Field of the invention

The invention relates to a latch module for a door. The latch module has a hous- ing, a latch bolt, a guard bolt and a stem. Description of the related art

Latch modules are usually inserted into a door jamb facing narrow side of a door. For example, US 2018/0187464 suggests a double latch lockset having a first latch module and a second latch module. The latch modules each have a housing with a first end and a second end. The first end of the housing, as well referred to as front end or as distal end of the housing, faces towards door jamb, assuming the door to be closed. The second end, i.e. the rear end or proximal end, is in- serted into a mounting recess of the door leaf. One of the two latch modules has a dead bolt that can be extended into a whole of a striking plate. The other latch module has a latch bolt and a guard bolt. The latch bolt is coupled to a door lever and actuation of the door leaver retracts the latch bolt and a guard bolt from an extended position to a retracted position, thereby releasing an engagement of the latch bolt and the guard bolt with the striking plate. The guard bolt prevents the latch bolt from being shifted into its retracted position by pressing a credit card or a screw driver into the gap between the door leaf and the striking plate and against an oblique surface of the latch bolt.

Another latch module is suggested in US 2020/0056403, similarly the latch mod- ule has a housing being inserted in a mortise of a door leaf. A latch bolt is config- ured to reciprocate between an extended and a retracted position.

GB 647372A, US 2,576,648 A, GB 790414, US 1,876,081 and US 3,876,236A each disclose a latch module for releasably engaging into a striking plate of a door jamb. The latch modules have a housing, a latch bolt, a guard bolt, a blocking member and a stem. These type of latch modules have a doorjamb facing end and door leaf facing end extending into a mortise of a door. The housing movably supports the latch bolt and the guard bolt. The stem has a block that in operation entrains an abutment of movably supported the latch bolt, if the stem reaches a first intermediate position while being moved from the stem's closed position to- wards the stem's open position.

Summary of the invention

The problem to be solved by the invention is to provide a reliable and safe latch module for a door leaf that can be manufactured at reduced cost.

Solutions of the problem are described in the independent claim. The dependent claims relate to further improvements of the invention.

The latch module, as usually, can be inserted into a mortise of a door jamb facing narrow side of a door leaf. The latch module comprises a housing, a latch bolt, a guard bolt and a stem. The latch module and thus as well the housing has a first end (as well distal end) and a second end (as well proximal end), wherein the first end is configured to face towards the door jamb and the second is config- ured to extend into a mounting hole of a door, i.e. into the mortise.

The housing may movably support the latch bolt and the guard bolt. For exam- ple, the housing may provide a linear bearing enabling to shift the latch bolt and the guard bolt relative to the housing. Both, i.e. the latch bolt and the guard bolt may each have an extended position and a retracted position. In the extended position the latch bolt and/or the guard bolt protrude over the distal end of the housing. In this extended position the latch bolt can engage into a recess of a striking plate. Assuming the latch module to be mounted, it would inhibit the door leaf to swing open. Retracting the latch bolt releases the engagement with the striking plate and the door leaf can be opened. Preferably, the latch bolt and/or the guard bolt are biased towards their respective extended positions.

For example, a biasing spring (or any other elastic means) may be supported by the housing or at least relative to the housing and may be loaded by a movement of the latch bolt or the guard bolt, respectively, towards the corresponding re- tracted position.

As implicit, the latch bolt as usual has an inclined surface enabling to swing the door into its closed position without retracting the latch bolt manually by actuat- ing the stem. This inclined surface, however, would allow for the above ex- plained "credit-card attack". To avoid this, the guard bolt preferably senses if the door is open or closed. In case the door leaf is open, the guard bolt extends and preferably releases a blocking mechanism of the latch bolt, enabling the door leaf to be slammed into its closed position. However, if the door is closed, the guard bolt is preferably retracted and may ensure a blocking mechanism pre- vents the latch bolt from being pushed into its retracted position, while its re- traction by operating the stem preferably remains possible. Hence, the guard bolt can as well be referred to as a "sensor bolt" for detecting if the door leaf is in its open position or in its closed position. For example, based on the result of the detection, retraction of the latch bolt by applying a force to the inclined sur- face may be blocked or released. In other words, the guard bolt may control the state of a blocking mechanism being configured to releasably prevent the latch bolt from being retracted. The blocking mechanism may further be released by actuating the stem.

