Abstract:
A bicycle warning device is capable of providing a turning or braking signal and is mounted on the bicycle such that the main body of the warning device faces the front and the rear of the bicycle. The main body is provided with at least two groups of reflector-type display pieces which are of a strip like construction and arranged alternately in rows. The display pieces are provided with symbols capable of forming in combination to indicate the turning direction or the braking action of the bicycle in motion. The display pieces are colored to enhance the warning effect of the device and are capable of being driven by the pull rods to displace up and down. The effects of the left-turn signalling, the right-turn signalling and the braking signalling are attained by the alternate and reciprocating motions of the display pieces.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a bicycle warning device capable of providing a turning o r braking signal, and more particularly to a bicycle warning device which is mounted on a predetermined position of the bicycle frame such that the warning device faces forward and backward in relation to the bicycle. The warning device is composed of at least two long strip like colored reflector-type display pieces, which are arranged alternately and provided respectively with a symbol, word, or figure capable of indicating the turning or braking motion of the bicycle. Each of the display pieces can be driven to move up and down by a pull rod which is located behind the display piece. The display pieces are capable of an alternate motion repeatedly to bring about a turning or braking signal so as to enhance the safety of the bicycle. 
     BACKGROUND OF THE INVENTION 
     The conventional bicycle warning devices in existence are generally grouped into two categories, which are described hereinafier. 
     The reflector is mounted on the bicycle such that the reflector is capable of reflecting the light existing in the environment so as to warn the operators of vehicles as well as the pedestrians. The reflector is incapable of providing a turning or braking signal. As a result, the bicyclist must use his or her hand to signal his or her intention to turn left or right. Without being equipped with a braking warning device, a bicycle is prone to cause a traffic incident at the time when the bicycle in motion is stopped without an advance warning. 
     Another kind of the warning device is composed of an electrically-driven light-emitting element, such as LED (light emitting diode). The operation of the warning device is controlled by a power source switch. 
     Such conventional warning devices as described above are defective in design in that they do not work effectively, and that their efficiency may be undermined by the poor working condition of the battery. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a bicycle warning device capable of providing a turning or braking signal to safeguard the bicycle in motion as well as the bicyclist. The warning device is mounted on a predetermined position of the bicycle such that the warning device faces forward and backward in relation to the bicycle. The warning device is composed of at least two long strip like colored reflector-type display pieces, which are arranged alternately and provided respectively with a symbol, word, or figure capable of indicating the turning or braking motion of the bicycle. Each of the two display pieces can be driven to move up and down by a pull rod which is located behind the display piece. The two display pieces are capable of an alternate motion repeatedly to bring about a turning or braking signal so as to enhance the safety of the bicycle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a first preferred embodiment of the present invention. 
     FIG. 2 shows a side schematic view of the first preferred embodiment of the present invention. 
     FIG. 3 shows an exploded view of a warning device of the first preferred embodiment of the present invention. 
     FIG. 4 shows the side schematic view of the first preferred embodiment of the present invention at work. 
     FIG. 5 shows a schematic view of a bicycle braking device. 
     FIG. 6 shows a partial sectional view of a turning signal operating structure of the present invention. 
     FIG. 7 shows a perspective view of the turning signal operating structure of the present invention as shown in FIG.  6 . 
     FIG. 8 shows a perspective of a second preferred embodiment of the present invention. 
     FIG. 9 shows a schematic view of the internal construction of the second preferred embodiment of the present invention. 
     FIG. 10 shows a side schematic view of the second preferred embodiment of the present invention at work. 
     FIG. 11 shows another side schematic view of the second preferred embodiment of the present invention at work. 
     FIG. 12 shows still another side schematic view of the second preferred embodiment of the present invention in action. 
     FIG. 13 shows an exploded view of a warning device of a third preferred embodiment of the present invention. 
     FIG. 14 shows a side schematic view of the third preferred embodiment of the present invention. 
     FIG. 15 shows a perspective view of a fourth preferred embodiment of the present invention. 
     FIG. 16 shows a schematic view of the in tern al construction o the fourth preferred embodiment of the present invention. 
     FIG. 17 shows a side schematic view of the fourth preferred embodiment of the present invention in action. 
     FIG. 18 shows an other side schematic view of the fourth preferred embodiment of the present invention in action. 
