GB2462837A - Programming Memory Devices for Replaceable Printer Components - Google Patents

Abstract

A process for re-programming a memory device for use in a reusable printer component, for example a printer toner or ink cartridge, comprises connecting the memory device to a processing means, and causing the processing means to select a start address then send a read transaction from the processing means to said address and determine whether a response is received. The steps of sending a read transaction and determining if a response is received are repeated for a pre-determined number of times where no response is received. Next a determination is made as to whether the number of responses received exceeds a predetermined limit and, if it does not the next numerical address in the memory device is selected and the method repeated from the step of sending the read transaction. If a memory address is found it is used to update the data in the memory device.

Description

PROGRAMMING MEMORY DEVICES FOR REPLACEABLE PRINTER

COMPONENTS

Field of the Invention

This invention relates to a process for re-programming a memory device in a re-usable component of a printing device, for example an ink or toner car-tridge for a printer, and to apparatus for use in carrying out the process.

Background to the Invention

Modern electronic printers such as those used with personal computers, photocopiers, and facsimile machines generally have detachable replaceable cartridges in which ink or toner powder is stored, to be dispensed during the printing process. When the ink or toner becomes depleted, the cartridge can readily be removed and replaced.

Many such cartridges now incorporate a memory device which stores various data such as ink/toner levels, manufacturing date, batch number, expiry date and so on. Such memory devices, in concert with the printing device itself, typically keep track of the consumption of ink/toner and give the user a graphi-cal indication, on the printing device or through the attached personal computer, of the amount consumed, as well as warnings that the ink/toner levels are run-ning low. Additionally, most printing devices inhibit attempts to print once the ink/toner is exhausted, since such printing may cause permanent damage to the printing device itself.

Many printers are capable of printing in colour, and will therefore contain a plurality of cartridges, each containing a single colour of ink/toner, or at least a subset of the total number of colours.

Because the memory device is an integral part of the cartridge assembly, electrical connections need to be provided on the cartridge body to connect the memory device to the electronics of the printing device. For reasons of manu-facturing cost and reliability, for example, it is generally desirable to minimise the number of connections, and so many of the memory devices employ a se- rial' data architecture whereby the data are sent back and forth in a serial, time-multiplexed fashion. Such architectures have the further advantage that the data can be addressed', i.e. preceded by an indication of which of the plurality of cartridges in the printing device the particular data are intended for. This al-lows the memory devices to be connected together in a daisy-chain' fashion such that they all simultaneously receive data sent by the printing device con- troller. Since the data are preceded by a unique address, only one of the mem- ory devices recognises this address and reacts to the data. It will be under-stood that the memory devices are of the type having a limited, hard-wired, processing capability permitting the reading of the address associated with in-coming data, comparison of this address with the stored address for the device, and passing of data only if the comparison is positive.

It is a simple exercise to assign a unique address to each type of car- tridge which will be co-connected (for example black, cyan, magenta and yel-low) at the time it is manufactured in accordance with the colour of the ink/toner it contains. Because there will only be a single cyan cartridge in the printing de-vice, for example, only this cartridge will respond to data addressed to a cyan cartridge -the other cartridges will simply disregard such a transaction.

This technique is ubiquitous amongst modern printing devices and pre-sents no significant manufacturing difficulties for the cartridge manufacturers.

Typically, printing device manufacturers will use the same design of memory device for multiple cartridge types, each differing only in terms of its address and data content, with the hardware type of chip being the same. To further simplify the manufacture of the memory devices, it is normal practice to use one standard memory location in the memory device to store the device's own ad-dress. This is frequently location zero, i.e. the first location in a contiguously arranged block of memory. By allowing the device address to be programmed at the time the data portion is stored, the process of programming the memory device becomes a simple one-step process which can take place during manu-facture of the cartridge into which it is already incorporated.

There exists a growing trend towards refilling and recycling of printer car-tridges on the grounds of environmental sustainability. As well as the obvious replenishment of the ink or toner, it is generally necessary also to replace the memory device with a compatible device which reads full, so that the printing device recognises the cartridge as being full again when re-inserted, thus allow-ing printing to resume.

Several companies manufacture such replacement memory devices for supply to cartridge refilling organisations. In every case, the memory device is manufactured much as it would be manufactured by the original cartridge manu- facturer, with a specific address and other relevant data to allow the printing de-vice to recognise the cartridge as being of the correct type. Because there are many different types of memory device to accommodate different types of print- ing device and specific colour cartridges, the number of ostensibly similar mem- ory devices can be very large. For example, for one computer printer manufac-turer, there are in excess of fifty such memory devices sharing a common hardware design and differing only in the device address and the data con-tained therein.

