Patent Description:
This invention relates to a method for assembling a Braille cell assembly.

A Braille display is an electromechanical device that connects to a computer by way of a wired or wireless connection. The display consists of a line of tactile cells. Typical displays include <NUM>, <NUM>, or even <NUM> cells. Each cell, in turn, contains six or eight tactile pins that move up and down in response to electrical voltage. The tactile pins can be driven by mechanical, electromechanical, piezoelectric, pneumatic, or magnetic effects. When in the raised position, the pins extend above a tactile surface and can be felt by a user. By raising certain pins and keeping others below the tactile surface, individual Braille characters can be generated. The series of cells together represent a line of text. After a line has been read the user can refresh the display to allow for additional lines to be presented and read. Braille displays are often combined with other hardware and software to make up an integrated unit. For instance Braille displays are connected in place of video monitors to serve as the display unit, and many units incorporate speech output of the screen prompts. In this regard, computer software is employed to convert a visual image in a screen buffer of the computer into text to be displayed on the Braille display.

Electromechanical tactile cells for use in refreshable Braille displays and graphical tactile displays are known in the art. An exemplary tactile cell as known in the art consists of eight piezoelectric reed elements corresponding to eight tactile pins. The necessary electrical connections and driving forces are provided to actuate the reeds, thereby causing the tactile pins to protrude above a tactile surface to allow the Braille character or graphic element to be displayed. The Braille cells known in the art have not been designed for manufacturability and ease of repair and replacement.

The present state of the art employs piezoelectric bimorph reeds to drive the tactile pins. The bimorph reeds have a common center conductor positioned between two piezoelectric transducers. A simple circuit drives the center conductor and fixes the outer conductor. This arrangement additionally requires that special metallic plating be applied to the outer piezoceramic contacts to enable soldering of the leads to the printed circuit board.

The need for such special metallic plating and individual attachment of the leads increases the manufacturing costs associated with each Braille cell. Current technology requires the use of sixteen hand-soldered leads, requiring thirty two hand- soldered solder joints to establish the electrical connections for each Braille cell in the display. Precise positioning of the reeds is necessary to ensure that the tactile pins extend a definite distance beyond the tactile surface upon actuation of the reed and fully retract below the surface upon request. This precise positioning and alignment of the reeds with the upward trajectory of the tactile pins proves to be very difficult with hand-soldering manufacturing techniques. Additionally, replacement of the reeds for repair of the Braille cell is complicated due to the large number of hand-soldered leads employed in the design.

Prior art Braille cells employ one individual tactile pin cap per individual Braille cell. The tactile pin cap serves to position and align the pins, and provides the cursor control buttons. The Braille cells and associated tactile pins caps positioned adjacent to each other establish the tactile surface. The use of individual cell caps for each Braille cell increases the manufacturing cost and the cost of materials. Additional stabilizers are necessary to position and align the individual cell caps. Strict tolerances are required to provide an acceptable tactile feel for the reader. The reader is sensitive to the separation that is inherent between each cell with this design. This unevenness between each cell plagues all Braille displays known in the prior art. To tactile users, the tactility of the grooves and cell-to-cell unevenness is comparative to the noise or flicker on a computer monitor experienced by a visual user. Additionally, maintenance and replacement of the individual tactile pins is often necessary. Contaminants that build up on the pins must be removed or the pins must be replaced upon excessive wear.

Accordingly, there is a need in the art for an improved electromechanical tactile cell for use in a refreshable Braille display. Improvements in manufacturability and repair are necessary in addition to enhancements in the tactile experience of the user. There is a need for an improved means for securing the piezoelectric reeds to the printed circuit board and establishing the necessary electrical connections. There is additionally a need for an improved alignment procedure for the individual cells that enhances the user interface and allows for easy maintenance of the tactile pins.

However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this field that the identified improvements should be made nor would it have been obvious as to how to make the improvements if the need for such improvements had been perceived.

<CIT> discloses an electromechanical Braille cell assembly with a plurality of parallel bimorph reeds. The bimorph reeds are mounted to opposing sides of a printed circuit board.

<CIT>discloses an electromechanical tactile cell assembly with piezoelectric element reeds and a plurality of conductive fulcrum pins. The electromechanical tactile cell is adapted for use with a Braille display.

One of the advantages afforded by the present Braille display is that it can be made in a very small form factor thereby permitting the display to be transportable and hand held.

Another advantage of the disclosed display is that it can be constructed with minimal labor thereby minimizing manufacturing time and costs.

Yet another advantage is realized by constructing a Braille cell assembly with the aid of an alignment guide, whereby contacts associated with the cell assembly can be quickly and properly oriented upon a printed circuit board.

