An adaptive packaging for a reflective optical encoder chip

Abstract

This invention provides an adaptive packaging for a reflective optical encoder chip. The complete system consists of a light source (201), a code disk (202), a focusing lens (203), a photodiode array chip (204), a feedback circuit (205), a MEMS chip (206), and a mechanical column (207). This invention can be widely applied to various optical measurements such as laser ranging, lidar, and grating rulers.

Description

Technical Field

[0001] This invention relates to an adaptive packaging of a reflective optical encoder chip, which can be used for various optical measurements such as laser ranging, lidar, and grating rulers. Background Technology

[0002] MEMS (Micro-Electro-Mechanical Systems) are miniaturized electronic and mechanical systems that integrate micro-mechanical components, sensors, actuators, and electronic circuitry onto a tiny chip or substrate. Here are some key characteristics and applications of MEMS: **Small Size:** MEMS devices are typically very small, ranging in size from micrometers to millimeters, making them ideal for embedding in small devices or systems. **Integration:** MEMS technology allows for the integration of multiple sensors, actuators, and electronic components onto a single chip, resulting in highly integrated, multifunctional devices. **Sensing Functions:** MEMS devices can be used to detect and measure a wide variety of physical quantities, such as pressure, acceleration, temperature, humidity, and light intensity. These sensors are used in many applications, such as accelerometers and gyroscopes in smartphones. **Actuation Functions:** MEMS devices can also include micro-actuators, such as micro-motors or micro-valves, for controlling physical processes, such as fluid flow or mechanical motion. **Application Areas:** MEMS technology has wide applications in various fields, including but not limited to medical diagnostics, automotive safety systems, aerospace, industrial automation, consumer electronics (such as smartwatches and smartphones), and environmental monitoring. **Manufacturing Processes:** MEMS devices are typically manufactured using microfabrication techniques similar to semiconductor manufacturing processes. This includes process steps such as photolithography, thin film deposition, etching, and ion implantation. Cost-effectiveness: Because MEMS devices can integrate multiple functions on the same chip, they typically offer lower manufacturing costs and smaller size, making them very attractive for mass production applications.

[0003] An optical encoder is a sensor device used to measure the position, velocity, or positional change of an object. They typically use optical principles to achieve high-precision position measurement and convert the measurement results into digital signals for further processing by a computer or control system. Here are some key characteristics and working principles of optical encoders: Basic Principles: An optical encoder typically includes a light source, a grating or encoder disk, a photosensitive element, and signal processing circuitry. The light source emits a light beam that passes through the grating or encoder disk and forms a spot on the photosensitive element. The movement of the object causes a change in the spot on the photosensitive element, generating a changing photoelectric signal. Absolute Encoders and Incremental Encoders: There are two main types of optical encoders: absolute encoders and incremental encoders. Absolute encoders provide the absolute position information of an object immediately without recalibration. They typically use multiple grating disks or encoder channels, each representing one bit of position information. Incremental encoders provide information about the relative motion of an object. They typically contain two channels, one for measuring forward motion and the other for measuring reverse motion. By counting the number of pulses in each channel, the position and velocity can be determined. Resolution: Resolution is a key parameter of an optical encoder, representing the number of pulses per encoder disk cycle. Higher resolution generally translates to higher measurement accuracy. Accuracy and repeatability: Optical encoders typically offer high-precision position measurements; however, their accuracy and repeatability depend on manufacturing quality and environmental conditions. Applications: Optical encoders are widely used in fields requiring high-precision position measurement, such as machine tool control, printing machinery, medical equipment, automation and robotics, aerospace, and astronomy. Interference immunity: Optical encoders generally offer some resistance to external light and vibration, but additional measures, such as housing protection or noise reduction techniques, may be necessary in harsh environments. Optical encoders are widely used in industrial automation, robotics, CNC machine tools, medical equipment, and aerospace.

