Optical character generator for an electrographic printer or copier device

• US 6,097,419 A
• Filed: 11/24/1997
• Issued: 08/01/2000
• Est. Priority Date: 05/22/1995
• Status: Expired due to Term

• Current Assignee: Oce Printing Systems GmbH (Canon Inc.), Hennessy Technology Corporation
• Original Assignee: Oce Printing Systems GmbH (Canon Inc.)
• Inventors: Morris, Edward, Jorgens, Klaus-Dieter, Klapettek, Gerhard, Faust, Martin, Pachonik, Klaus, Eichstetter, Josef, Low, Alfons
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Pham, Hai C.
• Application Number:
  US08/952,916
• Time in Patent Office: 981 Days
• Field of Search: 347/117, 347/118, 347/119, 347/130, 347/237, 347/238, 347/247
• US Class Current: 347/237
• CPC Class Codes: B41J 2/45 using light-emitting diode [LED] or laser arrays
• CPC Class Codes: G06K 15/1247 using an array of light sources, e.g. a linear array
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

A printer or copier has an optical character generator for reproducing raster image data in grey-scale displays. Integrated light sources in the form of LEDs arranged in arrays are aligned to form a print line. A control IC is provided for each LED array. Groups of the control ICs are formed in which information is shifted for the switch on time of all LEDs of a group starting with the first control IC to the next IC. The ICs are connected together by bonding. A ramp circuit is provided to prevent current surges when the LEDs are switched on. A flat unit that extends along the character generator is used to transmit information and power to the control ICs. Busbars ensure that power is provided to the LEDs.

Claims

1. An optical character generator for an electrographic printer or copier device, comprising

a plurality of controllable light sources arranged in at least one row, said plurality of controllable light sources being divided into even-numbered and into odd-numbered groups;

a plurality of groups of control means for controlling said plurality of controllable light sources;

a character generator control connected to said plurality of groups of control means to supply in parallel data comprising a plurality of bits and corresponding to illumination stages of individual ones of said controllable light sources;

said plurality of groups of control means being provided for both the even-numbered groups of light sources and the odd-numbered groups of light sources,

individual ones of said control means being arranged successively within the groups of control means,

an electrical bond connection directly coupled from an output to an input of successively arranged ones of said control means, and

a data input connected only to an input of a first successively arranged one of said control means, said control means at said data input including;

a parallel shift register arrangement whose bit width corresponds to a bit width of the input data,

an intermediate memory connected to said parallel shift register arrangement to receive the data in parallel;

a carrier on which said plurality of controllable light sources and said control means are arranged; and

conductors directly electrically coupling said plurality of controllable light sources and said control means to one another.

2. An optical character generator according to claim 1, wherein said control means;

sets an average energy supply for all of said plurality of controllable light sources of a group, and

enables an individual control of on time of each of said plurality of controllable light sources of a group.

3. An optical character generator according to claim 2, further comprising:

an integrated circuit in which said control means is integrated, said control means including

a data memory being a shift register into which data for individual control of on time of each of said controllable light sources is serially written;

an intermediate memory into which the data of the data memory is written in parallel;

switch means that switch an energy supply of individual ones of said controllable light sources dependent on respective data available in the intermediate memory; and

wherein said function of setting an average energy supply is performed by means for setting an average energy supply that is coupled to a further intermediate memory serving as a correction value memory.

4. An optical character generator according to claim 3, wherein said means for setting an average energy supply includes

a digital-to-analog converter connected to receive a predetermined reference voltage, said digital-to-analog converter deriving a control voltage from said predetermined reference voltage dependent on a correction value obtained from said correction value memory,

an external resistor connected to said integrated circuit to convert the control voltage into a control current.

5. An optical character generator according to claim 4, wherein said data memory is a shift register that includes an expanded memory location for the correction value for the digital-to-analog converter.

6. An optical character generator according to claim 3, further comprising:

a succession of said integrated circuits, such that an output of a respective one of said shift registers is directly electrically coupled by bonding to an input of a successively arranged one of said shift registers, and data are externally supplied only to the shift register of a first of said integrated circuits.