A further advantage is achieved by providing housings to hold a series of Braille pins, thereby allowing the pins to be easily installed and removed from the Braille display for replacement and/or repair.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:.

Similar reference characters refer to similar parts throughout the several views of the drawings.

The present disclosure relates to a method for assembling a Braille cell assembly. A braille display supports an array of individual Braille cells with corresponding tactile pins. A Braille cell assembly controls the operation of each cell. The cell assembly includes a number of reeds that are attached to a printed circuit board (PCB) via electrical contacts. The reeds function to selectively lift tactile pins that generate Braille characters that can be felt by the user. The tactile pins associated with a series of cells are housed together in modular blocks. The Braille characters generated by the display correspond to visible characters, such as characters on a computer screen. The display is refreshable to allow for the sequential display of lines, paragraphs, or pages. In accordance with the disclosure, the display is constructed in a manner that minimizes labor and manufacturing costs and that permits the size of the display to be greatly reduced. The various components of the present invention, and the manner in which they interrelate, are described in greater detail hereinafter.

<FIG> is a perspective view of a Braille display <NUM> manufactured in accordance with the present disclosure. The side of display <NUM> includes a power button and a power port <NUM> for coupling display <NUM> to a conventional wall outlet. Alternatively, display <NUM> can be battery powered. A micro B USB port <NUM> is also included for coupling display <NUM> to a device such as a computer. Display <NUM> can alternatively be coupled via a wireless connection, such as Bluetooth ®.

Refreshable Braille cells <NUM> are aligned across the front of display <NUM>. In the depicted embodiment, display <NUM> includes a row of <NUM> Braille cells with <NUM> individual tactile pins. Displays utilizing other cell arrangements, such as <NUM> or <NUM> cells, are within the scope of the invention. It is also within the scope of the invention to use a portable <NUM> cell arrangement. The cells <NUM> extend across a monolithic surface. As a result, there are no spaces or gaps between adjacent cells <NUM> of display <NUM>. A cursor routing button <NUM> is associated with and located above each Braille cell <NUM>. For sake of clarity, not all cells <NUM> and buttons <NUM> have been labeled with reference numerals. Cursor routing buttons <NUM> are used to move the cursor to a particular point or to select text. These serve as function keys or panning buttons. At either end of the display are a rocker key <NUM> and push button <NUM>. Rocker key <NUM> is used to scroll up or down through the text being displayed. Push button <NUM> is a toggle control that selects whether the rocker key scrolls <NUM> through lines, paragraphs or pages of material. Display <NUM> can be programmed by the user to determine the scroll rate and the sensitivity of rocker keys <NUM>.

A series of keys <NUM> are also aligned along the back of display <NUM>. These include six inner keys <NUM>(b) and two outer keys <NUM>(a). In the depicted embodiment, keys <NUM> are Braille keys and are similar to those found on a conventional Perkins style keyboard. Keys <NUM> are angled inwardly towards the center line of the display to conform to the natural placement of a user's fingers. The space between the keys is not uniform. Namely, the two outer keys <NUM>(a) are spaced further apart than the inner keys <NUM>(b). The outer keys <NUM>(a) are spaced further away to accommodate the natural extension and placement of a user's pinkey. A space key <NUM> is also centrally located adjacent the front edge of display <NUM> and is accessible via the user's thumbs.

The front surface of display <NUM> also contains selector buttons <NUM> that control an auto advance feature. Also included are rocker bars <NUM> for controlling upward and downward movement of the lines being displayed by Braille cells <NUM>. Panning buttons <NUM> are also included that allow for panning left or right one display width. Display <NUM> includes an outer housing <NUM> formed from an upper cover <NUM> and a lower tray <NUM>. Upper cover <NUM> and lower tray <NUM> can be injected molded from an impact resistant plastic. The upper cover and lower tray (<NUM> and <NUM>) are releasably joined together, such as by screws or other mechanical fasteners (not shown). As illustrated in <FIG>, upper cover <NUM> includes openings <NUM> to accept tactile pins and keys associated with the display. <FIG> is an illustration of upper cover <NUM> in an inverted or upside down configuration so as to display features on the inner surface of cover <NUM>.

