Camera module clock impedance matching device based on cable length

Abstract

The utility model discloses a camera module clock impedance matching device based on cable length relates to image sensor technical field, including host board, sensor module and chip resistor, the first serial resistance R1 is integrated in the host board, and its resistance value is optimized and is determined according to reference cable length, and sensor module includes image sensor chip OV6946 and its bearing plate, on the bearing plate of sensor module, between the clock input pin of OV6946 sensor and the golden finger, set up the solder pad structure for welding chip resistor, and the first serial resistance R1 is fixed resistance, and it sets up in the PCB circuit of host board, is used for optimizing the signal integrity when the signal integrity of standard length cable connection. The scheme has high flexibility, and the host board does not need to make different design for different line length sensor, realizes the standardization and universality of host board. The scheme is extremely simple, and only adds the cost of a resistance pad, and it is far lower than the scheme of redesigning host board or using active device.

Description

Technical Field

[0001] This utility model belongs to the field of image sensor technology, specifically, it relates to a clock impedance matching device for a camera module based on cable length. Background Technology

[0002] Ultra-miniature image sensors such as the OV6946 are widely used in integrated devices with extremely stringent size requirements, such as medical endoscopes and industrial endoscopes. In these devices, the sensor is located at the end of a cable and connects to the main board via a long, flexible cable to transmit signals.

[0003] Clock signals (CLK) are high-frequency signals that produce transmission line effects when transmitted through long cables. The longer the cable, the greater the impact of the equivalent capacitive load and characteristic impedance on the signal, leading to flattened signal edges (longer rise / fall times), overshoot / undershoot, and ringing.

[0004] The traditional solution is to place a series resistor or potentiometer on the motherboard near the connector for impedance matching and to eliminate signal reflection. However, this solution requires a fixed cable length.

[0005] To adapt to different application scenarios (such as endoscopic examinations at different depths), the same all-in-one PC may need to be equipped with sensor modules of different cable lengths. Since the PCB and its series resistance inside the all-in-one PC are fixed and cannot be changed by the user, when the cable length is changed, the fixed series resistance value can no longer provide optimal impedance matching for the new cable length, resulting in a decrease in signal quality, which may cause image jitter, stripes, or even failure to function properly.

[0006] No effective solutions have yet been proposed to address the problems in the relevant technologies.

[0007] Therefore, in order to solve the above problems, this utility model provides a camera module clock impedance matching device based on cable length. Utility Model Content

[0008] In order to overcome the above-mentioned technical problems, the purpose of this utility model is to provide a camera module clock impedance matching device based on cable length.

[0009] The objective of this utility model can be achieved through the following technical solutions: A camera module clock impedance matching device based on cable length includes a motherboard, a sensor module, and surface mount resistors. The motherboard integrates a first series resistor R1, the value of which is optimized and determined based on the length of the reference cable. The sensor module includes an image sensor chip OV6946 and its carrier board. On the carrier board of the sensor module, a pad structure for soldering the chip resistor is provided between the clock input pin of the OV6946 sensor and the gold finger.

[0010] As a preferred embodiment of this utility model, the first series resistor R1 is a fixed-value resistor, which is installed in the PCB circuit of the motherboard to optimize the signal integrity when connecting standard length cables.

[0011] As a preferred embodiment of this invention, the chip resistor is used to dynamically compensate for the impedance of the clock signal according to the change in the actual length of the connecting cable.

[0012] As a preferred embodiment of this invention, the carrier board of the sensor module is a flexible printed circuit board or a rigid printed circuit board, and the pad structure allows for the replacement of surface mount resistors with different resistance values ​​as needed.

[0013] As a preferred embodiment of this invention, the resistance value of the chip resistor ranges from 0Ω to 100Ω.

[0014] As a preferred embodiment of this invention, the first serial resistor R1 and the surface mount resistor are connected in series to form the total impedance matching resistor on the clock signal transmission path.

[0015] As a preferred embodiment of this utility model, the size of the pad structure is adapted to the package size of the chip resistor, and the circuit connection of the pad structure is connected in series to the signal path between the clock input pin and the gold finger.

[0016] As a preferred technical solution of this utility model, the reference cable length is the preset shortest cable length or the most commonly used cable length.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. High flexibility: The motherboard does not need to be designed differently for sensors with different line lengths, realizing the standardization and universality of the motherboard.

[0018] 2. Guaranteed performance: Ensures that the sensor module of any cable length can operate under its optimal impedance matching condition, achieving the best signal integrity and image quality.

[0019] 3. Low cost: The solution is extremely simple, adding only the cost of a resistor pad, which is far lower than redesigning the motherboard or using active components.

[0020] 4. Easy to manufacture: Sensor module manufacturers can complete the soldering and testing of R2 according to the cable length before leaving the factory, so users can plug and play without any debugging. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is one of the schematic diagrams of the Sensor module structure of this utility model; Figure 3 This is the second schematic diagram of the Sensor module structure of this utility model.

