KR20150098485A - Automatic focuser of thermal imaging camera and method thereof - Google Patents

Abstract

Disclosed are an automatic focus adjustment device of a thermal imaging camera and a method thereof. The automatic focus adjustment device comprises: an infrared-ray lens which images infrared ray energy of an object to be imaged; an infrared ray detector outputs infrared ray energy, which is imaged on an incident surface of the infrared ray lens, as an analog signal; an infrared ray signal generation unit which converts the analog signal, output by the infrared ray detector, into a digital signal and outputs the digital signal; a lens temperature sensing unit which senses change in the temperature of the infrared ray lens in real time; an outline detection unit which detects an outline of the object to be imaged from the digital signal, output by the infrared ray signal generation unit in real time, when change of the temperature is sensed by the lens temperature sensing unit; an automatic focus adjustment unit which calculates a location where an automatic focus coefficient is maximized as a focus location by using the outline detected by the outline detection unit; and an actuator which adjusts the distance between the infrared ray detector and the infrared ray lens based on the focus location calculated by the automatic focus adjustment unit by operating the infrared ray detector. The automatic focus adjustment device senses change of the temperature of the infrared ray lens and, if change of the temperature is sensed, automatically adjusts the focus distance by operating the infrared ray detector. Therefore, the automatic focus adjustment device can automatically prevent a defocus phenomenon depending on change of the external temperature.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an automatic focus adjusting apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a thermal imaging camera, and more particularly, to an automatic focusing device and a method thereof for a thermal imaging camera

A thermal imaging camera, also called an infrared camera, is configured to output an image formed by sensing infrared rays. It is very useful for detecting a specific temperature in a dark environment, a fogged place, or the like, since an image is generated by sensing infrared rays emitted by an object, which is not visible light, even in the absence of light.

Typical examples are medical / quarantine areas where the temperature of an immigrant from the airport is monitored remotely to detect high temperature patients, industrial fields where the temperature of a transformer installed on a telephone pole is measured while traveling on the ground or in a vehicle, There is a military / security field that detects and detects enemy or abnormal objects in darkness without light.

The thermal camera has an infrared sensor or an infrared sensor array arranged in the form of an infrared sensor array, and the thermal camera generates an image based on the temperature of the object obtained through the respective infrared detectors.

The infrared rays incident through the optical lens of the thermal camera are directly incident on the infrared ray detectors assigned to the respective pixels. Each infrared ray detector measures the changing resistance value in response to the incident infrared ray energy, And generates an image using this.

Since the thermal camera accepts the energy of the infrared wavelength band, the lens can not use a general lens and a lens that passes through the infrared wavelength band is used.

And lens makers have different specifications, so lens mounts should be manufactured according to the manufacturer.

Normally used infrared lenses change the focus of the lens when the ambient temperature changes, so you have to manually adjust the focus whenever you change.

A special lens, infrared athermal lens, can maintain accurate focus regardless of changes in ambient temperature, eliminating the need for the user to adjust the focus separately. However, there is a problem that the cost is high.

The thermal lens is not standardized. In the case of an autofocus lens, an actuator control line is externally formed at an interface between an actuator of a lens for focusing and a thermal camera, unlike a lens of a general camera. It is necessary to further configure the actuator controller.

On the other hand, the thermal manual focus lens must be adjusted manually whenever the distance from the subject is changed. So it is not easy to adjust the focus from time to time after installing the camera outdoors.

An object of the present invention is to provide an automatic focusing device for a thermal imaging camera.

It is another object of the present invention to provide a method for automatically adjusting a focus of a thermal image camera.

According to an aspect of the present invention, there is provided an autofocusing apparatus for a thermal imaging camera, comprising: an infrared lens for imaging infrared energy of an object to be imaged; An infrared ray detector that forms an image on an incident surface by the infrared lens and outputs infrared energy as an analog signal; An infrared signal generator for converting the analog signal output from the infrared detector into a digital signal and outputting the digital signal; A lens temperature sensing unit for sensing a temperature change of the infrared lens in real time; A contour detector for detecting contours of the object to be photographed from the digital signal output from the infrared signal generator in real time when a temperature change is detected in the lens temperature sensor; An auto-focus adjusting unit for calculating a position at which the auto-focus coefficient becomes maximum using the outline detected by the outline detecting unit as a focus position; And an actuator for driving the infrared ray detector to adjust the distance between the infrared ray detector and the infrared ray lens according to the focal position calculated by the auto focus adjusting unit.

