Flattened reading head and encoder

A flattened reading head and an encoder, the flattened reading head comprises a reading head main body, the reading head main body is internally provided with an accommodating cavity, and the bottom of the accommodating cavity is provided with a through hole. And the circuit board is arranged in the accommodating cavity. And the sensing module is arranged on the circuit board and used for receiving an optical signal and converting the optical signal into an electric signal, and the sensing module extends into the through hole. And the cover plate is arranged at the opening of the accommodating cavity and is used for sealing the accommodating cavity. According to the utility model, the circuit board is arranged in the accommodating cavity, and the sensing module extends into the through hole at the bottom of the accommodating cavity, so that the internal structure of the reading head main body is more compact, the overall volume of the reading head is reduced, the weight is reduced, and the reading head can be