blind_html [Fwd: opticon design]

  • From: Nimer <nimerjaber1@xxxxxxxxx>
  • To: blind_html@xxxxxxxxxxxxx
  • Date: Fri, 30 Jan 2009 19:24:12 -0700

This email was passed along by Sarah Alawami. Thank you Sarah for this email. I found this interesting.

Nimer J

-------- Original Message --------
Subject:        opticon design
Date:   Fri, 30 Jan 2009 17:56:23 -0600
From:   Sarah Alawami <marrie12@xxxxxxxxx>
To:     <nimerjaber1@xxxxxxxxx>

This was written by James C. Bliss on January 26, 2009.

The Optacon was designed in the late 1960's at the dawn of integrated circuits, silicon photocell arrays, and before microprocessors. The design was based on extensive experiments with human subjects, blind and sighted, that used computer simulation of various designs to determine the most effective for reading text. The final design incorporated a novel array of tactile stimulators composed of piezoelectric reeds, or bimorphs, a custom integrated array of silicon photocells, and custom integrated circuits of shift register/bimorph drivers.

The custom integrated circuits and unique piezoelectric reeds, together with the small market, made the Optacon a difficult product to source parts and manufacture. However, for those that mastered its use, the Optacon filled an essential need. Even though the Optacon has been out of production for over 15 years, there are still over 150 avid users trying to maintain their Optacons and demanding a new Optacon.

Now, almost 40 years after the original Optacon design, advances in technology make possible a new Optacon design that could have greater resolution, be easier to learn and use, and could have features that would greatly extend the applications of use.

To reach the widest possible market, it is important to keep the simplicity of the original Optacon while enabling new capabilities and applications. Below are my thoughts on design possibilities that could be considered. Not all of these ideas may be worth developing, but considering them to assign priorities could help the process toward a new Optacon.

1. Resolution and Field of View. The original Optacon was designed around an array of 24 rows and 6 columns of pixels that drove a corresponding array

of 24 rows and 6 columns of bimorph tactile stimulators.   The 24 by 6 was

based on tests with human subjects that indicated this was the minimum number of pixels for reading and tracking text at a practical speed.

Actually, if you consider 24 pixels across a 0.1 inch letterspace, this is equivalent to only 240 dots/inch compared to the 300 dots/inch typically considered to be the minimum needed for OCR. Also, the Optacon's 24 pixels across a 0.1 inch letterspace is equivalent to a visual resolution of only 20/40. In addition, reading with an Optacon requires the user to move the hand held camera along a line of text. The limited field of view of the Optacon camera requires this scan to be very precise; else the images of the text are cut off. So reading would be easier and faster if the field of view of a new design could be greater, thereby relaxing the precision needed for line tracking. Thus, for ease of tracking and reading a wider range of text fonts and text quality, more pixels would certainly be better, analogous to the greatly enhanced picture quality resulting from the recent television change from a 480 line interlaced scan to a 1080 progressive line scan. Fortunately, advances in technology make an improved resolution and field of view possible at a reasonable cost. Therefore, I believe that a goal of basing a new design on 36 vertical pixels to provide both improved resolution and greater field of view should be considered. Unfortunately, the Optacon II, which was designed by Canon, had only a 20 by 5 array. This reduction in resolution and field of view was one of the reasons reading is more difficult with it. In the original Optacon design, the pixels were not square, but rectangles that were twice as wide as they were high. This is because when camera is moved along a horizontal line of text the letterspace is sampled in the vertical direction, but an analog signal is obtained horizontally across the letterspace. All of the image information can be obtained from one column of pixels moved horizontally across the letterspace. However, tests with human subjects clearly showed that reading accuracy increased as more columns were added. Based on these considerations, I suggest that a new design have 12 columns across the same horizontal field of view as the original Optacon. Thus, the newly designed Optacon's pixels would be square, with the vertical and horizontal resolutions being the same. The 36 by 12 array would increase the number of pixels to 432, compared to the 144 in the original Optacon, perhaps justifying a name for the new model as "Optacon HD" for "high definition".

2. Tactile Array. In the past 40 years, there have been some significant advances in piezoelectric materials. Several years ago, there was a study at Stanford University that indicated the bimorph reeds in the Optacon tactile array could be half as long as in the original design. This would allow incorporating the increased number of bimorphs in approximately the same space as before. A complaint about the Optacon has been the noise that it makes. This noise comes from the bimorphs, which are being driven by a 250 hertz square wave, a frequency of maximum tactile sensitivity. This provides a strong tactile sensation. The bimorph reeds were designed to be at near resonance at this frequency to consume a minimum amount of power from the battery. After the Optacon design was finalized and production had begun, we discovered this noise was greatly reduced if the bimorphs are driven with a 250 hertz sine wave instead of a square wave. This is because the human ear is much more sensitive to the harmonics of a square wave than to the fundamental 250 hertz frequency. However, we never had the opportunity to test whether there was any detrimental effect on the tactile sensation when a sine wave drive is used instead of a square wave. In a new design, this should be tested and the sine wave used if desirable. At Telesensory, the assembly of the tactile array was labor intensive requiring considerable skill. Modern manufacturing techniques, including robotics, could help reduce this cost.