A backplane board <NUM> is secured within the interior of housing <NUM> (note <FIG>). As is known in the art, a series of Braille cell assemblies <NUM> are interconnected to backplane board <NUM>. For sake of clarity, <FIG> only shows only cell assembly <NUM>, but a series would be included in a complete display <NUM>. Backplane board <NUM> includes an integrated motherboard. An example of a Braille cell assemblies being secured to a backplane board is disclosed in commonly owned <CIT> The contents of the '<NUM> Patent are incorporated by reference herein for all purposes. Each Braille cell assembly <NUM> (note <FIG>) corresponds to an individual Braille cell <NUM> and supports a corresponding number of either six or eight tactile pins <NUM>. More specifically, each cell assembly <NUM> includes a printed circuit board (PCB) <NUM> to which six or eight bimorph reeds <NUM> are secured. In the preferred embodiment, eight reeds <NUM> are included, with four reeds <NUM> being removably fastened to each side of PCB <NUM>. The lower extent of each tactile pin <NUM> contacts the distal end of a corresponding reed <NUM>. As explained in more detail hereinafter, an individual tactile pin <NUM> can be selectively raised by applying a voltage to the corresponding reed <NUM>. The applied voltage creates a bending moment in the corresponding reed <NUM> which, in turn, flexes the distal end of reed <NUM> upwardly to lift an associated pin <NUM>.

Reeds <NUM> are preferably parallel polled bimorphs. As is well known in the art, bimorphs are flexure elements that consist of two expander plates bonded to a metal vane. The polarization of the plates causes one plate to expand and the other to contract upon the application of a voltage. This, in turn, causes the bimorph to bend.

Bimorphs can either be series polled or parallel polled. In a series polled bimorph, the plates are polarized in the same direction with respect to the vane. In a parallel polled bimorph, the plates are polarized in opposite directions with respect to the center vane. In the series type bimorphs, electrical connections are made to the two outer plates (via electrodes) and no connection is made to the center vane. In the parallel type bimorphs, one electrical lead goes to the center vane and the other lead goes to the two outer plates (via electrodes). Examples of series and parallel polled bimorphs are disclosed in commonly owned <CIT> Contents of the '<NUM> patent are incorporated by reference herein for all purposes. Although either parallel or series polled bimorphs can be employed in connection with the present disclosure, parallel polled bimorphs are preferred.

In accordance with the present disclosure, tactile pins <NUM> are held in groups via a mounting block <NUM>. Each mounting block includes a housing <NUM> with an array of apertures. Blocks <NUM> can support pins <NUM> in either four or six cell arrangements. <FIG> illustrates a four cell mounting block <NUM>; <FIG> illustrates a six cell mounting block <NUM>. Each block <NUM> further includes a depending forward edge <NUM>. Depending forward edge <NUM> is received within a channel positioned within the lower tray <NUM> of housing <NUM> (note <FIG>). As best illustrated in <FIG>, the inside surface of upper cover <NUM> includes a channel <NUM> formed from two opposing walls <NUM>. Walls <NUM> are adapted to receive a block <NUM> in a friction-type fit. To accomplish this, walls <NUM> include locking features <NUM>(a) (which may be male features) that snap fit into corresponding locking features <NUM>(a) (which may be female features) within housing <NUM> (note <FIG>). Walls <NUM> span the length of upper cover <NUM>. Thus, a series of different blocks <NUM> can be snap fit into the length of channel <NUM>. For example, for the <NUM> cell display depicted in <FIG> , a series of ten, four cell blocks <NUM> can be snapped into channel <NUM>.

During assembly, mounting blocks <NUM> can be initially held within upper cover <NUM> and thereafter inserted into the forward edge of lower tray <NUM>. Once positioned, the lower extent of each pin <NUM> contacts the reed <NUM> of an associated cell assembly <NUM>.

Different configurations of mounting blocks <NUM> can be utilized depending upon the size of display <NUM>. For instance, for a portable display utilizing <NUM> total Braille cells, one six cell block and two four cell blocks can be utilized. In a display using <NUM> Braille cells, two six cell blocks and two four cell blocks can be utilized. Still yet other arrangements can be used for different sized displays. One benefit of encasing the tactile pins <NUM> in modular groups via blocks <NUM> is that it creates a more serviceable product. In prior art units, pins <NUM> would become loose and scatter when removing the cover. Modular arrangements of pins also eliminates tolerance stack up across the length of the display. By providing the blocks <NUM> in four and six cell arrangements, a variety of sized displays <NUM> can be created.

As best illustrated in the exploded view of <FIG>, each of the tactile pins <NUM> includes a rounded upper extent <NUM> that is adapted to be extended above cover <NUM> and felt by the user. A collar <NUM> is also included about each pin along its length. A plate <NUM> is secured over top of each mounting block <NUM> via a snap fit connection (note <FIG>). Plate <NUM> includes apertures that are sized to accommodate the upper extent <NUM> of pins <NUM> but that are smaller than collars <NUM>. Thus, plates <NUM> function in limiting the upward travel of pins <NUM>. Plate <NUM> is particularly useful during the assembly process. Namely, after installing blocks <NUM> into channel <NUM> of upper cover <NUM>, pins <NUM> may be inverted as cover <NUM> is mated with lower tray <NUM>.