     FIG. 19 shows still another side schematic view of the fourth preferred embodiment of the present invention in action. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     As shown in FIGS. 1-4, a bicycle warning device embodied in the present invention is composed of component parts which are described hereinafter. 
     A main body  10  of a hollow box like construction is provided with at least one hollow receiving compartment which is provided in one side thereof with a present window  11 , a frame like fixed display plate  12 , and a plurality of thin first display pieces  13  which are made of a pliable material and are of a grating construction The first display pieces  13  are fastened with one side of the display plate  12  such that the first display pieces  13  face the window  11 , and that the first display pieces  13  are parallel to one another and are equidistantly located, and further that two adjoining display pieces  13  are separated by a gap  121 . 
     A movable display plate  14  is located between the fixed display plate  12  and two protrusions  17  of two opposite sides of the receiving compartment such that the movable display plate  14  is capable of moving up and down. The movable display plate  14  is provided in the rear side thereof with a pulled portion  16  opposite to one side of the fixed display plate  12 . The movable display plate  14  is provided with a plurality of thin second display pieces  15  which are made of a pliable material and are arranged equidistantly such that the width of a gap between two adjoining second display pieces  15  should not be greater that the gap between two adjoining first display pieces  13 , so as to enable the second display pieces  15  to be inserted into the gaps  121  in a superimposing manner. Each of the second display pieces  15  is marked with a turning or braking symbol  18  (as shown in FIG. 8) capable of reflecting light. The symbol  18  is similar in color to the first display piece  13  so as to be easily recognized. When the movable display plate  14  is located at a down position, the second display pieces  15  are longer than the first display pieces  13 . Before the second display pieces  15  are lifted, the upper ends of the second display pieces  15  can not be higher than the top ends of the first display pieces  13 , as shown in FIG.  2 . 
     The movable display plate  14  is provided in the back side thereof with a pulled portion  16  capable of being caused by a tension element P to bring about a tension action . As a result, both the pulled portion  16  and the tension element P have a simultaneous displacement effect, as shown in FIG.  1  . On the other hand, both the pulled portion  16  and the tension element P are capable of a sliding motion in relation to each other, thereby enabling the tension element P to cause the pulled portion  16  to bring about an up-and-down displacement effect, as shown in FIGS. 2 and 4. 
     The warning device of the present invention can be fastened with a bicycle frame or a bicycle handlebar such that another end of the tension element P is so extended to connect directly or indirectly with a brake cable  21  of the bicycle brake  20 , as shown in FIG.  5 . The tension element P can be also connected at another end thereof with the handlebar . The tension element P may be a brake cable or a cable for controlling the turning indicator. 
     As shown in FIG. 4, when the tension element P is pulled upwards, the movable display plate  14  and the second display pieces  15  are lifted such that the second display pieces  15  are no longer concealed by the first display pieces  13 , and that the second display pieces  15  are thus visible, and further that the first display pieces  13  are concealed by the second display pieces  15 . As a result, the symbols  18  of the second display pieces  15  are perceptible to the naked eye to attain the intended purpose . 
     The warning device of the present invention can be mounted in various directions or at various angles such that the first display pieces  13  and the second display pieces  15  can be caused to displace horizontally. 
     The embodiments of the present invention are provided with at least two tension elements P, one of which is a brake cable PB for controlling the braking signal, and other one of which is a turning cable PD of controlling the turning signal. 
     As shown in FIG. 5, the tension element P may be fastened with a braking device  20  such that the tension element is a brake cable PB which is located by a connection piece  22 . The brake cable PB and a brake line  21  are fastened by a fastening piece  23  so as to enable the brake cable PB and the brake line  21  to displace simultaneously. 
     As shown in FIGS. 6 and 7, the tension element P may be fastened with a switching seat  31  of the handlebar  30  such that the tension element is a turning cable PD. The switching seat  31  has a terminal  34  extending from the end of the turning cable PD, and a hollow receiving compartment  32 . The terminal is provided in other side with a push portion  35  capable of jutting out of the receiving compartment  32 , and a locating slot  33  located at the outlet of the receiving compartment  32 , so as to provide a retaining effect at the time when the push portion  35  of the turning cable PD is pushed. When the terminal  34  is pushed to displace, the second display pieces  15  are pulled by the turning cable PD to move up and down such that the symbols  18  can be seen to show the turning direction. 