At this time, the contour detection unit calculates the differential values between the pixels for the digital signal output from the infrared signal generation unit, detects the contour line of the object, calculates an integral value for the differential values of the contour line And output to the auto-focus adjusting unit.

The automatic focus adjustment unit may be configured to compute an integrated value of the calculated contour line with a previous integral value and calculate a position at which an auto focus coefficient becomes maximum as a focus position.

According to another aspect of the present invention, there is provided a method for adjusting an auto focus of a thermal imaging camera, the method comprising: outputting infrared signals of infrared rays of an object to be imaged on an incident surface by an infrared lens; Converting the analog signal output by the infrared detector into a digital signal and outputting the digital signal; Sensing a temperature change of the infrared lens in real time; Detecting an outline of the object to be photographed in real time from the digital signal output from the infrared signal generator when the temperature change is detected by the lens temperature sensor; Calculating a position at which an auto-focus factor becomes maximum using the outline detected by the outline detecting unit as a focus position; And an actuator driving the infrared ray detector to adjust the distance between the infrared ray detector and the infrared ray lens according to the focal position calculated by the auto focus adjusting unit.

At this time, when the temperature change is detected in the lens temperature sensing unit, the contour detection unit detects the contour of the object in real time from the digital signal output from the infrared signal generation unit, Calculating an integral value of the differential values of the detected contour line, and outputting the integrated value to the automatic focus adjusting unit.

The step of calculating the position at which the auto-focus coefficient becomes maximum using the outline detected by the outline detecting unit as the focus position may be performed by comparing the integrated value of the calculated outline with the previous integrated value, And calculate a position at which the focus coefficient becomes maximum to the focal position.

According to the automatic focus adjusting apparatus and method of the thermal camera described above, when the temperature change of the infrared lens is detected in real time and the infrared detector is driven when the temperature change is detected, the focal distance is automatically adjusted in real time, It is possible to automatically prevent the phenomenon that the focus is blurred.

In particular, the present invention is applicable to an infrared camera equipped with a passive focus lens, rather than an existing expensive autofocus lens, by driving a camera module equipped with an infrared detector, not an infrared lens, to focus.

1 is a block diagram of an automatic focusing device of a thermal imaging camera according to an embodiment of the present invention.
2 is an exemplary view showing an actuator of a thermal imaging camera according to an embodiment of the present invention.
3 is a flowchart of a method of adjusting an auto focus of a thermal imaging camera according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail to the concrete inventive concept.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an automatic focusing device of a thermal imaging camera according to an embodiment of the present invention.

Referring to FIG. 1, an automatic focusing device 100 of a thermal imaging camera according to an exemplary embodiment of the present invention includes an infrared lens 110, an infrared ray detector 120, A signal generating unit 130, a lens temperature sensing unit 140, an outline detection unit 150, an auto focus control unit 160, and an actuator 170.

The automatic focusing device 100 is applied to an infrared camera of a manual focus lens other than an autofocus lens that drives a lens using an external control line and a controller.

The automatic focus adjustment apparatus 100 is configured to adjust the focal distance to the infrared lens 110 by driving the camera module itself equipped with the infrared ray detector 120 using the internal actuator 170. No external control lines or external controls are required.

Detects the temperature change of the infrared lens 110 in real time, and automatically detects the focus position when the temperature change is sensed, so that the actuator 170 drives the infrared ray detector 120.

Hereinafter, the detailed configuration will be described.

The infrared lens 110 is an optical system configuration for imaging the infrared energy of the object to be imaged.

The infrared ray detector 120 is configured to form an image on the incident surface by the infrared ray lens 110 and output the infrared ray energy as an analog signal.

The infrared signal generator 130 is configured to convert the analog signal output by the infrared detector 120 into a digital signal and output the digital signal.

