Claims:
Having described my invention, I now claim
1. A device for use on shades carried on a spring loaded shade roller and guided at the shade bottom edge in opposed generally U-shaped channels, including at least one stop element extending from a wall of said channel into said channel, and wherein the improvement comprises:
2. The latch device for shades as claimed in claim 1 wherein:
3. A latch device for shades as claimed in claim 1 wherein:
4. The latch device for use on shades according to claim 1 wherein:
5. The latch device for use on shades according to claim 1 wherein:
6. The latch device for use on shades according to claim 1 wherein:
7. The latch device for shades according to claim 1 wherein:
Description:
BACKGROUND OF THE INVENTION
In window shades of the roller type, especially those which are employed in commercial installations, it is freqnently necessary and desirable to provide a means for latching all of the shades at a plurality of selectible and identical levels.
Various devices have been provided for this purpose and generally incorporate a spring-loaded, centrally-operated latch member which, when turned, squeezed, or otherwise operated causes latches to engage and disengage the U-shaped channel on either side of the window opening. Such devices as presently provided are expensive, and not easily operated or installed. They are susceptible to damage, when the device is released from a given stop and then drawn downward fully resulting in impact with a stop and potential damage to the mechanism.
Thus it is desirable to have an improved shade position latch device that is easily adaptable to shade lower edge configurations, and which is easily installed within the conventional shade track channel, is durable in use, and easy to operate and install.
SUMMARY OF THE INVENTION
An exemplary embodiment of the invention incorporates a latch unit comprising a helical spring within a spring barrel. The spring is secured at one end to the barrel, and at the opposite end to a shaft so that both torsional and axial resilient force may be produced. A latch pawl is mounted on the outer end of the shaft and is sized so that it may pass into the channel and be biased by the spring into engagement with opposite walls of the channel. A generally eliptical elongated configuration for the latch pawl is preferred, however any configuration which has a major dimension (the longest straight line distance between portions of the device) that is greater than the distance between the walls of the channel and a minor dimension (the narrowest projected width of the pawl) which is less than the unobstructed distance between the walls of the channel will operate as described. The shaft is notched to accomodate the inwardly directed flanges across the open end of a channel so that the lower edge of the shade may be drawn transversely away from the stop elements in the channels, and cause the latch pawl to be cammed out of engagement with the stop elements. The spring tension from the conventional shade roller then draws the shade upwardly. When the operator releases the transverse pressure on the lower edge of the shade, the latch pawl rotates and places the upper edge into engagement with the channel wall, so that when the next stop is encountered the shade is again restrained from upward movement.
The use of a spring barrel permits a single helical spring to be utilized for either right hand or left hand torsion since the spring is trapped from diametrical expansion and distortion. The axial resiliency in compression is utilized so that the device can accomodate out-of-plum or distorted channels by providing a pistoning effect as the shade moves up or down.
In the preferred configuration the minor dimension of the latch pawl is smaller than the opening between the flanges of the channel so that by rotating the latch pawl manually to the appropriate orientation it is possible to withdraw the pawl from the channel. In normal operation spring bias will prevent inadvertant disengagement of the latch pawl from the channel.
The shade may be drawn downwardly without concern for the latch damage. In the downward direction the stop elements automatically cam the latch pawl over the elements. When the shade is fully drawn and released the tension of the conventional spring shade roller raises the shade lower edge until the first stop element is engaged. By providing the stop elements the same positions on each of a plurality of shades a uniform and level shade position is obtained.
It is therefore an object of the invention to provide a new and improved shade position latch device.
It is another object of the invention to provide a new and improved shade position latch device which is relatively simple to manufacture.
It is another object of the invention to provide a new and improved shade position latch device which incorporates few parts and is relatively low in cost.
It is another object of the invention to provide a new and improved shade position latch device which may be used on either side of a shade track installation.
It is another object of the invention to provide a new and improved shade position latch device which produces an easy to operate shade installation.
It is another object of the invention to provide a new and improved shade position latch device which minimizes the damage due to careless operation.
It is another object of the invention to provide a new and improved shade position latch device which is easily installed and repaired.
It is another object of the invention to provide a new and improved shade position latch device which may be easily accomodated to conventional shade configurations.
It is another object of the invention to provide a new and improved shade position latch device which eliminates unsightly latch actuaters.
It is another object of the invention to provide a new and improved shade position latch device that accomodates dimensional variations in channel placement.
Other objects and many important advantages of the invention will become more apparent upon a reading of the following detailed description together with the drawings in which like reference numerals refer to like parts throughout and in which:
FIG. 1 is a front view of a window shade installation incorporating the latch.
FIG. 2 is an enlarged sectional view taken on line 2--2 of FIG. 1.
