FIELD OF THE INVENTION

This invention relates to an automatic surgical lan¬ cet device. BACKGROUND OF THE INVENTION

Various automatic surgical lancets have been pro¬ posed which have a lancet needle on the free end of a pivoted arm which is moved by spring force from a retract¬ ed, cocked position to an operating position in which the needle pricks a person's finger to yield a blood sample. Typically, the arm is released from its cocked position by the pressure of a finger different from the finger that will be penetrated by the lancet needle.

U.S. patent application Serial No. 06/930,516, filed November 14, 1986, by one of the co-inventors herein, discloses a disposable, single-use lancet in which the cocked arm carrying a lancet needle assembly inside the housing is released by the force of a patient's finger that is to be pricked by the lancet needle. SUMMARY OF THE INVENTION

The present invention is directed to a novel automa¬ tic lancet designed for repeated uses and having a novel arrangement for releasing the cocked arm, which carries a lancet needle assembly on the outside of the housing, in response to the force of the patient's finger that is to be pricked by the lancet needle.

Another object of this invention is to provide a reusable automatic lancet device having a novel arrange-

ment for preventing an inadvertent release of the cocked arm which carries the lancet needle.

Preferably, the present automatic lancet device has a pivoted pressure lever inside its housing which is ar- ranged to hold a lancet needle-carrying arm in a raised, cocked position as long as the lever is down. The lever is held down by a slidably displaceable ejector, which is prevented from releasing the lever by a pivoted ejector lock arm above and a slidable and pivoted ejector lock bar behind it. The ejector lock bar also holds the arm cocked. The ejector lock arm releases the ejector when an apertured finger rest for the patient's finger is in¬ serted into a slot in the pressure lever from in front of the housing. This permits the ejector to be slid back, pushing the ejector lock bar back so that it releases the cocked arm. When the patient's finger presses up against the finger rest in front of the housing, this pivots the pressure lever in a direction to release the cocked arm. The arm moves down quickly from its cocked position and the lancet needle penetrates the patient's finger which is pushing up on the finger rest. Afterwards, the finger rest may be removed by sliding the ejector forward.

Further objects and advantages of this invention will be apparent from the following detailed description of a presently-preferred embodiment shown in the accompanying drawings. DESCRIPTION OF THE DRAWINGS

Figure 1 is a side elevation of the present automatic lancet device; Figure 2 is a front elevation taken from the left side of Figure 1;

Figure 3 is an exploded perspective view showing most of the moving parts in the lancet device;

Figure 4 is a longitudinal section showing the posi- tions of the parts before the lancet device is used;

Figure 5 is a perspective view of a manually insert- able and removable finger rest for the lancet device;

Figure 6 is a view like Figure 4, showing the posi¬ tions of the parts when the finger rest is partially but not fully inserted;

Figure 7 is a similar view showing the finger rest fully inserted;

Figure 8 is a fragmentary vertical cross-section taken along the line 8—8 in Figure 7;

Figure 9 is a longitudinal section taken along the horizontal line 9—9 in Figure 7; Figure 10 is a vertical cross-section taken along the line 10—10 in Figure 7;

Figure 11 is a view like Figures 6 and 7, showing the needle-carrying arm moved down from its cocked posi¬ tion (shown in phantom) to its operating position in which the needle penetrates a patient's finger;

Figure 12 is a side elevation, with part of the hous¬ ing of the device broken away, showing the needle-carrying arm raised to its cocked position;

Figure 13 is a similar view showing the finger pad being ejected after the lancet device has operated;

Figure 14 is a top plan view of the pressure lever in this lancet device;

Figure 15 is a side elevation of this pressure lever, with part of it in section, and with the finger rest eject- or in phantom;

Figure 16 is a vertical cross-section taken along the line 16—16 in Figure 15;

Figure 17 is a similar view taken along the line 17—17 in Figure 15; Figure 18 is a bottom plan view of the pressure lever; Figure 19 is a perspective view of the pressure lever with parts broken away for clarity.

