JP5721547B2 - Bubble volume measuring method and bubble volume measuring apparatus - Google Patents

Description

  The present invention relates to a method for measuring the volume of bubbles existing in a sealed container containing a liquid, and an apparatus for measuring the volume of the bubbles.

  2. Related Art An ink jet recording apparatus that records an image on a recording medium by discharging a liquid such as ink is known. The ink jet recording apparatus includes a discharge head that discharges a liquid and a liquid storage container that stores the liquid, and the liquid is supplied from the liquid storage container to the discharge head.

  The liquid container is detachably provided in the ink jet recording apparatus, and the ink can be replenished by replacing the liquid container.

  A liquid container mounted on the ink jet recording apparatus will be described with reference to FIGS. FIG. 7A is a perspective view of an ejection head cartridge 2 having a plurality of liquid storage containers 1. The discharge head cartridge 2 includes a discharge head 3 and a container holder 4. FIG. 7B is a perspective view showing a state in which the liquid container 1 is removed from the container holder 4. By mounting the liquid container 1 on the container holder 4, the liquid is supplied from the liquid container 1 to the ejection head 3.

  FIG. 8 is a cross-sectional view of one of the plurality of liquid containers 1 shown in FIG. As shown in FIG. 8, the liquid container 1 includes a box member 5 having a shape opened by removing one side surface of a hollow substantially rectangular parallelepiped, and a lid member that closes the opened side of the box member 5. 6 are provided. The box member 5 is divided into two chambers, a liquid storage chamber 8 and a liquid absorber storage chamber 9, by a partition wall 7 provided in the box member 5.

  The partition wall 7 is formed with a communication port 10 that connects the liquid storage chamber 8 and the liquid absorber storage chamber 9 so that the liquid stored in the liquid storage chamber 8 can move to the liquid absorber storage chamber 9. It has become.

  The liquid absorber storage chamber 9 stores a liquid absorber 11 that absorbs and holds the liquid. The liquid moved from the liquid storage chamber 8 to the liquid absorber storage chamber 9 is held by the liquid absorber 11.

  On the bottom surface of the liquid absorber housing chamber 9, a liquid supply port 12 that communicates the inside and outside of the liquid absorber housing chamber 9 and supplies the liquid to the ejection head 3 (FIG. 7) is formed. A supply cylinder 13 is formed around the periphery. The ink held by the liquid absorber 11 is supplied from the liquid supply port 12 to the ejection head 3 through the joint member 14 inserted inside the supply cylinder 13.

  Further, an air communication port 15 that connects the liquid absorber housing chamber 9 to the atmosphere is formed in an area of the lid member 6 that constitutes the liquid absorber housing chamber 9. By maintaining the inside of the liquid absorber housing chamber 9 at atmospheric pressure, the liquid is stably supplied from the liquid absorber 11 to the ejection head 3 (FIG. 7).

  In the liquid storage container 1, liquid is injected into the liquid storage chamber 8 and the liquid absorber storage chamber 9 using the liquid injection port 16 and the liquid supply port 12 in the manufacturing process. After injecting the liquid, the liquid injection port 16 is sealed with an elastic seal member 17, and the liquid supply port 12 and the atmosphere communication port 15 are sealed with a seal member (not shown). When the liquid container 1 is used by being mounted on an ink jet recording apparatus, the sealing member that has sealed the liquid supply port 12 and the air communication port 15 is peeled off.

  By the way, in the process of injecting the liquid into the liquid storage container 1 during the production of the liquid storage container 1, depending on the liquid injection conditions or the like, gas may be entrained at the time of liquid injection, or the air in the liquid storage chamber 8 may be entirely consumed by the liquid. A state may occur in which air remains as bubbles without being completely replaced. When the bubbles have a size greater than or equal to a predetermined volume, there is a concern that liquid leaks from the liquid supply port 12 or the atmosphere communication port 15 due to the surrounding environment when the sealing member is peeled off. For example, when the sealing member is peeled off under a pressure lower than the pressure in the sealed liquid storage container 1, there is a concern about liquid leakage. This is because the bubbles in the liquid storage chamber 8 expand.