[0023] Figure label: 1. Motherboard; 2. Sensor module; 3. Surface mount resistors. Detailed Implementation

[0024] The utility model will now be further described with reference to the accompanying drawings and specific embodiments: Please see Figure 1 , Figure 2 and Figure 3 According to an embodiment of the present invention, a camera module clock impedance matching device based on cable length includes a motherboard 1, a sensor module 2 and a surface mount resistor 3. The motherboard 1 has an integrated first series resistor R1, the value of which is optimized and determined based on the length of the reference cable. Sensor module 2 includes the image sensor chip OV6946 and its carrier board. On the carrier board of Sensor module 2, between the clock input pin of the OV6946 sensor and the gold fingers, there is a pad structure for soldering the chip resistor 3. This method can split the impedance matching task that originally required a fixed resistor into a task completed by a fixed resistor and a configurable resistor. The fixed part remains on the motherboard, while the configurable part is recessed onto the replaceable sensor module. It only increases the cost of a resistor pad and ensures that the sensor module of any cable length can work under its optimal impedance matching state, obtaining the best signal integrity and image quality.

[0025] Please see Figure 1The first series resistor R1 is a fixed-value resistor, which is set in the PCB circuit of the motherboard 1 to optimize the signal integrity when connecting standard length cables. The goal of the optimization is to achieve the best signal integrity index.

[0026] Please see Figure 2 The chip resistor 3 is used to dynamically compensate for the impedance of the clock signal according to the change in the actual connection cable length. The resistance value of the chip resistor 3 can be manually selected and replaced according to the actual connection cable length to compensate for the impedance mismatch introduced by cables of different lengths.

[0027] Please see Figure 2 and Figure 3 The carrier board of Sensor module 2 is a flexible printed circuit board or a rigid printed circuit board, and the pad structure allows for the replacement of surface mount resistors 3 with different resistance values ​​as needed.

[0028] Please see Figure 2 The resistance value of the chip resistor 3 ranges from 0Ω to 100Ω. For actual connection cables of different lengths, the required resistance value of the chip resistor 3 is determined by simulation calculation, table lookup method or empirical formula, and then soldered onto the pad structure.

[0029] Please see Figure 1 and Figure 2 The first series resistor R1 and the chip resistor 3 are connected in series to form the total impedance matching resistor on the clock signal transmission path. The total series resistance value (R1 + chip resistor 3) should be roughly matched with the characteristic impedance of the target cable minus the output impedance of the source end. Longer cables require a smaller chip resistor 3 to reduce the total series resistance, while shorter cables require a larger chip resistor 3 to increase the total series resistance.

[0030] Please see Figure 2 The size of the pad structure is compatible with the package size of the chip resistor 3, and the circuit connection of the pad structure is connected in series to the signal path between the clock input pin and the gold finger.

[0031] Please see Figure 1 and Figure 2 The reference cable length is either the preset shortest cable length or the most commonly used cable length. Selecting the shortest length as the reference means that the first series resistor R1 is optimized for the scenario where overdamping is most likely to occur. In this case, connecting a longer cable requires compensation by reducing the total series resistance through the chip resistor 3. Selecting the most commonly used length as the reference means that in most application scenarios, only a standard chip resistor 3 needs to be used, and the chip resistor 3 only needs to be replaced when connecting non-standard length cables.

[0032] The working principle of a camera module clock impedance matching device based on cable length is as follows: The first series resistor R1 integrated on the motherboard 1 has a fixed resistance value determined by simulation or testing according to the preset reference cable length to ensure initial impedance matching under the reference scenario. When the actual connection cable length deviates from the reference length, the surface mount resistor 3 on the carrier board of the sensor module 2 is replaced to adjust its resistance value so that the total impedance after the first series resistor R1 and the surface mount resistor 3 are connected in series is equal to the characteristic impedance of the cable. The total impedance matching resistor cancels out the impedance mismatch caused by the change in cable length, reduces the reflection and attenuation of the signal in the transmission path, and ensures that the clock signal is stably input to the image sensor chip OV6946, ultimately improving the imaging quality and system reliability of the camera module.

[0033] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A camera module clock impedance matching device based on cable length, characterized in that: Includes motherboard (1), sensor module (2) and surface mount resistor (3); The motherboard (1) has an integrated first serial resistor R1, the resistance of which is determined by optimization based on the length of the reference cable. The Sensor module (2) includes an image sensor chip OV6946 and its carrier board. On the carrier board of the Sensor module (2), a pad structure for soldering the chip resistor (3) is provided between the clock input pin of the OV6946 sensor and the gold finger.

2. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The first serial resistor R1 is a fixed resistance resistor, which is set in the PCB circuit of the motherboard (1) to optimize the signal integrity when connecting standard length cables.

3. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The chip resistor (3) is used to dynamically compensate for the impedance of the clock signal according to the change in the actual connection cable length.

4. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The carrier board of the sensor module (2) is a flexible printed circuit board or a rigid printed circuit board, and the pad structure allows for the replacement of chip resistors (3) with different resistance values ​​as needed.

5. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The resistance value of the chip resistor (3) ranges from 0Ω to 100Ω.

6. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The first serial resistor R1 and the patch resistor (3) are connected in series to form the total impedance matching resistor on the clock signal transmission path.

7. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The size of the pad structure is adapted to the package size of the chip resistor (3), and the circuit connection of the pad structure is connected in series to the signal path between the clock input pin and the gold finger.

8. The camera module clock impedance matching device based on cable length according to claim 1, characterized in that: The reference cable length is the preset shortest cable length or the most commonly used cable length.

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