JP7243368B2 - Image acquisition device and image acquisition method - Google Patents

Description

The present invention relates to an image acquisition apparatus and an image acquisition method capable of acquiring a high-quality image with a high SN ratio (Signal-Noise Ratio) by performing lighting control according to the shape of an object.

2. Description of the Related Art In a photographing device that obtains an image of an object that moves at high speed (eg, 1 m/sec to 4 m/sec), it is necessary to shorten the shutter speed of the camera in order to suppress blurring of the image due to the movement of the object.
Under such shooting conditions with a short shutter speed, it is inevitable that the exposure time of the image sensor of the above-mentioned shooting device becomes short, and in order to obtain an image with a high SN ratio, there are cases where a moving object is illuminated with high brightness. be.

For example, in the scanning device disclosed in Patent Document 1, a translucent table on which a subject can be placed, first and second illumination means for projecting light from below the translucent table toward the subject on the table, and scanning reading means for scanning and reading the concave shape of the object illuminated by the illumination means.
Further, in this scanning device, when photographing the concave portion of the subject, the first illumination means is turned on or off and the second illumination means is turned on while the scanning head of the scanning and reading means scans and reads. do
Further, in this scanning device, when photographing a normal flat object, the second illumination means is turned off, the first illumination means is turned on, and scanning is performed by the scanning head of the scanning and reading means.

JP 2004-177698 A

In the scanning device disclosed in Japanese Patent Application Laid-Open No. 2002-200310, lighting/light-out of the first and second lighting means is switched according to the condition of the subject.
However, in the scanning device of Patent Document 1, the first and second illumination means are installed at positions that are substantially equidistant from the subject in the optical axis direction. There is a problem that, for example, when the illumination is strong, the specular reflection component returns to cause saturation.

The present invention has been made in view of the circumstances described above, and provides an image acquisition device and an image acquisition method capable of capturing clear images of subjects having various shapes without generating saturation.

In order to solve the above problems, the present invention proposes the following means.
The image acquisition device according to the first aspect of the present invention includes a photographing unit that acquires an image of a subject moving in a predetermined direction, and an illumination unit that irradiates the subject with a light beam from a direction different from the optical axis of the photographing unit. , wherein the illumination unit has a plurality of light sources that irradiate the subject with light rays, and each point at which the optical axis of each light source and the optical axis of the photographing unit intersect is the photographing unit are set at different positions along the direction of the optical axis.

In the image acquisition method shown in the second aspect of the present invention, an irradiation step of irradiating a subject moving in a predetermined direction with a light beam, and a photographing step of photographing the subject irradiated with the light beam by an imaging unit. and in the irradiating step, a point at which an optical axis of a plurality of light sources for irradiating light rays toward the subject and an optical axis of the photographing unit intersect is set at different positions in a direction of the optical axis of the photographing unit. characterized by

According to the present invention, it is possible to shoot an object moving at high speed with good image quality while suppressing saturation.

1 is a schematic configuration diagram of an image acquisition device according to the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the image acquisition apparatus which concerns on embodiment of this invention, Comprising: (A) is a front view, (B) is a top view. 3 is a schematic configuration diagram including a light control unit of the image acquisition device shown in FIG. 2, (A) is a front view, and (B) is a plan view; FIG. 4 is a flow chart showing the contents of control of the image acquisition device; 5 is an explanatory diagram showing lighting control of a light source for explaining the control content in FIG. 4; FIG. 1A and 1B are schematic configuration diagrams of an image acquisition device according to Modification 1 of the embodiment, where (A) is a front view and (B) is a plan view; FIG. 10 is a schematic configuration diagram of an image acquisition device according to Modification 2 of the embodiment, where (A) is a front view and (B) is a plan view;

An image acquisition device 100 according to the present invention will be described with reference to FIG.
This image acquisition device 100 has an imaging unit 1 and an illumination unit 2 .
The photographing unit 1 continuously photographs images of a subject W moving at a constant speed in a predetermined direction (direction of arrow M).
The illumination unit 2 irradiates the object W with light from a direction different from the optical axis 1A of the photographing unit 1 .