     The locating slot  33  has a corrugated edge, which may be replaced with a plate like elastic piece or an equivalent body. 
     As shown in FIGS. 8 and 9, an embodiment of the present invention is provided with “braking”, “left turn”, and “right turn” signaling effects which are operated separately. In other words, the main body  10  consists of a fixed display plate  12 , a movable display plate  14 , and the first display pieces  13  and  15  having symbols  18 , which are operated independently . The display pieces, which are marked with the symbol  18  “braking”, the symbol  18  “left turn”, the symbol  18  “right turn ”, are independent of one another . The main body  10  is provided with the braking effect and is located at the center of the vehicle body The main body  10  which is provided with “left turn”, is located at the left side of the vehicle body, whereas, the main body  10 , which is provided with “right turn”,is located at the right side of the vehicle body. 
     In addition, the movable display plate  14  is provided in the rear side thereof with a transmission device comprising: 
     a right turn connection rod  40  located horizontally on the rear side of the movable display plate  14  and fastened with the main body  10  by a shaft  41  such that the connection rod is capable of swinging only from another end, and that the movable end thereof is provided with a pull rod  43  capable of driving the movable display plate  14  to move up and down. The turning cable PD is provided with a spring  61  to provide a pressing effect. Located in proximity of the movable end is a retaining portion  81  capable of keeping the right turn connection rod  40  on a horizontal position. The right turn connection rod  40  is capable of an upward reciprocating motion only from the position of the retaining portion  81 ; 
     a left turn connection rod  50  located horizontally on the rear side of the movable display plate  14  and located in proximity of the central position of the underside of the right turn connection rod  40 . The left turn connection rod  50  is located on the main body  10  by a shaft  51  such that both ends of the left turn connection rod  50  are capable of swinging in a reciprocating manner. The left turn connection rod  50  is provided with a pull rod  52  corresponding in direction to the shaft  41  and capable of driving the corresponding movable display plate  14  to move up and down. The left turn connection rod  50  is further provided at other end thereof with a retaining portion  81  capable of keeping the left turn connection rod  50  to remain at the horizontal state. The pull rod  52  end of the left turn connection rod  50  is capable of an upward reciprocating motion only from the position of the retaining portion  81 ; 
     a turning cable PD traversing between the retaining portions  81  of the left turn connection rod  40  and the right turn connection rod  50 , and capable of moving in relation to each other. The turning cable PD is provided between the two connection rods  40  and  50  with an urging portion  60  of a spherical columnar construction, and is further provided respectively at the opposite back sides of the two connection rods  40  and  50  with a compression spring  61  and a retrieval spring  611 . When the turning cable PD is moved up and down repeatedly, the two connection rods  40  and  50  are caused to bring about an upward urging motion or a downward urging motion. The compression spring  61  and the retrieval spring  611  serve to enable the two connection rods  40  and  50  to return to their original position after the two connection rods  40  and  50  have displaced upwards or downwards; 
     a braking connection rod  70  located horizontally between the two connection rods  40  and  50 , with one end thereof being pivoted to a shaft  71  which is connected with the main body  10 , with another end thereof being capable of turning upwards and downwards freely . The movable end is fastened with the main body  10  by a retaining portion  81  for confining the connection rod  70  to move upward from the horizontal position by a fixed end thereof serving as an axis. The movable end is provided with a pull rod  72  for controlling the up-and-down motion of the movable display plate  15  so as to bring about the warning effect of the symbols  18  indicating the braking state. 
     A brake cable PB has one end longitudinally engaged with a midsection of the braking connection rod  70  such that they are capable of moving in relation to each other. The brake cable PB has another end is extended to connect with the braking device  20  such that the brake cable PB is capable of acting along with the brake shoes at the same time. The brake cable PB is provided at the lower side thereof with an urging portion  60  of a spherical columnar construction, by means of which the braking connection rod  70  is caused to swing up and down when the brake cable PB is moved up and down repeatedly. The pull rod  72  of the end thereof causes the movable display plate  15  to move up and down to attain the warning effect of the symbols  18  indicating the braking state; 
     In addition, the braking connection rod  70  is provided with a compression spring  61  for enabling the movable display plate  15  to return to its original position after the movable display plate  15  has moved upwards. 
