Hot-melt adhesive temperature control method, applicator therefor, and bookbinding apparatus

An adhesive applicator comprising:

• a container for storing hot-melt adhesive;
• heating means disposed on the container, for melting to a predetermined temperature solid adhesive filled in the container;
• sensor means for detecting the temperature of the adhesive in the container;
• temperature control means for controlling the heating temperature of the heating means in response to the temperature detected by the sensor means, the temperature control means being configured to operate in a plurality of heating modes in which the temperature control means controls supplying of power to the heating means at supply levels and supply durations that differ by mode, and being configured to vary the supply of power stepwise, with predetermined mode-dependent delay periods intervening, in each mode in order that the adhesive in the container reach a preestablished temperature;
• and
• application means for applying the adhesive in the container to a body of documents;
• wherein
• the sensor means is configured with a liquid temperature sensor for directly detecting the temperature of the adhesive within the container, and a heating unit temperature sensor for detecting the temperature of a heating unit disposed in the heating means;
• and
• based on the temperature detected by liquid temperature sensor or the heating unit temperature sensor when the applicator is turned on, the temperature control means selects one of the plurality of heating modes, and in the selected heating mode, controls supply of power to the heating means by varying the current level supplied to the heating means in time-dependent stages separated by delay periods, based on the temperature detected by the heating unit temperature sensor, until the adhesive reaches the preestablished temperature.