Electronic hand stamp

Abstract

The electronic hand stamp (1) includes an inkjet printhead with nozzles directed toward a bottom side (4) of the electronic hand stamp (1), a control circuit (30) and a motion detector. The control circuit (30) is connected to the motion detector and to the inkjet printhead and configured to control the inkjet printhead in response to readings received from the motion detector. The electronic hand stamp (1) includes at least four indicator LEDs (10-17) connected to the control circuit (30). At least one of the at least four indicator LEDs (10-17) is arranged on every side perpendicular to the bottom side (4) of the electronic hand stamp (1).

Claims

1. An electronic hand stamp comprising: a bottom side; an inkjet printhead with nozzles directed toward the bottom side; a control circuit; a motion detector, wherein the control circuit is connected to the motion detector and to the inkjet printhead and configured to control the inkjet printhead in response to readings received from the motion detector; at least four indicator LEDs connected to the control circuit, wherein the at least four indicator LEDs indicate an operating status of the electronic hand stamp, and wherein at least one of the at least four indicator LEDs is arranged on each of four sides of the electronic hand stamp perpendicular and adjacent to the bottom side; and a diffuser and all of the at least four indicator LEDs are optically connected with the diffuser; wherein the control circuit is configured to control interdependently the at least four indicator LEDs to together indicate one or more same signals concerning the operating status of the electronic hand stamp.

2. The electronic hand stamp according to claim 1, wherein the electronic hand stamp comprises at least six indicator LEDs connected to the control circuit.

3. The electronic hand stamp according to claim 2, wherein the electronic hand stamp comprises at least eight indicator LEDs connected to the control circuit.

4. The electronic hand stamp according to claim 1, wherein the indicator LEDs are multicolor LEDs, wherein the control circuit is configured to control the indicator LEDs to glow in the same color.

5. The electronic hand stamp according to claim 4, wherein the control circuit is configured to control the indicator LEDs to glow in the same color either simultaneously or time-delayed.

6. The electronic hand stamp according to claim 1, wherein the distance between the indicator LEDs is small enough that brightness of LED light through the diffuser is substantially homogeneous.

7. The electronic hand stamp according to claim 1, wherein the diffuser circumferentially surrounds the electronic hand stamp.

8. The electronic hand stamp according to claim 1, wherein the at least four indicator LEDs are arranged on two or more printed circuit boards.

9. The electronic hand stamp according to claim 1, wherein the electronic hand stamp comprises at least one target LED for illuminating a print area adjacent the printhead, wherein the at least one target LED is connected to the control circuit.

10. The electronic hand stamp according to claim 9, wherein the electronic hand stamp comprises at least two target LEDs for illuminating a print area adjacent the printhead, wherein the at least two target LEDs are connected to the control circuit.

11. The electronic hand stamp according to claim 10, wherein the control circuit is configured to switch on at least one target LED on one of the sides of the printhead.

12. The electronic hand stamp according to claim 11, wherein the control circuit is configured to switch on at least one target LED on a side of the printhead corresponding to a direction in which the printhead is being moved.

13. A method for controlling the electronic hand stamp according to claim 11, comprising switching on at least one target LED on one of the sides of the printhead when a direction of movement of the electronic hand stamp is detected, and switching off the other target LEDs.

14. The method for controlling an electronic hand stamp according to claim 13, comprising switching on at least one target LED on the side of the printhead corresponding to the direction in which the printhead is being moved when a direction of movement of the electronic hand stamp is detected, and switching off the other target LEDs.

15. The electronic hand stamp according to claim 9, wherein the at least one target LED is optically connected to a prism for deflecting light emitted by the at least one target LED to the print area.

16. A method for controlling the electronic hand stamp according to claim 1, comprising controlling the at least four indicator LEDs in an interdependent fashion and to glow in a time-delayed fashion and in order of circumferential arrangement to indicate an ongoing operation.

17. The method according to claim 16, comprising controlling the at least four indicator LEDs to glow in a time-delayed fashion and in the order of circumferential arrangement for at least one turn to indicate an ongoing operation.

18. An electronic hand stamp comprising: a bottom side; an inkjet printhead with nozzles directed toward the bottom side; a control circuit; a motion detector, wherein the control circuit is connected to the motion detector and to the inkjet printhead and configured to control the inkjet printhead in response to readings received from the motion detector; at least four indicator LEDs connected to the control circuit, wherein at least one of the at least four indicator LEDs is arranged on each of four sides of the electronic hand stamp perpendicular and adjacent to the bottom side; and a diffuser optically connected with all of the at least four indicator LEDs; wherein the at least four indicator LEDs are arranged on two or more printed circuit boards.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Referring now to the drawings, wherein the figures are for purposes of illustrating the present invention and not for purposes of limiting the same,

(2) FIG. 1 schematically shows a figurative view of an electronic hand stamp according to the present invention,

(3) FIG. 2 schematically shows a partial figurative view of the electronic hand stamp according to FIG. 1 in an opened configuration,

(4) FIG. 3 schematically shows a horizontal cut of the electronic hand stamp according to FIGS. 1 and 2, and

