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The invention relates to an identification device, in particular a code reader, to detect incoming and / or two-dimensional codes with a housing arranged in a spatially resolving light receiver and this also associated in the housing built-receiving optical system.

In the identification devices known from the prior art of the receiving optical system, an image of an actual object in the level code designed in the image plane. In this image plane is the spatially resolving light receiver in which a plurality of light receiving pixels are arranged in rows or a matrix.

The present in the Code and, consequently, in the image of the code different contrasts generate in the individual light receiver pixels different photocurrents from which is then identified by means of a signal processing of the code content.

Such codes are used in diverse applications, such as for the identification and control of individual objects in conveyor technology. Here, the code is not limited to determine code type, but includes all, with an image processing device recognizable variants of information carriers. From powerful identification devices is expected today that ever larger amounts of information can be read on the smallest possible code areas. This means that a high spatial resolution is required by the identification device. In particular, if the code additionally located within a large depth of field range of the identifying means high requirements. Another requirement for powerful identification devices is the high read rate, which makes high-intensity receiving optics required. These two conditions, ie large depth of field and simultaneously bright reception optics require that the identification device must be equipped with an automatic focusing system.

In the known identification devices with automatic focusing system, the focusing is effected either in that the entire receiving optical system or possibly only assemblies or individual components thereof are moved in the optical axis direction, while the spatially resolving light receiver is stationary positioned. Typically the mounted in a threaded socket optics to moved by rotation by means of a servomotor. are for bright langbrennweitigen receiving lenses, due to the relatively large mass of the moving components thereby, the limits specified. Also because of the mechanical stress in the bearings and the continuous use over a long period of time, such systems provide since no solution. Moreover, this focusing process usually requires a lot of time and is therefore unable to respond to rapidly changing code distances.

In the second group of well-known identification devices with automatic focusing system, the focusing is achieved in that the receiving optical system is stationary, while the spatially resolving light receiver is possibly adjustably mounted in the optical axis direction together with its underlying circuit board incl. Other electronic components. Such a device is known for example from US 5,245,172. In addition to occurring during this auto focusing operation of the light receiver mechanical load incl. Another electrically he is components additionally necessary that a multi-wire electrical connection is continuously exposed to a movement. Since this focus over the life of an identification device considered in the range of 10⁷ until 10⁹ can be cycles, interruptions in the electrical connection or damage to the mechanically stressed components can not be excluded.

From WO 93/14470 a portable optical code reader system is known, wherein the optical path that is the effective distance between the receiving optics and the spatially resolving light receiver for the purpose of focusing is changed. This is achieved according to WO 93/14470 in that the beam path between the optical receiving system and the spatially resolving light receiver is Z-folded. An optical element in this folding of the beam path is a planner deflecting mirror which is mounted on the coupling of a four-bar linkage.

It is advantageous if a generic device having an automatic focusing system which is optimal for identification to be able to quickly and non-wearing suit over a longer period to different object distances.

It is advantageous that the entire receiving optical system and the spatially resolving light receiver are firmly and immovably arranged in the housing of the identification device and the effective optical back focal distance can be changed only by an arranged between the light receiver and the receiver optics adjustable deflection mirror.

The advantage of this design of the focusing can be seen in the fact that only a simple deflection mirror is adjusted to the electrical connections are present and furthermore only has a low mass. The reception lens, the light receiver and all electrical connections are arranged in precise optical alignment invariably in housing. Such an identification device is thus able to focus with very little energy relatively fast and wear-free for a longer period on codes that are located at different distances from the identification device.

The deflection mirror is connected to a swivel arm, which is mounted movably about an axis of rotation. By rotation of the pivot arm and thus of the deflection mirror about the rotation axis, which is aligned perpendicular to the optical axis of the receiving optical system, extended, or the effective optical back focal distance between the receiving optics and the spatially resolving light receiver shortened.

According to the invention the mechanical coupling for the adjustment of the deflection mirror with the housing of the identification device only from a flexible spring band. The inventive device is superior to the slide or cam guides of the prior art both economically and technically. This advantage applies in particular to the change of the deflection mirror on the pivot arm. Especially when it comes to a crossed spring strip arrangement, a very well defined, play-free pivot function is given for this purpose, which ensures a stable, wear-free rotation even over extended periods.

Advantageously, the position of the rotational axis and the length of the swing arm are so matched to the optical data of the optical receiving system, in addition to this image length change at the same time, the deflection angle is changed so that the center of the image on the light receiver does not or only insignificantly changed. It is provided that the image does not shift the center by focusing on the light receiver in focusing on the deflection mirror. Maintaining these correspondences between image center and the position-sensitive light detector within the focusing range offers the advantage that thus does not change the direction of the viewing area. The identification means is thus able, in addition to the identification of the code content to determine a statement about the current position of the code for Emp-fang axle.

Advantageously, it is provided that means only a mechanical manipulated variable a spatial and angular adjustment of the deflection mirror is feasible simultaneously. This means that the necessary expenses for focusing is space-saving and inexpensive to produce.

Depending on the required Fokussierparametern, ie, the focusing speed, the repetition, as well as the focusing area are both linear and circular actuators usable. This enables the optimal actuator, comprising eg magnetic voice coil, pneumatic / hydraulic cylinder, etc. are to be able to use.