The stem has a longitudinal axis. This axis his herein used as reference axis and briefly referred to as the longitudinal axis. The stem is movably supported rela- tive to the housing and has a closed position and an open position. Movable sup- port may be provided, e.g. by a plain bearing restricting the movement for exam- ple to a movement at least essentially parallel to the longitudinal axis. The posi- tion of the stem may control the position of the latch module and of the guard module. For example, pulling the stem along the longitudinal axis away from the first side (i.e. in the proximal direction) retracts the latch bolt and optionally the guard bolt. The end position of the stem in which the latch bolt and optionally the guard bolt are extended is referred to as closed position, whereas the posi- tion of the stem in which the latch bolt and the guard bolt are retracted is re- ferred to as open position, i.e. closed position and open position reference to the state of the corresponding door, which can be opened if the stem is in the open position and remains closed if the stem is in the closed position.

Alternatively or in addition to a translational movement, the stem may as well be pivotally supported or rotationally supported, but without intending to be limit- ing, herein we will assume a translational movement of the stem.

Preferably, the stem is as well movably supported relative to the latch bolt. Fur- ther, the stem may have a block configured to entrain an abutment of the latch bolt. Thus, for example initially, the stem may be moved from its closed position in the direction of the open position without entraining the latch bolt. Once the stem reaches a first intermediate position while being moved from the stem's closed position towards the stem's open position the stem's block entrains the abutment of the latch and thereby couples the movement of the latch bolt to the movement of the stem. Shifting the stem from the first intermediate position to towards the closed position releases the coupling. In the field of rotary couplings one would use the terms 'coupling is closed' or 'coupling is open'. In this sense the stem and the latch bolt are coupled by a position selective coupling, being closed if the stem is between the first intermediate position and the open posi- tion and open if the stem is between the closed position and the first intermedi- ate position. Thus, a position selective coupling defines a first path of the stem, wherein the stem travels without entraining the latch bolt. This first path may be used to control for example a blocking mechanism. For example, the first portion of the movement may be used to release a blocking mechanism maintaining the latch bolt in its extended position.

Preferably, the latch bolt has a first end and a second end. The latch bolt's first and second ends may face into the same directions as the first and second ends, respectively, of the latch module. Only to avoid ambiguities, the latch modules first end is configured to face towards the door jamb and the latch module's sec- ond end is configured to face in the opposite direction.

In a preferred example, the second end of the latch bolt has a recess being de- limited by at least one bearing surface. For example, the bearing surface may be defined by at least one protrusion extending from the latch bolt. In another ex- ample, the bearing surface may be ring surface or a ring segment surface. The bearing surface is preferably at least essentially parallel to the stem's longitudi- nal axis. The bearing surface may thereby be configured to support the stem per- pendicularto the stem's longitudinal axis while enabling a movement of the stem relative to the latch bolt's bearing surface at least essentially parallel to the longitudinal axis. In other words, the stem and the latch bolt may be connected via a linear bearing, wherein the bearing may be integrated in the stem and/or the latch module. Each of these measures is cheap to manufacture and contrib- ute to a reliable and failsafe operation of the latch module.

A first end of the stem may extend into the recess, wherein 'into the recess' may include 'through the recess'. It may further be configured to enable a translation of the stem along the stem's longitudinal axis and relative to bearing surface. The translation may be limited in axial direction by the stem's block and the latch bolt's abutment. Each of these measures is cheap to manufacture and contribute to a reliable and failsafe operation of the latch module.

