Medium transport device and image reading device

A medium transport device comprising:

• a first roller pair configured to transport a medium in a transport direction;
• an ultrasonic detection section positioned downstream of the first roller pair in the transport direction;
• a second roller pair disposed downstream of the first roller pair in the transport direction;
• and
• a transmission-side path forming member that is configured to form a medium transport path between the first roller pair and the second roller pair and that fixes the transmission board holder, wherein
• the ultrasonic detection section includes
• a transmission sensor chip configured to emit ultrasonic waves along a first axis toward a first surface of the medium being transported,
• a receiving sensor chip that is configured to receive the ultrasonic waves and that is disposed at a position sandwiching the medium with the transmission sensor chip, the position being on the first axis,
• a transmission board on which the transmission sensor chip is provided,
• a receiving board on which the receiving sensor chip is provided,
• a first protection member that is a protection member provided on the first axis and that is positioned between the transmission sensor chip and the medium,
• a second protection member that is a protection member provided on the first axis and that is positioned between the receiving sensor chip and the medium,
• a transmission board holder configured to hold the transmission board and the first protection member, and
• a receiving board holder configured to hold the receiving board and the second protection member, wherein
• the first roller pair includes a separation roller configured to contact the first surface of the medium,
• the transmission-side path forming member is provided with an attachable and detachable cover,
• when the cover is attached, the transmission board holder is covered by the cover, and
• when the cover is detached, the separation roller is replaceable and the transmission board holder is exposed.

A medium transport device comprising:

• a first roller pair configured to transport a medium in a transport direction and
• an ultrasonic detection section positioned downstream of the first roller pair in the transport direction, wherein
• the ultrasonic detection section includes
• a transmission sensor chip configured to emit ultrasonic waves along a first axis toward a first surface of the medium being transported,
• a receiving sensor chip that is configured to receive the ultrasonic waves and that is disposed at a position sandwiching the medium with the transmission sensor chip, the position being on the first axis,
• a transmission board on which the transmission sensor chip is provided,
• a receiving board on which the receiving sensor chip is provided,
• a first protection member that is a protection member provided on the first axis and that is positioned between the transmission sensor chip and the medium,
• a second protection member that is a protection member provided on the first axis and that is positioned between the receiving sensor chip and the medium,
• a transmission board holder configured to hold the transmission board and the first protection member, and
• a receiving board holder configured to hold the receiving board and the second protection member, wherein
• the transmission board is provided with a first enclosing member that is a member surrounding the transmission sensor chip and that is a plate-shaped member provided along the transmission board and
• the receiving board is provided with a second enclosing member that is a member surrounding the receiving sensor chip and that is a plate-shaped member provided along the receiving board.