Before explaining the disclosed embodiment of the present invention in detail it is to be understood that the invention is not limited in its application to the details of the particular arrangement shown since the invention is capable of other embodiments. Also, the terminology used

herein is for the purpose of description and not of limita¬ tion. DETAILED DESCRIPTION

In broad outline, the embodiment of the invention shown in the drawings has a housing 10 (Figure 1) , and ejector 20 (Figure 3) slidably mounted on the bottom of the housing, a pressure lever 30 pivotally mounted in the housing above the ejector (Figure 4) and having its front end projecting outside the housing, an ejector lock arm 70 slidably and pivotally mounted in the housing on the same pivot as pressure lever 30, an ejector lock arm 95 pivotal¬ ly mounted on the pressure lever, a plastic spring 110 which biases the ejector lock arm 95 down against the pres¬ sure lever, a lancet holder arm 120 pivotally mounted in the housing and carrying a holder 138 for a lancet needle assembly on its free end in front of the housing, a spring 127 for moving the arm down, and a finger rest 145 (Figure 5) which is slidably insertable into and removable from the pressure lever 30 at the front of the housing. Referring to Figure 1, the housing 10 of the lancet has a flat vertical back wall 11, a flat horizontal bottom wall 12 extending perpendicular to the back wall, and a convex wall 13 at the top which, as shown in Figure 4, extends forward and then downward from the upper end of the back wall. Housing 10 has flat opposite side walls 14 and 15 (Figures 8 and 9) and it is open at the front below the lower edge 13a (Figure 4) of its convex top wall 13. As shown in Figure 9 , the back wall 11 is molded integral with side wall 15, and this is also true of the bottom wall 12 and the top wall 13. Side wall 14 is a separately molded piece which is attached to the other piece 11-12-13-15 of the housing by screws. Approximately the front half of the bottom wall 12 is recessed immediately behind side wall 14 to provide a narrow slot 12a (Figure 10) which ex- tends from the bottom front corner of the housing back along the bottom wall. As shown in Figure 8, a cylindri¬ cal upper pin 16 and a cylindrical lower pin 17 extend in¬ ward from the housing side wall 15 and terminate a short

distance from the opposite side wall 14. These pins are aligned vertically, as shown in Figure 7.

As best seen in Figure 3, the ejector 20 has a flat bottom segment 21 with a serrated outside face 22, a short vertical side segment 23 which extends up from the bottom segment 21 at the side of the ejector closest to the hous¬ ing side wall 14, and a flat intermediate segment 24 which extends in from the top of side segment 23 parallel to the bottom segment 21 to form a recess 25 of rectangular cross-section which extends the full length of the ejector and is open at its opposite ends. Thus, the segments 21,23 and 24 of the ejector form a channel which is slidable along the bottom wall 12 of the housing where it has the slot 12a. As shown in Figure 10, the side segment 23 of the ejector is slidably received in slot 12a, with the intermediate segment 24 of the ejector slidably engaging the housing bottom wall 12 from above and the bottom seg¬ ment 21 of the ejector closely below the housing bottom wall. Referring again to Figure 3, the ejector 20 has a vertical post segment 26 of rectangular cross-section ex¬ tending up from the intermediate wall 24 at its front end. At the top of this post segment 26 is a generally T-shaped top element having a pair of rectangular legs 27 and 28 extending out on opposite sides of post segment 26 (toward the respective side walls 14 and 15 of housing 10, as shown in Figure 10) and a front segment 29 of rectangular cross- section extending forward beyond the front edge of the ejector at its segments 26,24,23 and 21. Toward its back end (the right end in Figure 3) , the horizontally elongated pressure lever 30 has a longitudinal slot 31 which is open at the top and closed at the bottom. This slot separates opposite longitudinal legs 32 and 33 along the top of the pressure lever. These legs are joined integrally along the bottom of the pressure lever. A transverse end segment 34 extends up from leg 32 at its back end in Figure 3, presenting a flat front face 35

which extends upward and forward at a 70 degree angle to the longitudinal axis of the pressure lever and a convex outer face 36 at the top which forms a sharp corner at 37 with the flat front face 35. The other leg 33 has an identical transverse end segment 38 with a flat front face 39 and a convex outer face 40 at the top which intersects the inside face at a sharp corner 41.