The lighting unit 2 has its irradiation position set so that the distances (d1 to d3) from the subject W along the optical axis direction (the direction of the arrow 1a) of the photographing unit 1 are different. It has a plurality of light sources 2A, 2B, 2C, .
Specifically, the illuminating unit 2 is arranged such that each point at which the optical axis of each of the light sources 2A, 2B, 2C, . . . 1 are set at different positions along the direction of the optical axis 1A (the direction of the arrow 1a).
In this lighting unit 2, for example, based on the shape of the object W measured by the shape measuring unit 3 located upstream of the photographing unit 1, lighting of these light sources 2A, 2B, 2C, . Based on the shape of the object W measured by the shape measuring unit 3, the built-in light control unit 4 can automatically control the ON/OFF of the light sources 2A, 2B, 2C, . . .

According to the image acquisition apparatus 100 configured as described above, the irradiation positions are set such that the distances (d1 to d3) from the subject W along the optical axis direction (arrow 1a direction) of the photographing unit 1 are different. can be controlled based on the shape of the object W measured by the shape measuring unit 3. The light sources 2A, 2B, 2C, .
For example, based on the shape of the subject W measured by the shape measuring unit 3, the illumination unit 2 can partially turn off the plurality of light sources 2A, 2B, 2C, . A sharp image can be captured without generating saturation for the subject W having a shape.

(embodiment)
An image acquisition device 101 according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5. FIG.

As shown in FIG. 2, the image acquisition device 101 has an imaging unit 11, an illumination unit 12, and a shape measurement unit 13 (to be described later) as main components.
The photographing unit 11 continuously photographs images of the subject W moving at a constant speed in a predetermined direction (direction of arrow M1) by the conveying device 10 .
Note that the photographing unit 11 uses a line sensor or the like that scans along a planar direction (direction of arrow M2) perpendicular to the direction of arrow M1, which is the direction in which the subject W is conveyed.
As the subject W moves, the line sensor can read, for example, identification information such as characters and barcodes attached to the upper surface of the subject W as an image.
The photographing unit 11 is installed so that the photographing lens 14 faces downward and the optical axis 11A of the photographing lens 14 is perpendicular to the conveying path of the conveying device 10 .

The illumination unit 12 irradiates the subject W with light from a plurality of directions different from the optical axis 11A of the photographing unit 11 .
Specifically, the lighting unit 12, as shown in FIGS. 2A and 3A, the distance (d4, d5) from the subject W along the optical axis direction (arrow a11 direction) of the photographing unit 11 light sources 20R/20L and 21R/21L whose irradiation positions are set to be different from each other, and a light controller 15 for controlling these light sources 20R/20L and 21R/21L.
With such a configuration, the point at which the optical axis 11A of the photographing unit 11, that is, the axis captured by the line sensor and the optical axes K11 to 14 of the lighting unit 12 intersect (that is, the irradiation position) are at different positions in the direction of the optical axis 11A of the photographing unit 11. FIG.

In these light sources, the light sources 20R/20L are located at the lower stage near the subject W at the same height (indicated by reference numeral d4), and the light sources 21R/21L are located above the light sources 20R/20L and at the upper stage away from the subject W. at the same height (indicated by symbol d5).
The light sources 20R and 21R are located downstream of the optical axis 11A of the photographing unit 11 on the right side of the drawing, and the light sources 20L and 21L are located upstream of the optical axis 11A of the photographing unit 11 on the left side of the drawing. and are positioned symmetrically with respect to the optical axis 11A.

The shape measuring unit 13 is a sensor for measuring the shape of the subject W on the upstream side of the photographing unit 11 and the lighting unit 12 along the conveying path of the conveying device 10 as shown in FIG. Shape data such as whether the subject W has a flat shape, has a certain height, or in which direction the upper surface is inclined is acquired. The shape data of the object W measured by the shape measuring section 13 is supplied to the light control section 15 of the illumination section 12 .
The shape measuring unit 13 is provided on both sides of the transport path of the transport device 10. In addition to the image sensor, the shape measuring unit 13 detects the shape of the object W by detecting that the object W blocks light at a specific location. A sensor or the like is used.

Then, the light control unit 15 of the illumination unit 12 turns ON/OFF the light sources 20R/20L and 21R/21L based on the shape data of the object W output from the shape measurement unit 13 as shown in FIG. 3B. , light amount adjustment, etc.
For example, in this light control unit 15, as shown in FIG. In order to prevent saturation, specific light sources 20R/20L and 21R/21L are selectively turned off or the amount of light is adjusted.
In this example, in the light control unit 15, as shown in FIG. In order to prevent saturation caused by entering the photographing section 11, the lower light sources 20R/20L and the upper left light source 21L can be turned off, and only the upper right light source 21R can be turned on.

