Patent Description:
Medical containers must be as free of contaminants as possible. For example, if a small particle is present in or on an inner surface of the medical container defining an internal volume of the container, this particle may cause contamination of a medical product stored in the medical container, or cause injury to the user to whom the medical product is injected. Nonetheless, even if extreme care is taken, it is not always possible to prevent such particles from being formed during a manufacturing process of medical containers or a foreign particle from being attached to the medical container.

In order to avoid possible contamination due to presence of particles, visual inspection is carried out. Inspection with the naked eye, however, typically allows only a particle of <NUM> or larger to be identified. An optical or digital microscope may be optionally used in order to find small particles. However, microscopic inspection tends to require significant resources and thus is not suitable to a large scale of inspections. Further, in-depth assessment of a particle by a microscope may require extraction of a liquid from the container and subsequent observation of the particle on a filter. As such, it is a destructive inspection method and possible applicability is limited.

It may also be desirable to obtain geometric information of a particle in three dimensions (3D). Microscopic or camera inspection only allows for generation of particles information in two dimensions (2D).

Confocal chromatic technique is known as a non-destructive, non-contact sensing process for determining a thickness or surface roughness of a transparent object. It is also known to apply confocal chromatic technique in order to observe particles. For example, <CIT> discloses confocal chromatic imaging to generate a topographical representation of a surface of a culture medium where clusters of biological particles may be cultured. <CIT> describes an optical device for use in measurement of the size, quantity and/or presence or speed of particles in a fluid or gas or in a method for depth measurement.

Confocal chromatic sensing involves subjecting a white light to chromatic aberration (chromatic aberration along a light axis) through a diffractive lens, and directing the light to a measurement object through an object lens. The light reflected by the measurement object is directed to an optical pinhole, allowing only a light beam that has been focused on the object to go through. Due to the chromatic aberration, the focal positions of the light beams along the light axis are dependent on the wavelengths. Therefore, the distance to the measurement object can be determined by monitoring the wavelength of the reflected light.

In view of the above-mentioned problems in inspecting a medical container, the objective of the present invention is to implement a method for inspecting a medical container and a system used for such a method.

According to the present invention, there are provided the method and the system as defined in the appended claims.

Specifically, there is provided a method for inspecting a medical container made of a light transmissive material, the method comprising: scanning a portion of the medical container to be inspected, by a white light emitted from a confocal chromatic system, the confocal chromatic system being configured to direct the light on an inner surface of the medical container; detecting light reflected by the portion of the medical container by the confocal chromatic system; and determining whether a particle is present or not in or on the said portion of the medical container, based on a detection result obtained by the confocal chromatic system.

The medical container has a cylindrical shape, and the method comprises: during the scanning, rotating the medical container around a central axis of the medical container to perform inspection of the portion of the medical container at different positions along a circumference of the medical container.

The medical container may have a longitudinal shape, and the method may further comprise: during the scanning, moving the confocal chromatic system relative to the medical container to perform inspection of the portion of the medical container at different positions along a longitudinal direction of the medical container.

The confocal chromatic system used in the method of the invention may comprise a 2D sensor, and the scanning and the detecting is carried out by the 2D sensor, and the method may further comprises: generating a 2D image of the portion of the medical container indicating presence or absence of the particle, wherein the determining is carried out based on the 2D image.

If it is determined that at least one particle is present, the method may further comprise: counting the number of particles on the 2D image.

The confocal chromatic system used in the method of the invention may further comprise a 3D sensor, and if it is determined that at least one particle is present, the method may further comprise: scanning the portion of the medical container including the particle by a white light emitted from the 3D sensor of the confocal chromatic system; detecting light reflected by the portion of the medical container by the confocal chromatic system; and obtaining 3D geometric information of the portion of the medical container including the particle, based on a detection result obtained by the confocal chromatic system.

The method may further comprise: generating a 3D image of the portion of the medical container including the geometric information of the particle.

In the method of the invention, the scanning may be carried out by the light substantially orthogonal to the portion of the medical container.

There is also provided a system for inspecting a medical container made of a light transmissive material, the system comprising: a confocal chromatic system configured to determine whether or not a particle is present in or on a portion of the medical container.

The system may further comprise: a holder configured to rotatably hold the medical container; and a rotary actuator configured to rotate the medical container on the holder.

The system of the invention may further comprise: a linear actuator configured to move the confocal chromatic system relative to the holder.

The confocal chromatic system may comprise a 2D sensor and may be configured to generate a 2D image of the portion of the medical container and determine on the 2D image at least one of the followings: the number of particles; the location of each particle; and the dimensions of each particle.

The confocal chromatic system may comprise a 3D sensor and may be configured to obtain 3D geometric information of the portion of the medical container including the particle.