This creates difficulties in distributing replacement memory devices, since each must be individually marked to identify the printing device with which it is compatible, and the colour of the ink or toner with which it is to be used, and this marking needs to be correctly read at each step in the supply chain from manufacturer to warehouse and to refilling business, not only to ensure that the correct device is delivered and then used in the correct cartridge, but also that the stock levels at each step in the chain are accurately monitored.

Such difficulties may be circumvented if the refilling store were to have the means to program the memory devices according to the specific printing device and ink/toner colour at the point of use. This would allow the memory devices to be shipped blank', or at least containing a constant set of data which may be over-programmed with specific data at point of use. This would render all memory devices identical throughout the supply chain until the point of use, reducing the number of stock items at the warehouse and shop to just one.

A programming means which stores, or can calculate, the address and data for any specific memory device is readily achievable. However, the means for transferring said data into the blank memory device is not straightforward.

As explained hereinbefore, a blank memory device must have a particular ad-dress. If the memory device has not previously been over-programmed, this may be a constant address which is known to the programming means. In this particular case over-programming is straightforward.

The difficulty arises if the memory device has been used before and re-turned to the refilling store for subsequent refilling of the ink/toner (or possibly for transfer to an alternative type of cartridge). In this instance it must previously have been assigned an address and this address is unknown to the program-ming means. In order to successfully over-program the memory device, the programming means must contain an algorithm to determine the unknown ad-dress of the target memory device, re-assign it to a new value and then proceed to over-program the data. Since the memory device can only respond to trans-actions to its pre-determined address, it is not possible to over-program the data content of the memory device unless the previous address is determined and subsequently changed.

The present invention seeks to overcome these problems.

Summary of the Invention

Accordingly, the invention provides a process for re-programming a memory device for use in a reusable printer component, comprising connecting the memory device to a processing means, and causing the processing means to: (a) select a start address; (b) send a read transaction from the processing means to said address; (c) determine whether a response is received; (d) repeat steps (b) and (c) for a pre-determined number of times; (e) determine whether the number of responses received exceeds a pre-determined limit and, if it does not, select the next numerical address in the memory device and re-start at step (b); (f) use the found address to update the data in the memory device.

In a first preferred embodiment, step (f) comprises writing a new address to the memory device to overwrite the found address, and then using the new address to write data to the memory device.

In an alternative preferred embodiment, step (f) comprises writing new data into the memory device using the found address, and then writing a new address to the memory device to overwrite the found address.

In either embodiment, it is preferred that, after overwriting the found ad- dress with the new address, the writing of the new address is confirmed by us-ing steps (b), (c) and (d) hereinbefore defined, and then determining whether the number of responses received exceeds a predetermined limit. If it does not, an error is indicated, and the memory device is rejected.

It will be appreciated that the memory device may be used in printer components such as ink or toner cartridges, replaceable print heads, or waste ink/toner receivers. Each of these components may be duplicated within a printer to accommodate different printing colours, and each will typically need to record data related to the usage and life of the component.

Brief Description of the Drawings

In the drawings, which illustrate exemplary embodiments of the method of the invention and the apparatus involved: Figure la is a flowchart illustrating the algorithm by which the address is detected; Figure 1 b illustrates the address writing stage according to a first method according to the invention; Figure 1 c illustrates the checking stage of the first method; Figure id illustrates the data writing stage of the first method; Figure 2a is a flowchart illustrating the second step of a second method according to the invention, the first step being the same as that illustrated by Figure la; Figure 2b illustrates the third step of the second method, the address writing step; Figure 2c illustrates the fourth step of the second method, the checking stage; Figure 3 is a diagrammatic representation of the memory chip which is the subject of the method of the invention; Figure 4 is a diagram illustrating the address locations within the chip; Figure 5 is a diagram illustrating the data structure employed; and Figure 6 is a diagram of the apparatus used in the method of the inven-tion.

Detailed Description of the Illustrated Embodiment

Referring first to Figures la, in a first process contained within the algo-rithm of a first embodiment, the programming means recursively attempts to transact with the memory device, beginning at the smallest possible numerical address. The attempted transaction is chosen to be innocuous, such that no change to the device data would result, such as a read operation. If no re- sponse is obtained from the memory device it is likely that the address is incor-rect. To increase the level of certainty, it would be normal practice to attempt this transaction a small number of times (herein referred to as n times) before concluding that there is no response and therefore this address is not correct.

The first process then increments the address by the smallest address division (usually one) and then re-attempts the transaction n times, monitoring for a response on each occasion.

This process ensues until a response is obtained on all, or at least a ma-jority, of the n attempts at a particular address. Once this has been achieved, the address of the memory device has been correctly ascertained.

A second process, illustrated in Figure ib, is defined within the algorithm of the first embodiment to re-assign the address to the new required value, based upon a knowledge of the target printing device and ink/toner colour.