Next, the control contents of the entire image acquisition apparatus 101 including the control contents of the light control unit 15 of the illumination unit 12 will be specifically described with reference to FIGS. 4 and 5. FIG.
Trigger input (1) shown in the following flowchart is a signal indicating that subject W has entered the measurement area of shape measuring unit 13, and trigger input (2) indicates that subject W has entered the measurement area of shape measuring unit 13. It is a signal indicating that the Trigger input (3) is a signal indicating that subject W has entered the photographing area of photographing section 11, and trigger input (4) is a signal indicating that subject W has left the photographing area of photographing section 11. be.

[Step S1]
First, as shown in FIGS. 2 and 3, when the subject W is started to be transported to the shape measuring unit 13, the process proceeds to step S2 below.

[Step S2]
When the trigger input (1) indicating that the subject W has entered the measurement area of the shape measuring section 13 is received, the shape measuring section 13 is caused to start measuring the shape of the subject W. FIG.

[Step S3]
When the trigger input (2) indicating that the subject W has left the measurement area of the shape measuring section 13 is received, the shape measuring section 13 is caused to finish measuring the shape of the subject W. FIG.

[Step S4] to [Step S5]
The shape data of the object W measured by the shape measuring unit 13 is taken in (step S4), and the shape data is analyzed (step S5).

[Step S6]
It is determined whether or not the height of the object W is equal to or higher than a predetermined value, and if NO, the process proceeds to step S7, and if YES, the process proceeds to step S11.

[Step S7]
For a thin object W that does not have a height higher than a predetermined value, it is determined whether or not the degree of inclination of the upper surface is equal to or greater than predetermined values (+A degree, -A degree), and the "flat +A degree or more" is determined. If so, the process proceeds to step S8, if "less than ±A degrees on the plane", the process proceeds to step S9, and if "greater than -A degrees on the plane", the process proceeds to step S10.
As shown in FIG. 5, the angle here indicates how much the upper surface of the subject W is inclined with respect to the plane when viewed from the front. degrees”, and the tilt of the upper surface of the subject W in the counterclockwise direction is “-A degrees”.

[Step S8]
As shown in S8 in FIG. 5, a light control signal is output to the illumination unit 12 to turn off the light sources 21R/21L on the upper stage and the light source 20R on the right side of the lower stage and turn on only the light source 20L on the left side of the lower stage.
[Step S9]
As shown in S9 of FIG. 5, a light control signal is output to the illumination section 12 to turn off the upper light sources 21R/21L and to turn on the lower light sources 20R/20L by 50%. Note that the lighting of 50% is an example, and the setting can be changed as appropriate.
[Step S10]
As shown in S10 in FIG. 5, a light control signal is output to the illumination unit 12 to turn off the light sources 21R/21L on the upper stage and the light source 20L on the left side of the lower stage and turn on only the light source 20R on the right side of the lower stage.

[Step S11]
For a subject W having a height equal to or higher than a predetermined value, it is determined whether or not the degree of inclination of the upper surface is equal to or greater than predetermined values (+A degrees, −A degrees). Proceeding to step S12, if it is "less than ±A degrees on the plane", proceed to step S13, and if "greater than -A degrees on the plane", proceed to step S14.

[Step S12]
As shown in S12 of FIG. 5, a light control signal is output to the illumination section 12 to turn off the light sources 20R/20L in the lower stage and the light source 21R in the upper right side and turn on only the light source 21L in the upper stage left.
[Step S13]
As shown in S13 of FIG. 5, a light control signal is output to the lighting unit 12 to turn off the lower light sources 20R/20L and to turn on the upper light sources 21R/21L by 50%. Note that the lighting of 50% is an example, and the setting can be changed as appropriate.
[Step S14]
As shown in S14 in FIG. 5, a light control signal is output to the illumination section 12 to turn off the light sources 20R/20L on the lower stage and the light source 21L on the left side of the upper stage, and turn on only the light source 21R on the right side of the upper stage.

[Step S15]
When the trigger input (3) indicating that the object W has entered the imaging area of the imaging unit 11 is received, the illumination unit 12 turns on the light source based on the irradiation content determined in steps 8 to 10 and 12 to 14. Lighting control of 20R/20L and 21R/21L is performed.