The confocal chromatic system may be configured to generate a 3D image of the portion of the medical container including the particle.

By virtue of use of a confocal chromatic system according to the invention and/or of the method of the invention, any particle present in and/or on a portion of the medical container may be detected, counted and/or measured reliably and efficiently. When thorough inspection is required involving measurement of any particle found, the invention can also provide time-efficient geometric measurement of a particle in three dimensions.

Embodiments of the invention will be described in further detail with reference to the accompanying drawings, in which:.

The present invention uses confocal chromatic technique in order to detect, count and/or measure a particle that may be present in and/or on a portion of a medical container.

As of today, confocal chromatic technique is widely known by the skilled person and mainly used for measurement of a distance to an object, a thickness of an object and/or surface roughness of an object. No case has been reported to apply the technique in order to detect potential presence of a particle in and/or on a portion of a medical container. Particles that can be detected according to the invention are not limited to, but include glass, plastic or cotton particles, or foreign particles such as medical product agglomerates. Said particles may be formed during the manufacturing process of said medical container; the foreign particles may be attached to the medical container further said manufacturing process.

<FIG> schematically illustrates an inspection system <NUM> according to an embodiment. In the illustrated embodiment, the inspection system <NUM> is used to perform inspection of medical container such as a syringe <NUM> made of glass.

The syringe <NUM> generally has a longitudinal shape extending along its longitudinal axis that may define X-axis. The syringe <NUM> includes a hollow cylindrical barrel <NUM> extending along the longitudinal axis, a tip portion <NUM>, to which a needle may be attached, and a flange portion <NUM> for holding the syringe <NUM> at the time of injection. The barrel <NUM> defines an internal cavity within which a plunger (not shown) can be pushed toward or pulled away from the tip portion <NUM> in order to perform injection.

The glass syringe <NUM> is herein indicated as an object to be inspected, by way of example. However, any other medical containers may also be inspected according to the invention in a similar manner as long as those containers are made of a light transmissive material or a non-opaque material, irrespective of their size, shape and usage. The material may be transparent or translucent, preferably glass but may also be plastic.

As shown in <FIG>, the inspection system <NUM> includes a confocal chromatic system <NUM> for performing inspection of the syringe <NUM> and a holder <NUM> for rotatably and translationally holding the syringe <NUM> during the inspection.

The syringe <NUM> may be rotated on the holder <NUM> around the central axis of the barrel <NUM> by a rotary actuator <NUM>. The rotary actuator <NUM> may be any known rotary actuator. The holder <NUM> may also be configured to be movable along the X-axis together with the syringe <NUM>.

The confocal chromatic system <NUM> includes a sensor head <NUM> and a control device <NUM> connected to each other via an optical cable <NUM>.

The optical cable <NUM> may include optical fiber bundles. The control device <NUM> further includes a light source <NUM> and an optical system <NUM>, a two-dimensional (2D) data processing unit <NUM> and, optionally, a three-dimensional (3D) data processing unit <NUM>.

Although not illustrated, the control device <NUM> includes a computer configured to perform data processing that is required for inspection of the syringe <NUM>. The control device <NUM> thus includes a processor for executing various calculations, random access memory (RAM) for temporarily storing information or data that is obtained by sensing devices or calculations, read only memory (ROM) for storing operating software, and non-volatile memory for storing parameters, reference tables, program for controlling operation of the sensor head <NUM> for scanning an intended area of the syringe <NUM> and program necessary to carry out image processing for detecting, counting and/or measuring particles based on the obtained information, etc..

The light source <NUM> may be any known lighting device configured to emit a light, such as a polychromatic light or a white light, preferably a white light. The optical system <NUM> may include optical devices for transmitting the light emitted by the light source <NUM> to the sensor head <NUM> through the optical cable <NUM>. The optical system <NUM> may also include optical devices for transmitting light received by the sensor head <NUM> to the 2D data processing unit <NUM> and to the 3D data processing unit <NUM>.

The sensor head <NUM> comprises a 2D sensor <NUM> and a 3D sensor <NUM>. The 2D sensor <NUM> and the 3D sensor <NUM> may be provided in the same sensor head <NUM>. For the sake of better legibility, only one of the 2D sensor <NUM> and the 3D sensor <NUM> is illustrated in <FIG>. Alternatively, the 2D sensor <NUM> and the 3D sensor <NUM> may as well be provided in separate, dedicated sensor heads.

The 2D sensor <NUM> is configured to scan a portion of the syringe <NUM> to be inspected with a white light; and receive light reflected by said portion of the syringe <NUM>. The reflected light is then transmitted to the 2D data processing unit <NUM>. The 3D sensor <NUM> is configured to scan the portion of the syringe <NUM> where the particle is detected based on the 2D data processing and receive light reflected by said portion of the syringe <NUM>. The reflected light is then transmitted to the 3D data processing unit <NUM>.