  Therefore, the volume of bubbles in the sealed liquid storage chamber 8 is visually measured, and an inspection is performed as to whether or not the predetermined volume is exceeded. As a method of measuring the volume of the bubble, there is a method of specifying the shape of the bubble by combining images obtained by shooting the bubble from a plurality of directions by an image processing means, and measuring the volume of the bubble by integration calculation from the specified shape. Proposed. Further, Patent Document 1 discloses a method and apparatus for measuring the volume of a bubble by regarding the shape of the bubble as an ideal sphere.

  The bubble volume measuring device disclosed in Patent Document 1 takes a bubble from one direction using an imaging unit, measures the diameter of the bubble taken as a two-dimensional shape using an image processing unit, and measures the volume of the bubble. Is calculated. According to this method, since it is not necessary to perform complicated image processing for synthesizing bubbles images taken from a plurality of directions, the volume of the bubbles can be measured in a shorter time.

JP-A-4-359106

  However, in the bubble volume measuring method disclosed in Patent Document 1, the bubble shape is regarded as an ideal spherical shape. Therefore, when the actual shape of the bubble has an ellipsoidal shape, the method cannot accurately measure the volume of the bubble. In particular, since the bubbles in the low-viscosity liquid such as ink move upward in the liquid storage chamber 8 and are in contact with the wall surface constituting the liquid storage chamber 8, the bubbles have a shape close to an ideal spherical shape. I don't have it. Therefore, the bubble volume measured by regarding the bubble shape as an ideal spherical shape and the actual bubble volume are greatly different.

  Accordingly, an object of the present invention is to provide a method capable of more accurately measuring the volume of bubbles in contact with the wall surface constituting the liquid storage chamber without requiring complicated image processing, and the volume of the bubbles. It is in providing the apparatus which measures.

  In order to achieve the above object, the present invention relates to a method for measuring the volume of bubbles in a liquid storage container in which at least a part of wall surfaces constituting the liquid storage chamber has a planar shape. In this aspect, the bubble volume measuring method includes a holding step for holding a liquid storage container with a wall surface having a planar shape directed vertically downward and horizontal, and a flat surface inside the liquid storage container held in the holding step. A horizontal shooting step of shooting bubbles in contact with a wall having a shape from one horizontal direction, and in the horizontal shooting step, the bubbles in the image shot with the horizontal direction as the horizontal axis direction and the vertical direction as the vertical axis direction Find the first and second points on the contour that are farthest in the horizontal axis direction, find the third point on the contour that is located at the lowest position in the vertical axis direction, and the plane on the contour An image processing step for finding a contact portion that is in contact with a portion corresponding to a wall surface having a shape, and a first, second, and third point arrangement found in the image processing step Using the contact portion, the shape of the bubble is in the position where the first line segment connecting the first and second points is the long axis, and the third point is axisymmetric with respect to the first line segment. From a virtual spheroid shape formed by rotating a virtual ellipse shape with the second line segment connecting the virtual point and the third point as a short axis around the second line segment A volume calculation step of calculating the volume of the bubble by regarding the shape as a shape in which the portion above the contact portion in the vertical direction is removed.

  The present invention also relates to a bubble volume measuring device that measures the volume of bubbles inside a liquid storage container in which at least a part of wall surfaces constituting the liquid storage chamber has a planar shape. In this aspect, the bubble volume measuring apparatus has a holding means for holding the liquid storage container with the wall surface having a planar shape directed downward in the vertical direction and horizontal, and one horizontal position from the position of the liquid storage container held by the holding means. The horizontal direction photographing means for photographing bubbles that are provided at the position in the direction and in contact with the wall having a planar shape, and the image photographed by the horizontal direction photographing means with the horizontal direction as the horizontal axis direction and the vertical direction as the vertical axis direction Image processing means for processing the first and second points farthest in the horizontal axis direction on the outline of the bubble in the image, and the first point located on the lowermost side in the vertical axis direction on the outline An image processing means for finding a contact portion that is in contact with a portion corresponding to a wall surface having a planar shape on the three points, and the first, second and third point arrangements found by the image processing means From the contact portion, the shape of the bubble, the first line segment connecting the first and second points is the long axis, and the virtual point is in a position symmetrical with the third point with respect to the first line segment And a virtual ellipsoidal shape having a second line segment connecting the third point as a minor axis and rotating the virtual ellipsoidal shape around the second line segment one time around the second ellipsoidal shape. A calculation means for calculating the volume of the bubble, assuming that the upper part in the vertical direction is removed.

