Capacitor and inductor shared switching type cavity filter

Abstract

The utility model discloses a switching type cavity filter shared by a capacitor and an inductor, and belongs to the technical field of filters. A capacitor and inductor shared switching type cavity filter comprises a filter cavity and further comprises an input connector and an output connector which are fixedly connected to the outer wall of the filter cavity. The first arc-shaped baffle and the second arc-shaped baffle are fixedly connected to the inner wall of the filter cavity; the fixed table is fixedly connected between the first arc-shaped baffle and the second arc-shaped baffle; the coupling copper sheet is mounted on the fixed table; the cover plate is connected to the filter cavity, a connecting piece is arranged on the cover plate, and one end, arranged in the filter cavity, of the connecting piece is connected with the coupling copper sheet; on the premise that the coupling copper sheets are kept unchanged, random switching of capacitance and inductance can be achieved, different passband suppression requirements of customers are met, the structure is simple and easy to achieve, the size is easy to control, cost is low, and the adjustable range is large.

Description

Technical Field

[0001] This utility model relates to the field of filter technology, and in particular to a capacitor-inductor shared switching cavity filter. Background Technology

[0002] A cavity filter is an electronic product with frequency selection capabilities. It is a microwave filter that uses a resonant cavity structure to filter electromagnetic signals, allowing desired signals to pass through while suppressing unwanted signals. It has a robust structure, stable and reliable performance, and good frequency selection filtering effect in circuits and high-frequency electronic systems.

[0003] In filter design, due to the special requirements, there are usually two types of requirements: left passband suppression and right passband suppression. This requirement leads to the need for two different products to meet the left or right suppression requirements, resulting in unnecessary design and manufacturing costs. In view of this, this utility model is proposed. Utility Model Content

[0004] The purpose of this invention is to solve the problems existing in the prior art by proposing a capacitor-inductor shared switching cavity filter.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A capacitor-inductor shared switching cavity filter includes a filter cavity and further includes:

[0007] The input and output connectors are fixedly connected to the outer wall of the filter cavity.

[0008] A first arc-shaped baffle and a second arc-shaped baffle are fixedly connected to the inner wall of the filter cavity. The second arc-shaped baffle is connected to the inner wall of the filter cavity on one side near the input connector and the output connector.

[0009] A fixed platform is fixedly connected between the first arc-shaped baffle and the second arc-shaped baffle;

[0010] Coupling copper strips are mounted on a fixed platform;

[0011] A cover plate is connected to the filter cavity, and the cover plate is provided with a connector. One end of the connector, which is located inside the filter cavity, is connected to the coupling copper sheet.

[0012] Preferably, the fixing platform is provided with a support base, the support base is provided with a slot, the coupling copper plate is connected in the slot, and a non-metallic fixing screw is connected to the coupling copper plate. One end of the non-metallic fixing screw passes through the coupling copper plate and is threaded to the support base.

[0013] Furthermore, the connector uses two capacitor non-metallic screws, both of which are connected to the cover plate, and one end of each capacitor non-metallic screw is placed inside the filter cavity and connected to both ends of the coupling copper sheet.

[0014] Furthermore, the connector uses inductive metal screws, and two inductive metal screws are provided. Both inductive metal screws are mounted on the cover plate, and one end of each inductive metal screw, located inside the filter cavity, is respectively connected to both ends of the coupling copper sheet.

[0015] Preferably, the input connector is provided with an input fixing plate, and the input fixing plate is provided with an input fixing screw, which passes through the input fixing plate and is threaded to the outer wall of the filter cavity.

[0016] Furthermore, the output connector is provided with an output fixing plate, which is attached to the outer wall of the filter cavity. The output fixing plate is connected with an output fixing screw, and the output fixing plate is connected to the outer wall of the filter cavity by the output fixing screw. The input connector and the output connector are both located on the same side of the filter cavity.

[0017] Furthermore, the inner wall of the filter cavity is provided with four resonant pillars, each of which has a recessed hole. A resonant rod is connected to the cover plate. One end of the resonant rod, which is placed inside the filter cavity, is inserted into the recessed hole on the resonant pillar. A resonant nut is threaded onto the outer wall of the other end of the resonant rod, which abuts against the outer wall of the cover plate.

