Cryptographic printhead

• US 10,373,032 B2
• Filed: 08/01/2017
• Issued: 08/06/2019
• Est. Priority Date: 08/01/2017
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Datamax-O'Neil Corporation (Honeywell International Inc.)
• Inventors: d'Armancourt, Sebastien Michel Marie Joseph
• Primary Examiner(s): Ameh, Yaovi M
• Application Number:
  US15/665,705
• Publication Number:
  US 20190042901A1
• Time in Patent Office: 735 Days
• CPC Class Codes: B41J 2/355 Control circuits for heating-element selection
• CPC Class Codes: B41J 2/362 Correcting density variation
• CPC Class Codes: G06K 15/028 by thermal printers
• CPC Class Codes: G06K 15/4095 Secure printing computer driven secure printing G06F3/1238
• CPC Class Codes: H04N 1/32272 Encryption or ciphering
• CPC Class Codes: H04N 2201/3281 Encryption; Ciphering

Abstract

A printer is configured with a processor which calculates printhead control parameters, the control parameters being determined by the processor in such a way as to optimize the printing process of the printer'"'"'s printhead. The processor determines the printhead control parameters according to an optimization algorithm stored in the printer. To maintain the internal security of the optimization algorithm, the printhead control parameters are encrypted by the processor. The encrypted printhead control parameters are then transmitted to the printhead via an internal data path of the printer. If a third party monitors the data along the internal data path, the encryption algorithm remains secure because the control parameters are encrypted. The printhead contains a second, dedicated processor. The printhead processor receives the encrypted printhead control parameters, and decrypts the control parameters. The printhead then prints according to the decrypted printhead control parameters, ensuring optimized printing.

Claims

1. A method for printing process control within a printer, comprising:

determining, via a hardware processor of the printer, a printhead control signal (PCS) to regulate a print process of a printhead of the printer, said PCS comprising printhead control parameters to maintain a designated acceptable level of print quality by the printhead;

encrypting, via the hardware microprocessor, the PCS;

transmitting from the hardware microprocessor to the printhead the encrypted PCS;

decrypting at the printhead the received encrypted PCS to obtain the unencrypted PCS; and

regulating the print process of the printhead according to the PCS.

2. The method of claim 1, further comprising:

transmitting print data from the hardware processor to the printhead along a first hardware data path; and

transmitting the encrypted PCS from the hardware processor to the printhead along a second hardware data path which is isolated from the first hardware data path.

3. The method of claim 1, further comprising decrypting at the printhead the received encrypted PCS via at least one of a general purpose hardware processor of the printhead and a dedicated hardware decryption processor of the printhead.

4. The method of claim 1, wherein the encryption and decryption of the PCS comprises encrypting and decrypting the PCS according to an asymmetric encryption/decryption algorithm.

5. The method of claim 1, wherein the PCS comprises data to determine, for a contrast-inducing element to be applied by the printhead to a print media of the printer, at least one of:

a quantity of the contrast-inducing element to be applied along a line of the print output;

an intensity of the contrast-inducing element to be applied along the line of the print output; and

a time duration of application of the contrast-inducing element along the line of the print output.

6. The method of claim 5, wherein:

the line printed on the print media comprises a plurality of segments, wherein;

each segment of the plurality substantially overprints, on the print media, the other segments of the plurality; and

each segment of the plurality is generated in series in time, each segment being generated at least one of prior to or subsequent to any other segment of the plurality; and

the PCS comprises data to determine a respective quantity of the contrast-inducing element, a respective intensity of the contrast-inducing element, or a respective time duration of the contrast-inducing element for each respective segment of the plurality of substantially overprinted segments.

7. The method of claim 5, wherein:

the line is printed via a plurality of overprinted, time-consecutive print operations on the print media by the printhead, and;

the PCS comprises data to determine a respective quantity of the image-inducing element, a respective density of the image-inducing element, or a respective time-duration of the image-inducing element for each respective overprint operation of the plurality.

8. The method of claim 1, wherein decrypting at the printhead the received encrypted PCS to obtain the unencrypted PCS comprises using a decryption key to recover the printhead control parameters.

9. The method of claim 1, wherein the encrypting and decrypting occur internally within the printer.

10. A printer, comprising:

a first hardware processor;

a printhead comprising;

a contrast-generating element for printing an image on a print media; and

a second hardware processor configured for data decryption;

wherein;

said first hardware processor is configured to;

determine a printhead control signal (PCS) to regulate a print process of the printhead, said PCS comprising printhead control parameters to maintain a designated acceptable level of print quality by the printhead; and

encrypt the PCS; and

said second hardware processor is configured to

decrypt the received encrypted PCS to obtain the unencrypted PCS, wherein the print process of the printhead is regulated according to the PCS.

11. The printer of claim 10, wherein said printhead further comprises:

a data connection internal to the printhead between the contrast-generating element and the second hardware processor, wherein said connection is configured and arranged so as to physically secure the printhead from external monitoring of data signals internal to the printhead.

12. The printer of claim 11, wherein said printhead comprises a casing which substantially shields the contrast generating element, the second hardware processor, and the internal data connection from external signal monitoring.

13. The printer of claim 10, further comprising:

a first hardware data path configured to transmit print data from the first hardware processor to the printhead; and

a second hardware data path which is data-isolated from the first hardware data path, and is configured to transmit the encrypted PCS from the first hardware processor to the printhead.

14. The printer of claim 10, wherein:

said printhead comprises a thermal printhead which applies heat to a heat-sensitive print media of the printer; and

said processor is configured to generate a PCS to regulate an application of heat by the thermal printhead to the heat-sensitive media.

15. The printer of claim 14, wherein:

the thermal printhead is configured to print a raster line on the print media, the line being printed via a plurality of overprinted, time-consecutive heat applications on the print media by the thermal printhead, and

the processor is configured to generate a PCS comprising timing data to determine a respective on/off time-segment duration for heat generation for each respective overprint operation of the plurality.

16. The printer of claim 10, wherein decryption of the received encrypted PCS to obtain the unencrypted PCS recovers the printhead control parameters.

17. The printer of claim 10, wherein encryption and decryption occur internally within the print.