite to each other, and therefore it is only necessary to have either the increase rate standard line L1 or the decrease rate standard line L3. Note that Ls in Equation 1 is the distance between the left workpiece detection sensor 56 and the right workpiece detection sensor 56.

The foreign object detection is performed in three parts: an increasing region where the combined received light amount increases, a constant region where the combined received light amount is constant, and a decreasing region where the combined received light amount decreases.
As shown in FIG. 6A, foreign matter detection in the increased region is performed by receiving the above-described increased standard received light amount (two-dot chain line) and the received light amount actually received by the light receiving unit 62 (66) (solid line). If the amount difference corresponds to a work gap between the work W and the functional liquid droplet ejection head 6 on the increase rate standard line L1 (Δ2), it is determined as “foreign matter ant”. On the other hand, when the distance between the increased standard received light amount and the received light amount line is equal to or smaller than the work gap between the work W and the functional liquid droplet ejection head 6 (Δ1), it is determined as “no foreign matter”. That is, the foreign matter detection unit 54 (55) determines that the foreign matter ants are present when the increase rate of the combined received light amount exceeds a predetermined threshold.

  As shown in FIG. 6 (b), the foreign object detection in the fixed region is performed by measuring the distance between the standard received light amount L2 (two-dot chain line) 9 and the received light amount line (solid line) in the fixed region at the standard received light amount L2. When it corresponds to the work gap between the work W and the functional liquid droplet ejection head 6 or more (Δ4), it is determined as “foreign matter ant”. On the other hand, when the distance between the standard received light amount L2 and the received light amount line is equal to or smaller than the work gap between the work W and the functional liquid droplet ejection head 6 (Δ3 and Δ5), it is determined as “no foreign matter”. In other words, the foreign matter detection unit 54 (55) determines that the foreign matter ants are present when the amount of received light temporarily exceeds a predetermined threshold.

  As shown in FIG. 6 (c), the foreign object detection in the decrease region is based on the difference in received light amount between the above-described reduced standard received light amount (two-dot chain line) and the received light amount line (solid line). If it corresponds to the work gap between the work W and the functional liquid droplet ejection head 6 (Δ6), it is determined as “foreign matter ant”. On the other hand, when the distance between the reduced standard received light amount and the received light amount line is equal to or smaller than the work gap between the work W and the functional liquid droplet ejection head 6 (Δ7), it is determined as “no foreign matter”. That is, the foreign matter detection unit 54 (55) determines that the foreign matter ants are present when the rate of decrease in the amount of received light exceeds a predetermined threshold.

  According to the above configuration, the control device 19 detects and controls the foreign object detection unit 54 (55) using the detection of the tip of the work W by the work detection sensor 56 as a trigger. Therefore, the foreign matter detection unit 54 (55) can reliably perform foreign matter detection from the leading end to the tail end of the workpiece W. That is, since the foreign object detection unit 54 (55) can be detected while the workpiece W is on the optical axis 63 of the foreign object detection unit 54 (55), the foreign object is reliably detected over the entire surface of the workpiece W. be able to. Further, in the droplet discharge device 1, since the functional droplet discharge head 6 and the workpiece W can be reliably prevented from being damaged, the quality of the product can be improved and the drawing efficiency can be increased.

  In the present embodiment, the foreign object detection unit 54 (55) is driven after the elapse of td after the tip of the tip is detected by the work detection sensor 56, but it may be adjusted by detecting the signal. That is, the foreign object detection unit 54 (55) is always driven, and the signal is canceled when the workpiece W does not exist on the optical axis 63. Then, the tip of the tip may be detected by the workpiece detection sensor 56, and after the elapse of td, the workpiece W may be detected by detecting a signal. Thereby, detection light can be irradiated stably and detection accuracy can be improved.

  Although not particularly illustrated, the foreign matter determination method in the increase region and the decrease region may be performed according to the area. In this case, the control device 19 stores a standard area corresponding to the tilt angle of the workpiece W in advance, and compares this standard area with the detection area calculated from the detection result. As a result, if the difference between the two areas is equal to or greater than that of the work gap, it is determined as “foreign matter ant”, and conversely if it is equal to or smaller than that of the work gap, it is determined as “foreign matter no”.

  DESCRIPTION OF SYMBOLS 1 ... Droplet discharge device 6 ... Functional droplet discharge head 19 ... Control device 53 ... 3rd foreign material detection device 54 ... Left foreign material detection unit 55 ... Right foreign material detection unit 56 ... Work detection sensor 61 ... Left light emission part 62 ... Left light reception Part 65 ... Right light emitting part 66 ... Left light receiving part W ... Workpiece

Claims (7)

Provided in a droplet discharge apparatus that performs drawing on the workpiece by discharging the functional droplet discharge head while feeding a rectangular workpiece in any one feeding direction to the inkjet functional droplet discharge head, A foreign matter detection device for detecting foreign matter attached to the surface of the workpiece,
A foreign matter detection means for detecting foreign matter attached to the surface of the workpiece by the detection light, comprising a light emitting portion and a light receiving portion disposed across the workpiece while the optical axis of the detection light is orthogonal to the feeding direction; ,
A pair of workpiece detection means, each of which faces the workpiece and detects the arrival of the tip and tail ends of the workpiece to the optical axis position, and is disposed apart from each other on a virtual line parallel to the optical axis When,
Of the arrival detection of the tip of the work to the optical axis position by the pair of work detection means, the detection operation of the foreign matter detection means is started using the previous arrival detection as a trigger, and the tail end of the work is A foreign matter detection apparatus comprising: a detection control means for ending the detection operation of the foreign matter detection means triggered by the later arrival detection among the arrival detection to the optical axis position.   The foreign object detection device according to claim 1, wherein the pair of workpiece detection units are arranged to correspond to both ends in the width direction of the workpiece. The pair of workpiece detection means includes:
Detecting the tip and tail of the workpiece,
It is disposed at an upstream side in the feed direction with respect to the optical axis by a distance at which the work is sent at least from the detection by each work detection means to the start of the detection operation of the foreign matter detection means. The foreign object detection device according to claim 1 or 2.   The angle of the optical axis is set so that the detection light from the light emitting part is reflected by the work at a shallow angle and reaches the light receiving part. The foreign matter detection device described. The foreign object detection means includes
The amount of light received by the light receiving unit increases, maintains an increased state, and detects until the workpiece decreases,
When the amount of light received by the light receiving unit temporarily falls below a predetermined threshold in an increased state, the rate of increase in the amount of received light exceeds a predetermined threshold, and the rate of decrease in the amount of received light exceeds a predetermined threshold The foreign object detection device according to claim 4, wherein the foreign object is detected as the foreign object.   The foreign object detection device according to claim 5, wherein the threshold corresponds to a work gap between a nozzle surface of the functional liquid droplet ejection head and the surface of the work. A droplet discharge device that performs drawing on the workpiece by discharging the functional droplet discharge head while feeding a rectangular workpiece in an arbitrary one feeding direction to the functional droplet discharge head of an ink jet system,
A liquid droplet ejection apparatus comprising the foreign matter detection apparatus according to claim 1.

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