(5) FIG. 4 shows a bottom view of the electronic hand stamp according to the previous figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(6) FIG. 1 shows an electronic hand stamp 1 having a generally opaque cover 2 with a windowed portion 3 and a bottom side 4. The windowed portion 3 is made of a transparent material. In the operating position shown in FIG. 1, the electronic hand stamp 1 is positioned with its bottom side 4 flat on a plane substrate 5. In this position, an inkjet printhead (not shown) has its nozzles directed toward the bottom side 4 and the substrate 5 in order to print thereon. The inkjet printhead is controlled by a control circuit 30 (see FIG. 2) integrated in the electronic hand stamp 1. The control circuit 30 is connected to a motion detector, for example an optical sensor directed at the substrate 5, a gyroscope and/or an accelerometer, and configured to received readings from the motion detector and control the inkjet printhead in response to those readings. Specifically, the control is configured to produce an undistorted print image irrespective of a speed of movement of the electronic hand stamp 1 relative to the substrate 5 or variations in said speed. The windowed portion 3 allows a user to supervise the printing process immediately next to the printhead. Extending from the windowed portion 3 of the cover 2, the electronic hand stamp 1 comprises indicator projections 6 on each side (compare FIG. 3). The indicator projections 6 have a central notch 7 marking the centre of the arrangement of nozzles of the inkjet printhead, i.e. on a line connecting the notches 7 of the two indicator projections 6.

(7) Embedded in the cover 2, the electronic hand stamp 1 comprises a light strip 8 (also “light pipe”). The part of the light strip 8 visible on the outside of the assembled electronic hand stamp 1 is a diffuser 9 that circumferentially surrounds the electronic hand stamp 1. The diffuser 9 comprises a diffusion filter 9′ having a light scattering surface.

(8) FIGS. 2 and 3 show the other components of the light strip 8. As can be seen, the electronic hand stamp 1 comprises eight indicator LEDs 10, 11, 12, 13, 14, 15, 16, 17. Two indicator LEDs 10, 11; 12, 13; 14, 15; 16, 17 are arranged on every side of the electronic hand stamp 1 perpendicular to the bottom side 4. All eight indicator LEDs 10-17 are optically connected with a light guide 18 of the diffuser 9. The light guide 18 comprises four segments 19-22, each connected to one or more of the indicator LEDs 10-17. More specifically, the segments 19-22 of the light guide 18 together define a continuous outer surface 23, on which the diffusion filter 9′ of the diffuser 9 is attached. The diffusion filter 9′ may be for example a scattering foil adhered to the continuous outer surface 23. The segments 19-22 comprise a main portion that is parallel to the continuous outer surface 23 and from which legs 24 extend to each of the connected indicator LEDs 10-17. Each leg 24 at its end facing the respective indicator LED 10-17 has a flat end surface 25 that is perpendicular to the principal direction of light emitted from the respective indicator LED 10-17. This arrangement provides for an efficient coupling of light into the light guide 18.

(9) The distance between the indicator LEDs 10-17 is small enough that the brightness of the LED-light through the diffuser 9 is essentially homogeneous. The homogeneous distribution of light is achieved by total internal reflection in the light guide 18 and partial back scattering from the diffusion filter 9′ into the light guide 18. The scattering of the light can optionally be improved by using a material which contains scattering particles for the light guide 18. However, a homogeneous distribution can also be achieved without scattering, a scattering surface or scattering particles. Hence, it is those two elements and their respective optical properties that define the number of indicator LEDs required to homogeneously illuminate or “supply” a given length of the light strip 8. Another influence is the optical coupling between adjacent segments 19-22 of the light guide 18 parallel to the continuous outer surface 23.

(10) The indicator LEDs 10-17 are arranged on two vertical printed circuit boards (PCBs) 26, 27, one horizontal PCB 28 and one flexible PCB 29 extending from one of the vertical PCBs 27. All indicator LEDs 10-17 are connected to a common control circuit 30 arranged on one or more of the PCBs 26. Accordingly, all PCBs 26-29 are electronically connected, e.g. with a common bus system. The indicator LEDs 12, 13 arranged on the horizontal PCB 28 are right angle LEDs, i.e. having a principal light emission direction parallel to the principal plane of the horizontal PCB 28. All eight indicator LEDs 10-17 are multicolour LEDs. The control circuit 30 is configured to control the indicator LEDs 10-17 in an interdependent fashion, for example to glow in the same colour, in particular either simultaneously or time-delayed.

(11) In addition to the indicator LEDs 10-17, the electronic hand stamp 1 comprises two target LEDs 31, 32, one on each of the vertical PCBs 26, 27. The target LEDs 31, 32 are bright white-light LEDs that are each optically connected to a respective prism 33, 34 for deflecting light emitted by the associated target LED 31, 32 to the print area on the substrate 5 adjacent the printhead, thereby illuminating the print area. The target LEDs 31, 32 are connected to the control circuit 30 of the electronic hand stamp 1. The control circuit 30 is configured to switch on the target LED 31; 32 on the side of the printhead corresponding to the direction in which the printhead is being moved (according to the reading of the motion sensor).

(12) FIG. 4 shows a view from below onto the bottom side 4 of the electronic hand stamp 1. The printhead 36 is positioned essentially centred between the prisms 33, 34 of the target LEDs 31, 32. Motion of the electronic hand stamp 1 is detected with an optical motion detector 35, which is in principle similar to detectors used for optical computer mice. During printing, the electronic hand stamp 1 is moved in one or the other direction along an essentially linear axis of motion 37. A row of inkjet nozzles of the printhead 36 is arranged perpendicular to the axis of motion 37. The rollers 38 guide and help to maintain a straight path of movement during printing, i.e. along the axis of motion 37.