This invention is directed to a printer with type-bearing printing bands, each of which is positively guided around a selector wheel and around a counter-pressure element spaced apart from the wheel. Selected print types are set into printing position on the counter-pressure element by rotation of the selector wheel. The selector wheel has engagement recesses into which a stop member elastically engages when a printing position is reached, thereby fixing the selector wheel, and hence the printing band, in the printing position.
The exact positioning of the print types represents a major problem in the functioning capability of hand-labeling devices, such as those described in EP 187 986 and DE 198 48 977. Various proposals for securely positioning the types are known from the prior art.
For example, DE 26 21 294 describes a printer head with a transport wheel and a support means, about which a band of types is stretched. The printing block, designed as a tape, has projections on its back that engage with a groove formed in the support. The types are positioned by means of this engagement.
DE 30 34 923 shows a band printer in which the bands of type are each stretched around a selector wheel and a star wheel. The star wheels, each designed as a square, are held in position by an elastic tongue arranged on a base part. One single elastic tongue is assigned to each star wheel. The elastic tongues, which are arranged on the star wheel at a specific angle to the print surface, exert spring action in a lateral and upward direction when the type tape is moved. Thus, each star wheel according to DE 30 34 923 is individually spring-biased for the positioning of a specific type. This cannot ensure that the types involved in the printing process and arranged at a distance from the switching system are held precisely in one line. This detracts from the appearance of the print.
A hand printing device with a plurality of selector wheels and a type locator is known from EP 0 628 420. The bands of type are stretched about the selector wheels and the type locator. A click component is pressed into the tooth gaps of the selector wheel via an elastic pre-stressing component to prevent an unnecessary turning of the selector wheels. According to EP 0 628 420, all selector wheels are acted upon simultaneously in that the click component is pressed into a tooth gap of each respective selector wheel. As a result, if one single selector wheel is moved, the click component frequently escapes from all of the tooth gaps. Therefore, it is not possible to guarantee that the remaining selector wheels stay in a fixed position.