     The aforementioned springs  61  and  611  may be replaced with a plate like spring or similar elastic element. 
     For the combination of the components described above, please refer to FIGS. 9 and 10 . When the bicycle is moving forward, the terminal  34  of the end of the turning cable PD may be located at the center of the locating slot  33  of the switching seat  31  such that the left turn connection rod  50  and the right turn connection rod  40  are in a horizontal and stationary state. 
     If a left turn is desired, the push portion  35  of the switching seat  31  of the handlebar  30  is activated to push the terminal  34  to displace leftwards, thereby resulting in the downward displacements of the turning cable PD and the urging portion  60  which forces the left turn connection rod  50  to turn clockwise on the shaft  51  acting as an axis. The pull rod  52  of another end acts to cause the movable display plate  14  to move upwards, thereby causing the second display pieces  15  to be free from the obstruction of the first display pieces  13  . As a result, the second display pieces  15  are visible such that the first display pieces  13  are concealed by the second display pieces  15 , and that the second display pieces  15  can be seen through the window  11  such that the symbols  18  of the second display pieces  15  are seen to indicate “left turn”. 
     In order to eliminate the “left turn” signal, the above-mentioned operation is carried out in reverse such that the movable display plate  14  and the second display pieces  15  are caused to displace downwards, and that the second display pieces  15  are once again concealed by the first display pieces  13  . 
     As shown in FIG. 11, a right turn signal can be initiated by activating the push portion  35  of the switching seat  31  of the handlebar  30  such that the terminal  34  is displaced rightwards, and that the turning cable PD and the urging portion  60  are displaced upwards together, thereby resulting in the urging portion  60  to urge upwardly the right turn connection rod  40  such that the right turn connection rod  40  is caused to turn counterclockwise on the shaft  41  acting as an axis, and that the pull rod  43  of the movable end thereof pulls the movable display plate  14  to move upwards , and further that the second display pieces  15  are no longer concealed by the first display pieces  13  . As a result, the symbols  18  of the second display pieces  15  are seen through the window  11  to indicate “right turn”. 
     The “right turn” signal described above can be eliminated by carrying out the above-described operation in reverse such that the movable display plate  14  and the second display pieces  15  are caused to displace downwards, and that the second display pieces  15  are once again concealed by the first display pieces  13  . 
     When the “turning” operation is at work, the components in connection with the “braking” operation do not take part in the “turning” operation. 
     As shown in FIG. 12 in conjunction with FIG. 5, the operation of the braking signal can be activated by triggering the braking device  20  such that the brake line  21  is pulled upwardly to result in the upward displacement of the braking cable PB. In the meantime, the braking connection rod  70  is urged by the urging portion  60  to swing upwards such that the pull rod  72  is at work to pull the movable display plate  14  to displace upwards, and that the second display pieces  15  are no longer concealed by the first display pieces  13  . As a result, the symbols  18  of the second display pieces  15  are visible through the window  11  to indicate “braking”. 
     The “braking” signal described above can be cancelled by carrying out the above-described operation in reverse such that the movable display plate  14  and the second display pieces  15  are displaced downwards, and that the second display pieces  15  are once again concealed by the first display pieces  13 . 
     As shown in FIGS. 13 and 14, the strip like first display pieces  13  and the strip like second display pieces  15  may be of an arcuate construction and superimposed alternately to form a sect oral object which is provided at the center thereof with a rotary shaft  44  which is in turn fastened with the main body  10 . As a result, the movable display plate  14 , which is located behind the fixed display plate  12 , is capable of turning in the main body  10  such that the second display pieces  15  of the movable display plate  14  are capable of being seen or being concealed by the first display pieces  13  which are in the state of being superimposed alternately. 
     As shown in FIG. 13-19, the present invention is provided with arcuate first and second display pieces  13  and  15 , which are superimposed alternately to form a sectoral object which is provided at the circle center thereof with a rotary shaft  431 ,  44  fastened with the main body  10  for operating separately “braking signal”, “left turn signal”, and “right turn signal”. In other words, the symbols  18  of the first display pieces  13  and the second display pieces  15  of the fixed display plate  12  and the movable display plate  14  are independently marked with “braking”, “left turn”, and “right turn”. The control receiving compartment having the braking effect is located at the center of the main body  10 , whereas the semicircular control receiving compartment having the “left turn” signal is located at the left side of the main body  10 . The semicircular control receiving compartment having the “right turn” signal is located at the right side of the main body  10 . 
