An optical scanning apparatus includes a deflector configured to deflect a light beam from a light source and scan a surface to be scanned in a main-scanning direction and a single imaging optical element configured to guide the light beam deflected by the deflector to the surface to be scanned. Scanning speeds of the light beam on the surface to be scanned at an on-axis image height and at an off-axis image height are different from each other, and conditions
0.0<(R1.sub.h/2+R2.sub.h/2)/(R1.sub.h/2R2.sub.h/2)<1.7 and
0.8<h/TC<2.0
are satisfied.

A printer is configured to print on a print medium having a thermal color developing layer and includes: a thermal head having a plurality of heating elements that are arranged in a line; and a processor configured to: set a first application period of a pulse of energizing current, during a scanning line time for one line, the pulse of energizing current applying thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements, correct a length of the first application period, which is set by the processor, based on an image to be printed, and determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the processor.

A printer is configured to print on a print medium having a thermal color developing layer and includes: a thermal head having a plurality of heating elements that are arranged in a line; and a processor configured to: set a first application period of a pulse of energizing current, during a scanning line time for one line, the pulse of energizing current applying thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements, correct a length of the first application period, which is set by the processor, based on an image to be printed, and determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the processor.

A drive signal generator of an inkjet printer includes a first electronic component that generates a greater amount of heat than a second electronic component. A heat sink includes wall members and first and second ends. The wall members include first and second wall members having an outer wall. The heat sink has a tubular shape defined by the wall members and is open at the first and second ends. A portion of a cooling fan faces the first end of the heat sink, and another portion of the cooling fan protrudes at least from the first end toward the first wall member. The first electronic component is in contact with the outer wall of the first wall member, and the second electronic component is in contact with the outer wall of the second wall member.

A printer includes: a printing head including a plurality of resistors; a controller configured to drive the printing head by dividing the printing head into at least two areas; and an assisting circuit that assists power supply, wherein the controller controls to overlap time periods for driving two different areas, and the assisting circuit supplies an electric current to the printing head together with an electric current supplied from the power source during the overlapping period.

A control method for printer, the control method includes: controlling a first group of heating units of a printing head to output first printing energy to form printing dots with a first density on a printing medium; and controlling a second group of heating units of the printing head to continue outputting second printing energy to form printing dots with a second density on the printing medium, wherein the second group of heating units consists of heating units need to implement printing energy compensation in the first group of heating units. By means of the control method, the printing densities of the printing dots corresponding to the heating units need to implement printing energy compensation are improved, and the problem of non-uniform printing density of each printing dot caused by non-uniform pressure exerted on the printing platen by the printing head can be effectively solved.

A control method for printer, the control method includes: controlling a first group of heating units of a printing head to output first printing energy to form printing dots with a first density on a printing medium; and controlling a second group of heating units of the printing head to continue outputting second printing energy to form printing dots with a second density on the printing medium, wherein the second group of heating units consists of heating units need to implement printing energy compensation in the first group of heating units. By means of the control method, the printing densities of the printing dots corresponding to the heating units need to implement printing energy compensation are improved, and the problem of non-uniform printing density of each printing dot caused by non-uniform pressure exerted on the printing platen by the printing head can be effectively solved.

A printer is configured to print on a print medium having a thermal color developing layer and includes: a thermal head having a plurality of heating elements that are arranged in a line; and a processor configured to: set a first application period of a pulse of energizing current, during a scanning line time for one line, the pulse of energizing current applying thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements, correct a length of the first application period, which is set by the processor, based on an image to be printed, and determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the processor.

A printer is configured to print on a print medium having a thermal color developing layer and includes: a thermal head having a plurality of heating elements that are arranged in a line; and a processor configured to: set a first application period of a pulse of energizing current, during a scanning line time for one line, the pulse of energizing current applying thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements, correct a length of the first application period, which is set by the processor, based on an image to be printed, and determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the processor.