FIG. 3 is an enlarged sectional view taken on line 3--of FIG. 1.
FIG. 4 is a view similar to FIG. 1, but in the unlatched position.
FIG. 5 is an enlarged sectional view taken on line 5--5 of FIG. 1.
Referring now to FIG. 1 there is illustrated a shade 10 carried on a conventional spring shade roller 12. The roller 12 has a spring bias toward winding the shade onto the roller and thus produces an upward tension on the dispensed portion of the shade 10. The lower end of the shade terminates in a wood strip 20 which is wrapped with the shade material. The wood strip 20 is undercut to house the latch units 14 according to the invention. Each latch unit 14 includes a spring barrel 22 which is capped by an end 24 and houses the helical spring 28 and pawl shaft 26. The latch pawl 30 is mounted on the outer end of shaft 26 and is carried within the shade track channels 16 and 18. Channel 18 is typical and is illustrated in its association with the latch pawl in FIG. 2. The channel 18 comprises a base 40, opposed sides 32 and 34, and open side flanges 36 and 38. The latch pawl 30 has a depth along the axis of the shaft 26 to substantially fill the channel. An anti-friction protrusion 46 engages the base 40 of channel 18.
The ends of spring 28 are secured against rotation on the end cap 24 and shaft 26 so that the latch pawl may be wound in either direction to create a spring bias as will appear more fully hereinafter. The spring is wound to create a bias such that the latch pawl is normally rotated to the position illustrated in FIG. 3. The preferred cross section for the latch pawl is a generally elliptical elongated shape. The major dimension of the latch pawl 30 is in excess of the width of the channel so that it will not rotate under the bias of the spring, but rather will turn until the elongated ends of the pawl 30 engage the wall 34 and 32 of the channel. The minor dimension of pawl 30 is narrow enough in its projected width so that the entire latch pawl may pass along the channel in the unobstructed width available. In the usual application the unobstructed width is that width of the channel which is not interferred with by stop elements. In FIG. 3 a stop element is the form of an installed pop rivet 42 is illustrated. The rivet 42 is secured in wall 34 and projects transversely into the opening between the walls of the channel and provides a transverse lower surface. This lower surface of the rivet 42 is engaged by the upper end of the spring biased latch pawl 30 preventing further upward vertical movement of the shade 10. The latch pawl may be cammed out of interference with the stop by transverse movement of the strip 20. With the stops installed in the rear wall 34 of the channel, the strip 20 would be drawn toward the user (out from the window) to cam the pawl 30 out of engagement, such as is illustrated in FIG. 4. The notch 44 is positioned to receive the flange 38 of channel 18 during this operation and permits this camming action to proceed until the long axis of the latch pawl 30 is aligned with the longitudinal axis of the channel 8.
As will be most apparent in FIG. 4 the minor dimension of the latch pawl is smaller than the opening between the flanges 30 and 36 so that by manually rotating the latch pawl 30 and maneuvering the latch pawl out of the channel it is possible to completely remove the device without tools.
OPERATION
In use, two latch units are installed along the lower edge of a conventional shade strip 20. The shade roller is secured so that the spring bias provides a tendency to wind the shade and draw the lower edge upwardly. The latch units are installed on the shade track channels 16 and 18 by manually rotating the shaft 26 to produce a rotational bias on the latch pawl tending to cause the upper end of the latch pawl to be rotated toward the side of channel in which the stop elements 42 are installed. The latch pawl is manually held with the major axis vertical, that is the latch pawl is held with the major axis aligned with the longitudinal axis of the channel, whereupon it is possible to insert the latch pawl between the flanges 38 and 36 of the channel and to then release the latch pawl, causing it to engage the walls 32 and 34 as is illustrated in FIG. 3. A similar installation is accomplished for the opposing latch unit and the unit is then ready for operation.
When it is desired to raise the shade beyond a particular stop, the shade is drawn toward the user causing the latch pawl to cam out of engagement with the wall 34 and the stop member 42 into the position illustrated in FIG. 4. With the latch pawl in this position the user allows the tension from the spring roller 12 to draw the shade upwardly and beyond the stop 42. Once beyond the stop 42 the user may release the shade which will cause the latch pawl to engage the walls 32 and 34. Since the latch pawl is made of a relatively low friction plastic such as `nylon` it continues to be drawn up the channel 18 by the spring roller tension until it contacts the upwardly adjacent stop 42. During upward movement any irregularities in the channel are compensated for by the compression aspect of the helical spring 28 which allows for side play in the mechanism.
In lowering the shade the latch pawls will be cammed by the stop members 42 as the device is drawn downwardly until it reaches the level desired by the user whereupon it is only necessary to release the shade 10. The shade 10 will then be drawn upwardly and the pawl 30 will contact the next stop element 42.