7. An optical character generator according to claim 3, wherein said data memory includes a plurality of clock-controlled individual memories forming respective groups of successively connected individual memories at least said successively connected individual memories arranged at an input side and an output side changing their status isochronically and said successively connected individual memories respectively lying farther toward an inside then changing their status.

8. An optical character generator according to claim 3, wherein said switch means includes a switchable circuit element parallel to said controllable light sources so that energy supply to said character generator ensues independently of activation of said controllable light sources.

9. An optical character generator according to claim 8, wherein said switchable circuit element includes a shunt transistor for each of said controllable light sources, neighboring ones of said shunt transistors being switched offset in time relative to one another.

10. An optical character generator according to claim 2, wherein said control means controls the average energy supply dependent on predetermined boundary conditions.

11. An optical character generator according to claim 2, wherein said control means controls individual on time of each of said controllable light source dependent on a specific luminous intensity of said controllable light sources and on a gray scale information reproduced with said controllable light source.

12. An optical character generator according to claim 1, wherein said plurality of controllable light sources are light-emitting diodes, said light-emitting diodes (LED) being combined in groups as respective LED arrays, said light-emitting diodes being arranged in a row on a rectangular semiconductor chip such that an LED line is formed of a plurality of LED arrays adjoining one another.

13. An optical character generator according to claim 12, wherein said LED arrays include sub-groups formed by even-numbered and odd-numbered light-emitting diodes, and ones of said control means being allocated to each of said sub-groups.

14. An optical character generator according to claim 1 further comprising:

a distributor flat module arranged on said carrier and coupling said character generator control to said control means.

15. An optical character generator according to claim 14, further comprising:

busbars formed as inner layers of said distributor flat module to deliver current directly to said integrated circuit.

16. An optical character generator according to claim 14, further comprising:

a busbar on said carrier serving as a ground line for a ground connection to said controllable light sources.

17. An optical character generator according to claim 16, wherein said busbar is angled off L-shaped in a direction of its longitudinal extent, and said distributor flat module is glued onto the busbar.

18. An optical character generator according to claim 17, wherein said busbar defines at least one recess including a thread,

said carrier defining an opening,

a screw guided through said opening of said carrier and screwed into said at least one recess in said busbar.

19. An optical character generator as claimed in claim 1, wherein said optical character generator includes at least two character generators connected to one another module-like.

20. A method for operating an optical character generator for an electrographic printer or copier device, comprising the steps of:

providing a plurality of controllable light sources arranged in a least one row;

controlling said plurality of controllable light sources with a switch for each of said controllable light;

driving a driver stage of the switch at least one of before activation and after deactivation of said controllable light sources such that a flow of current through a switchable component connected parallel to said controllable light sources is temporarily generated at an output of said driver stage so that energy supply to the character generator temporarily ensues independent of activation of said controllable light sources;

generating the flow of current at an output of the driver stage through the parallel connected component, the flow of current rising relatively slowly up to a predetermined amount; and

activating one of said controllable light sources by shutting off the parallel connected component so that the flow of current through the controllable light source assumes the predetermined amount relatively quickly for activating the light sources.

21. A method according to claim 20, further comprising the step of:

controlling the flow of current.

22. A method according to claim 21, wherein said controlling step ensues via a control voltage from said driver stage that has a ramp curve.

23. A method according to claim 22, further comprising the step of:

applying the control voltage to an input of the operational amplifier.

24. A method according to claim 21, further comprising the step of:

varying the flow of current slowly.

25. A method according to claim 20, further comprising the steps of:

for deactivating the controllable light sources, turning on the parallel connected component at the output of the driver stage so that the current previously flowing through the light source flows through the component after a relatively short time; and

subsequently dropping the current flowing through the component slowly with a predetermined characteristic.

26. A method according to claim 20, further comprising the steps of:

allocating a parallel component to each light source; and

switching neighboring parallel components with time offset relative to one another.

27. A method according to claim 20, further comprising the steps of:

providing an operational amplifier as the driver stage whose output is connected to a control output of a first transistor for switching; and

conductively connecting a second transistor to the first transistor as the parallel connected component.