JPS559862A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a useful thermal head to be used for a thermal printing and recording device, which is so designed that even if a selection line or a data line were open due to improper connection, a corresponding heat-generating body does not generate heat so that extreme shortening of service life can be prevented. CONSTITUTION:As shown in S1, a voltage pulse is impressed onto S1 for a length of time t o at a voltage sufficient to enable a heat-generating resistance 11 to generate heat toward a heat-generating driving source 15, and a voltage pulse is impressed on a selection line 13a as shown in S2 to maintain selection lines 13b and 13c at a high level. Current is sent over from a terminal 24 through a resistance 23 to a thyrister's gate, S2 voltage pulse is selectively impressed onto a data line 14 during a time t1 required for making the thyrister to become in a conductive condition, the data line which is not to be selected is kept at a high level, a thyrister on a driving circuit 12 becomes in a conductive condition selectively, and a large current is sent over to the resistance to make it start generating heat. A voltage pulse, as shown in S3, is impressed onto the selection line 13b and the data line 14, and impressions onto others are also carried out one after another in the similar manner.