Each of the 2D sensor <NUM> and the 3D sensor <NUM> may include optical lenses (not shown), such as a diffractive lens for subjecting the white light from the light source <NUM> to chromatic aberration. The sensor head <NUM> may also include an object lens (not show) for directing a light beam LB emitted from the sensor head <NUM> to the measurement object.

According to the invention, the light beam LB is directed to a portion of the syringe <NUM> to be scanned for inspection. In one embodiment, the inner surface <NUM> of the syringe <NUM> may be scanned for inspection, as shown in <FIG>. In another embodiment, the outer surface <NUM> of the syringe <NUM> may also be scanned for inspection. In yet another embodiment, any point in the syringe <NUM> extending between the outer surface <NUM> and the inner surface <NUM> may also be scanned.

Due to the chromatic aberration, the light beam LB has different focal positions along its light axis that may be defined in Z-axis, depending on the respective wavelengths. In <FIG>, only the light beam LB that has a focus on the measurement point M on the inner surface <NUM> of the syringe <NUM> is illustrated for the sake of better legibility. By virtue of the confocal configuration, only the light beam LB reflected by the measurement point M on the inner surface <NUM> can be collected and transmitted into the optical cable <NUM> and then to the optical system <NUM> of the control device <NUM>. The other light beams that do not have a focal point on the measurement point M of the inner surface <NUM> of the syringe <NUM> are not collected by the sensor head <NUM>.

Referring again to <FIG>, the sensor head <NUM> may be configured to move along the barrel <NUM> of the syringe <NUM>, i.e. along the X-axis. A linear actuator <NUM> may be used to allow the sensor head <NUM> to travel along an entire length of the barrel <NUM>. With this configuration, it is ensured that the inspection can be performed over the entire length of the barrel <NUM>. Alternatively or additionally, the holder <NUM> may be configured to be movable with the syringe <NUM> relative to the sensor head <NUM> to enable the inspection over the entire length of the barrel <NUM>. Additionally, the rotary actuator <NUM> enables to move the syringe <NUM> relative to the sensor head <NUM> to enable the inspection over the entire circumference of the barrel <NUM>.

<FIG> illustrates signal intensities with respect to wavelengths of light detected by the confocal chromatic system <NUM>. The signal intensity has a peak value with respect to the wavelength λ. The light beam of the wavelength of λ has a focal point on the inner surface <NUM> of the syringe <NUM> or on the measurement point M in <FIG>. The relationship between a particular wavelength and a focal position that corresponds to a distance to the measurement object can be determined in advance. Based on the predefined relationship, it is possible to determine the distance to the measuring point M on the inner surface <NUM> of the syringe <NUM> by monitoring the wavelength of the reflected light showing the highest signal intensity.

The 2D data processing unit <NUM> is configured to obtain measurement results based on the light reflected by the measurement object through the 2D sensor <NUM> to generate a 2D image of the measurement object. The 2D image may be used to calculate the dimensions of the particle on the 2D image, e.g. the length or width of the particle. The length herein refers to the dimension of the particle along its longitudinal direction on the 2D image, e.g. the dimension of the particle along the X-axis. The width herein refers to the dimension of the particle along a direction perpendicular to the longitudinal direction on the 2D image, e.g. the dimension of the particle along the Y-axis. The 2D image lacks information on the height (or thickness) of the particle. The height may be defined in a direction perpendicular to the directions in which the length and the width are defined. The height may also be defined as the dimension of the particle along the Z-axis.

<FIG> is a 2D image generated by the confocal chromatic system <NUM> based on data acquired by the 2D sensor <NUM> and the 2D data processing unit <NUM> according to the embodiment. The 2D image of <FIG> represents the inner surface <NUM> of the syringe <NUM> over the entire circumference (i.e. <NUM>° around the center) of the syringe <NUM> and over the distance of <NUM> along the longitudinal direction (X-axis) of the syringe <NUM>. As illustrated, the 2D image indicates the presence of a particle P on the inner surface <NUM> as highlighted by the circle and the arrow in <FIG>.

The 3D data processing unit <NUM> is configured to obtain measurement results based on the light reflected by the measurement object through the 3D sensor <NUM> to obtain a 3D geometric information of the measurement object, i.e. the width, length and the height of the particle. <FIG> shows a measurement result indicating the height of the detected particle. The highlighted region R in <FIG> indicates the location and the height of the detected particle.

Hereafter, the inspection method using the inspection system <NUM> will be explained.

A medical container to be inspected according to the invention may be emptied of any fluid (liquid and/or gas) before the inspection starts. Alternatively, the inspection may be performed with the medical container filled with a medical product.