[0018] Furthermore, mounting platforms are provided on both resonant pillars near the input and output connectors. Input copper plates and output copper plates are respectively connected to the two mounting platforms. Input locking screws and output locking screws are respectively connected to the input copper plates and output copper plates. The input copper plates are fixedly mounted on the mounting platforms by the input locking screws, and the output copper plates are fixedly mounted on the mounting platforms by the output locking screws.

[0019] Furthermore, the input connector is connected to an input core rod, the output connector is provided with an output core rod, and both the input copper sheet and the output copper sheet are provided with welding grooves. One end of the input core rod, which is placed inside the filter cavity, is welded to the welding groove on the input copper sheet, and the other end of the output core rod, which is placed inside the filter cavity, is welded to the welding groove on the output copper sheet.

[0020] Preferably, the filter cavity, the first arc-shaped baffle, and the second arc-shaped baffle are all provided with mounting holes on their outer walls. The cover plate is connected with mounting screws and is fixedly connected to the mounting holes by the mounting screws. The cover plate is also connected with a tuning rod, and a tuning nut is threaded onto the tuning rod. The tuning rod is inserted into the filter cavity, and the tuning nut abuts against the outer wall of the cover plate.

[0021] Compared with the prior art, this utility model provides a capacitor-inductor shared switching cavity filter, which has the following beneficial effects:

[0022] 1. This capacitor-inductor shared switching cavity filter has connectors on the coupling copper sheet. The connectors can be set with different screws to change the capacitor mode and the inductor mode, so as to achieve different suppression requirements. While keeping the coupling copper sheet unchanged, the capacitor and inductor can be switched at will by replacing the connectors and the connection of the coupling copper sheet on the outside of the assembled product, so as to meet different passband suppression requirements of customers. The structure is simple and easy to implement, the size is easy to control, the cost is low, and the adjustable range is large.

[0023] 2. This capacitor-inductor shared switching cavity filter, by using capacitor non-metallic screws for the connectors, enables the filter cavity to meet the requirements of capacitor mode suppression. The capacitor can be used as a filter on its own, effectively filtering out high-frequency noise.

[0024] 3. This capacitor-inductor shared switching cavity filter, by setting the connector as an inductor metal screw, can meet the requirements for suppressing inductor mode, weaken or eliminate high-frequency noise and interference, and has a good effect on improving the power supply system and signal transmission quality. Attached Figure Description

[0025] Figure 1 This invention presents a schematic diagram of the structure of a capacitor-inductor shared switching cavity filter. Figure 1 ;

[0026] Figure 2 This invention presents a schematic diagram of the structure of a capacitor-inductor shared switching cavity filter. Figure 2 ;

[0027] Figure 3 This is a top view of a capacitor-inductor shared switching cavity filter without a cover plate, as proposed in this utility model.

[0028] Figure 4 This is a schematic diagram of the connection between the cover plate and the coupling copper sheet in a capacitor-inductor shared switching cavity filter proposed in this utility model;

[0029] Figure 5This is a schematic diagram of a capacitor-nonmetallic screw as the connecting component in a capacitor-inductor shared switching cavity filter proposed in this utility model.

[0030] Figure 6 This is a top view of a capacitor-nonmetallic screw, which is the connecting component in a capacitor-inductor shared switching cavity filter proposed in this utility model.

[0031] Figure 7 This invention proposes a capacitor-inductor shared switching cavity filter. Figure 6 A schematic diagram of the AA section.

[0032] Figure 8 This is a schematic diagram of a capacitor-inductor shared switching cavity filter proposed in this utility model, in which the connecting component is an inductive metal screw.

[0033] Figure 9 This is a top view of an inductive metal screw, which is the connecting component in a capacitor-inductor shared switching cavity filter proposed in this utility model.

[0034] Figure 10 This invention proposes a capacitor-inductor shared switching cavity filter. Figure 9 A schematic diagram of the BB section.