     In other to attain the alternate display effect of the above-mentioned first and second display pieces  13  and  15 , the present invention is provided with a transmission device which is located behind the movable display plate  14  connected with the second display pieces  15  . The transmission device consists of components which are described hereinafter. 
     A right turn connection rod  40  is located horizontally behind the movable display plate  14  and is fastened at the left end thereof with the main body  10  by a shaft  41  . The right turn connection rod  40  is provided at another end thereof with a pull rod  43  which is pivoted to a pulled portion  16  located behind the movable display plate  14 . The right turn connection rod  40  is capable of swiveling on the shaft  41  acting as an axis. A turning cable PD is provided between the main body  10  and the right connection rod  40  with a spring  61  capable of pressing the right turn connection rod  40  . The turning cable PD is further provided with an urging portion  60  capable of urging upwardly the right turn connection rod  40  . Located under the right turn connection rod  40  and the movable end is a retaining portion  81  for keeping the right turn connection rod  40  to remain in the horizontal state. The right turn connection rod  40  is capable of moving upwards in a reciprocating manner only from the position of the retaining portion  81  . 
     A rotary shaft  431  is fastened pivotally with the main body  10 . The movable display plate  14  and the second display pieces  15  are capable of swinging up and down on the rotary shaft  431  acting as an axis. 
     A left turn connection rod  50  is located horizontally behind the movable display plate  14  and is fastened at the midsection thereof with the main body  10  by a pivot  51  . The left turn connection rod  50  is provided at the outer end thereof with a pull rod  52  which is pivoted to a pulled portion  16  located behind the movable display plate  14 . The left turn connection rod  50  is capable of swiveling on the pivot  51  and is connected with a turning cable PD corresponding in location to another movable end of a pulling member  441  such that the upper side is pressed by the urging portion  60 , and that the lower side is provided with a retrieval spring  611  which is fitted over the turning cable PD for urging the left turn connection rod  50  upwardly. The left turn connection rod  50  is capable of driving the movable display plate  14  to swing up and down in a reciprocating manner by means of its pull rod  52 , so as to bring about the left turn signalling effect. 
     Located at one side of the movable end of the left turn connection rod  50  is a retaining portion  81  for confining the pull rod  52  of the left turn connection rod  50  to remain in the horizontal state and to move upwardly in a reciprocating manner, so as to bring about the left turn signalling effect. 
     A turning cable PD is located longitudinally between the left and the right connection rods  40  and  50 , which are capable of moving in relation to each other . When the turning cable PD is moved up and down in a reciprocating manner, the left and the right turn connection rods  40  and  50  are urged upwards or downwards for bringing about the signalling effect of the symbols  18  . The left and the right turn connection rods  40  and  50  are provided with a compression spring  61  and a retrieval spring  611  for enabling the connection rods  40  and  50  to return to their original positions after the connection rods  40  and  50  have been displaced upwardly or downwards. 
     A braking cable PB has one end which is longitudinally put through the midsection of the braking connection rod  70 . The brake cable PB has another end which is connected with the braking device  20  . Located under the brake cable PB is a spherical columnar urging portion  60  capable of moving up and down to bring about the up-and-down motion of the braking connection rod  70 . A pull rod  72  is inserted into the pulled portion  16  of the movable display plate  14  for urging the movable display plate  14  to bring about the effect of braking signal of the symbols  18  . 
     The braking connection rod  70  is fitted into a compression spring  61  for pushing the right turn and the left turn connection rods  40  and  50  to move up or down for attaining the left turn signalling and the right turn signalling of the symbols  18  . The connection rods  40  and  50  are capable of returning to their original position after the upward displacement or the downward displacement, thanks to the compression spring  61  and the retrieval spring  611 . 