  According to the bubble volume measuring method and the bubble volume measuring device of the present invention, it is possible to more accurately measure the volume of bubbles in contact with the wall surface constituting the liquid storage chamber without requiring complicated image processing. Can do.

The schematic sectional drawing of the liquid container used as the object of the method which concerns on this invention. The schematic diagram when the bubble which exists in a liquid storage chamber is observed from a perpendicular direction upper direction and a horizontal direction. The graph which compared the volume of the bubble calculated | required by the method which concerns on a 1st Example, and the volume of the bubble calculated | required by the conventional method. The schematic diagram which shows the bubble volume measuring apparatus which concerns on a 2nd Example. The flowchart figure which shows the flow of the bubble volume measuring method which concerns on a 2nd Example. The graph which shows the relationship between the bubble flat part area used for a 3rd Example, and the volume of a bubble. FIG. 6 is a perspective view of an ejection head cartridge having a plurality of liquid storage containers. Sectional drawing of the liquid container shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The principle of bubble volume measurement according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a liquid container that is a measurement target of this embodiment.

  As shown in FIG. 1, the liquid storage container 1 is provided in a hollow box member 5, a lid member 6, and the box member 5, and the space in the box member 5 is divided into a liquid absorber storage chamber 9 and a liquid storage chamber. 8 and a partition wall 7 divided into two rooms. A surface of the lid member 6 constituting the liquid storage chamber 8 (hereinafter referred to as a lid member inner side surface 6a) has a planar shape.

  When the liquid to be stored is ink, the liquid storage container 1, the liquid absorber storage chamber 9, and the liquid storage chamber 8 are also referred to as an ink tank, an ink absorber storage chamber, and an ink storage chamber, respectively.

  A communication port 10 is formed in the partition wall 7 so that the liquid stored in the liquid storage chamber 8 can move to the liquid absorber storage chamber 9. A liquid absorber 11 is stored in the liquid absorber storage chamber 9, and the liquid that has moved from the liquid storage chamber 8 to the liquid absorber storage chamber 9 is held in the liquid absorber 11.

  A liquid supply port 12 is formed on the bottom surface of the liquid absorber housing chamber 9. The liquid supply port 12 can supply liquid to components such as an ejection head (not shown).

  An air communication port 15 is formed in a region of the lid member 6 that constitutes the liquid absorber housing chamber 9. When the injection of the liquid into the liquid storage chamber 8 is completed, the liquid supply port 12 and the atmosphere communication port 15 are sealed with a seal member (not shown). That is, the liquid storage container 1 is sealed, and leakage of the liquid from the liquid storage container 1 can be prevented.

  When the liquid is injected into the liquid storage chamber 8, gas may flow into the liquid storage chamber 8 together with the liquid. FIG. 1 shows a state in which gas flows into the liquid storage chamber 8 together with the liquid, and bubbles 18 are formed inside the liquid storage container 1.

  2A and 2B are schematic views when the bubbles 18 existing in the liquid storage chamber 8 are observed from above in the vertical direction and from the horizontal direction. 1 and 2, the liquid storage container 1 is disposed so that the lid member 6 is positioned on the upper side, and the liquid storage container 1 is held so that the inner surface 6a of the lid member faces downward in the vertical direction and is horizontal. It is a figure of a state.

  The bubble 18 moves vertically upward of the liquid storage chamber 8 and is in contact with the lid member inner surface 6a. As shown in FIG. 2A, in the two-dimensional shape observed from above in the vertical direction, the bubble 18 has a substantially perfect circle shape.

  Further, as shown in FIG. 2B, the two-dimensional shape of the bubble 18 observed from the horizontal direction is a horizontal plane that passes from the virtual elliptical shape having the major axis in the horizontal direction to the upper side in the vertical direction from the major axis. The upper part is removed. The horizontal plane coincides with the lid member inner surface 6a.

  That is, the three-dimensional shape of the bubble 18 is obtained by removing a portion above the horizontal plane in the vertical direction from the virtual spheroid shape formed when the virtual ellipse shape is rotated once around the short axis. It can be regarded as a shape (also called an ellipse partially missing). A method for calculating the volume of the bubbles 18 having such a shape will be described.