About midway along the pressure lever 30 on the out¬ side of the lever its longitudinal leg 32 is joined to a generally U-shaped segment 42 which defines an open- topped recess having a round bottom surface 43 between upwardly diverging, opposite, flat, rear and front side faces 44 and 45. Between this recess and the longitudinal slot 31 the pressure lever presents a rounded ear 46 hav- ing a circular opening 46a for receiving the lower pivot pin 17 on the housing. The longitudinal slot 31 is open at the bottom, as well as at the top, at the location of the U-shaped segment 42 and ear 46 and a short distance in front of and behind these elements lengthwise of the pres- sure lever, as shown at 31a in Figures 14 and 18.

The opposite side of pressure lever 30, where the longitudinal leg 33 is located, has an identical generally U-shaped segment extending from leg 33 and defining a re¬ cess 47 on the outside of the lever, and a rounded ear 48 next to the longitudinal slot 31 in the lever. Ear 48 has a circular opening 48a coaxial with the opening 46a in the ear 46 on the opposite side of slot 31 for receiv¬ ing the lower pivot pin 17.

Beginning a short distance in front of the pivot ears 46 and 48 (to the left in Figure 3) , the longitudinal slot in pressure lever is open at the top and closed at the bot¬ tom, as shown at 31b in Figures 14 and 15. The pressure lever presents an internal, vertical, rearwardly-facing shoulder 31' at the intersection of its slot segments 31a and 31b. An inclined top surface 49 in front of recess 47 in Figures 3,15 and 19 extends forward and upward at a slight angle to a horizontal top surface 50 which extends

forward the remaining length of the pressure lever. An identical inclined surface 51 extends up from the recess defined by the generally U-shaped segment 42 on the oppo¬ site side of the pressure lever. Next to the longitudinal slot segment 31b and laterally inward from the inclined surfaces 51 and 49, the pressure lever presents horizontal top faces 52 and 53 extending forward from the respective ears 46 and 48 at the same level as the top faces of legs 32 and 33 on the back side of the pivot ears 46 and 48. As shown in Figure 3, the top face 53 ends at a vertical face 54, which extends up to the back edge of top surface 50. A similar vertical face 55 (Figure 14) extends from the front end of top face 52 up to top face 50 on the op¬ posite side of the longitudinal slot in pressure lever 30. The longitudinal slot segment 31b in front of the pivot ears 46 and 48 has a horizontal bottom face 56 (Figs. 15 and 19) at the same level as the coaxial centers of the pivot pin openings 46a and 48a in these ears. Slot seg¬ ment 31b extends forward beyond the vertical faces 54 and 55 to the back end of a horizontal slot 58 of rectangular cross-section (Fig. 17) . Slot 58 is offset upwardly from the bottom face of slot segment 31b, as shown in Figure 15. Slot 58 extends forward through the front part of the pres¬ sure lever to a vertical front face 59 of the pressure lever (Figure 3) below a forwardly projecting extension or lip 60 on the front end of the pressure lever.

Directly below slot 58 the pressure lever 30 has a slot of generally T-shaped configuration (Fig. 18) , with the cross arm 61 at the back end of the T extending the full width of slot 58 at its back end and the longitudinal arm 62 of the T extending forward from the cross arm 61 centrally below slot 58 for substantially less than the full width of slot 58. The T-slot 61,62 is open its en¬ tire extent along the bottom of the pressure lever, and at the top it opens into the slot 58 above. At its inter¬ section with the narrower longitudinal arm 62 of the T-slot (Fig. 17) , the slot 58 provides a pair of upwardly-facing

horizontal surfaces 63 and 64 on opposite sides of the T slot. The front end of the longitudinal arm 62 of the T slot is at a vertical internal face 65 (Figs. 15, 18 and 19) spaced behind the front face 59 of the pressure lever. A short distance in front of this face 65, the pres¬ sure lever has a front top opening 66 (Figures 3 and 15) of elongated rectangular shape which extends down into the slot 58, as shown in Figure 16.