Particularly preferred, the guard bolt has a latch bolt facing abutment and the latch bolt has a guard bolt facing block and that the latch bolt's block is positioned to contact the guard bolt's abutment, when the latch module is en- trained by the stem towards the latch module's retracted position. The guard bolt's latch bolt facing abutment may thus have a surface facing at least essen- tially in the distal direction. Similarly, the latch bolt's guard bolt facing block may have a surface facing at least essentially in the proximal direction. The surface of the guard bolt's latch bolt facing abutment and the surface of the latch bolt's guard bolt facing block may each have at least one point being spaced relative to the longitudinal axis at the same distance than the respective point of the op- posed surface. In other words, the optional guard bolt's a latch bolt facing abut- ment protrudes into the traveling path of the latch bolt's guard bolt facing block. Thereby, if the latch bolt is retracted by a corresponding movement of the stem, it automatically entrains the guards bolt. These measures, as well, each contrib- ute to a reliable latch module and reduced manufacturing costs.

For example, the optional blocking mechanism may comprise a blocking mem- ber. The optional blocking member may be movably supported to enable a movement of the blocking member from a blocking position to a released posi- tion and back to the blocking position. The movement may be enabled, e.g., by a hinge mechanism and/or another type of bearing. Preferably, the blocking mem- ber is configured to block a retraction of the latch bolt, when in the blocking member's blocking position and to release blocking the retraction of the guard bolt, when the blocking member is in the released position. Thereby, manipula- tion of the closed latch is successfully prevented at low manufacturing costs.

Preferably, the guard bolt maintains the blocking member in the blocking mem- ber's released position, if the guard bolt is in the guard bolt's extended position. For example, a portion of the guard bolt may be positioned at the blocking mem- bers blocking position, if the guard bolt is in the guard bolt's extend position. Thus, if an open door is slammed into the door jamb, the latch bolt can retract and the door closes. "Slamming" herein means pivoting the door leaf until it reaches a final position in the door jamb without actuating the door lever. Thus when slamming a door the stem is not manually pulled into its open position by actuating of a door lever.

As explained above, the latch bolt may entrain the guard bolt. Alternatively, other measures for retracting the guard bolt may be taken when the latch bolt retracts. For example, the guard bolt may have an oblique or inclined surface like the latch bolt.

In case the guard bolt is in its retracted position, the guard bolt, preferably, does not inhibit the blocking member from being shifted, e.g. by a spring, into the blocking position, thereby preventing the latch bolt from being retracted by use of a credit card being inserted into a gap between the door leaf and the door jamb. Now, assuming the case in which the door is closed (and the stem is not maintained in its open position), the guard bolt may be maintained retracted, e.g. by a doorjamb and/or striking plate, whereas the latch is extended. Thus, opening the latch bolt by a manipulation via the gap between the door jamb and the door leaf is impossible, because the blocking member has been shifted into its blocking position, e.g. by a spring. Generalizing, one may say that in a pre- ferred example, the guard bolt is preferably configured to maintaining the block- ing member in the blocking member's blocking position, if the guard bolt is in the guard bolt's retracted position. Further, the guard bolt and the blocking member are preferably coupled, be it directly or indirectly, to shift the blocking member into its blocking position when the guard bolt is retracted and/or to shift the blocking member into its released position when guard bolt moves into extended position. For example, the guard bolt when shifted into its retracted position may free a space of the blocking member in the blocking member's blocking position. In slightly different words, in the retracted position the guard bolt may provide the space for the blocking member to be shifted into the blocking member's blocking position. However, in its extended position, the guard bolt may occupy at least a portion of the space the blocking member occupies when entering the blocking position, thereby inhibiting the blocking member to be shifted, e.g. by a spring, into the blocking position. Shifting the guard bolt from its extended position into its retracted position thereby opens a space into which the blocking member maybe shifted, e.g. by a spring until it reaches the blocking member's blocking position.