The confocal chromatic system <NUM> may be configured in advance so as to direct the light beam LB emitted by the sensor head <NUM> to focus on a portion of the medical container where inspection is needed. For example, the confocal chromatic system <NUM> may be configured to direct the light beam LB to focus on the inner surface of the medical container, e.g. the inner surface <NUM> of the syringe <NUM> as shown in <FIG>. The inner surface of the medical container defines an internal cavity and is typically the part where the presence of particles has to be avoided and therefore inspection is needed. For the illustrative purpose, the inspection on the inner surface <NUM> of the syringe <NUM> will be described below.

Firstly, the detection of particle is performed by obtaining the 2D image of the whole inner surface <NUM> of the syringe <NUM> using the 2D sensor <NUM>. The confocal chromatic system <NUM> is controlled to scan the inner surface <NUM> of the syringe <NUM> with the light beam LB emitted from the 2D sensor <NUM>. The sensor head <NUM> is disposed in place relative to the syringe <NUM> in such a way that a white light is emitted from the 2D sensor <NUM> substantially orthogonally to the inner surface <NUM> of the syringe <NUM>. In order to scan an entire circumference of the syringe <NUM>, the scanning is carried out while the syringe <NUM> is rotated by the rotary actuator <NUM>. The rotational speed is adjusted depending on the processing speed of the confocal chromatic system <NUM>. It is to be noted that at this stage, only the 2D information is obtained, namely the length and the width of the particles are measured, without measuring the height of the particle if any particle is detected. Therefore, the processing speed is significantly fast.

While the scanning is processing around the circumference of the syringe <NUM>, the sensor head <NUM> or the holder <NUM> is moved along the longitudinal axis of the syringe <NUM>, i.e. the X-axis, to continue scanning until the entire length of the barrel <NUM> is scanned by the confocal chromatic system <NUM>.

After completion of the scanning, the 2D data processing unit <NUM> generates the 2D image from data acquired by the 2D sensor <NUM> as shown in <FIG>, in which the particle P appears as a result of interference caused to the signal detection by the 2D sensor <NUM>.

The 2D data processing unit <NUM> processes the 2D image in order to detect any particle that appears to be present on the image. As a result of the image processing, the dimensions (e.g. length and width) and the location of the particle P on the 2D image can be identified. The 2D processing unit <NUM> may also obtain the number of particles on the 2D image.

Therefore, by assessing the 2D image generated from data acquired by the 2D sensor <NUM> of the confocal chromatic system <NUM>, it can be determined whether or not any particle is present in or on the inner surface <NUM> of the syringe <NUM>.

Next, the height measurement of the particle detected by the previous step may be carried out. Since the location of each particle is now known, the confocal chromatic system <NUM> scans only the portion(s) of the inner surface <NUM> of the syringe <NUM> that include(s) the particle detected in the previous detection process.

In this second step the 3D measurement is performed by the 3D sensor <NUM> and the 3D data processing unit <NUM>. Therefore, the full profile of the detected particles can be identified, including the height. Based on the result of the 3D measurement, 3D graphics representing geometric information of the portion near the particle may be generated, for example, as shown in <FIG>.

Through the inspection process explained above, the following information may be obtained: the number of particles found in the medical container; the location of each particle; and the 3D profile of each particle. The control device <NUM> may also generate the list of particles identified that is classified by size or by other geometric information.

The inspection system according to the invention allows for quick detection of particles of <NUM> or larger, including the locations of the particles. The subsequent 3D measurement is only carried out for a portion where the particle has been detected. Consequently, the entire operation may be complete for a substantially shorter period of time, e.g., less than <NUM> minutes. Depending on the length and diameter of the syringe to be inspected, the required time can be even shorter. The inspection system also allows for thorough inspection in a non-destructive manner. Confocal chromatic systems are widely available in the market, and thus it is easy to implement the invention.

Claim 1:
A method for inspecting a medical container (<NUM>) made of a light transmissive material, said medical container (<NUM>) having a cylindrical shape, the method comprising:
scanning a portion (<NUM>) of the medical container (<NUM>) to be inspected, by a white light emitted from a confocal chromatic system (<NUM>), the confocal chromatic system being configured to direct the light on an inner surface of the medical container;
during the scanning, rotating the medical container (<NUM>) around a central axis of the medical container (<NUM>) to perform inspection of the portion (<NUM>) of the medical container (<NUM>) at different positions along a circumference of the medical container (<NUM>),
detecting light reflected by the portion (<NUM>) of the medical container (<NUM>) by the confocal chromatic system (<NUM>); and
determining whether a particle is present or not in or on the said inner surface of the portion (<NUM>) of the medical container (<NUM>), based on a detection result obtained by the confocal chromatic system (<NUM>).