Low Paper Monitoring System
(May 02-03)
Project Design Report
December 16, 2001
Faculty Advisors/Clients: Patterson and Lamont
Team Members:
Bradley Leitz Phiane Noy Mekdara
Michael McWhirter Tze-Teik Poh
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Table of Contents
List of Figures …………………………………………………………………………
List of Tables ………………………………………………………………………….
Abstract ……………………………………………………………………………….
Acknowledgement …………………………….……………………………………...
Definition of Terms ………………………………………………………………...…
Introduction ……………………..……………………………………………………
Design Requirements ………………………………………………………………….
End Product Description ………………………………………………………………
Approach and Design ………………………………………………………………….
Financial Budget ………………………………………………………………………
Personal Effort Budget ………………………………………………………………...
Project Schedule ……………………………………………………………………….
Project Team Information ……………………………………………………………..
Summary ………………………………………………………………………………
References ……………………………………………………………………………..
List of Figures
Figure 1. Data Flow of Low Paper Monitor ……………………………………….
Figure 2. Logic Flow of Monitor Program …………………………………………
Figure 3. Mounting Option 1 ………………………………………………………
Figure 4. Mounting Option 2 ………………………………………………………
Figure 5. Strain Gage Option ………………………………………………….……
Figure 6. Entran Strain Gage ………………………………………………………..
Figure 7. Photodetector Array Option ………………………………………………
Figure 8. Form 1……………………………………………………………………..
Figure 9. Form 2 …………………………………………………………………….
Figure 10. Form 3 …………………………………………………………………..
Figure 11. Form 4 …………………………………………………………………...
Figure 12. Gantt Chart ………………………………………………………………
List of Tables
Table 1. Revised Financial Budget ……………..……………………..…………… 14
Table 2. Revised Effort Budget ……………….…………………………..………… 14
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Abstract
In the multi-tasking workplace of today, it is often necessary to start a large print job and leave it unattended while working on other tasks. If the printer is low on paper, a busy individual may return only to find an error message stating that the printer is out of paper and an incomplete print job waiting to be finished. A more efficient process would occur if a worker was warned when the printer did not have enough paper to complete the job. The purpose of this project is to develop and implement an inexpensive device that will measure the amount of paper in a printer and provide a warning when a print job is started that exceeds the paper resources available.
Acknowledgement
Dr. Vikram Dalal will act as the primary technical advisor during the design of the photodetector array that is currently the most attractive option to be used as the sensor for this project. Dr. Dalal will use his expertise in the area of microelectronic and photonic devices to guide the team in the design and fabrication of a photodetector array.
Definition of Terms
· Paper Weight – The weight in pounds of 500 uncut sheets. For letter paper the sheets are cut into fourths. Therefore, 500 sheets of 24-weight paper weigh 6 pounds.
· Ream – 500 sheets of paper.
· Photodetector – a semiconductor device that will produce an electric current when exposed to light.
Introduction
General Background. At the present time, printers only have the capability to alert users when the printer is out of paper. This project’s focus is to devise an inexpensive system that will inform users about how much paper the printer has compared with the number of pages the user wants to print. The system will initially be implemented on a DeskJet type printer; however, portability to other platforms, such as other printers, fax machines, and copiers will be an important consideration during all aspects of the design.
The system will consist of three distinct components. The first component will be a sensor that does measurements on the stack of paper in the tray. Next will be an analog-to-digital converter that receives analog measurement signals from the sensor and converts them into digital inputs for the computer. Software that calculates the number of pages from the digital inputs and interfaces with users will be the third component.
This system will interact with users by comparing the requested printing size and the actual amount of paper available as determined by the sensor, and then it will inform the user of the available paper. The system will warn users if the paper is inadequate for the current task. The system will mount on the paper tray but will not affect the time it takes to refill the printer.
Technical Problem. The system will require that the user input the weight of the paper loaded in the printer. To determine the amount of paper available, a sensor will perform continuous measurements of the paper loaded in the printer. Figure 1 shows the flow of data through the system.
Figure 1. Data Flow of Low Paper Monitor
The measurements will be performed with a sensor that will provide a minimum accuracy of five pages. An analog-to-digital converter (ADC) will be employed to convert the signal from the sensor into a digital signal that can be processed by the computer. Software will calculate the number of pages currently available as a function of the paper weight and sensor output signal. This software will be coded using C/C++. The software will be able to detect when there are fewer sheets of paper available than are required for printing the requested document. When a shortage is detected the system will trigger an LED to flash and provide a notification to the user through their personnel computer (PC). Figure 2 below shows the logic flow of the program.
Operating Environment. The paper monitor for printers will operate in a business or home environment. The system will be designed to withstand average temperatures and humidity levels. The system will not be water resistant or resistant to extreme temperatures since its expected use is with computer components.
Intended Use and User. People who frequently print large documents are the target audience of the paper monitor. This device will allow users to more efficiently utilize their time and resources. This system will also be valuable to users who have remote printing facilities. Since it will be inexpensive, it will also be efficient for everyday use.
Assumptions and Limitations. There are five major assumptions that will be utilized during the design of the low paper monitor:
· Humidity will change some paper parameters.
· All the paper loaded in the printer will be the same size and weight.
· The user will enter the correct paper size.
· None of the paper in the tray will have large folds or bent edges.