[Step S16]
A photographing unit 11 is caused to photograph a subject W. - 特許庁
[Step S17]
When the trigger input (4) indicating that the subject W has left the imaging area of the imaging section 11 is received, the imaging of the subject W by the imaging section 11 is terminated.
[Step S18]
After all the light sources 20R/20L and 21R/21L in the illumination unit 12 are turned off after the photographing is completed, this flow chart ends.

According to the image acquisition device 101 configured as described above, the plurality of light sources 20R provided so that the distances (d4, d5) to the subject W along the optical axis direction (arrow a11 direction) of the photographing unit 11 are different. /20L and 21R/21L are controlled based on the shape of the subject W measured by the shape measuring section 13. FIG.
For example, the light control unit 15 of the illumination unit 12 selectively turns on/off the plurality of light sources 20R/20L and 21R/21L based on the shape of the object W measured by the shape measurement unit 13, and adjusts the light amount. As a result, it is possible to take clear images of subjects W having various shapes without generating saturation.

(Modification 1)
In the image acquisition device 101 of the above embodiment, each pair of the light sources 20R/20L and the light sources 21R/21L is positioned at the same height (d4, d5) away from the subject W. As shown in FIG.
However, without being limited to this, in the image acquisition device 102 of Modification 1, as shown in FIG. In addition, the height may be changed stepwise so that the light irradiation to the object W may be varied.

(Modification 2)
In the image acquisition device 101 of the above embodiment, two pairs of light sources 20R/20L and light sources 21R/21L are provided.
However, it is not limited to this, and in the image acquisition device 103 of the modified example 2, as shown in FIG. Left and right ON/OFF control and light amount control may be performed for a large number of pairs of light sources provided in pairs or more.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are included within the scope of the present invention.

The present invention relates to an image acquisition apparatus and an image acquisition method capable of acquiring a high-quality image with a high SN ratio by performing lighting control according to the shape of an object.

1 Photographing Part 1A Optical Axis 2 Illuminating Part 2A Light Source 2B Light Source 2C Light Source 3 Shape Measuring Part 4 Light Controlling Part 10 Conveying Device 11 Photographing Part 11A Optical Axis 12 Illuminating Part 13 Shape Measuring Part 14 Photographing Lens 15 Light Controlling Part 20R Light Source 20L Light Source 21R light source 21L light source 100 image acquisition device 101 image acquisition device 102 image acquisition device 103 image acquisition device

Claims (6)

an imaging unit that acquires an image of a subject moving in a predetermined direction;
an illumination unit that illuminates the subject from a direction different from the optical axis of the imaging unit;
The illumination unit has a plurality of light sources that irradiate light rays toward the subject, and each point at which the optical axis of each light source and the optical axis of the photographing unit intersect corresponds to the direction of the optical axis of the photographing unit. set at different positions along the
a shape measuring unit that measures the shape of the subject on the upstream side of the imaging unit;
The image acquisition device, wherein the illumination unit has a light control unit that controls the light source based on the shape of the subject measured by the shape measurement unit. A plurality of light sources constituting the illumination unit irradiate light beams from both sides of the optical axis of the photographing unit toward the subject on the transport path,
2. The method according to claim 1, wherein each point where the optical axis of the photographing unit and the optical axis of each light source intersect is set at different positions along the direction of the optical axis of the photographing unit. Image acquisition device. 3. The light control unit according to claim 1, wherein the light control unit controls the amount of light or ON/OFF of a plurality of light sources constituting the illumination unit based on the shape of the object measured by the shape measurement unit. 2. The image acquisition device according to item 1 . 3. The light control unit controls the light source positioned below to turn off when the height of the surface of the subject measured by the photographing unit is greater than a predetermined value. 4. The image acquisition device according to 3 . The light control unit turns off the light source on either side of the optical axis of the photographing unit when the inclination of the surface of the subject measured by the photographing unit is larger than a predetermined value. 5. The image acquisition device according to claim 3, wherein the control is performed such that an irradiation step of irradiating a light beam toward a subject moving in a predetermined direction;
a photographing step of photographing a subject irradiated with the light beam by a photographing unit;
In the irradiating step, a point at which the optical axes of a plurality of light sources that irradiate light rays toward the subject and the optical axis of the photographing unit intersect are set at different positions in the direction of the optical axis of the photographing unit,
A shape measuring step of measuring the shape of the subject on the upstream side where the photographing is performed;
and a light control step of controlling a light source in the irradiation step based on the shape of the object measured in the shape measurement step .

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