The lens temperature sensing unit 140 is configured to detect a temperature change of the infrared lens 110 in real time. The lens temperature sensing unit 140 is configured to detect a change between a previous temperature and a current temperature of the infrared lens 110 in real time.

The contour detection unit 150 is configured to detect the contour of the object to be photographed from the digital signal output from the infrared signal generation unit 130 in real time when a temperature change is sensed by the lens temperature sensing unit 140. The focus can be adjusted by the outline of the shooting object.

Here, the contour detection unit 150 calculates differential values between pixels for the digital signal output from the infrared signal generation unit 130, detects contours of the object to be photographed, calculates integral values of the detected contour values And outputs it to the auto-focus adjusting unit 160. [0033] FIG.

Since the differential between each pixel indicates the degree of change of the digital signal, the boundary or outline of the object to be photographed is highlighted by the differential value. The contour line is detected by the differential values, and the integrated value of the differential values is output to the automatic focus control unit 160.

The automatic focus adjustment unit 160 is configured to calculate a position at which the auto focus coefficient becomes maximum using the outline detected by the outline detection unit 150 as the focus position.

The automatic focus adjustment unit 160 may be configured to compute an integrated value of the calculated outline with the previous integral value and calculate a position at which the auto focus coefficient becomes maximum as the focus position. And the position where the integral values coincide with each other is calculated as the focal position.

The auto-focus algorithm of the conventional CCD camera can be used as it is. For example, an algorithm may be used that compares the boundary line change of each frame of an object image received from the image sensor and forms a focus position to move to a higher position.

The actuator 170 is configured to drive the infrared ray detector 120 and adjust the distance between the infrared ray detector 120 and the infrared ray lens 110 according to the focal position calculated by the auto focus adjusting unit 160.

The actuator 170 transmits a driving force to the camera module 102 to control a focal distance between the infrared lens 110 and the infrared ray detector 120. The actuator 170 may be a voice coil motor (VCM), a micro-electromechanical system (MEMS), or a stepping motor actuator. Examples of the actuator 170 include a means for receiving an electric signal and transmitting driving force to the camera module 102 .

2 is an exemplary view showing an actuator of a thermal imaging camera according to an embodiment of the present invention.

2, an actuator 170 of a thermal imaging camera according to an embodiment of the present invention may be configured to include a leadscrew 171, a nut 172, a stepping motor 173, a guide shaft 174, have.

The actuator 170 is configured to drive the camera module 102. The camera module 102 may be equipped with an infrared ray detector 120 in front of the camera module 102 and may include all components necessary for image conversion such as an infrared signal generator 130 and an outline detector 140.

The focal distance between the infrared lens (not shown) and the infrared ray detector 120 mounted on the lens holder 101 is adjusted by the actuator 170.

The lead screw 171 is a screw type screw used for pulling or pushing the camera module 102 to adjust the focal distance between the infrared lens 110 and the infrared ray detector 171.

The nut 172 is connected to the camera module 102. When the lead screw 171 rotates, the nut 172 approaches or moves away from the lens. When the nut 172 moves, the camera module 102 is also moved to adjust the focal distance.

The stepping motor 173 receives the driving signal sent from the auto-focus adjusting unit 160 and rotates the lead screw 171. When the stepping motor 173 rotates in the forward direction or the reverse direction, the lead screw 171 also rotates in the forward direction or the reverse direction. The nut 172 connected to the lead screw 171 also approaches or moves away from the lens.

The guide shaft 174 is a member capable of preventing a collision of the drive shaft caused by the biasing of the drive shaft center position and the shaking of the drive shaft when the stepping motor 173 is driven.

3 is a flowchart of a method of adjusting an auto focus of a thermal imaging camera according to an embodiment of the present invention.

Referring to FIG. 3, the infrared ray detector 120 outputs the infrared ray energy of the object to be imaged on the incident surface by the infrared ray lens 110 as an analog signal (S101).

Next, the infrared signal generator 130 converts the analog signal output by the infrared detector 120 into a digital signal and outputs the digital signal (S102).

Next, the lens temperature sensing unit 140 senses the temperature change of the infrared lens 110 in real time (S103).