[0004] In recent years, methods to improve the accuracy of optical encoders have involved multiple aspects, including hardware design, calibration, environmental control, and signal processing. Here are some ways to improve the accuracy of optical encoders: High-resolution encoder disks or gratings: Use encoder disks or gratings with more lines or markings to increase the number of pulses per cycle, improving measurement resolution. High-quality light sources and optics: Employ high-quality light sources and optics to ensure a stable beam and minimal optical distortion. Environmental control: Place the optical encoder in a stable environment, avoiding light interference, vibration, and temperature variations. Use housings or sealed designs to protect the optics. Calibration: Perform regular calibration to eliminate potential errors. This includes zero-point calibration (determining the zero position) and gain calibration (correcting proportional errors). Vibration and shock suppression: In environments exposed to vibration or shock, take measures to reduce or isolate these disturbances, such as using mechanical isolators or vibration compensation techniques. External interference suppression: Use optical filters to suppress the effects of external light sources to reduce errors. Signal processing: Employ high-quality signal processing circuitry and algorithms to eliminate noise, filter signals, and improve measurement accuracy. Mechanical design: Consider the rigidity and stability of mechanical components to reduce mechanical stray errors. Temperature Compensation: Implement temperature compensation algorithms to correct for the impact of dimensional changes caused by temperature variations on measurement results. Use of Multiple Sensors: Improve the accuracy and robustness of position measurements by simultaneously using multiple optical encoders or other sensors, such as accelerometers or gyroscopes. Regular Maintenance: Perform regular maintenance and cleaning to ensure the equipment remains in optimal operating condition.

[0005] The methods described above for improving the accuracy of optical encoders have the following problems: they are too costly, complex, time-consuming, and cannot adjust factors affecting accuracy during operation.

[0006] To address the above problems, this invention discloses an adaptive packaging for a reflective optical encoder chip, applicable to various optical measurements such as laser ranging, lidar, and grating rulers. It employs a photodiode array chip as the photosensitive device. The optical signal carrying angle-encoded information is converted into an electrical signal and decoded by the photodiode array chip to obtain the angle information. A feedback circuit then distinguishes the electrical signal converted by the photodiode array chip and issues adaptive commands to the MEMS chip. The MEMS chip adjusts the height of four mechanical posts according to the commands, thereby adaptively adjusting the orientation of the focusing lens to achieve real-time alignment with the photodiode array chip, thus improving the accuracy of the optical encoder. Summary of the Invention

[0007] The purpose of this invention is to provide an adaptive packaging for a reflective optical encoder chip.

[0008] The system comprises a light source, a code disk, a focusing lens, a photodiode array chip, a feedback circuit, a MEMS chip, and four mechanical posts. The light beam generated by the light source illuminates the code tracks on the code disk, reflecting a beam carrying angular encoding information that is focused by the focusing lens and then projected onto the photodiode array chip. The photodiode array chip converts the optical signal into an electrical signal and decodes the angular information. The feedback circuit distinguishes the processed electrical signal from the photodiode array chip and sends adaptive commands to the MEMS chip. The MEMS chip adjusts the four mechanical posts according to the commands, thereby adaptively aligning the lens with the photodiode chip to achieve adaptive alignment.

[0009] In the above scheme, the light source can be LEDs of different wavelengths, which can be replaced according to the sensitive wavelength of different photodiodes.

[0010] In the above scheme, the code disk is a dual-channel absolute code disk.

[0011] In the above scheme, the diameter of the focusing lens is much larger than the diameter of the spot formed on the focusing lens by the beam reflected back from the code disk, ensuring that the angle encoding information carried by the beam is not lost.

[0012] In the above scheme, the feedback circuit can distinguish the electrical signal converted by the photodiode array chip and issue adjustment and adaptive commands to the MEMS chip.

[0013] In the above scheme, the MEMS chip can adjust the height of the four mechanical columns according to the adaptive command issued by the feedback circuit.

[0014] The four mechanical pillars 207 can be raised and lowered under the adjustment of MEMS, and the orientation of the focusing lens 203 can be adjusted by physical adhesion.

[0015] This invention utilizes a feedback circuit and a MEMS chip to adaptively control the lens, achieving real-time alignment with the photodiode array chip and improving the accuracy of the optical encoder. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the adaptive packaging structure of a reflective optical encoder chip according to an embodiment of the present invention.

[0017] Figure 2 This is a front view of a dual-track code disk with adaptive packaging of a reflective optical encoder chip according to an embodiment of the present invention.