[0035] In the diagram: 1. Filter cavity; 101. Cover plate; 102. Mounting screw; 103. Mounting hole; 2. Input connector; 201. Input fixing plate; 202. Input fixing screw; 203. Input core rod; 3. Output connector; 301. Output fixing plate; 302. Output fixing screw; 303. Output core rod; 4. First arc-shaped baffle; 401. Second arc-shaped baffle; 402. Resonant column; 403. Concave hole; 404. Resonant rod; 405. Resonant nut; 406. Tuning rod; 407. Tuning nut; 408. Mounting platform; 409. Input copper plate; 410. Input locking screw; 411. Output copper plate; 412. Output locking screw; 413. Fixing platform; 5. Connector; 501. Coupling copper plate; 502. Non-metallic fixing screw; 503. Capacitor non-metallic screw; 504. Inductor metal screw; 505. Support base. Detailed Implementation

[0036] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0037] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Example

[0038] Reference Figures 1-4 A capacitor-inductor shared switching cavity filter includes a filter cavity 1, an input connector 2 and an output connector 3 fixedly connected to the outer wall of the filter cavity 1, and a first arc-shaped baffle 4 and a second arc-shaped baffle 401 fixedly connected to the inner wall of the filter cavity 1. The second arc-shaped baffle 401 is connected to the inner wall of the filter cavity 1 near the input connector 2 and the output connector 3. A fixing platform 413 is fixedly connected between the first arc-shaped baffle 4 and the second arc-shaped baffle 401. A coupling copper sheet 501 is installed on the fixing platform 413. A cover plate 101 is connected to the filter cavity 1, and a connector 5 is provided on the cover plate 101. One end of the connector 5, which is placed inside the filter cavity 1, is connected to the coupling copper sheet 501.

[0039] In this invention, during use, a signal is first input through the input connector 2, allowing the signal to enter the filter cavity 1. Since the second arc-shaped baffle 401 is connected to the inner wall of the filter cavity 1 near the input connector 2 and the output connector 3, the signal entering the filter cavity 1 can pass between the first arc-shaped baffle 4 and the second arc-shaped baffle 401, thereby passing through the coupling copper sheet 501, which enhances the coupling effect. Then, the signal is output through the output connector 3. It should be noted that the coupling copper sheet 501 in this application is provided with a connector 5. The connector 5 can be set with different screws to change the capacitance mode and inductance mode, achieving different suppression requirements. Under the premise of keeping the coupling copper sheet 501 unchanged, the capacitance and inductance can be switched at will by replacing the connection between the connector 5 and the coupling copper sheet 501 on the outside of the assembled product, thereby meeting different passband suppression requirements of customers. Moreover, the structure is simple and easy to implement, the size is easy to control, the cost is low, and the adjustable range is large.

[0040] The fixed platform 413 is provided with a support base 505, and the support base 505 is provided with a slot. The coupling copper plate 501 is connected in the slot. The coupling copper plate 501 is connected with a non-metallic fixing screw 502. The non-metallic fixing screw 502 passes through the coupling copper plate 501 and is threaded to the support base 505.

[0041] In this invention, the fixed platform 413 facilitates the support of the coupling copper sheet 501, and the support base 505 is made of non-metallic material. The coupling copper sheet 501 is fixed on the support base 505 by non-metallic fixing screws 502. Furthermore, the non-metallic material of the support base 505 and the non-metallic fixing screws 502 provides insulation, effectively preventing short circuits between the coupling copper sheet 501 and other metal components. It can also withstand certain mechanical stress, ensuring the stability of the coupling copper sheet 501 in the filter and preventing it from moving or being damaged due to vibration or external force. This allows the coupling copper sheet 501 to better perform its function in the filter, ensuring the performance and stability of the filter. Example

[0042] Reference Figures 5-7 A capacitor-inductor shared switching cavity filter includes a filter cavity 1, an input connector 2 and an output connector 3 fixedly connected to the outer wall of the filter cavity 1, and a first arc-shaped baffle 4 and a second arc-shaped baffle 401 fixedly connected to the inner wall of the filter cavity 1. The second arc-shaped baffle 401 is connected to the inner wall of the filter cavity 1 near the input connector 2 and the output connector 3. A fixing platform 413 is fixedly connected between the first arc-shaped baffle 4 and the second arc-shaped baffle 401. A coupling copper sheet 501 is installed on the fixing platform 413. A cover plate 101 is connected to the filter cavity 1, and a connector 5 is provided on the cover plate 101. One end of the connector 5, which is placed inside the filter cavity 1, is connected to the coupling copper sheet 501.

