Archived — Patent Agent Examination Paper A 2008 (1 of 4)

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Patent Agent Examination - Paper A - 2008 (PDF - 5.3 MB - 32 pages)

2008 Patent Agent Exam | Next

You have received from your client the attached letter and drawings describing a mechanism for showing a missing battery in a smoke detector or carbon monoxide detector.

Your prior art search subsequently reveals US Patent Nos. XXXX428, XXXX063 and XXXX830.

On the basis of your client's letter, drawings, and the known prior art patents, prepare a patent application with Disclosure and Claims using the attached drawings to cover the invention. Claim all inventive features and, in particular, there are two distinct points of invention to independently claim. Both independent claims are of the device type. For each independent claim, limit yourself to 3 to 4 dependent claims, which are relevant to the invention. The preparation of formal portions of the application, e.g. petition, is not required.


3 marks


1 mark

Field of the Invention:

1 mark

Background of the Invention:

10 marks

Summary of the Invention:

2 marks

Brief Description of the Drawings:

3 marks

Description of the Embodiments:

20 marks

Independent Claim #1:

25 marks

Independent Claim #2:

25 marks

Dependent Claims:

10 marks


100 marks

Dear Agent,

The advent of smoke detectors has led to the saving of countless lives each year. The effectiveness and decreasing costs of smoke detectors has resulted in their widespread use. More recently, carbon monoxide detectors have found growing appeal and use in both residential and commercial applications. Carbon monoxide detectors include an active element which is sensitive to carbon monoxide, and like smoke detectors, a loud alarm is activated upon detection of dangerous levels of carbon monoxide.

The trend has been to make smoke and carbon monoxide detectors battery-powered. While there are known line-powered devices, battery-powered devices have the advantage of not being susceptible to electrical supply brown-outs or outages. Battery power also provides a back-up power source for a line-powered device in the event of loss of line power, for example, during a power outage.

The principal drawback with battery-powered detectors is the need to ensure that the batteries have been loaded and that the batteries are sufficiently charged to power the detector.

When a smoke detector is accidentally activated, for example from food burning on a stove element, there is a tendency to quickly silence the smoke detector by pulling out the batteries. While such an action is effective to deactivate the detector, there is always the risk that the batteries will not be replaced immediately, and as a result the smoke detector will remain in an inactive state.

I have designed a new battery compartment cover latching mechanism which I feel is an improvement over the prior art. The features of my invention should be apparent from viewing the attached drawings.

The following parts list will help you with the drawings:

  1. alarm device (a)
  2. housing (b)
  3. active sensing element and electronic circuitry to generate alarm (c)
  4. battery compartment (d)
  5. battery compartment cover door (e)
  6. battery compartment cover door hinge (f)
  7. battery compartment cover stop (g)
  8. battery (B)
  9. battery terminals (h)
  10. battery terminal slot (i)
  11. latch (j)

Movable battery terminals are provided which when batteries are present in the alarm device, move to a position which permits the battery compartment cover to be closed, but when no batteries are present, the terminals are in a position that prevents the cover from being closed thus ensuring that the device is not closed when inoperative.

The movable terminals are spring contacts that are normally biassed in a position that prevents the cover from being closed. When batteries are placed in the compartment, the ends of the spring contacts move into a cover closing position. The batteries move the spring contacts laterally when placed in the battery compartment so that the cover is not blocked from closing or being put into a closed position.

In one form of the device, the movable terminals include apertures that receive or block latches on the cover depending on whether batteries are present in the battery compartment. The latches may engage catches that lock the cover into position. In another form of the device, the ends of the movable terminals block the cover from closing. The cover may include a projection that engages the terminal ends, which ends move out of alignment with the projections when the batteries are in place.

The cover may be hinged to the device housing, or it may be secured in another suitable manner, such as by a push fit or friction fit.

Both forms of my invention provide a clear indication that a battery is missing or not present and the device is inoperative. The cover cannot be replaced unless the batteries are in place.

My invention is applicable to both smoke detectors and carbon monoxide detectors which are battery powered. In Fig. 1, the electronics and detector component are indicated generally by reference letter "c" and the batteries in the battery compartment are indicated by generally by reference letter "B". Figs. 2(a)-2(c) show a first embodiment, and Figs. 3(a) to 3(c) show another embodiment.

I feel that my invention provides a very effective mechanism for preventing the closure of the battery compartment door in a smoke detector or a carbon monoxide detector when there are no batteries present or a battery is missing. This provides a readily discernable indication that the detector is without batteries and therefore inoperable. My latching mechanism has the additional advantage of being simple and inexpensive to manufacture and does not add parts or substantially increase the complexity of the detector.

I would like to seek patent protection for both embodiments and I am not concerned if I have to subsequently file a divisional application for one of the embodiments.

Duplicate copies of the drawings are provided so that you can make annotations on one copy and add reference numerals on the other.

Client's drawings

Fig 1

Please provide a description for figure 1

Fig 2a

Please provide a description for figure 2a

Fig 2b

Please provide a description for figure 2b

Fig 2c

Please provide a description for figure 2c

Fig 3a

Please provide a description for figure 3a

Fig 3b

Please provide a description for figure 3b

Fig 3c

Please provide a description for figure 3c

2008 Patent Agent Exam | Next