     A braking cable PB has one end which is longitudinally put through the midsection of the braking connection rod  70 . The brake cable PB has another end which is connected with the braking device  20 . Located under the brake cable PB is a spherical columnar urging portion  60  capable of moving up and down to bring about the up-and-down motion of the braking connection rod  70 . A pull rod  72  is inserted into the pulled portion  16  located at the rear side of movable display plate  14  for urging the movable display plate  14  to bring about the braking signalling effect of the symbols  18 . 
     The braking connection rod  70  is fitted into a compression spring  61  which acts to enable the movable display plate  15  to return to an original position thereof after the movable display plate  15  is displaced upwardly. 
     As shown in FIGS. 5-7, when the bicycle is cruising, the terminal  34  of the end of the turning cable PD is located at the center of the locating slot  33  of the switching seat  31  so as to keep the left turn and the right turn connection rods  40  and  50  to remain almost in the horizontal and stationary state. 
     As shown in FIGS. 15,  16  and  19 , the effect of the braking signalling is brought about whenever the braking device  20  is triggered in view of the fact that the brake line  21  is pulled upwards, and that the braking cable PB is actuated to displace upwards, and further that the braking connection rod  70  is urged to swing upwards by the urging portion  60 . As a result, the second display pieces  15  of the movable display plate  14  are no longer concealed by the first display pieces  13  and can be seen through the window  11 , thereby bringing about the braking signalling effect of the symbols  18  of the second display pieces  15  . 
     The braking signal can be cancelled by carrying out the above operation in reverse such that the movable display plate  14  and the second display pieces  15  are displaced downwards, and that the second display pieces  15  are once again concealed by the first display pieces  13  . When the braking signalling effect is brought about, the mechanism of turning signalling remains inactive. 
     As shown in FIGS. 6,  7 ,  13 ,  16 , and  18 , when the urging portion  35  of the switching seat  31  of the handlebar  30  is activated to push the terminal  34  to displace rightwards, the turning cable PD and the during potion  60  are urged to move upwards such that the right turn connection rod  40  is pushed by the urging portion  60  to turn counterclockwise on the shaft  41  acting as an axis. In the meantime, the pull rod  43  of the movable end pulls the movable display plate  14  upwards, thereby resulting in the second display pieces  15  of the movable display plate  14  being visible through the window  11 , . As a result, the right turn signalling effect is brought about. 
     The right turn signalling effect can be cancelled by carrying out the above process in reverse such that the movable display plate  14  and the second display pieces  15  are displaced downwards, and that the second display pieces  15  and the symbols  18  are once again concealed by the first display pieces  13  . 
     As shown in FIGS. 6,  7 ,  13 ,  16 , and  19 , the left turn signalling effect is brought about by activating the push portion  35  of the switching seat  31  of the bicycle handlebar  30  such that the terminal  35  is displaced leftwards, and that the turning cable PD and the urging portion  60  are displaced downwards and further that the left turn connection rod  50  is pushed downwards by the urging portion  60 . As a result, the pulled portion  16  of the movable display plate  14  is actuated by the pull rod  52  such that the movable display plate  14  and the second display pieces  15  are caused to turn clockwise on the rotary shaft  44  acting as an axis, and that the second display pieces  15  are no longer concealed by the first display pieces  13  so as to be visible through the window  11 . The left turn signal formed by the combination of the symbols  18  of the second display pieces  15  is thus visible through the window  11 . 
     The left turn signal can be cancelled by carrying out the above process in reverse such that the movable display plate  14  and the second display pieces  15  are displaced downwards, and that the second display pieces  15  are once again concealed by the first display pieces  13  . 
     When the left turn signalling effect or the right turn signalling effect is brought about, the braking signalling mechanism remains inactive . 
     The embodiments of the present invention have been tested in the field, with the test results being far superior to those of the prior art devices. The present invention has advantages which are described hereinafter . 
     The present invention can be operated manually without electricity and is simple in construction and cost-effective. 
     The present invention eliminates the old-fashioned hand signalling which is often hazardous to the safety of a bicyclist . The present invention allows the bicyclist to operate the bicycle with both hands even when the bicycle is about to make a turn . 
     The braking signal warning device can be operated easily and separately from the braking action. The warning symbols of the first and the second display pieces may be colored differently or provided with a reflective quality to enhance the signalling effect as well as the safety of the operator of the vehicle . 
     The turning signal warning device of the present invention can be easily operated with one finger of the operator hand.