The invention is exemplified below with reference to the figures; in which:<dl id="dl0001"><dt><b>Fig. 1</b></dt><dd>a schematic side view of an identification device having a focusing device by displacement of a deflecting mirror via a pivot arm at a focus on an average intercept distance object,</dd><dt><b>FIG. 2</b></dt><dd>a schematic side view, corresponding to FIG. 1, at a focus on the object maximum sectional width</dd><dt><b>Fig. 3</b></dt><dd>a schematic side view of an identification device having a focusing device by displacement of a deflecting mirror via a four-bar linkage.</dd></dl>

In Fig. 1, the identification device is exemplified as a code reader 1. The code reader 1 has a housing 2 in a spatially resolving light receiver 3. This spatially resolving light receiver 3 may be formed in the detection a one-dimensional code, for example, as a CCD line or CMOS line. When using the code reader for the detection of two-dimensional information of the spatially resolving light receiver 3 is then, for example, a CCD area, or a CMOS area. Also in housing 2 an optical receiving system 4 is installed, the designs an image of an object 5 on the surface 6 of the spatially resolving light receiver 3rd Depending on the condition and use of the particular task of the code reader then the object is illuminated by a lighting device, not shown in FIG. 1. This illumination device, which is equipped with one or more light sources, can be either integrated into the code reader 1 is or as a separate external unit executed.

Located, as shown in FIG. 1, the object 5 in an object distance s₀ from the code reader, then the image of the object in an image distance s₀'(S₀'= S1₀'+ S2₀') Designed. The size of the image distance s' is essentially determined by the object distance s and the focal length of the optical receiving system. 4 The course of the light between the optical receiving system 4 and the spatially resolving light receiver 3 is deflected by a planar reflection mirror 7 by about 90 °. The image distance s' is characterized into two sections s1 '' split and s2. The surface of the deflection mirror 7 is perpendicular mounted on a swivel arm. 8 Mechanically connected to the housing 2, the swivel arm 8 about an axis of rotation 9, which is perpendicular to the optical axis 10 of the receiving optics. Via a movable connecting rod 11, a linear actuator 12 is connected to the pivot arm eighth The actuator 12 is thus able to pivot arm 8 and thus the reflection mirror 7 to pivot around the rotational axis. 9 In addition to the actuator 12 symbolically shown in Figure 1 also actuators for movement of the pivot arm are possible. Thus it can be arranged for example at the axis of rotation 9, a circular actuator in the form of a stepping motor. In principle, magnetic voice coil, pneumatic / hydraulic cylinder, etc. are also possible for the movement of the pivot arm.

In FIG. 2, the object focal distance has s relative to the state shown in FIG. 1 is increased, that is the code is further from the code reader. As a result, the back focal distance is s' = S 1 '+ S 2' is less. So on the surface 6 of the spatially resolving light receiver 3 an exact copy exists, the swing arm 8 and thus the deflection mirror 7 is moved so far towards the receiving optics 4, until the object distance s coordinated image distance s' = s1 '+ s2' reached is.

Analogously to FIG. 2 is s from the state of the arm 8 and thus also the deflection mirror 7 shown in Fig. 1 as far away at a shortening of the object focal distance of the receiving optics 4, until the now enlarged image distance s' = S 1 '+ S 2' is reached.

In Fig. 3 the reflection mirror 7 is mounted on a coupling 13 of a four-bar linkage. The four-bar linkage is in addition to the coupling 13 of two arms 14 and 15. The link 14 is connected on one side to a fixed in the housing 2 pivot 16th The other end of the link 14 is connected by means of a non-fixed pivot bearing 17 with the coupling. 13 The link 15 connects the second side of the coupling 13 on a bearing 18 fixed in the housing with a second pivot bearing 19. The axes of all four pivot bearings 16, 17, 18 and 19 are perpendicular to the optical axis 10 of the receiving optics aligned. If the link 14 pivots α in the rotary bearing 16 by a defined angular amount, so the link 15 rotates due to the connection via the coupling 13 by an angle β. The sequence of movements of the coupling 13 and thus also the spatial and angular change of the deflection mirror 7 for the optical axis 10 of the receiving optical system is therefore determined by the geometry of the four-bar linkage. The key parameters are the length of the coupling 13, the lengths of the links 14 and 15 and the distance a of the two fixed in the housing pivot bearing 16 and 19th The issues identified in the description of FIG. 1 ways to Einkoppelegung the manipulated variable for the location and change in position of the deflection mirror 7 can be carried out also in the solution with a four-bar linkage. For example, a linear actuator engaging one of the two links 14 or 15 or a circular actuator can be coupled to one of the two fixed pivot bearing 16 or 19th

Since the measures necessary to adjust the deflection mirror 7 angle changes both to the one described in Fig. 1 and 2 solution with an arm, and in the solution by means of a four-bar linkage are relatively few in the pivot bearings, each pivot bearing can also through mechanical connections in the form a hinge to run. Such hinge function can be produced according to the invention very inexpensive with a flat, flexible spring band. Namely, one end of the spring strip is firmly clamped at a fixed point in the housing, while at the other free end, for example, the swing arm 8 or the arm 14 or 15 is fixed. Such hinges meet especially at small angles of rotation, a very good, backlash-free rotation function that ensures a stable, wear-free rotation even over extended periods.