In a preferred example, the stem may comprise a releasing member. The releas- ing member may be positioned to entrain the blocking member from the block- ing member's blocking position into the blocking member's released position, when the stem is moved from its closed position into a second intermediate po- sition. In other words, the stem may be (preferably releasably) coupled via the releasing member, e.g. by a transmission, to the blocking member. The releasing member may comprise, e.g., a protrusion interacting with an abutment of the blocking member while the stem is shifted from the second intermediate posi- tion towards the stem's open position. The coupling between the stem and the blocking member provides a safe and reliable mechanism for releasing the block- ing member and thus the latch bolt. Preferably, the second intermediate position is in between of the closed position of the stem and the first intermediate position of the stem. Particularly pre- ferred, the second intermediate position of the stem is closer to the closed posi- tion of the stem than to the first intermediate position. These measures provide a very failsafe mechanism, while reducing 'unused' traveling path of the stem, which immediately translates in less material consumption when manufacturing the latch module. A preferred example blocking member may comprise at least a first leg and a second leg. A front-end portion of the first leg may be connected, e.g. by a front hinge, to the latch bolt. The front hinge has an axis around which the front leg may pivot, i.e. the front hinge defines a front hinge axis. A rear-end portion of the second leg may be connected by a rear hinge at least indirectly to the hous- ing, wherein the rear hinge defines a rear hinge axis. The rear hinge axis and the front hinge axis are preferably at least essentially parallel, i.e. parallel within ±15°, more preferred with ±10°, ±5° or less. In this sense the front hinge axis and the rear hinge axis are in a single plane. A rear-end portion of the first leg and a front-end portion of the second may be are connected by a middle hinge. Accordingly, the first and second legs may pivot relative to each other, thereby enabling a movement of the latch bolt towards its retracted position and from the retracted position back into the extended position. The middle hinge defines a middle hinge axis, which is the axis of the pivotal movement of the front and rear leg relative to each other. This middle hinge axis may be on a first side of the plane if the blocking member is in the blocking position and on the opposite side of the plane, if the blocking member has been shifted to the open position. Pref- erably, the front leg and the rear leg define an angle a, wherein the vertex is on the middle hinge axis. In the blocking position the angle a is preferably smaller than 180°, e.g. α _min ≤ a ≤ 180°, wherein α _min is a constant. In the released po- sition the angle a may be greater than 180° (a > 180°). α _min is preferably be- tween 90° and 180°, to be more precise, α _min ∈ [90°, 180°]. The such obtained blocking member can be assembled with in a very short amount of time and reli- ably inhibits the guard bolt from unintentional retraction. Preferably, the block- ing member may be biased towards the blocking position, e.g. by a spring or any other elastic biasing member.

The angle α _min may be defined by a block of the front leg abutting the rear leg at α = α _min . Alternatively, α _min may be defined by a block of the rear leg abutting the front leg at α = α _min . In another example, at least one of the front leg or the rear leg may abut the housing at α = α _min .These alternatives can as well be combined, i.e. they are independent options.

As already apparent from the above, herein the term "spring" is used as a pars pro toto for an "elastic biasing member".

Description of Drawings

In the following, the invention will be described by way of example, without limi- tation of the general inventive concept, on examples of an embodiment with ref- erence to the drawings. Figure 1 shows two perspective views of a latch module,

Figure 2 shows a side view of the latch module,

Figure 3 shows a sectional view of the latch module along the plane A-A indi- cated in Figure 2.

Figure 4A and B show a sectional view of the latch module along the plane B-B in- dicated in Figure 3, but with different positions of a blocking member.

Figure 5A and 5B show a sectional view of the latch module along the plane C-C indicated in Figures 4A and 4B, respectively.

Figure 6 shows an exploded view of the latch module.