The Braille cell assemblies <NUM> are described next. Each cell assembly <NUM> includes a PCB that is removeably and electronically coupled to backplane board <NUM>. When secured, PCB's <NUM> are perpendicular to backplane board <NUM>. The total number of cell assemblies <NUM> involved will correspond to the number of Braille cells <NUM> contained within display <NUM>. Each PCB includes a female electrical connector <NUM> at its proximal end. This female electrical connector <NUM> is adapted to be coupled to a corresponding male connector <NUM> on the backplane board <NUM>. PCBs <NUM> can be removed and replaced as needed. Each PCB <NUM> also includes a series of stops <NUM> along the intermediate extent (note <FIG>). The function of stops <NUM> is described in greater detail hereinafter.

A series of bimorph reeds <NUM> are interconnected to either side of the PCB <NUM> by way of electrical contacts <NUM>. More specifically, four reeds <NUM> are connected to each side of PCB <NUM>. The distal end of each reed <NUM> is positioned beneath a corresponding tactile pin <NUM> (note <FIG>). Upon the application of a voltage, an individual reed <NUM> applies the upward force necessary to expose a corresponding pin <NUM> through upper housing <NUM>. Each PCB <NUM> controls the operation of an individual Braille cell <NUM>. Each of the contacts <NUM> includes a base portion <NUM>, a support arm <NUM>, and a biasing arm <NUM>. Base portion <NUM> can include a series of apertures to decrease the weight of the contact. Each base <NUM> is adapted to be soldered to a PCB <NUM> using any of a variety of well known soldering techniques. When installed, support arm <NUM> of contact <NUM> is perpendicular to the face of PCB <NUM> and parallel to the backplane board <NUM>. Additionally, biasing arm <NUM> is angled at approximately a <NUM>° angle relative to support arm <NUM>. Contacts <NUM> are preferably mounted in a staggered or stairstep arrangement. Namely, the uppermost contact <NUM> is closest to the proximal end of PCB <NUM> and the lowermost contact <NUM> is closest to the distal end of PCB <NUM>. When installed, reeds <NUM> have a similar staggered configuration. The staggered arrangement of reeds <NUM> allows the pins <NUM> to be aligned in rows. Each row of the Braille cell <NUM> corresponds to one side of the PCB <NUM>.

When soldered in place, contacts <NUM> are separated from one another and are electrically insulated. Adjacent contacts <NUM> form a fulcrum point <NUM> for an associated bimorph reed <NUM>. Each of these fulcrum points <NUM> is created between the biasing arm <NUM> of an upper contact <NUM> and the support arm <NUM> of a lower and adjacent contact <NUM>. When so arranged, biasing arm <NUM> forms an electrical contact with an electrode on the upper surface of reed <NUM> and support arm <NUM> of the immediately adjacent contact <NUM> forms an electrical contact with an electrode on the lower surface of reed <NUM>. Reed <NUM> is configured to bend about this fulcrum point <NUM> upon application of a voltage to upper and lower contacts <NUM>. Each of the bimorph reeds <NUM> is adapted to be inserted into one of these fulcrum points <NUM>. The intermediate extent of the bimorph <NUM> is then placed adjacent to a corresponding stop <NUM>. Stop <NUM> functions in limiting the downward bending moment of reed <NUM> and otherwise prevents interference between adjacent reeds <NUM>. Stops <NUM> thereby permit reeds <NUM> to be more closely positioned and allows for much tighter tolerances.

Once installed, the electrical connectors (<NUM> and <NUM>) provide voltage to the corresponding PCB <NUM> and allow voltage of opposite polarity to be delivered to the contacts <NUM> on PCB <NUM>. Namely, a negative voltage is applied to a first series of contacts <NUM> and a positive voltage is applied to a second series of contacts <NUM>. Thus, for example, a positive voltage may be applied to the upper most contact <NUM> while a negative voltage is applied to the adjacent and lower contact <NUM>. Adjacent contacts <NUM> are exposed to voltages of opposite polarity. This, in turn, allows opposite polarity voltage to be applied to the upper and lower surfaces of an individual reed <NUM>. Namely, biasing arm <NUM> can apply a positive voltage to the upper surface of reed <NUM> while the lower support arm <NUM> of an adjacent contact <NUM> applies a negative voltage to the lower surface of the same reed <NUM>. By applying the voltage in this manner, each bimorph reed <NUM> can be bent upon application of opposite polarity voltage. As a result, a corresponding tactile pin <NUM> is lifted. The pin <NUM> is lowered when the voltage is removed.