[0043] The connector 5 uses two capacitor non-metallic screws 503, both of which are connected to the cover plate 101. One end of each capacitor non-metallic screw 503 is placed inside the filter cavity 1 and is connected to both ends of the coupling copper sheet 501.

[0044] In this embodiment, by using capacitor non-metallic screws 503 for connector 5, the filter cavity 1 can meet the suppression requirements of capacitor mode. The capacitor can be used as a filter on its own, effectively filtering out high-frequency noise. Furthermore, the coupling copper sheet 501 can be fixed by two capacitor non-metallic screws 503, improving the stability of use. Example

[0045] Reference Figures 8-10A capacitor-inductor shared switching cavity filter includes a filter cavity 1, an input connector 2 and an output connector 3 fixedly connected to the outer wall of the filter cavity 1, and a first arc-shaped baffle 4 and a second arc-shaped baffle 401 fixedly connected to the inner wall of the filter cavity 1. The second arc-shaped baffle 401 is connected to the inner wall of the filter cavity 1 near the input connector 2 and the output connector 3. A fixing platform 413 is fixedly connected between the first arc-shaped baffle 4 and the second arc-shaped baffle 401. A coupling copper sheet 501 is installed on the fixing platform 413. A cover plate 101 is connected to the filter cavity 1, and a connector 5 is provided on the cover plate 101. One end of the connector 5, which is placed inside the filter cavity 1, is connected to the coupling copper sheet 501.

[0046] The connector 5 uses an inductive metal screw 504. There are two inductive metal screws 504. Both inductive metal screws 504 are installed on the cover plate 101. One end of the two inductive metal screws 504 is placed inside the filter cavity 1 and is respectively connected to the two ends of the coupling copper sheet 501.

[0047] In this embodiment, by setting the connector 5 as an inductive metal screw 504, the requirement for suppressing inductive mode can be met, high-frequency noise and interference can be weakened or eliminated, and the power system and signal transmission quality can be improved. In addition, the two inductive metal screws 504 can fix the coupling copper sheet 501, improving the stability of use. Example

[0048] Reference Figures 1-10 A capacitor-inductor shared switching cavity filter includes a filter cavity 1, an input connector 2 and an output connector 3 fixedly connected to the outer wall of the filter cavity 1, and a first arc-shaped baffle 4 and a second arc-shaped baffle 401 fixedly connected to the inner wall of the filter cavity 1. The second arc-shaped baffle 401 is connected to the inner wall of the filter cavity 1 near the input connector 2 and the output connector 3. A fixing platform 413 is fixedly connected between the first arc-shaped baffle 4 and the second arc-shaped baffle 401. A coupling copper sheet 501 is installed on the fixing platform 413. A cover plate 101 is connected to the filter cavity 1, and a connector 5 is provided on the cover plate 101. One end of the connector 5, which is placed inside the filter cavity 1, is connected to the coupling copper sheet 501.

[0049] The input connector 2 is provided with an input fixing plate 201, and the input fixing plate 201 is provided with an input fixing screw 202. The input fixing screw 202 passes through the input fixing plate 201 and is threaded to the outer wall of the filter cavity 1.

[0050] The output connector 3 is provided with an output fixing plate 301, which is attached to the outer wall of the filter cavity 1. The output fixing plate 301 is connected with an output fixing screw 302. The output fixing plate 301 is connected to the outer wall of the filter cavity 1 by the output fixing screw 302. The input connector 2 and the output connector 3 are both located on the same side of the filter cavity 1.

[0051] When installing the input connector 2 and the output connector 3, first connect the input fixing plate 201 and the output fixing plate 301 to the outer wall of the filter cavity 1 on the same side, and then fix the input fixing plate 201 and the output fixing plate 301 with the input fixing screw 202 and the output fixing screw 302 respectively, thereby completing the installation of the input connector 2 and the output connector 3. The input connector 2 and the output connector 3 can realize the input and output of signals.