[0018] Figure 3 This is a left view of a focusing lens in an adaptive package of a reflective optical encoder chip according to an embodiment of the present invention.

[0019] Figure 4 This is an isometric view of a lens-free beam receiving device with adaptive packaging of a reflective optical encoder chip according to an embodiment of the present invention.

[0020] Figure 5 This is a top view of a reflective optical encoder chip adaptively packaged beam receiving device without a lens, according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0022] Figure 1 An adaptive package for a reflective optical encoder chip is presented. The package consists of a light source 201, a code disk 202, a focusing lens 203, a photodiode array chip 204, a feedback circuit 205, a MEMS chip 206, and four mechanical pillars 207. Light source 201 generates a beam with a small diffusion angle. Code disk 202 encodes the angle information and transmits the angle-encoded information to the beam through the beam generated by the reflected light source 201. Focusing lens 203 focuses the beam carrying the angle-encoded information onto photodiode array chip 204. Four mechanical posts 207 are attached to the focusing lens 203 and serve to fix and adjust the focusing lens 203. Photodiode array chip 204 converts the light signal carrying the angle-encoded information into an electrical signal for decoding. Feedback circuit 205 distinguishes the electrical signal converted by photodiode array chip 204 and sends an adaptive command to MEMS chip 206. MEMS chip 206 adjusts the position of focusing lens 203 by raising and lowering the four mechanical posts 207 according to the command of feedback circuit 205, thereby achieving the purpose of adaptively aligning the beam carrying the angle-encoded information with photodiode array chip 204.

[0023] LEDs provide a stable beam with a small diffusion angle.

[0024] The dual code channels on the code disk encode the angle, and the light beam reflected from the dual code channels carries the angle-encoded information.

[0025] The diameter of the focusing lens is much larger than the diameter of the spot formed on the focusing lens by the beam reflected back from the code disk, ensuring that the angular encoding information carried by the beam is not lost.

[0026] The photosensitive element uses a photodiode array, which can collect more light information.

[0027] The feedback circuit can distinguish the electrical signals converted by the photodiode array chip and issue adjustment and adaptive commands to the MEMS chip.

[0028] The MEMS chip can adjust the height of the four mechanical columns according to the adaptive commands issued by the feedback circuit.

[0029] The four mechanical pillars 207 can be raised and lowered under the adjustment of MEMS, and the orientation of the focusing lens 203 can be adjusted by physical adhesion.

[0030] It should be noted that although the embodiments described above are illustrative, they are not intended to limit the invention. Therefore, the invention is not limited to the specific embodiments described above. Any other embodiments obtained by those skilled in the art under the guidance of this invention without departing from its principles are considered to be within the protection scope of this invention.

Claims

1. An adaptive packaging for a reflective optical encoder chip, characterized in that: The package consists of a light source (201), an encoder disk (202), a focusing lens (203), a photodiode array chip (204), a feedback circuit (205), a MEMS chip (206), and four mechanical pillars (207). The light source (201) generates a beam with a small diffusion angle. The encoder disk (202) encodes the angle information and transmits the angle-encoded information to the beam through the beam generated by the reflected light source (201). The focusing lens (203) focuses the beam carrying the angle-encoded information onto the photodiode array chip (204). The four mechanical pillars (207) are bonded to the focusing lens (203). The fixed focusing lens (203) is used to convert the light signal carrying angle encoding information into an electrical signal for decoding. The feedback circuit (205) distinguishes the electrical signal converted by the photodiode array chip (204) and sends an adaptive command to the MEMS chip (206). The MEMS chip (206) adjusts the position of the focusing lens (203) by raising and lowering the four mechanical columns (207) according to the command of the feedback circuit (205), thereby achieving the purpose of aligning the beam carrying angle encoding information with the photodiode array chip (204).

2. The adaptive packaging of a reflective optical encoder chip according to claim 1, characterized in that: The feedback circuit (205) can distinguish the electrical signal converted by the photodiode array chip (204) and issue adjustment and adaptive commands to the MEMS chip (206).

3. The adaptive packaging of a reflective optical encoder chip according to claim 1, characterized in that: The four mechanical columns (207) can be raised and lowered under the adjustment of MEMS, and the orientation of the focusing lens (203) can be adjusted under the action of physical adhesion.

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