The latch module as shown in Fig. 1 to 6 has a housing 10 with a doorjamb facing surface 11 and a door leaf facing surface 12. The doorjamb facing surface 11 de- fines a first end of the housing, a so called distal end of the housing. At the oppo- site side of the distal end of the housing is a door leaf facing surface 12, defining a second end, the so called proximal end of the housing 10 (see Fig. 1 and 2). As can be seen, i.a., in Fig. 6, the housing may comprise a sleeve portion, a stem guide 16, a rear plate 17 and a front plate 18.

Generally, the housing 10 movably supports a latch bolt 30 and guard bolt 50. A stem 20 extends to the proximal side out of the housing 10 and is configured to be connected to a transmission configured to convert a pivotal movement of a door handle into a translation, thereby pulling the stem 20 in the proximal direc- tion 3 (see Fig. 1 and 2). As will be explained in more detail below, a movement of the stem 20 (from its closed position as shown in Fig. 2 to 4) in the proximal direction 3 first releases the blocking mechanism and subsequently entrains the latch bolt 30 into a retracted position. The latch bolt 30 entrains the guard bolt 50 until both reach their respective retracted position. Now, the door leaf can be swung and thus opened open. In case the door has been opened and the door handle (or any other kind of actuation means) is released, the latch bolt 30 and the guard bolt 50 are advanced by elastic biasing means 19 (springs 19, for short) into their respective extended position. This extended position of the latch bolt 30 is shown in Fig. 1 to 5. Fig. 1 to 3, 4B and 5B show the latch module with the guard bolt 50 is in its extended position as well. Fig. 4A and Fig. 5A show a blocking member (70) in a blocking position, which is taken by the blocking mem- ber if the guard bolt 50 is retracted while the latch bolt 30 is extended. As will be apparent below, in the extended position, the guard bolt 50 maintains a blocking mechanism released and the latch bolt 30 can retract if the door is slammed into its closed position.

In case the door is closed, the corresponding striking plate or any other portion of the doorjamb maintains the guard bolt 50 in its retracted position. The block- ing member 70 can thus engage and block a retraction of the latch bolt, until the blocking member 70 is released by pulling the stem in the proximal direction 3. As can be seen in Fig. 3, the housing 10 may have at least one bearing rod 13, 15 being essentially parallel to the longitudinal axis 2. These bearing rods 13, 15 may each have a cylindrical peripheral surface. For the definition of a cylinder and a cylindrical surface see Bronstein, Semendyayev, Musiol & Muehlig Hand- book of Mathematics, Springer Berlin Heidelberg, 2007, 5th ed.; Chapter 3.3.4. Cylinders may have circular and non-circular direction curves and thus corre- sponding cross sections, herein surfaces with a circular cylindrical volume are preferred.

At least a portion of this peripheral surface may be a plain bearing surface config- ured to enable a translation of the latch bolt 30 and the guard bolt 50, respec- tively, essentially parallel to the longitudinal axis 2 along the respective bearing rod 13, 15. Accordingly, the latch bolt 30 and the guard bolt 50 may each have at least one recess 33, 55 (respectively) having an inner surface, providing a com- plementary plain bearing surface. Further, an inner surface 14 of the housing 10 may provide a further plain bearing surface movably supporting the latch bolt 30 and the guard bolt 50. The latch bolt 30 and the guard bolt 50 may slide along the inner surface 14 of the housing 10 with at least a portion of their respective peripheral surfaces.

The guard bolt 50 may have a latch bolt 30 facing abutment 35. The abutment 35 may be integrally formed, e.g., by a protrusion of the guard bolt 50. Alterna- tively, as depicted, the abutment 35 may be provided by an abutment plate 54. Like in the depicted example, the abutment plate 54 may extend orthogonally to the longitudinal axis 2 into the path of the latch bolt 30. Thus, when retracting the latch bolt 30, the abutment 35 may contact a guard bolt 50 facing block 53 of the latch bolt 30, thereby entraining the guard bolt 50 towards the retracted po- sition. In other words, if the latch bolt 30 is in its retracted position, the guard bolt 50 is as well. The guard bolt 50, in contrast may be shifted (and/or maintained) into (in) its retracted position while the latch bolt 30 remains ex- tended or is in the process of being extended.