[0052] The filter cavity 1 has four resonant pillars 402 on its inner wall, and each of the four resonant pillars 402 has a recess 403. A resonant rod 404 is connected to the cover plate 101. One end of the resonant rod 404 is inserted into the recess 403 on the resonant pillar 402 inside the filter cavity 1. A resonant nut 405 is threaded onto the outer wall of the other end of the resonant rod 404 outside the cover plate 101. The resonant nut 405 abuts against the outer wall of the cover plate 101.

[0053] In this embodiment, the resonant frequency of the filter can be adjusted by the resonant post 402, and the depth of the resonant rod 404 located in the recessed hole 403 on the resonant post 402 can be adjusted, thereby changing the resonant frequency of the filter. This allows the filter to adapt to different operating frequency requirements, improving the flexibility and applicability of the filter. After adjustment, the resonant nut 405 is tightened so that it abuts against the outer wall of the cover plate 101, thereby fixing the resonant rod 404. Furthermore, there are four resonant posts 402, which can further enhance the coupling effect.

[0054] Mounting platforms 408 are provided on the two resonant pillars 402 near the input connector 2 and the output connector 3. An input copper plate 409 and an output copper plate 411 are respectively connected to the two mounting platforms 408. An input locking screw 410 and an output locking screw 412 are respectively connected to the input copper plate 409 and the output copper plate 411. The input copper plate 409 is fixedly mounted on the mounting platform 408 by the input locking screw 410, and the output copper plate 411 is fixedly mounted on the mounting platform 408 by the output locking screw 412.

[0055] The input connector 2 is connected to the input core rod 203, and the output connector 3 is provided with the output core rod 303. Both the input copper plate 409 and the output copper plate 411 are provided with welding grooves. The end of the input core rod 203 placed inside the filter cavity 1 is welded to the welding groove on the input copper plate 409, and the end of the output core rod 303 placed inside the filter cavity 1 is welded to the welding groove on the output copper plate 411.

[0056] In this embodiment, after the input connector 2 and the output connector 3 are fixedly connected to the outer wall of the filter cavity 1, the input core rod 203 and the output core rod 303 are placed inside the filter cavity 1. Then, the input core rod 203 is welded into the welding groove on the input copper plate 409, and the output core rod 303 is welded into the welding groove on the output copper plate 411, thereby achieving stable fixation. Welding can help reduce signal loss during transmission and improve transmission efficiency. At the same time, it can make the connection between the input copper plate 409 and the output copper plate 411 more stable. The input locking screw 410 and the output locking screw 412 can be used to further fix the input copper plate 409 and the output copper plate 411.

[0057] The filter cavity 1, the first arc-shaped baffle 4, and the second arc-shaped baffle 401 are all provided with mounting holes 103 on their outer walls. The cover plate 101 is connected with mounting screws 102 and is fixedly connected to the mounting holes 103 by the mounting screws 102. The cover plate 101 is also connected with a tuning rod 406 and a tuning nut 407 is threaded onto the tuning rod 406. The tuning rod 406 is inserted into the filter cavity 1 and the tuning nut 407 abuts against the outer wall of the cover plate 101.

[0058] In this utility model, when installing the cover plate 101, the mounting screw 102 is inserted into the mounting hole 103 to fix the cover plate 101. The coupling frequency can be adjusted by the tuning rod 406, and the depth of the tuning rod 406 inserted into the filter cavity 1 is adjustable. After adjustment, the tuning rod 406 can be fixed by the tuning nut 407 to make the connection more stable.

[0059] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A capacitively-inductively shared switched cavity filter comprising a filter cavity (1), characterized in that, Also include: The input connector (2) and output connector (3) are fixedly connected to the outer wall of the filter cavity (1); The first arc-shaped baffle (4) and the second arc-shaped baffle (401) are fixedly connected to the inner wall of the filter cavity (1); The fixed table (413) is fixedly connected between the first arc-shaped baffle (4) and the second arc-shaped baffle (401); The coupling copper sheet (501) is installed on the fixed table (413); The cover plate (101) is connected to the filter cavity (1), and the connecting piece (5) is arranged on the cover plate (101), one end of the connecting piece (5) arranged in the filter cavity (1) is connected to the coupling copper sheet (501).

