KR-102963794-B1 - ToF Sensor for Measuring Depth Based on Reliability and Camera Including the Same

Abstract

A ToF sensor that measures depth based on reliability and a camera including the same are disclosed. According to one aspect of the present embodiment, a ToF sensor is provided, comprising: a light source unit that irradiates light of an infrared wavelength band having different frequency bands to a detection area for detecting an object; a light receiving unit that receives reflected light that is output from the light source unit and reflected from the outside; a shooting unit that photographs the detection area; a data processing unit that measures the correlation between the reflected light and each reference signal using the sensing value of the light receiving unit, calculates the phase difference between the irradiated light and the reflected light of each wavelength band, the distance between the sensor and the object, and the IR intensity from the phase difference; and a data correction unit that distinguishes between a dynamic area and a static area based on the result calculated by the data processing unit and the shooting result from the shooting unit, and determines reliability based thereon.

Inventors

• 김장선
• 조수영
• 김대연
• 김이섭
• 고상주
• 김선재
• 박민우
• 고영표

Assignees

• (주)팬옵틱스

Dates

Publication Date

20260512

Application Date

20250910

Claims (10)

1. Regarding ToF sensors, A light source unit that sequentially outputs light in a relatively low frequency band and light in an infrared wavelength band having a relatively high frequency band as a detection area for detecting an object; A light receiving unit that receives reflected light reflected from the outside after being output from the light source unit; A shooting unit that photographs the above detection area; A data processing unit that measures the correlation between reflected light and each reference signal using the sensing value of the light receiving unit, calculates the phase difference between the irradiated light and the reflected light of each wavelength band, the distance between the sensor and the target, and the IR intensity from the phase difference; and It includes a data correction unit that distinguishes between dynamic and static regions based on the result calculated by the data processing unit and the shooting result from the shooting unit, and determines reliability based thereon. The light receiving unit includes a plurality of pixels, and each pixel includes a plurality of tabs that store an amount of charge generated in proportion to the amount of incident light, A ToF sensor characterized in that each tap receives and stores photoelectrons generated from a light receiving sensor, wherein one tap operates in the same phase as the light irradiated from the light source and receives and stores photoelectrons, another tap operates in a phase delayed by π/2 compared to the light irradiated from the light source and receives and stores photoelectrons, yet another tap operates in a phase delayed by π compared to the light irradiated from the light source and receives and stores photoelectrons, and the remaining tap operates in a phase delayed by 3π/2 compared to the light irradiated from the light source and receives and stores photoelectrons.
2. delete
3. delete
4. delete
5. delete
6. In paragraph 1, The above data processing unit is, A ToF sensor characterized by calculating a first differential value of a charge stored in a tab that stores photoelectrons and operates in the same phase as the light irradiated from the light source, and a charge stored in a tab that stores photoelectrons and operates in a phase delayed by π compared to the light irradiated from the light source.
7. In paragraph 6, The above data processing unit is, A ToF sensor characterized by operating with a phase delayed by π/2 compared to the light irradiated from the light source and calculating a second differential value of the charge stored in a tab storing photoelectrons and operating with a phase delayed by 3π/2 compared to the light irradiated from the light source.
8. In Paragraph 7, The above data processing unit is, A ToF sensor characterized by calculating the phase difference between the incident light and the reflected light using an arctangent function with a first differential value and a second differential value as inputs.
9. In paragraph 8, The above data processing unit is, A ToF sensor characterized by calculating the distance between the sensor and the target from the calculated phase difference.
10. In Paragraph 9, The above data processing unit is, A ToF sensor characterized by calculating the distance between the final sensor and the target using a distance value calculated according to the illumination light of each wavelength band.

Description

ToF Sensor for Measuring Depth Based on Reliability and Camera Including the Same The present embodiment relates to a ToF sensor that measures the depth to a target relatively accurately based on reliability, and a camera including the same. The content described in this section merely provides background information regarding the present embodiment and does not constitute prior art. Recently, LiDAR sensors are being utilized in various fields. In particular, LiDAR sensors can detect objects around a user and determine the distance between the object and the user, thereby preventing accidents that the user might not be aware of and further enabling autonomous driving for various electronic devices. Meanwhile, ToF sensors are used to identify the distance to an object in LiDAR sensors. Depending on their operating method, ToF sensors can be classified into dToF (direct Time of Flight) sensors and iToF (indirect Time of Flight) sensors. In the case of dToF-based LiDAR sensors, the distance between an object and the LiDAR sensor is identified based on the flight time required for light emitted from the LiDAR sensor to be reflected by an object and received. However, dToF sensors require SPADs (Single-Photon Avalanche Diodes) for high-speed measurement of the light's flight time, which leads to the problem of high manufacturing costs for LiDAR sensors. Furthermore, for long-distance measurements, the plano-convex lens that collects light reflected by objects of the dToF sensor must be made larger, which not only leads to the problem of increasing the manufacturing cost of the lidar sensor but also creates another problem where dToF sensor-based lidar sensors cannot be installed in small electronic devices. As a result, the use and development of iToF sensors are increasing. Since iToF sensors can be implemented relatively more cheaply than dToF sensors, they are widely used in various electronic products, such as mobile terminals and AR/VR devices. Instead of directly measuring the travel time of light, iToF sensors transmit light carrying a specific pattern (e.g., a periodic waveform) and measure how much the returned light pattern deviates from the original pattern (phase shift). Since it is obvious that the pattern of a nearby object will return with only a slight deviation and that of a distant object will return with a significant deviation, iToF sensors indirectly calculate the distance between the sensor and the object by utilizing the 'degree of deviation'. However, ToF sensors, including iToF sensors, have the following structural problems. When a sensor or a measurement target moves, 'motion artifacts' occur where inaccurate depth values appear at the object's boundaries due to data distortion caused by the sensor's characteristic of collecting data across multiple frames. This resulted in a problem where the detection rate decreased. In addition, if a highly reflective object suddenly enters the measured frame or if a moving subject occupies a large area, the Auto-Exposure (AE) system mistakenly perceives the entire screen as having become brighter and drastically reduces the exposure time. As a result, problems such as the entire screen flickering, including the background suddenly becoming dark, occur, making it difficult to ensure stable measurement quality. FIG. 1 is a drawing illustrating an example of operation of a ToF sensor according to one embodiment of the present invention. FIG. 2 is a diagram illustrating the configuration of a ToF sensor according to one embodiment of the present invention. FIG. 3 is a diagram illustrating the configuration of a light receiving unit according to an embodiment of the present invention. FIG. 4 is a diagram illustrating the operation of a light receiving unit according to an embodiment of the present invention. FIG. 5 is a diagram illustrating the configuration of a data correction unit according to an embodiment of the present invention. FIG. 6 is a flowchart illustrating a method in which a ToF sensor senses an object according to an embodiment of the present invention. FIG. 7 is a flowchart illustrating a method for a ToF sensor according to an embodiment of the present invention to analyze whether movement occurs in a target. FIG. 8 is a flowchart illustrating a method for determining reliability of a ToF sensor according to an embodiment of the present invention. FIG. 9 is a flowchart illustrating a method for a ToF sensor to adjust a frame exposure time according to an embodiment of the present invention. The present invention is susceptible to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have bee