As already mentioned initially, the stem 20 is preferably movably supported rela- tive to the housing 10. A rear portion 22 of the stem 20 may be configured to be coupled to a transmission. As can be seen in Fig. 4A and 4B, the stem 20 may be movably supported relative to the latch bolt 30, as well. For example, as de- picted, a front-end portion 21 (as well referred to as distal portion 21) of the stem 20 may engage, e.g. via a through hole in an optional rear plate 34 of the latch bolt 30 into a(nother) recess 36 of the latch bolt 30. For simplicity, we con- sider the through hole as a part of the another recess 36. At least a portion of the surface delimiting the trough hole may be a plain bearing surface enabling a translation of the stem 20 relative to the latch bolt 30 essentially parallel to the longitudinal axis 2. This movement of the stem 20 relative to the latch bolt 30 may be limited in the proximal direction 3. For example, as can be seen in Fig. 4a and 4b, the stem 20 may have a block 23 configured to entrain an abutment 32 of the latch bolt 30. The position of the stem 20, when the block 23 contacts the abutment 32 is referred to as first intermediate position. Retracting the stem 20 from the first intermediate position towards its open position, retracts the latch bolt 30. The latch module 1 may further comprise a blocking member 70. The blocking member 70 can be seen in Fig. 4a, 4b, 5a and Fig. 5b: The blocking member 70 may comprise a first leg 80 and second leg 90. The first leg 80, as well referred to as front leg 80, has a front-end portion 81 and a rear-end portion 82. Similarly, the second leg 90, as well referred to as rear leg 90 has a front-end portion 91 and a rear-end portion 92. The front-end portion 81 of the first leg 80 may be pivotably hinged to the latch bolt 30 by a front hinge. The front hinge has a front hinge axis 71. The first leg 80 may thus pivot relative to the front hinge axis 71. The rear-end portion 82 of the first leg 80 may be connected by a middle hinge (indicated by middle hinge axis 73) to the front-end portion 91 of the second leg 90, enabling a pivotal movement of the first and second legs 80, 90 relative to each other around the middle hinge axis 73. The rear-end portion 92 of the sec- ond leg 90 may be connected by a rear hinge, as indicated by a rear hinge axis 72, relative to the housing 10 or any other structure being firmly attached to a door leaf (or doorjamb) when the latch module 1 is mounted to the door leaf (or doorjamb).

As can be seen, the three axes 71, 72 and 73 are preferably at least essentially parallel to each other enabling to define a plane 74 comprising the front and rear hinge axes 71 and 72 (see Fig. 5). The front and rear legs 80, 90 may define an angle a. This optional angle a can take different values, depending on the rela- tive position of the first and second legs 80, 90 relative to each other, but it has a minimum as shown in Fig. 4a and Fig. 5a. This minimum may be defined by a block 79 being attached to the housing 10 or being integrally formed by the housing 10. In the depicted example, the block 79 is provided by the stem guide 16 of the housing 10. It is noted that the block 79 may be provided by any other part, provided the block 79 limits the movement of the second leg 90. Al- ternatively, or in addition the block 79 may be positioned to block the movement of the first leg, e.g. by abutting the first leg 80 in case the blocking member is in its blocking position. Regardless of the position of the block 79, it preferably de- limits a movement of the hinged legs 80, 90 in a direction perpendicular to the plane 74 to thereby define a minimum angle α _min . In Figures 4A and 5A the posi- tions of the first and second legs 80, 90 correspond to said angle α _min , i.e. α = α _min . When applying a force in the proximal direction 3 to the extended portion of the latch bolt 30, a movement of the latch bolt 30 is blocked by the blocking member 70, as the first and second legs 80, 90 are blocked from pivoting in a di- rection which would reduce the angle α below α _min . It is recalled that in Fig. 4A and 5A the guard bolt 50 is in its retracted position (in Fig. 4 the guard bolt is hidden by the stem 20 and in Fig. 5 the guard bolt 50 is below the section plane CC). However, when pulling the stem 20 towards its open position (i.e. in the proximal direction 3) a releasing member 29 of the stem may contact an abutment 99 of the blocking member 70. The position of the stem 20, when this contacting takes place is referred to as second intermediate position. Shifting the stem 20 from the second intermediate position to the first intermediate position, shifts the middle axis 73 of the blocking member 70 on the opposite side of the plane 74 (i.e. α > 180°). The result is similar to the situation in Fig. 4B and 5B, however, in these two Figures the blocking member 70 is maintained in its re- leased position by the guard bolt 50. In Fig. 4B and 5B the stem is in its closed po- sition.