The pressure lever has two rear top openings 67 and 68 of rectangular shape which extend down into slot 58 immediately in front of the cross arm 61 of the T slot in the bottom of the pressure lever.

Figure 15 shows in phantom the ejector 20 in the posi¬ tion on the pressure lever 30 in which it permits pivotal movement of the ejector lever on the lower pivot pin 17. In this position of the parts, the post segment 26 of the ejector is centered in the cross arm 61 of the T slot 61, 62 in the bottom of the pressure lever, the lugs 27 and 28 on the top of the ejector are slidably received in slot 58 above the cross arm 61 of the T slot, and the front segment 29 at the top of the ejector is received centrally in slot 58 directly above the narrower longitudinal arm 62 of the T-slot. The front top segment 29 of the ejector is slightly narrower than the longitudinal arm 62 of the T-slot, per- mitting pressure lever 30 to pivot upward in front of its pivot pin 17.

When the ejector 20 is displaced forward from the position shown in Figures 14-16 its top lugs 27 and 28 slide across the bottom surfaces 64 and 63 of slot 58 on opposite sides of the narrower longitudinal arm of T-slot 61,62, so now the pressure lever cannot move pivotally be¬ cause the ejector 20 (which is coupled at its slot 25 to the bottom wall 12 of the housing, as shown in Figure 10) prevents it. Referring to Figure 3, the ejector lock bar 70 has an oblong, horizontally elongated, rounded opening 71, which slidably passes the lower pivot pin. The vertical dimension

of this opening is substantially equal to the diameter of each pivot ear opening 46a and 48a in pressure lever 30. The horizontal dimension of opening 71 in the ejector lock bar is substantially greater than the diameter of openings 46a and 48a in the ^' pressure lever, so that the ejector lock bar can be slid horizontally back and forth across the lower pivot pin 17.

At the top, the ejector lock bar 70 presents an up¬ wardly extending projection 72 having a vertical rear face 73 aligned with the center of its opening 71, a short horizontal top face 74 extending forward from the rear face 73, and a forwardly and downwardly inclined, flat front face 75.

In front of the projection 72 the ejector lock bar has a horizontally elongated front leg 76 with a flat horizontal top face 77 extending forward from the in-= clined face 75, and a short vertical surface 78 extending down from the front end of face 77 to a forwardly extend¬ ing horizontal top face 79. A convex front surface 80 of the ejector lock bar curves downward and rearward from the front edge of top face 79 and merges smoothly with a flat elongated bottom face 81, which lies in the same horizontal plane as the center of opening 71.

Below the opening 71, the ejector lock bar presents a convex oblong segment 82.

In back of the opening 71, the ejector lock bar has an elongated, horizontal bottom face 83 which is coplanar with its bottom face 81 in front of the opening. At its back end the ejector lock bar presents an upwardly ex- tending, forwardly inclined projection 84 which forms a convex bottom rear corner 85 with the bottom surface 83. Projection 84 presents a convex top surface 86 which ex¬ tends forward to a downwardly and rearwardly inclined, flat front face 87 lying in a plane at 70 degrees to the longitudinal axis of the ejector lock bar.

In front of its rear projection 84 the ejector lock bar presents an elongated, flat top face 88 lying in the

same horizontal plane as the top face 77 in front of opening 71. Face 88 extends forward along the ejector lock bar to a rounded rearwardly-facing shoulder 89 which joins it to a short horizontal top face 90 extend- ing forward to the lower end of vertical face 73.

The ejector lock bar 70 fits snugly but slidably in the longitudinal slot 31 in pressure lever 30, with the back end projection 84 of the ejector lock bar between the back end segments 34 and 38 of the pressure lever, the bottom face 83 on the back part of the ejector lock bar resting on the bottom of slot 31 in the pressure lev¬ er behind the lower pivot pin 17, as shown in Figure 4, the bottom face 81 on the front part of the ejector lock bar resting on the bottom face 56 of slot segment 31b in the pressure lever in front of pivot pin 17, the oblong opening 71 in the ejector lock bar registering with the pivot ear openings 46a and 48a in the pressure lever, and the projection 72 on top of the ejector lock bar above its opening 71 extending up above the top of the pivot ears 46 and 48 on the pressure lever.