Since the address is contained within the memory device's own data storage area, re-assignment of the address is a matter of writing a new value into the data location which assigns the address. However, it is of great importance to note that this transaction takes place using the pre-existing address since the new address has not yet taken effect.

A third process, illustrated in Figure ic, is defined within the algorithm of the first embodiment which then checks that the new address has taken effect by attempting an innocuous transaction at the new address (as before, this is likely to be read operation). The process checks that a response is obtained on all, or at least a majority, of the n attempts to transact with the new address. If the process fails to establish that the address has been changed successfully because fewer than the pre-determined majority of transactions are successful, the programming means announces a failure message to the user and the en-tire algorithm is started again either automatically or with the input of the user.

Where the third process has concluded successfully a fourth process, il-lustrated in Figure id, is defined within the first embodiment which allows the remainder of the memory device's data to be filled. This takes the form of a number of write transactions as required to fill the remaining data memory space. It is important to note that all said transactions in the fourth process take place at the newly defined address.

In an alternative embodiment, illustrated by Figures 2a-2c, after the de-tection step as hereinbefore described with reference to Figure la, the data area of the memory device is filled with new data using the pre-existing ad-dress, with the exception of the address value location, as illustrated in Figure 2a, and then, once complete, the address is re-assigned to the new value (Fig-ure 2b) and checked (Figure 2c).

Figure 3 is a diagram of a typical memory device for use with an inkjet printer. The device is fabricated using silicon fabrication techniques known to those skilled in the art. The silicon 1 is bonded to a printed circuit board carrier 2 by means of epoxy adhesive or similar. The interconnections between the sili-con and the printed circuit board are made by means of small bond-wires which are electrically attached at each end. Once these interconnections are made, the silicon and the bond wires are encased in an epoxy compound to render them more robust. A memory device typically has a Prog pad 3, whose function will be explained hereinafter, and four large gold plated pads 4 which allow the memory device to connect to a similar number of resilient contacts in the printer, thereby affording connection to the printer electronics. These four signals are Power, Ground, Clock and Data.

Figure 4 shows a map of the individual locations of memory within the device (a memory-map). In this particular type of device the memory locations fall into one of three categories: * Lockable * Read-Write Write-once, read-many locations are characterised in that the eight bi-nary digits (bits) that make up the location may each have their logical state written from 0 to 1 once only. There is no facility to write a 1 back to a 0 even if such an operation were attempted. Those skilled in the art will understand the similarity between this area of memory and EPROM type memories.

The WORM area of memory is typically used to store a number repre-sentative of an ink level by means of a contiguous string of bits, all of which are initially set to a logical 0 state and successively written to 1 during the course of a printing operation as successively more ink is consumed. Because of the characteristics of the WORM area of memory, it is not ordinarily possible to re-set the string of bits back to 0 once the empty cartridge is removed from the printer and therefore re-use of the memory device is not possible.

The Lockable area of memory begins as fully readable and writable but by setting a single bit in the WORM area (the Lock bit), the Lockable area of memory is rendered Locked and from that point on becomes Read-only. It should be understood that since the Lock-bit is in the WORM area, and a logical 1 as the Lock-bit renders the Lockable area Locked, once this is done, this op- eration cannot be undone and the Lockable area is therefore permanently read-only.

Typically this area is used to store information during the initial installa- tion of the cartridge to which the memory is attached and may record such in-formation as installation date.

The Read-Write area of memory is fully readable and writable at all times and is used to record general-purpose information from time to time during the course of a printing operation.

Location 0 of the memory, in accordance with Figure 3, is WORM. How-ever, it has special significance in that it contains both the Lock-bit and also the three least significant bits of the memory device's address. Figure 5 shows the locations of these special bits within Location 0.

Ordinarily, the memory space of the entire device is pre-programmed at the time of manufacture with data that is appropriate to the cartridge to which it is attached. This data will include the three-bit address field within Location 0 and will ordinarily have the Lock-bit set as 0 so that writes to the Lockable area are initially permitted.

Once the cartridge is installed in the printing device, the Lock-bit will be set to 1 rendering the Lockable area locked and as the ink in the cartridge is consumed the contiguous string of ink level bits become successively written to logical 1 until eventually they are all set to 1, whereupon the cartridge is empty.

Since no reset of the ink levels is possible, the cartridge must ordinarily be dis-carded at this point; refilling it with ink is futile.

It is important to understand that the various areas of memory within the device, and the reading and writing rules attaching thereto, would also render it impossible to over-write the data contained within the said areas. Ordinarily therefore, when using a memory device manufactured by the printer manufac-turers themselves, the Programming means would have no means to write to the WORM area under any circumstances, limited means to write to the Lock- able area only if the Lock-bit is not set, and full means to write to the Read-Write area. An inability to write to the WORM area makes it impossible for the Programming means to change the address of the memory device, which is the object of this invention.

