Image forming apparatus

An image forming apparatus comprising:

• a document conveying unit which conveys a document;
• an image reading section which reads the document being conveyed;
• a storage which stores data;
• a controller which
• finds a skew angle indicating how each read document is skewed relative to a main scanning direction or a sub scanning direction,
• stores angle data as to the skew angle in the storage,
• generates distribution data indicating a distribution of the skew angle corresponding to documents read during a previously defined period,
• performs a previously defined test to check whether or not there is a significant difference between the distribution data and reference distribution data previously stored in the storage, and
• judges whether or not the image forming apparatus needs maintenance based on a result of the test;
• a communicator which
• is communicably connected to a service system of a service provider that provides maintenance services for the image forming apparatus, and
• transmits to the service system a maintenance request notification to request maintenance of the image forming apparatus when the controller judges that the image forming apparatus needs maintenance;
• and
• an acceptor which accepts a setting as to in which of reading modes to read a document out of
• a normal reading mode for reading a document comprising a plurality of sheets of a same document size and
• a mixed reading mode for reading a document comprising a plurality of sheets of varying document sizes,
• wherein
• a set of the distribution data is generated for each document size, each document type, and each reading mode, and
• the controller
• classifies the angle data as to the skew angle stored in the storage into groups according to a previously defined criterion,
• generates a set of the distribution data for each group,
• when a number of sets of the distribution data that exhibit a significant difference from the reference distribution data is equal to or larger than a threshold number,
• judges that the image forming apparatus needs maintenance, and transmits the maintenance request notification to the service system, and
• when the number of sets of target distribution data that exhibit a significant difference from the reference distribution data is smaller than the threshold number,
• does not transmit the maintenance request to the service system.