The ejector lock bar 70 is slidable across the lower pivot pin 17 lengthwise of the pressure lever 30 between a forward position (Figures 4,6 and 7) and a rearward position (Figure 11) . In its forward position the rounded front end 80 of the ejector lock bar extends in to the back end of slot 58 in the pressure lever directly above cross arm of the T-slot 61,62 in the bottom of the pres¬ sure lever. In its rearward position the front end of the ejector lock bar is behind the slot 58 in the pressure lever.

The ejector lock arm 95 (Fig. 3) has a horizontally elongated front segment 96 of rectangular cross-section with a depending lug 97 at its front end, which is receiv¬ able in the front top opening 66 in pressure lever 30, and a pair of laterally spaced, depending rear lugs 98 and 99 (Fig. 9) , which are receivable in the rear top openings 67 and 68 in the pressure lever. The front lug 97 has a rearwardly. and downwardly inclined front face 100

and a vertical back face 101. The rear lug 98 has a vertical front face 102 and a rearwardly and upwardly inclined back face 103. The other rear lug 99 is iden¬ tical to lug 98. At its back end the ejector lock arm 95 presents a pair of laterally spaced downwardly extending, generally U-shaped segments 104 and 105. Laterally inward from these U-segments the ejector lock arm presents longitudi¬ nal, straight, top segments 106 and 107, which are con- tinuations of its front segment 96. The ejector lock arm is open at 108 between the straight segments 106 and 107. At the extreme back end of the ejector lock arm, its U- segments 106 and 107 are connected at the top by a cross- piece 109. The bottom curvature of the U-segments 104 and 105 of ejector lock arm 95 is approximately complementary to the recesses in pressure lever 30 outside its pivot ears 46 and 48 such that the two parts fit snugly together but each can pivot a limited angular amount with respect to the other about the axis of the lower pivot pin 17.

The top opening 108 at the back end of the ejector lock arm 95 receives the projection 72 on the top of the ejector lock bar 70, as shown in Figure 4.

The plastic spring 110 has a ring 111 on its back end which receives the upper pin 16 on the inside of the hous¬ ing with a tight fit to mount the spring on this pin. A rear lug 112 extends down from ring 111 into the top rear opening 108 in ejector lock arm 95 behind the top projec¬ tion 72 on ejector lock arm 70, as shown in Figure 4. The plastic spring 110 presents an elongated flexible and resilient front arm 113 extending horizontally in front of its rear ring 111. A front lug 114 extends down from arm 113 and engages the top of the front segment 96 of ejector lock arm 95, as shown in Figure 4. In front of this lug the plastic spring presents a slightly curved extension 115 of its arm 113. Extension 115 is concave on the top and convex on the bottom.

As shown in Figure 4, the spacing between the verti¬ cal back face 101 of the depending front lug 97 on ejector lock arm 95 and the vertical front face 102 of its rear lug 98 and the coplanar front face of its other front lug 99 is greater than the length of ejector 20 along the top 27,28 and 29. Therefore, when the ejector lock arm 95 is down, the ejector 20 can be positioned anywhere between the stops provided by these lugs on the bottom of the ejector lock arm. Throughout this limited range of positions of ejector 20 from front to back on the housing, its top lugs 27 and 28 overlie the internal upwardly facing surfaces 63 and 64 (Figure 17) of the pressure lever 30 at the bottom of its slot 58. Thus, throughout this limited range of positions of ejector 20, which can be called its "normal position", it locks the pressure lever 30 against pivotal movement.

The lancet holder arm 120 has an elongated straight seg¬ ment 121 extending forward from a generally cylindrical segment 122, which defines a cylindrical opening 123 for slidably receiving a rear pivot pin 124 (Fig. 4) located inside the housing behind and above the upper pin 16 on which spring 110 is mounted. A vertical ear 125 projects up from the cylindrical segment 122 of the lancet holder arm and presents an opening 126 for anchoring the lower end of a coil spring 127 (Figure 4) whose upper end is fastened to the inside of the housing at 128. Spring 127 is under tension.

