Document placement detecting device, image reading device, image forming apparatus, method, and non-transitory recording medium

A method of detecting placement of a document with a document placement detecting device, the document placement detecting device including a document table and a plate, the document table transmitting light, and the plate being openable and closable relative to the document table and covering the document table in a closed state of the plate,

• the method comprising:
• irradiating a placement area with invisible light via the document table, the placement area being an area of the document table on which the document is placed;
• receiving reflected light from the document with an imaging device;
• outputting read data from the imaging device;
• and
• with a change in a read value of the read data output from the imaging device based on the irradiation with the invisible light, detecting the placement of the document.

Anon-transitory recording medium storing a plurality of instructions which, when executed by one or more processors, causes the processors to perform a method of detecting placement of a document with a document placement detecting device, the document placement detecting device including a document table and a plate, the document table transmitting light, and the plate being openable and closable relative to the document table and covering the document table in a closed state of the plate,

• the method comprising:
• irradiating a placement area with invisible light via the document table, the placement area being an area of the document table on which the document is placed;
• receiving reflected light from the document with an imaging device;
• outputting read data from the imaging device;
• and
• with a change in a read value of the read data output from the imaging device based on the irradiation with the invisible light, detecting the placement of the document.