The present disclosure also relates to an improved method for installing the electrical contacts <NUM> upon a PCB <NUM>. The method utilizes an alignment guide <NUM> for orienting a series of contacts <NUM> upon PCB <NUM>. Alignment guide <NUM> includes first and second surfaces (<NUM> and <NUM>) that are angled with respect to each other. In the depicted embodiment, the first and second surfaces (<NUM> and <NUM>) are at a right angle to each other. Alignment tabs <NUM> are formed at either end of second surface <NUM>. Alignment tabs <NUM> are dimensioned to fit into corresponding apertures <NUM> present on PCB <NUM>. The series of contacts <NUM> are releasably secured to a peripheral edge <NUM> of the second surface <NUM> of guide <NUM>. Contacts <NUM> are preferably connected to the second surface <NUM> via a score line. The score line is frangible and allows the contacts <NUM> to be separated by bending alignment guide <NUM> after contacts <NUM> have been soldered to PCB <NUM>. In the depicted and preferred embodiment, a series of five contacts <NUM> are secured to the second surface <NUM> of alignment guide <NUM>.

The installation method involves positioning the alignment guide <NUM> with the attached contacts <NUM> upon the PCB <NUM>. As best illustrated in <FIG>, this is accomplished by inserting the tabs <NUM> on guide <NUM> into the alignment apertures <NUM> of PCB <NUM>. With the alignment guide <NUM> so positioned, the series of contacts <NUM> are properly aligned and spaced upon PCB <NUM> and are ready to receive reeds <NUM> between adjacent contacts <NUM>. Base portion <NUM> of each contact <NUM> is adapted to rest against the surface of PCB <NUM>. This also places each of the contacts <NUM> in a staggered relationship to each other. Namely, the uppermost contact <NUM> is closest to the rearward edge of PCB <NUM> and the lowermost contact <NUM> is closest to the forward edge of PCB <NUM>. This arrangement allows the bimorph reeds <NUM> to be similarly arranged in a staggered - or stairstep - fashion.

Once the contacts <NUM> have been properly positioned via the alignment guide <NUM> (and tabs <NUM> and apertures <NUM>), they are ready to be affixed to PCB <NUM>. In the preferred embodiment, the base <NUM> of each contact <NUM> is soldered into place. This can be done via a conventional soldering iron. Other known soldering techniques can be employed, such as wave soldering or reflow soldering. In the preferred embodiment, an infrared ("IR") reflow solder process is employed. Regardless of the technique employed, an electrical contact is formed between the base <NUM> of each contact <NUM> and an underlying circuit upon PCB <NUM>.

When properly oriented, the support and biasing arms (<NUM> and <NUM>) of each contact <NUM> are perpendicular to the face of PCB <NUM>. Additionally, the biasing arm <NUM> is oriented at approximately a <NUM> ° angle to the interconnected support arm <NUM>. A space is created between the lower extent of a biasing arm <NUM> and the support arm <NUM> of an adjacent contact <NUM>. This space is the fulcrum point <NUM> into which a bimorph reed <NUM> is inserted. As noted, in the preferred embodiment, five different contacts <NUM> are secured to each side of PCB <NUM>. This results in the formation of four fulcrum points <NUM> between the adjacent contacts <NUM>. As illustrated, the biasing arm <NUM> of the lowermost contact can be eliminated. Likewise, the support arm <NUM> of the uppermost contact, while present, is unused.

Claim 1:
A method for assembling a Braille cell assembly, the Braille cell assembly including a printed circuit board (PCB) (<NUM>) having a pair of alignment apertures (<NUM>), the method utilizing an alignment guide (<NUM>), the alignment guide (<NUM>) having first and second surfaces (<NUM>, <NUM>) that are angled with respect to each other,
the second surface (<NUM>) having a pair of alignment tabs (<NUM>) that are formed at either end of second surface (<NUM>) and a peripheral edge (<NUM>), a series of contacts (<NUM>) releasably secured to the peripheral edge (<NUM>) of the second surface (<NUM>) of the alignment guide (<NUM>), the method
comprising the following steps:
positioning the alignment guide (<NUM>) upon the printed circuit board (<NUM>) by inserting the pair of alignment tabs (<NUM>) into the pair of alignment apertures (<NUM>), whereby the series of contacts (<NUM>) are aligned upon the PCB (<NUM>);
soldering each contact (<NUM>) onto the PCB (<NUM>);
separating the alignment guide (<NUM>) from the soldered contacts (<NUM>).