3. Retina Module. When the Optacon was designed, no suitable integrated solid state arrays of photocells were available, so a custom design was developed in the Stanford Laboratories. Finding and maintaining sources for this custom part at the relatively low quantities needed made Optacon production difficult and expensive. Now integrated solid state arrays of photocells are widely used in digital cameras, web cams, cell phones, etcetera. Thus in a new design, a standard off-the-shelf part should be used if at all possible.

4. Lens Modules. The original Optacon lens is not a true zoom lens, because only the lens is moved to change the magnification. This meant that the image is only in true focus at two points along the zoom range, and out of focus at the ends and middle of the zoom range. The amount of out of focus is sufficiently small to not be a problem given the low resolution of the original Optacon retina. Because of the increased resolution, I'm suggesting in a new design a better zoom system will be required. Actually, one of the Optacon prototypes built at SRI and Stanford did have a zoom system that moved both the lens and the retina to keep the image in true focus. This did not change the size of the camera, and would not be a significant increase in cost after tooling for production. Various lens modules, such as the typing attachment and CRT screen module, were very important for the Optacon market, because they increased employment applications. While these particular accessory lens modules are not as important today, others could be developed for producing handwriting, reading LCD screens, viewing and taking pictures at a distance,

> etcetera.  In addition to image signals from the Optacon camera, an

> independent signal indicating camera movement should be considered.

> While sometimes this can be derived from the camera images, there may

> be situations in which it may be desirable to have signals from the

> lens module rollers.

5. Electronics. Since the original Optacon was designed before microprocessors, the electronics did not include a microprocessor, however, Optacon II did, and any future designs most certainly would. In addition, a new design could include some image storage as well as a port for an external memory stick. This would enable camera scans to be stored for later retrieval and/or further processing on a PC. OCR and synthetic speech capability could be built into the Optacon electronics. These capabilities, together with the storage capability, means that the new design would need to have file handling and other software built-in. A very important control on an Optacon is the threshold, which determines the photocell signal level between black and white. Especially for poor quality print and for different colored print, how the threshold is set can determine whether the text is readable or not. For precision threshold setting, I think this part of the circuitry should be analog with a high resolution potentiometer.

Unfortunately, in Optacon II this control was digital with too few bits for precision. In addition to threshold and tactile stimulator intensity, there would need to be some additional controls, or buttons, similar to those on a "point and shoot" digital camera, for deleting images from storage, cycling through a menu, etcetera.

6. Ports. A new design could have a port for the camera (possibly wireless), a port for power (batteries could be charged in the Optacon or on a separate charging station), a port for a memory stick, and a USB port for sending camera images to a PC, for enabling the PC to write on the tactile array, and for enabling new software to be installed in the Optacon.

7. Battery. The Optacon II design was an improvement in battery convenience over the original Optacon, and a new Optacon design could improve things further. A system with readily available batteries that the user could easily replace and charge should be the goal.

8. Packaging. The Optacon II design was an improvement in packaging over the original Optacon, and a new Optacon design could improve things further.

9. PC Software for the Optacon. By providing a new Optacon with a USB port where camera images can be transferred to a PC and the PC can write tactile images on the Optacon means, that the basic simplicity of the Optacon can be maintained while providing the possibility of adding many new features for expanding Optacon use. Here are some examples.

a. Optacon Reading Lessons and Speed Building. Optacon training was essential in producing so many people that were successful in Optacon use.

Teaching someone to use an Optacon effectively was a labor intensive process. The most successful Optacon training programs involved one teacher full time for every student for several weeks. Since the '70's when these programs started, labor costs have dramatically increased relative to the cost of technology. However, with the widespread availability and increased capability of PCs, it is now feasible to develop software that could automate at least part of the training process. The PC could write letters, words, and text on the Optacon tactile screen, build speed by presenting these at various rates, test student progress, and provide feedback through synthetic speech.

b. Speech and Braille Output. By OCR processing the images from scans from the Optacon camera, the PC could provide speech or Braille output. Several tactile stimulators could be combined to simulate a Braille dot on the Optacon's tactile screen. Speech and Braille files could be stored in the PC in addition to image files.

c. Optacon Screen Reader Software. Optacon screen reader software could be developed in which images from the PC screen were displayed on the Optacon tactile array. The PC mouse could be used to move the field of view of the tactile image around on the screen. This could be particularly useful in understanding screen layout, viewing graphics on the screen, and in formatting documents.

10. Conclusion. I believe that developing and disseminating a new Optacon along the lines described here would significantly enhance the educational and vocational opportunities, as well a personal independence, of blind people around the world. I've described a design that would preserve the basic simplicity of the original Optacon, greatly improve the quality of the tactile image, and make tracking along a line of text easier. By adding the capabilities of memory storage and communication with a PC, new features could be developed to make reading easier and faster through speech and Braille, and that would expand Optacon applications. These design ideas need to be evaluated by the blindness community.

My guess is that the development of this basic Optacon alone could cost several million dollars. (The PC software and other accessories could be developed later by third parties.) However, the relatively small market coupled with the cost of development and the difficulties of selling to this market will discourage private companies from taking on such a project. The situation is analogous to that with low incidence diseases where biopharmaceutical companies don't develop treatments unless there is some consideration such as "orphan drug status". The hope for bringing back a new Optacon might rest on obtaining grant support for development and dissemination from private foundations or government. For this to be viable would require strong support from the blindness community, and leadership from an organization with the capability of accomplishing the task.

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