Abstract: A cooling fan control device for regulating the speed of a fan cooling a printing device. The control includes apparatus for determining whether a printing head and a paper feeder are to be driven, and when at least one of the printing head or paper feeder is to be driven, the cooling fan is driven at a high speed, while when neither the printing head nor the paper feeder is to be driven, the cooling fan is driven at a low speed. In a further aspect, the printing device sequentially adds the number of dots printed to a value previously stored in a memory and a subtracting device subtracts a predetermined value from the dot number newly stored in the memory every predetermined time.

Abstract: A serial printer adapted to print on a recording medium consisting of a plurality of paper sheets stacked on each other and temporarily bound with temporary binding or fastening portions provided along opposite side edges of the medium. The printer has a first memory for storing the rightmost character position of a current line, and a second memory for storing the position of the rightmost character of all the characters of previous lines printed in a rightward direction, or the position of the rightmost character of all the characters of all previously printed lines. When the rightmost character of the current line is located to the left of the rightmost character whose position is stored in the second memory, the medium is advanced to the next line.

Abstract: A dot-matrix printer with a print head having plural print elements which are disposed in a row and selectively activated to form a dot or dots in a vertical row of a dot matrix pattern representing a character, comprising: a device for calculating a dot ratio which is a ratio of the number of dots to be formed in a ratio-check area consisting of a predetermined number of vertical rows of dots in a print line, with respect to the maximum number of dots formable in the ratio-check area; a device for moving the ratio-check area along the print line; a device for checking if the dot ratio has exceeded a reference value; and a control device for printing the characters in the print line in plural movements of the print head if the print line includes the ratio-check area the dot ratio of which has exceeded the reference value.