By shifting the stem 20 from the second intermediate position into the first inter- mediate position the blocking member 70 is released. At the first intermediate position, the stem's block 23 contacts the latch module's abutment 32 and thus entrains the latch bolt 30 in the proximal direction, enabling a user to open the door by pulling (,e.g., via an optional transmission) on the proximal end 22 of the stem 20. After the door leaf has been swung to open, the pulling force may be released. The latch bolt 30 and the guide bolt 50 are shifted by the springs 19 into their extended positions. The blocking member 70 is as well biased by an elastic biasing member 19 (spring 19, for short) towards its blocking position, but the extended guard bolt 50 prevents the blocking member to enter the blocking position. This situation is depicted in Fig. 4B and Fig 5B. For example, a protru- sion 85 of the first leg 80 may interfere with a rear portion of the extended guard bolt 50. There are multiple possibilities, a first has already been indicated above, namely the protrusion 85 may abut the guard bolt 50, when the guard bolt 50 is in its extended position. In this example, the protrusion 85 may abut the abut- ment plate 54 when the guard bolt 50 is extended. Retracting the guard bolt 50 shifts the abutment plate 54 into another position and enables the blocking member 70 to enter its blocking position. Alternatively or in addition, the guard bolt 50, when being retracted may shift the blocking member 70 into the block- ing member's released position. In both cases, the latch bolt 30 (entraining the guard bolt 50), may become temporarily retracted if the door is slammed into the doorjamb and the door closes: The oblique surface of the latch bolt 30 hit- ting the door jamb's striking plate provides a pushing force in the proximal direc- tion 3. Because the guard bolt 50 is extended, the blocking mechanism 40 is re- leased (or becomes released when the guard bolt 50 is entrained by the latch bolt's block 35 contacting the guard bolt's abutment 53), i.e. the latch bolt 50 may retract until the door leaf reaches its closed position and the spring 19 ex- tends the latch bolt 30 to engage into the striking plate. The striking plate at the same time inhibits the guard bolt 50 from extending and in consequence, the blocking member's biasing spring 19 shifts the blocking member into its blocking position. Now, the latch bolt 30 is blocked in its extended position and retracting the latch bolt 30 by a credit card is reliably prevented.

List of reference numerals

1 latch module

2 longitudinal axis

3 proximal direction

4 distal direction 10 housing 11 first side 12 second side

13 bearing rod

14 inner surface (plain bearing surface)

15 bearing rod

16 stem guide

17 rear plate

18 front plate

19 elastic biasing means (e.g. spring)

20 stem 21 front-end portion (distal portion) of stem 20 22 rear-end portion (proximal portion) of stem 20 23 block 27 releasing member 30 latch bolt

32 abutment

33 recess

34 rear plate

35 guard bolt facing block

36 recess 50 guard bolt

53 latch bolt facing abutment

54 abutment plate 55 recess

70 blocking mechanism

71 front hinge axis

72 rear hinge axis

73 middle hinge axis

74 plane

80 first leg

81 front-end portion of the first leg

82 rear-end portion of the first leg

90 second leg

91 front-end portion of the second leg

92 rear-end portion of the second leg