  The ellipse equation in the two-dimensional orthogonal coordinate system in which the intersection point between the major axis and the minor axis of the virtual ellipse is the origin O, the major axis direction is the x axis, and the minor axis direction is the y axis is the length of the major axis. Is 2a and the length of the short axis is 2b, it is expressed as follows.

Next, the area S of the cross section of the spheroid cut by a plane passing through a certain point (t ₁ , t ₂ ) on the ellipse in the two-dimensional orthogonal coordinate system and perpendicular to the y-axis is obtained. Since the shape of the cross section is a perfect circle, the area S can be calculated by obtaining the radius of the cross section. The radius of the cross section is | t ₁ |, and | t ₁ | is expressed by the following equation ( ₁ ).

  The area S is expressed as follows from Equation 2.

  Finally, assuming that the distance from the origin O of the two-dimensional orthogonal coordinate system to the inner surface 6a of the lid member is h, the volume of the bubble 18 (hereinafter referred to as the bubble volume V) can be expressed by Equation 3 in the range from -b to h. It is obtained by integrating. That is, the bubble volume V is expressed as follows.

  In this way, the shape of the bubble 18 is observed from the horizontal direction, and the values of a, b, h in the bubble 18, that is, the major axis and the minor axis length of the virtual elliptical shape, and the inner surface 6 a of the lid member from the major axis. The bubble volume V can be calculated by measuring the distance up to.

  Hereinafter, the bubble volume measuring method and the bubble volume measuring device according to the present invention will be described in detail.

Example 1
A bubble volume measuring method and a bubble volume measuring apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  First, a liquid storage container 1 in which a liquid such as ink is injected and sealed is prepared. Next, using the holding means for holding the liquid storage container 1 provided in the bubble volume measuring device, the liquid storage container 1 is arranged so that the lid member 6 is positioned on the upper side, and the inner surface 6a of the lid member is placed vertically. The liquid container 1 is held downward in the direction and horizontally.

  Then, the bubble 18 is image | photographed from one horizontal direction using the horizontal direction imaging | photography means provided in the bubble volume measuring apparatus. An image captured from one direction is a two-dimensional image.

  A computer tomography apparatus (hereinafter referred to as an X-ray CT apparatus) using X-rays can be used as the horizontal imaging means. When the X-ray CT apparatus is used, the bubble 18 can be imaged even if the box member 5 is made of an opaque material.

  When the box member 5 is made of a transparent material and visible light can pass through the box member 5, an optical camera can be used. Use of an optical camera eliminates the safety measures required for using the X-ray CT apparatus and the space for the X-ray CT apparatus. In addition, the optical camera is generally cheaper than the X-ray CT apparatus, and the bubble volume measuring device can be made inexpensive.

  When the bubble 18 is photographed, image processing is performed on the photographed image using image processing means provided in the bubble volume measuring device.

  Specifically, the first and second most distant from each other in the abscissa direction on the outline of the bubble 18 in the image photographed using the photographic means in the horizontal direction with the horizontal direction as the horizontal axis direction and the vertical direction as the vertical axis direction. Find the second points P1, P2. The first line segment connecting the first and second points P1 and P2 corresponds to the major axis of the virtual elliptical shape, and the value of a in Equation 4 is obtained by halving the length of the first line segment. Can be obtained.

  Further, the third point P3 located at the lowest position in the vertical axis direction on the outline of the bubble 18 in the image photographed using the horizontal photographing means is found. The second line segment connecting the third point P3 and the virtual point P4 that is in a line-symmetric position with the third point P3 with respect to the first line segment corresponds to the short axis of the virtual elliptical shape, The value of b in Equation 4 can be obtained by halving the length of the second line segment.

  Further, the position of the contact portion that is in contact with the portion corresponding to the inner surface 6a of the lid member on the outline of the bubble 18 in the image photographed using the horizontal photographing means is acquired. The distance between the first line segment and the contact portion corresponds to the distance from the major axis to the lid member inner surface 6a in the virtual elliptical shape, and the value h in Equation 4 can be obtained.

  Finally, the values of a, b, and h obtained by performing image processing are substituted into Equation 4, and the bubble volume V is calculated using volume calculation means.

  FIG. 3 is a graph comparing the bubble volume V obtained by the bubble volume measurement method according to the present embodiment and the bubble volume V obtained by the bubble volume measurement method disclosed in Cited Document 1.