Hence a means of forcing data into the various memory locations is re-quired which may overcome the various reading and writing rules during the course of the Programming operation. Said means must then revert the memory device to normal operation once the Programming is complete such that it may operate correctly once re-inserted into the printer.

A fifth pad is provided on many currently available compatible memory devices manufactured by third parties. This is the Prog pad 3 shown in Figure 3.

This pad is provided with a local pull-down resistor device, fabricated within the silicon memory itself, which ensures that the pad is at a logical 0 voltage should it remain unconnected (as will be the case when installed in the printer). Under these conditions the normal rules are enforced, as previously described.

If the Prog pad is held high, however, by forcing a voltage at or near to the supply voltage onto the pad, this acts to temporarily disable the aforesaid reading and writing rules and renders the entire memory space as fully readable

and writable.

It is these third-party memory devices which are intended for use with the Programming device, for example as illustrated in Figure 6, since those manu- factured by the printer manufacturers cannot be over-programmed in the ab- sence of the Prog pad. The programming device comprises a CPU 6 which car-ries out all programming tasks and communications with the computer to which it is attached, and a number, for example three, of chip interface devices 7, each of which is fitted with an array 8 of five resilient contact pins which are fashioned in such a way as to cooperate with the five pads of the memory de- vice and in so doing make electrical contact with them. The programming de- vice is connected through a USB cable to a controlling computer 9. The inter-connecting means with the computer is ordinarily USB, although any similar means of communication would be equally possible.

At the time of writing data to the memory device, the Programming means first raises the voltage on the Prog pin, via the resilient contact, to a volt-age at or near to the supply voltage. Having rendered the entire memory space as a homogeneous, fully readable and writable entity, it may now write to each location at will with any data as appropriate to the operation it is carrying out, without restriction. Thus the processes described in the foregoing description may be carried out once the Prog pin has been set to a logical 1 state.

Once the Programming operation is complete, the Programming means may set the Prog pin back to a logical 0 state whilst it carries out any read op-erations that may ensue, by way of a verifying procedure, for example. Equally, it may simply disconnect the Prog pin and rely upon the pull-down resistor to render the Prog pin low.

By means of a series of menu selections, the user may use the screen and keyboard of the computer 9 to select the particular cartridge and ink colour to which the memory device will ultimately be attached. He may also select the operation he would like to carry out such as Program device, Read device, Ver-ify device etc. The CPU is also connected to the memory device in question by means of an array of five resilient pins (often referred to as pogo pins). It should be un- derstood that whilst a five pin array is appropriate to the topology shown in Fig-ure 3, other arrays of greater or fewer numbers of pins may be appropriate to other memory types.

In particular, the topology shown in Figure 3 is a generalisation of a se-ries of memory devices manufactured by one printer manufacturer and in fact comes in three physical sizes. It is appropriate therefore to have three arrays of pins, each appropriate to one size of memory device. A suitable method to se-lect between the arrays is therefore required, and in a preferred embodiment this is automatically selected by the Programming device via the computer 9 once the cartridge type is known, since the size of the memory device is then implicit. The preferred embodiment also provides a light emitting diode 10 adja-cent to each pin array to inform the user which array he should introduce the memory device to during the Programming operation. Other pin array selection methods are equally possible, including manual selection. -12-

Claims (6)

1. CLAIMS1. A process for re-programming a memory device for use in a reus- able printer component, comprising connecting the memory device to a proc-essing means, and causing the processing means to: (a) select a start address; (b) send a read transaction from the processing means to said address; (c) determine whether a response is received; (d) repeat steps (b) and (c) for a pre-determined number of times; (e) determine whether the number of responses received exceeds a pre-determined limit and, if it does not, select the next numerical address in the memory device and re-start at step (b); (f) use the found address to update the data in the memory device.
2. 2. A process according to Claim 1, wherein step (f) comprises writing a new address to the memory device to overwrite the found address, and then using the new address to write data to the memory device.
3. 3. A process according to Claim 1, wherein step (f) comprises writing new data into the memory device using the found address, and then writing a new address to the memory device to overwrite the found address.
4. 4. A process according to Claim 1, 2 or 3, wherein after overwriting the found address with the new address, the writing of the new address is con-firmed by using steps (b), (c) and (d), and then determining whether the number of responses received exceeds a predetermined limit.
5. 5. A process according to Claim 4, wherein if the number of re-sponses received does not exceed the predetermined limit, the memory device is rejected.
6. 6. A process for re-programming a memory device for use in a reus- able printer component, substantially as described with reference to the draw-ings.