At this time, if a temperature change is sensed (S104) and the temperature change is detected in the lens temperature sensing unit 140, the contour detecting unit 150 detects the contour of the object to be photographed from the digital signal output from the infrared signal generating unit 130 in real time (S105).

At this time, the lens temperature sensing unit 140 calculates the differential values between the pixels of the digital signal output from the infrared signal generator 130, detects the contour of the object to be imaged, and integrates And outputs the calculated value to the auto-focus adjusting unit 160. [

Next, the auto-focus adjusting unit 160 calculates the position at which the auto-focus coefficient becomes maximum using the outline detected by the outline detecting unit 150 as the focus position (S106).

At this time, the automatic focus adjustment unit 160 may be configured to compute an integrated value of the outline calculated by the outline calculation unit 150 with a previous integral value, and to calculate a position at which the auto focus coefficient becomes maximum as a focus position.

Next, the actuator 170 drives the infrared ray detector 120 to adjust the distance between the infrared ray detector 120 and the infrared ray lens 110 according to the focal position calculated by the auto-focus adjusting unit 160 (S107).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. There will be.

101: Camera module
102: Lens holder
110: Infrared lens
120: Infrared detector
130: Infrared signal generator
140: Lens temperature sensing unit
150: contour detection unit
160: Automatic focusing unit
170: Actuator
171: Lead Screw
172: nut
173: Stepping motor
174: guide shaft

Claims (6)

An infrared lens for imaging the infrared energy of the object to be imaged;
An infrared ray detector that forms an image on an incident surface by the infrared lens and outputs infrared energy as an analog signal;
An infrared signal generator for converting the analog signal output from the infrared detector into a digital signal and outputting the digital signal;
A lens temperature sensing unit for sensing a temperature change of the infrared lens in real time;
A contour detector for detecting contours of the object to be photographed from the digital signal output from the infrared signal generator in real time when a temperature change is detected in the lens temperature sensor;
An auto-focus adjusting unit for calculating a position at which the auto-focus coefficient becomes maximum using the outline detected by the outline detecting unit as a focus position;
And an actuator for driving the infrared ray detector to adjust the distance between the infrared ray detector and the infrared ray lens according to the focal position calculated by the automatic focus adjustment unit. The image processing apparatus according to claim 1,
Calculating an integral value of the derivative values of the detected contour line, and outputting the integrated value to the automatic focus adjusting unit; and calculating an integrated value of the derivative values of the detected contour line by calculating the differential values between the pixels of the digital signal output from the infrared signal generation unit Wherein the focus adjustment unit is configured to adjust the focusing position of the thermal imaging camera. The apparatus according to claim 2,
Wherein the automatic focus adjusting device is configured to compute an integrated value of the calculated contour line with a previous integral value and calculate a position at which an auto focus coefficient becomes maximum as a focus position. Outputting the infrared energy of the object to be photographed which is formed on the incident surface by the infrared lens as an analog signal;
Converting the analog signal output by the infrared detector into a digital signal and outputting the digital signal;
Sensing a temperature change of the infrared lens in real time;
Detecting an outline of the object to be photographed in real time from the digital signal output from the infrared signal generator when the temperature change is detected by the lens temperature sensor;
Calculating a position at which an auto-focus factor becomes maximum using the outline detected by the outline detecting unit as a focus position;
And driving an infrared detector by an actuator to adjust a distance between the infrared ray detector and the infrared ray lens according to the focal position calculated by the auto focus adjusting unit. The method of claim 4, wherein, when the temperature change is detected in the lens temperature sensing unit, the contour detecting unit detects the contour of the object in real time from the digital signal output from the infrared signal generating unit,
Calculating an integral value of the derivative values of the detected contour line, and outputting the integrated value to the automatic focus adjusting unit; and calculating an integrated value of the derivative values of the detected contour line by calculating the differential values between the pixels of the digital signal output from the infrared signal generation unit Wherein the focus adjustment unit adjusts the focus of the laser beam. 6. The method of claim 5, wherein the step of calculating the position at which the auto-focus factor reaches a maximum value using the outline detected by the outline detecting unit as the focus position,
And calculating a position at which the auto-focus coefficient is maximized by comparing the integrated value of the calculated contour with the previous integrated value as a focal position.

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