In FIG. 3, the horizontal axis indicates a cross section having the largest area when the bubble 18 is cut along a plane parallel to the horizontal direction, that is, a cross-sectional area when the bubble 18 is cut along a horizontal plane passing through the long axis of the virtual elliptical shape ( hereinafter, it shows a bubble of maximum cross-sectional area S _1). Moreover, the vertical axis | shaft has shown the bubble volume V measured by each method. The plot indicated by the rhombus indicates the bubble volume V ₁ obtained by this example. The plots indicated by squares and triangles indicate the bubble volumes V ₂ and V ₃ , which are disclosed in the cited document 1 and are obtained by regarding the shape of the bubble 18 as an ideal sphere or hemisphere.

As shown in FIG. 3, when the bubble maximum cross-sectional area S ₁ is 133 mm ² , the bubble volume V ₁ obtained by the method according to the present example is 370 mm ^3, which is obtained by the method disclosed in the cited document 1. bubble volume V _2, V ₃ which are are each 1150mm ^3, 575mm ^3. Thus, it was confirmed that there was a difference in the values of the bubble volumes V ₁ , V ₂ and V ₃ obtained by the respective methods as the bubble maximum cross-sectional area S ₁ increased.

In the liquid container 1 and the liquid used to obtain the graph shown in FIG. 3, if the bubble volume V is 370 mm ³ or less, the liquid container 1 will be liquid even if the sealing member of the liquid container 1 is peeled off. It has been confirmed that there is no leakage. That is, the quality of the liquid container 1 can be determined using the bubble volume V of 370 mm ³ as a threshold value.

The reason why the bubble volume V ₁ obtained by the method according to the present embodiment is 370 mm ³ is that the bubble maximum cross-sectional area S ₁ is about 133 mm ² , whereas the bubble volumes V ₂ and V ₃ are 370 mm ³ . The bubble has a maximum cross-sectional area S ₁ of about 60 mm ² and about 90 mm ² . That is, when the quality of the liquid container 1 is determined based on the volume of the bubbles 18 obtained by the conventional method, even if the bubble volume V is in a range that does not actually cause a problem, it is determined that the liquid container 1 is defective. . By measuring the volume of the bubble 18 by the method according to the present embodiment, the bubble volume V can be measured more accurately, and the quality of the liquid container 1 can be determined more appropriately.

  In the present embodiment, the lid member 6 is on the upper side. However, when some of the other wall surfaces constituting the liquid storage chamber 8 have a planar shape, the wall surface having the planar shape is in the vertical direction. The liquid container 1 may be held so as to face downward and be horizontal.

(Example 2)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a schematic diagram showing the bubble volume measuring apparatus according to the present embodiment. FIG. 5 is a flowchart showing the flow of the bubble volume measuring method according to the present embodiment.

As shown in FIG. 3, there is a correlation between the bubble volume V ₁ obtained by the method according to Example ₁ and the bubble maximum cross-sectional area S ₁ . When the shape of the liquid container 1 and the viscosity of the liquid are the same, the correlation is maintained.

In this embodiment, the bubble volume V is calculated using this correlation. A plurality of bubble volumes V having different sizes are measured by the method according to the first embodiment, and a correlation between the bubble volume V and the bubble maximum cross-sectional area S ₁ is derived. By using the correlation, the bubble volume V can be obtained by simpler processing.

That is, in Example 1, the bubble volume V must be calculated by measuring bubbles a, b, and h by image processing. In this embodiment, to calculate the bubble maximum cross-sectional area S ₁ to measure the a bubble, to calculate the volume V of the bubble the calculated bubble maximum cross-sectional area S ₁ based on. Since there is only one value to be measured by image processing, the bubble volume V can be measured in a shorter time.

  As shown in FIG. 4, the bubble volume measuring device measures a vertical direction photographing means 19 for photographing the bubbles 18 and an area of an image photographed by the vertical direction photographing means 19 (also referred to as a bubble area on a two-dimensional image). And an area measuring means 20 for performing. The vertical direction photographing means 19 is located above the liquid storage chamber 8 in the vertical direction, and can photograph the bubbles 18 downward in the vertical direction.

The area measuring unit 20 can measure the area of the two-dimensional bubble 18 photographed by the vertical direction photographing unit 19. Further, the area measuring means 20 stores the correlation between the bubble maximum cross-sectional area S ₁ and the bubble volume V ₁ shown in FIG. 3, and the bubble volume V based on the value of the bubble maximum cross-sectional area S _1. Is calculated.