Behind its cylindrical segment 122 the lancet holder arm has a rear segment 129 with a flat top face 130 in the same horizontal plane as the axis of the opening 123, a tapered top rear face 131 which is inclined downward and rearward from the back edge of top face 130, a convex bot¬ tom rear face 132 which curves downward and forward from a sharp corner 133 with face 131, and a flat bottom face 134 extending forward from the curved face 132 and merging smoothly with the bottom of cylindrical segment 122.

Referring to Figures 4 and 7, the position and curva-

ture of the convex bottom rear face 132 of lancet holder arm 120 are such that it slides across the curved top rear faces 36 and 40 of pressure lever 30 and the curved top rear face 86 of ejector lock bar 70 when the lancet holder arm is raised from its normal, substantially hor- zontal position in which spring 127 extends vertically and has its shortest length (Fig. 4) to a cocked position (Figure 7) in which it is raised clockwise to a position in which spring 127 is at an angle to the vertical and is stretched more. In this cocked position, the tapered top rear face 131 of lancet re¬ tainer arm ^' 120 engages the inclined faces 35 and 39 of pressure lever 30 and the similarly inclined face 87 of ejector lock bar 70.

At the front end of its elongated segment 121 the lancet holder arm 120 presents in succession a short, down- war ly extending vertical segment 135, a downwardly offset, forwardly extending, horizontal, bottom segment 136, and an upwardly and forwardly inclined segment 137 joined to a holder 138 for a lancet needle assembly. When the lancet holder arm 120 is in its normal lowered position (Fig. 4) its downwardly offset bottom segment 136 rests on top of the front end extension 115 of the plastic spring 110.

Preferably, the holder 138 is constructed substan¬ tially as described in U.S. patent 4,658,621 to Daniel J. Chiodo, et al for receiving a lancet needle assembly, shown at 139 in Figure 6, and a plunger 140 for pushing the lancet needle assembly out of holder 138 after use.

The finger rest 145 (Fig. 5) is a generally flat body having a wide front segment 146 and a narrow rear segment

147 extending behind the front segment. The front segment is formed with a circular opening

148 for passing the lancet needle when the lancet holder arm 120 moves down from the cocked position shown in phantom in Figure 11 to the operative position shown in full lines in that Figure. As best seen in Figure 6, finger rest 145 presents a frustoconical, flared surface 149 surrounding the opening 148 at the top. When the lancet retainer arm 120 moves down from its cocked position, the lancet needle

assembly strikes this flared surface 149 on finger rest 145 to limit the lancet needle's penetration into the patient's finger, as shown in full lines in Figure 11.

The rear segment 147 of the finger rest has a semi- circular, convex back face 150. The width of the rear segment is such that it can be slidably inserted from the front into the slot 58 in pressure lever 30. When it en¬ ters this slot (Figure 6) , its rounded back face 150 en¬ gages the tapered front face 100 of the depending front ι _U g 97 on ejector lock arm 95 to raise the ejector lock arm pivotally.

A short distance behind its juncture with the front segment 146, the rear segment 147 of the finger rest pre¬ sents an opening 151 having a vertical rear face 152 and downwardly and rearwardly inclined front face 153 with a slope that substantially matches that of the tapered front face 100 of the lug 97 on ejector lock arm 95. As shown in Figure 7, the front depending lug 97 on ejector lock arm 95 drops into this opening 151 in the finger rest after it has been fully inserted. OPERATION

Figure 4 shows the normal position of the parts of the lancet device, with the lancet holder arm 120 down and the finger rest 145 not yet inserted. The spring 127 is vertical, the opening 126 in the ear 125 on top of the lan¬ cet holder arm 120 being vertically aligned with the fasten¬ ing point 128 for the upper end of the spring. The ejector 20 is positioned forward along the pressure lever 30, and the cross lugs 27 and 28 on the top of the ejector overlie the upwardly facing surfaces 63 and 64 (Figure 17) at the bottom of slot 58 on opposite sides of the narrower longi¬ tudinal segment 62 of the T-slot 61,62 in the bottom of pressure lever 30. The recess 25 in ejector 20 receives the bottom wall 12 of the housing so that the ejector is held against the movement up or down in the housing. In turn, the ejector prevents pivotal movement of pressure lever 30 as long as the ejector is in this forward position.

