Components
The composition of a typical automatic ticket checker is as follows (it simplifies in part).
Some equipments exist in backyard except the body part which is visible to users.
Body
Handling unit
This unit carries tickets which is thrown and read/write tickets.
It is the example of an entrance slot. The machine which was used in the Hankyu had 5 inclination entrance slot for left-handed users.
Hankyu 
Transportation Bureau City of Sendai 
Bureau of Transportation Tokyo Metropolitan Government
Then, it is the example of an extraction mouth. The machine with which the camera is installed near the extraction mouth exists, such as used in Hankyu.
Keihan Electric Railway 
Eizan Electric Railway 
Hankyu
IC card R/W
The cushion made of rubber is attached in the antenna portion, and breakage of a machine is prevented. Nowadays, there are machines that can read the QR code.
IC card R/W (East Japan Railway) 
IC card R/W (Hankyu) 
QR code reader (Okinawa Urban Monorail)
Sensor
It is sensors for detecting the passenger who passes through a ticket gate passage. In the past, photoelectric tubes had been used as censor, but now an infrared rays are used. The sensor is built into several places of an automatic ticket checker case.
The purple points which is visible to a black bar in this photograph is a sensor.
Door unit
It only opened and closed simply in the early days. Recently a speed of the movement is controled, so even if a person is hit by the door the damage is very few.
In the case of a simplified machine, it does not habe a door unit.
Normal width (West Japan Railway) 
Wide width (Chiba Urban Monorail)
Passage display
An electric bulb was used before, but LED dot matrix is used nowadays. A fixed sign is used by the passage.
"o", "x", arrow or icon are used as a sign.
Fixed (Kintetsu Railway) 
Bulb (Hankyu) 
LED (Transportation Bureau City of Sendai) 
LED (Keisei) 
Full-color LED (Metropolitan Intercity Railway)
Guide display
Generally a guide display exists near the extraction mouth. There are some cases it exists near the entrance slot (for example, machine for the Shinkansen). The balance, a cause of an error, etc. are displayed.
LED, plasma display, color LCD are used.
LED (Transportation Bureau, City of Yokohama) 
Plasma display (Sapporo City Transportation Bureau) 
Color LCD (Central Japan Railway) 
Color LCD (West Japan Railway)
Peripheral equipment
Control unit
It is an unit which controls an automatic ticket checker. By making network connection with automatic ticket checkers, it becomes possible to transfer fare information. Moreover, it seems to be connected to the server for IC card via this unit.
There are few opportunities to see because in many case it is installed in a station office. The blue box of a photograph is an example of installation in Osaka Municipal Transportation Bureau (former).
Monitoring unit
It is an unit which supervises a status of an automatic ticket checker. When an error occured, the detail is displayed on it. Control of direction and reset operation also can be performed.
Most of the case, this unit is installed near the station staff in ticket gate.
Passage indicator
It is an unit which is installed in the ceiling of a ticket gate passage. It tends to be removed or not be installed from the begining.
Fluorescent light (Shizuoka Railway) 
Fluorescent light (Hankyu) 
Fixed (former, Osaka Municipal Transportation Bureau) 
Panel (TOBU RAILWAY) 
LED (Yurikamome)