  When the lid member 6 of the liquid container 1 is made of a transparent material and the vertical photographing means 19 is made of an optical camera, an illumination device 21 may be provided in the bubble volume measuring device. By irradiating the bubble 18 with light by the illumination device 21, the vertical direction photographing means 19 can photograph the outline of the bubble 18 more clearly.

  The irradiation direction of the illuminating device 21 is desirably set so that the outline of the bubble 18 can be detected without insufficient brightness and without causing halation. In the present embodiment, the illumination device 21 is arranged so that light can be irradiated from the upper oblique direction. Further, as a countermeasure against irregular reflection on the surface of the liquid storage chamber 8, it is preferable to use a deflection plate on the imaging side surface of the vertical direction imaging means 19 and the irradiation side surface of the illumination device 21.

  A flow of the bubble volume measuring method according to the present embodiment will be described.

The relationship between the bubble maximum cross-sectional area S ₁ and the bubble volume V ₁ derived by the method according to the first embodiment is stored in advance in a storage unit included in the area measurement unit 20. As shown in FIG. 5, the liquid storage container 1 is held such that the wall surface having the planar shape among the wall surfaces forming the liquid storage chamber 8 is horizontal (S501). Next, the bubble 18 is imaged using the vertical direction imaging means 19 (S502). The outline of the bubble 18 photographed by the vertical direction photographing means 19 is the same as the outline of a cross section obtained by cutting the bubble 18 on a horizontal plane passing through the long axis.

Next, the detection of the contour of the bubble 18 using area measurement means 20, to measure the bubble up to the cross-sectional area S ₁ (S503). The outline of the bubble 18 can be detected from the difference in brightness, saturation, hue, and the like between the liquid and the bubble.

When the bubble maximum cross-sectional area S ₁ is measured, the relationship between the bubble maximum cross-sectional area S ₁ and the bubble volume V ₁ stored in advance in the storage means is used to determine the bubble 18 corresponding to the measured bubble maximum cross-sectional area S ₁ . The value of volume V is selected (S504). Thus, the bubble volume V is obtained.

  By providing the step (S505) of comparing the bubble volume V obtained in S504 with a predetermined threshold value, it can be determined whether or not the liquid container 1 is a non-defective product. If the obtained bubble volume V is equal to or smaller than a predetermined threshold value, the liquid container 1 is determined as a non-defective product (S506), and if it is larger than the predetermined threshold value, the liquid container 1 is determined as a defective product (S507). Since the liquid container 1 and the liquid used for obtaining the graph shown in FIG. 3 are known to be good if the bubble volume V is 370 mm 3 or less, the predetermined threshold value may be set to 370 mm 3.

As described above, the bubble 18 is photographed so that the captured image has the same shape as that of the maximum bubble cross section, and the bubble volume V is obtained from the maximum bubble cross-sectional area S ₁ . When measuring the bubble maximum cross-sectional area S ₁ may be an image processing of an image taken from one direction. Therefore, the bubble volume V can be measured in a shorter time without requiring complicated image processing. Moreover, since the relationship between the bubble maximum cross-sectional area S ₁ and the bubble volume V is derived with high accuracy by the method according to the first embodiment, the bubble volume V can be obtained more accurately.

(Example 3)
Next, a third embodiment will be described. In this embodiment, the bubble 18, the area of the surface in contact with the lid member side 6a is planarized (hereinafter, the bubble that the flat portion area S ₂₎ and, derived by the method according to Example 1 bubble This is an example of measuring the bubble volume V using the correlation with the volume V.

This embodiment is advantageous when it is difficult to measure the bubble maximum cross-sectional area S ₁ due to the influence of the light transmittance of the liquid in the liquid storage chamber 8.

A plurality of bubble volumes V having different sizes are measured in advance by the method according to the first embodiment, and a correlation between the bubble volume V and the bubble flat portion area S ₂ is derived. In order to obtain the bubble flat part area S ₂ , the length of the part of the bubble 18 (FIG. 2B) photographed from the horizontal direction in Example 1 in contact with the lid member inner side surface 6b is measured. The bubble flat part area S ₂ can be measured as an area of a circle having the length as a diameter.

