工程师 - 水晶头接口

水晶头（Crystal Plug） 是一种非正式的称呼，主要用于描述 RJ 系列的接头，特别是 RJ45，这种接口在以太网中非常常见。水晶头一般是透明的塑料插头，带有金属引脚，用于传输信号。

虽然 Registered Jack 包括了我们常见的水晶头，但它其实是一个更广泛的术语，涵盖了多种接口标准，不仅仅限于我们通常理解的那种透明插头。

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注册插孔（RJ）是指用于连接电信或网络设备的标准化网络接口。这些连接器通常与电话线和以太网电缆有关。

以下是一些常见的注册插孔类型：

1. RJ11：这是最常用的电话连接类型。它通常有 4 或 6 个位置和 2 或 4 个导体（插针），因此适用于单线电话服务。

2. RJ14：与 RJ11 相似，但导体更多，通常有 6 个位置和 4 个导体，可处理两条电话线。

3. RJ45：广泛用于以太网联网。它通常有 8 个位置和 8 根导线（针脚），适用于将设备连接到网络，例如将计算机连接到路由器或交换机。

4. RJ21：通常称为 “电话座 ”或 “50 针连接器”，用于更大、更复杂的电话系统。

5. RJ50：这是一种 10 位、10 导体（10P10C）模块连接器。它的外观与 RJ45 相似，但有 10 个引脚而不是 8 个。常见于条形码扫描仪、某些销售点（POS）系统和其他外围设备，这些设备需要额外的导体来增强功能，如额外的信号或供电能力。它包括电源线、数据线或接地连接。

11、14、21、45 等数字是用于标记不同类型插座和布线配置的序列的一部分。

RJ "标准定义了物理连接器和连接器内的布线模式，以确保连接设备之间的兼容性和正确通信。

Registered Jack (RJ) refers to a standardized network interface used for connecting telecommunications or networking equipment. These connectors are most commonly associated with telephone lines and Ethernet cables.

Here are some common types of Registered Jacks:

1. RJ11: This is the most common type used for telephone connections. It typically has 4 or 6 positions and 2 or 4 conductors (pins), which makes it suitable for single-line telephone services.

2. RJ14: Similar to RJ11 but with more conductors, typically 6 positions and 4 conductors, allowing it to handle two telephone lines.

3. RJ45: This is widely used for Ethernet networking. It usually has 8 positions and 8 conductors (pins), making it suitable for connecting devices to networks, such as computers to routers or switches.

4. RJ21: Often called a "telephone block" or "50-pin connector," it's used for larger, more complex telephone systems.

5. RJ50: It is an 10-position, 10-conductor (10P10C) modular connector. It is similar in appearance to the RJ45 but with 10 pins instead of 8. Commonly found in equipment like barcode scanners, some Point of Sale (POS) systems, and other peripheral devices that require additional conductors for enhanced functionality, like additional signaling or power capabilities. It includes power lines, data lines, or ground connections.

The numbers like 11, 14, 21, 45, etc., are part of a sequence that was used to label different types of jacks and wiring configurations.

The "RJ" standard defines both the physical connector and the wiring pattern within the connector to ensure compatibility and proper communication between connected devices.

参考：

https://www.digikey.com/en/articles/understanding-and-specifying-modular-connectors