On occasion, children have been able to get entangled in one or more lift cords of a window covering. If the lift cord is around the child's neck and the child falls, the cord could act as a noose and strangle the child. There have been incidents of child entanglements in lift cords of venetian blinds, Roman shades, and other types of window coverings. As a result, the art has developed various types of child safety devices that are intended to prevent deaths of children who become entangled in lift cords. For instance, U.S. Pat. Nos. 7,318,251, 7,261,138, 7,225,850, 7,117,918, 7,086,446, 7,000,672, 6,948,546, 6,918,425, 6,860,312, 6,637,493, 6,431,248, 6,484,787, 5,630,458, 5,533,559 and 4,909,298 disclose child safety devices for window coverings. Child safety devices may be configured to keep the lift cords taught so that the cords cannot be pulled away from the window covering material and form a noose or release the cord from the shade when a child becomes entangled in the shade.
Roll-up shades typically include a headrail, window covering material that is configured to extend and retract adjacent to the headrail and lift cords that extend from the headrail to the window covering material. A cord lock is typically positioned on the headrail. Each lift cord usually extends from a cord lock positioned on the front of the shade. Each lift cord extends from the cord lock along the front surface of the window covering material, around a bottom edge of the window covering material, and upwards along the rear surface of the window covering material. A terminal end of each lift cord is typically affixed to the rear of the headrail. The other end of each lift cord typically extends out of the cord lock so a user may manipulate the cords and cord lock to raise or lower the window covering material. As the window covering material is raised, the window covering material is rolled upwards about its bottom edge. As the window covering material is lowered, the window covering material is unrolled about its bottom edge.
U.S. Pat. No. 7,318,251 discloses a roll-up shade that includes releasable cord connectors. Each releasable cord connector includes a male body and a female body. The male body is connected to an end of a lift cord and the female body is attached to the headrail of the shade. The female body is positioned on the rear face of the headrail of the roll-up shade. The male body is sized and configured to be releasably received within an opening formed in the female body adjacent to the rear of the shade. If a child becomes entangled within the lift cords, the male body may be released from the female body so that a child will not become entangled within the lift cord.
Roll-up shade cord lease devices are typically configured so that the cord release devices are only positioned on the rear face of the blind. However, there may still be a danger of entanglement that could occur along the front of a roll-up shade. If a child becomes entangled on a portion of a lift cord positioned on the front surface of the window covering material, the window covering material may interfere with the transfer of force along the lift cord such that a cord release device attached to a headrail adjacent the rear surface of the window covering material does not release or may not release unless a much larger than desirable force acts on the lift cord. As a result, there may be a danger of entanglement with a portion of a cord positioned along the front surface of window covering material that is not addressed by safety mechanisms for roll-up shades disclosed in the prior art, such as U.S. Pat. No. 7,318,251.
A new safety mechanism is needed for window coverings such as roll-up shades to prevent children from becoming entangled within cords of the window covering. Preferably, the new safety mechanism provides a sensitive safety device that provides for operation at relatively low release forces.