FIG. 6 is a graph showing the relationship between the bubble flat part area S ₂ and the bubble volume V derived in this manner. From the graph shown in FIG. 6, it is confirmed that there is a correlation between the bubble flat part area S ₂ and the bubble volume V.

In this embodiment, the correlation stored in advance in the area measuring means 20 and the step of measuring the bubble flat portion area S ₂ are different from those in the second embodiment, and the other configurations are substantially the same. Just explain.

The correlation between the bubble flat part area S ₂ and the bubble volume V shown in FIG. 6 is stored in the area measuring means 20. The liquid storage container 1 is held such that the wall surface having the planar shape among the wall surfaces forming the liquid storage chamber 8 is horizontal, and the bubbles 18 are imaged using the vertical imaging unit 19.

Next, the detection of the contour of the bubble 18 using area measurement means 20, to measure the bubble flat portion area S _2. The outline of the portion of the bubble 18 that is in contact with the inner surface 6 of the lid member is detected by setting threshold values such as brightness, saturation, hue, etc. between the liquid and the bubble to values different from those in the second embodiment. Can do.

When the bubble flat part area S ₂ is measured, the bubble volume corresponding to the measured bubble flat part area S ₂ using the relationship between the bubble flat part area S ₂ and the bubble volume V stored in advance in the area measuring means 20. V is calculated.

As has been described above, when it is difficult to measure the bubble maximum cross-sectional area S ₁ also, by using the method of the present embodiment, it is possible to measure the bubble volume V in a shorter time. Further, since the relationship between the bubble maximum cross-sectional area S ₁ and the bubble volume V is derived with high accuracy by the method according to the first embodiment, the bubble volume V can be measured more accurately.

DESCRIPTION OF SYMBOLS 1 Liquid storage container 6 Lid member 6a Inner side surface of a lid member 8 Liquid storage chamber 18 Air bubble 19 Vertical direction imaging | photography means 20 Area measurement means P1 1st point P2 2nd point P3 3rd point P4 Virtual point

Claims (14)

A method for measuring the volume of bubbles inside a liquid storage container in which at least a part of the wall surface constituting the liquid storage chamber has a planar shape,
A holding step for holding the liquid container in such a manner that the wall surface having the planar shape is directed vertically downward and horizontal;
A horizontal shooting step of shooting the bubbles in contact with the wall surface having the planar shape inside the liquid container held in the holding step from one horizontal direction;
In the horizontal photographing step, find first and second points that are farthest in the horizontal axis direction on the outline of the bubble in an image shot with the horizontal direction as the horizontal axis direction and the vertical direction as the vertical axis direction. Image processing for finding a third point located on the contour at the lowest position in the longitudinal axis direction, and finding a contact portion on the contour corresponding to a portion corresponding to the wall surface having the planar shape Steps,
Using the first, second and third points found in the image processing step and the contact portion, the shape of the bubble is elongated and the first line segment connecting the first and second points is long. An imaginary ellipse having a short axis in the second line segment connecting the third point with an imaginary point that is axially symmetric with respect to the third point with respect to the first line segment A volume for calculating the volume of the bubbles, assuming that the portion above the contact portion is removed from the virtual spheroid shape formed by rotating the second rotation around the second line segment. A bubble volume measuring method including a calculation step. In the volume calculation step, the length of half of the first line segment is a, the length of half of the second line segment is b, and the distance between the first line segment and the contact portion is h. When the volume V of the bubble is
(Equation 1)