In this position of the parts, the weight of the lan¬ cet holder arm 120 bears down on the plastic spring 110, which holds the ejector lock arm 95 down, with its depend¬ ing lugs 97,98 and 99 received in the corresponding top openings 66,67 and 68 in pressure lever 30. The rear lugs 98 and 99 project down far enough into slot 58 in pressure lever 30 to block the top of ejector 30 behind its cross lugs 27 and 28, so the user cannot retract the ejector past these lugs 98 and 99 on ejector lock arm 95. The e- jector 20 has a limited "play" from front to back along the housing between front lug 97 and rear lugs 98 and 99 on ejector lock arm 95 without changing the condition of any of the other parts. The ejector lock bar 70 is in its forward position on pressure lever 30, with the back edge of its oblong opening 71 engaging the lower pivot pin 17 on the inside of the housing.

The finger rest 145 may be inserted before or after the lancet holder arm 120 is raised clockwise from its Figure 4 position to the cocked position shown in Figure 6. When the finger rest 145 is pushed into slot 58 in pressure lever 30, its back edge raises the depending front lug 97 of ejector lock arm 95, pivoting this lock arm clockwise, as shown in Figure 6, and raising its depending rear lugs 88 and 89 far enough to permit the user to use light finger pressure to manually retract the ejector 20 against the front edge of the ejector lock bar 70. The plastic spring 110 flexes upward to permit such pivotal movement of the ejector lock arm. The ejector lock bar 70 remains in its forward position to which it is biased by plastic spring 110, whose depending rear lug 112 en¬ gages the vertical back face 73 of the top projection 72 on the ejector lock bar. This position of the ejector 20 is a partially retracted position.

The user continues to push the finger rest 145 in until it reaches the position shown in Figure 7. Here, the front depending lug 97 on ejector lock arm 95 has dropped into the opening 151 in finger rest 145 to lock

it in its fully inserted position. The depending rear lugs 98 and 99 on ejector lock arm 95 have dropped in front of the cross lugs 27 and 28 on ejector 20 at the top. When the user raises the lancet holder arm 120 (either before or after inserting finger rest 145) , the convex surface 132 on the bottom of its rear segment 129 rides forward across the convex top surfaces 36 and 40 on the upstanding rear segments 34 and 38 of pressure lever 30 and across the convex top surface 86 of the upstanding rear segment 84 of ejector lock bar until the inclined face 131 of the lancet holder arm engages the inclined front faces 35,39 and 87 of the pressure lever and the ejector lock bar. This pivotal movement of the lancet holder arm 120 lengthens, and therefore increases the ten¬ sion of, its spring 127. The upstanding rear segments 34 and 38 of pressure lever 30 and the upstanding rear segment 84 of ejector lock bar 70 lock the lancet holder arm 120 in its cocked position. To release the lancet holder arm from its cocked position, so that spring 127 can move it down forcefully, the ejector lock bar 70 must be moved back and the pressure lever 30 must be pivoted clockwise in Figure 7.

The ejector lock bar 70 is moved back by sliding the ejector 20 back from the partially retracted position shown in Figure 7 to the fully retracted position shown in Figure 11, in which the vertical segment 26 of the ejector abuts against the pressure lever 30 at the back of the cross arm 61 of the T-slot 61,62 in the bottom of the pressure lever. When slid back this way, the ejector 20 pushes the ejector lock bar 70 back (as permitted by its oblong opening 71 for pivot pin 17) , thereby disengaging the upstanding rear segment 84 of the ejector lock bar 70 from the rear segment 129 of lancet holder arm 120. The ejector 20 now is positioned with its cross lugs 27 and 28 at the top completely behind the shoulders 63 and 64 on the bottom of slot 58 in the pressure lever 30. Conse¬ quently, the pressure lever 30 can pivot on the lower

pivot pin 17.