· The total quantity of paper will never exceed one ream.
There are also three limitations that will play a key role in the design of the Low Paper Monitoring system:
· The device must be inexpensive ($25-$50).
· The device must be small enough to easily mount on a standard printer.
· The device will operate on the printer’s power supply.
· The device will not interfere with the operation of the printer or with paper loading.
Figure 2. Logic Flow of Monitor Program
Design Requirements
Design Objectives. The objective of this project is the design and implementation of a device that is able to warn a user when there is not enough paper in the printer to finish a queued print job. The following components will be implemented during the duration of this project:
· Printer-mounted sensor capable of measuring the quantity of paper remaining in the printer.
· Analog-to-digital converter to transform the analog output signal from the sensor into a digital signal capable of being processed by a PC.
· C/C++ program to process the signal from the printer, detect when a print job has been queued, and display a warning when there is not enough paper to finish the job.
Functional Requirements. The system must perform several specific tasks to meet the goals of the project. The system will not be acceptable until it can perform each of these functions.
· The Low Paper Monitoring System will be able to detect the number of remaining sheets in the paper tray with an accuracy of five pages.
· The system will warn users when paper is low. This will be accomplished in one or more of the following manners: flashing LED, on-screen display of the remaining number of pages, display of a warning message. Anytime a print job is queued, the system will display a window indicating the number of pages currently loaded in the printer. If the document is being printed with an application that provides a page count, an LED mounted on the sensor will flash, and a warning message will be displayed if there is a deficit of paper.
· The system will be portable to other printing devices such as laser printers, copiers, and fax machines.
· The system will be independent of the printer.
Design Constraints. The overall design of the system is constrained by several factors. These factors will help the team decide on the technology to use and the type of program to write.
· The final cost of the system should range from $25 to $50. Any greater cost would make the system undesirable in a market of falling printer prices.
· The size and weight of the device should be small compared to the size of the printer. The system will need to be used in crowded workspaces. If the system is large it will be cumbersome to use.
· The system needs to be easy to setup and use so that anyone who uses a printer can use the device. A complicated device will not only frustrate the user but will be more apt to experience failures.
· The device will have a limited amount of power dependant on what it is connected to or on its own power supply.
Measurable Milestones. The progress of the project will be measured with the following milestones:
· Selection of system technology (10%). The team will gather information from professors, the Internet, technical journals, and other resources to decide upon a sensor technology that can meet the design requirements of the project.
· Finalize computer interface model (10%). The team will design an appropriate user interface system, decide upon a data transfer scheme, and develop an algorithm to be implemented in the C/C++ program for calculating the paper quantity.
· Device Design Complete (30%). This will include designing the printer-mounted sensor, analog-digital converter, and all associated interfaces. Pseudo-code for the computer program will also be developed.
· Implement Design (30%). A working prototype will be built.
· Prototype Tested and Debugged (20%). The prototype will be tested for proper operation and any errors will be corrected.
End Product Description
The end product will efficiently and accurately warn users when a print job exceeds the current paper resources of the printer. It will consist of a printer-mounted sensor and associated electronics. The final system design will allow for mounting on the cassette of laser printers. The hardware will interface with the user through a simple desktop application. This application will provide for input of the currently loaded paper weight and will also provide the user with a warning when the paper is low. If the size of the current print job is not available, the system will provide the user with a display of the number of pages loaded in the printer.
Approach and Design
Technical Approaches. A number of technologies will be investigated for application in this project. Each of the three tasks of the system (measure, convert, and interface) has unique requirements that must be met for project success.
· Measure. A number of technologies are available that may meet the requirements for measuring the paper remaining. The team has investigated two different methods for measuring the paper quantity: weigh the paper that is remaining in the printer or measure the height of the paper remaining in the printer.
Weighing the paper is the most direct method since paper weight is a required system input. Determining the number of pages would only require computing the ratio of measured weight to the weight entered by the user and multiplying this value by 500 sheets. This method would require that the entire weight of the paper in the printer rest on the sensor. At this time no affordable pressure sensors have been located for use in this project.
On the other hand, the height of the paper stack in the printer could be measured. The height of the paper could then be used to calculate the number of sheets of paper in the printer. Initially, an ultrasonic or laser range finder was considered to be the sensor of choice to accomplish the measurements. The sensors could be mounted in either of two positions. As shown in Figure 3 below a sensor could be mounted above the paper tray. Either an ultrasonic sensor or a laser ranger could be used to measure the distance from the sensor to the paper. This distance could be subtracted from the distance that the sensor is mounted from the bottom of the paper tray. This would yield the height of the paper. The computer program would then use the paper weight entered by the user to cross-reference the thickness of one sheet of paper. The measured height would then be divided by this value to yield the number of pages remaining.
Figure 3. Mounting Option 1
A second mounting option is shown in Figure 4 below. This would allow a direct measurement of the paper thickness to be made. As with mounting option 1 the computer program would use the entered weight of the paper to cross-reference the thickness of one sheet of paper. The measured height would then be divided by this value to yield the number of pages remaining.
Figure 4. Mounting Option 2
So far no ultrasonic or laser sensors have been located that meet the budget requirements of this project. This method is still considered a viable option and will continue to be investigated.
The height of the paper in the tray could also be measured with the use a strain gage and suspended weight as shown in Figure 5 below.