The bubble volume measuring method according to claim 1, wherein the bubble volume is calculated from an expression expressed as:   The bubble volume measuring method according to claim 1 or 2, wherein in the horizontal imaging step, the bubble is imaged using an X-ray CT apparatus. The volume of bubbles inside the liquid container, wherein at least a part of the wall in the horizontal direction from the position of the bubbles of the liquid container held by the holding step is formed of a transparent member. The bubble volume measuring method according to claim 1 or 2, wherein
A bubble volume measuring method in which, in the horizontal photographing step, the bubbles are photographed from the position of the transparent member toward the bubbles using an optical camera. A method for measuring the volume of bubbles inside a liquid storage container in which at least a part of the wall surface constituting the liquid storage chamber has a planar shape,
The volume of a plurality of bubbles having different sizes and the area of a predetermined cross section parallel to the horizontal direction of the bubbles are measured in advance by the bubble volume measuring method according to any one of claims 1 to 4. Deriving a relationship between the volume and the area and storing the relationship in a storage means;
Holding the liquid container in such a manner that the wall surface having the planar shape is directed vertically downward and horizontal; and
A vertical shooting step of shooting the bubble in contact with the wall surface having the planar shape from above in the vertical direction;
An area measuring step for measuring an area in the predetermined cross section from the image of the bubbles taken in the vertical direction photographing step;
Selecting the value of the volume of the bubble according to the value of the area in the predetermined cross section measured in the area measuring step using the relationship stored in the storage means in advance. Measurement method.   The bubble volume measuring method according to claim 5, wherein the predetermined section is a section having the largest area when the bubbles are cut along a horizontal plane.   The bubble volume measuring method according to claim 5, wherein the predetermined cross section is a surface of a portion of the bubble that is in contact with a wall surface having the planar shape. A bubble volume measuring device that measures the volume of bubbles inside a liquid storage container in which at least a part of the wall surface constituting the liquid storage chamber has a planar shape,
Holding means for holding the liquid container with the wall surface having the planar shape directed vertically downward and horizontal;
A horizontal photographing means for photographing the bubbles that are provided at one horizontal position from the position of the liquid container held by the holding means and are in contact with the wall surface having the planar shape;
Image processing means for processing an image photographed by the horizontal direction photographing means with the horizontal direction as the horizontal axis direction and the vertical direction as the vertical axis direction, the image processing means being the most in the horizontal axis direction on the outline of the bubble in the image The first and second points that are separated from each other, the third point that is located at the lowest position in the longitudinal direction on the contour, and the portion on the contour that corresponds to the wall having the planar shape. An image processing means for finding a contact portion,
From the first, second and third points found by the image processing means and the contact portion, the shape of the bubble, the first line segment connecting the first and second points as the major axis, A virtual elliptical shape having a short axis as a second line segment connecting a virtual point that is line-symmetric with the third point and the third point with respect to the first line segment. A calculation means for calculating the volume of the bubbles, assuming that a virtual spheroid shape formed by one rotation around the second line segment is a shape obtained by removing a portion above the contact portion in the vertical direction. A bubble volume measuring device.   The bubble volume measuring apparatus according to claim 8, wherein the imaging unit is an X-ray CT apparatus. The volume of bubbles inside the liquid container, wherein at least a part of the wall in the horizontal direction from the position of the bubbles of the liquid container held by the holding means is formed of a transparent member. The bubble volume measuring device according to claim 8, wherein
A bubble volume measuring device, wherein the photographing means is an optical camera. An apparatus for measuring the volume of bubbles inside a liquid storage container in which at least a part of the wall surface constituting the liquid storage chamber has a planar shape,
Storage means for storing a relationship between the volume of the bubble measured by the bubble volume measuring device according to any one of claims 8 to 10 and an area of a predetermined cross section parallel to the horizontal direction of the bubble;
Holding means for holding the liquid container with the wall surface having the planar shape directed vertically downward and horizontal;
A vertical photographing means for photographing the bubbles that are provided vertically above the position of the liquid container held by the holding means and are in contact with the wall surface having the planar shape;
An area measuring means for processing an image of the bubble photographed by the vertical direction photographing means and measuring an area in a predetermined cross section of the bubble;
A selection unit that selects a value of the volume of the bubble according to an area value in the predetermined cross section measured by the area measurement unit using the relationship stored in the storage unit in advance. Volume measuring device.   The bubble volume measuring device according to claim 11, wherein the predetermined section is a section having the largest area when the bubbles are cut along a horizontal plane.   The bubble volume measuring device according to claim 11, wherein the predetermined cross section is a surface of a portion of the bubble that is in contact with a wall surface having the planar shape. A method of measuring the volume of bubbles existing in the ink storage chamber of an ink tank including a liquid supply port for supplying liquid to the ejection head, an air communication port communicating with the air, and an ink storage chamber. There,
A method of imaging a bubble existing inside the ink storage chamber and contacting the wall surface from a direction in which the bubble is in contact with the wall surface, and measuring a bubble area on the captured two-dimensional image; Ink characterized in that the bubble volume is derived from the bubble area using a method of measuring the bubble volume by approximating and integrating the shape of the bubble in contact with the ellipse partially missing A method for measuring the volume of bubbles in a tank.

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