Such pivotal movement of the pressure lever occurs when the patient's finger F (Figure 11) is pushed up against the bottom of finger rest 145. The upward force exerted by the patient's finger against finger rest 145 is exerted against the pivoted pressure lever 30 because of the close engagement of the rear segment 147 of the finger rest in slot 58 in the pressure lever. Pressure lever 30 pivots counterclockwise to the position shown in Figure 11. This lowers the back end of the pressure lever, moving its up¬ standing segments 34 and 38 down past the rear segment 129 of lancet holder arm 120. The tension spring 127 now pulls the released lancet holder arm 120 down from its cocked position and the lancet needle it carries pierces the patient's finger F, as shown in Figure 11. The curved front end segment 115 of plastic spring 110 cush¬ ions the impact of the lancet holder arm at the end of its downward travel and prevents the spring 127 from mov¬ ing over-center at the end of the downward movement of the free end of the lancet holder arm 120. That is, the lower end of spring 127 never moves forward past its up¬ per end (i.e., to the left in the drawings).

The finger rest 145 may be removed from pressure lev¬ er 30 by manually sliding the ejector 20 forward, as shown in Figure 13. This is the forwardmost position of the ejector, in which its vertical segment 26 engages the in¬ ternal vertical face 65 at the front end of the T-slot 61, 62 on the bottom of the pressure lever. The transverse lugs 27 and 28 on the top of the ejector engage the in- clined rear faces of the depending lugs 98 and 99 on ejector lock arm 95, causing it to pivot upward and lift its depending front lug 97 out of the opening 151 in the finger rest. This forward movement of the ejector 20 pushes the finger rest out of slot 58 in pressure lever 30. From the foregoing description and the drawings, it will be understood that the ejector 20 has four different positions along the housing:

(1) the normal position (Figure 4) in which its T- shaped top 27-29 is somewhere between the de¬ pending front lug 97 and the depending rear lugs 98 and 99 on ejector lock arm 95; (2) the partly retracted position (Figures 6 and 7) engaging the front end of ejector lock bar 70 when the ejector lock bar is in its foward posi¬ tion; (3) the fully retracted position (Figure 11) in which it has pushed ejector lock bar 70 back to its rear position; and (4) the forwardmost position (Figure 13) to which it is moved to push the finger pad 145 out of the pressure lever 30. From the foregoing it will be evident that:

(1) the functions of the pressure lever 30 are to hold the lancet holder arm 120 cocked, to receive and hold the finger rest 145 when it is inserted, and to re¬ lease the cocked arm in response to upward pressure of a patient's finger on the finger rest 145;

(2) the functions of the finger rest 145 are to re¬ lease the ejector 20 so that it can unlock the pressure lever 30, and -thereafter to move the pressure lever to re¬ lease the cocked lancet holder arm 120;

(3) the functions of the ejector 20 are to hold the pressure lever 30 locked against movement for releasing the cocked lancet holder arm 120 until after the finger rest 145 is fully inserted in the pressure lever, to push the ejector lock bar 70 back so that it releases the cocked lancet holder arm, and to eject the finger rest 145 after the lancet device has operated;

(4) the functions of the ejector lock bar 70 are to hold the lancet holder arm 120 cocked, to urge the e- jector 20 to a position locking the pressure lever 30 against movement, and to release the cocked lancet holder arm 120 when the ejector 20 is slid back;

(5) the functions of the ejector lock arm 95 are to

urge the pressure lever 30 down to a position holding the lancet holder arm 120 cocked before the finger rest 145 is inserted, to hold the ejector 20 positioned to lock the pressure lever in this down position before the finger rest is inserted, to release the ejector 20 when the finger rest is inserted part-way into the pressure lever 30, to lock the finger rest 145 in the pressure lever after it has been fully inserted therein, and to release the finger rest for ejection from the pressure lever when the ejector 20 is moved forward after an operation of the lancet de¬ vice; and (6) the functions of the plastic spring 110 are to bias the ejector lock arm 95 down against the pres¬ sure lever 30, to limit the movement of the lancet holder arm 120 when it is released from its cocked position, and to bias the ejector lock bar 70 forward to urge the eject¬ or 20 to a position locking the pressure lever 30 against movement.