2. A CLC switched cavity filter according to claim 1, wherein, The support seat (505) is arranged on the fixed table (413), the support seat (505) is provided with a clamping groove, the coupling copper sheet (501) is connected to the clamping groove, the non-metallic fixing screw (502) is connected to the coupling copper sheet (501), and one end of the non-metallic fixing screw (502) passes through the coupling copper sheet (501) and is screwed to the support seat (505).

3. A CLC switched cavity filter according to claim 2, wherein, The connecting piece (5) adopts two capacitive non-metallic screws (503), both ends of the coupling copper sheet (501) are respectively connected to the two capacitive non-metallic screws (503) arranged in the filter cavity (1).

4. The CLC switched cavity filter of claim 2, wherein, The connecting piece (5) adopts an inductive metal screw (504), the inductive metal screw (504) is provided with two, both ends of the coupling copper sheet (501) are respectively connected to the two inductive metal screws (504) arranged in the filter cavity (1).

5. The CLC switched cavity filter of claim 1, wherein, The input fixed plate (201) is arranged on the input connector (2), the input fixed plate (201) is provided with an input fixed screw (202), the input fixed screw (202) passes through the input fixed plate (201) and is screwed to the outer wall of the filter cavity (1).

6. A CLC switched cavity filter according to claim 5, wherein, The output fixed plate (301) is arranged on the output connector (3), the output fixed plate (301) is attached to the outer wall of the filter cavity (1), the output fixed plate (301) is provided with an output fixed screw (302), the output fixed plate (301) is connected to the outer wall of the filter cavity (1) through the output fixed screw (302), and the input connector (2) and the output connector (3) are arranged on the same side of the filter cavity (1).

7. A CLC switched cavity filter according to claim 6, wherein, Four resonant columns (402) are arranged on the inner wall of the filter cavity (1), and a recess (403) is arranged on each of the four resonant columns (402); a resonant rod (404) is connected to the cover plate (101), one end of the resonant rod (404) inserted into the recess (403) on the resonant column (402) is arranged in the filter cavity (1), and a resonant nut (405) is threadedly connected to the outer wall of the other end of the resonant rod (404) arranged outside the cover plate (101), and the resonant nut (405) abuts against the outer wall of the cover plate (101).

8. A CLC switched cavity filter according to claim 7, wherein, An installation table (408) is arranged on each of the two resonant columns (402) close to the input connector (2) and the output connector (3), an input copper sheet (409) and an output copper sheet (411) are respectively connected to the two installation tables (408), an input locking screw (410) and an output locking screw (412) are respectively connected to the input copper sheet (409) and the output copper sheet (411), the input copper sheet (409) is fixedly installed on the installation table (408) through the input locking screw (410), and the output copper sheet (411) is fixedly installed on the installation table (408) through the output locking screw (412).

9. A CLC switched cavity filter according to claim 8, wherein, An input core rod (203) is connected to the input connector (2), an output core rod (303) is arranged on the output connector (3), and a welding groove is arranged on each of the input copper sheet (409) and the output copper sheet (411); one end of the input core rod (203) inserted into the welding groove on the input copper sheet (409) is arranged in the filter cavity (1), and one end of the output core rod (303) inserted into the welding groove on the output copper sheet (411) is arranged in the filter cavity (1).

10. The CLC switched cavity filter of claim 1, wherein, Mounting holes (103) are arranged on the outer walls of the filter cavity (1), the first arc-shaped baffle (4) and the second arc-shaped baffle (401), a mounting screw (102) is connected to the cover plate (101), the cover plate (101) is fixedly connected in the mounting hole (103) through the mounting screw (102), a tuning rod (406) is further connected to the cover plate (101), a tuning nut (407) is threadedly connected to the tuning rod (406), the tuning rod (406) is inserted into the filter cavity (1), and the tuning nut (407) abuts against the outer wall of the cover plate (101).

Images