projection system

Abstract

This application discloses a projection system belonging to the field of projection display. In this projection system, the light valve driver board and lens assembly are arranged parallel to the projection screen. The first circuit board in the light valve driver board is perpendicular to the projection screen, and the display board is parallel to the projection screen. This arrangement effectively reduces the number of optical lenses in the lens assembly arranged perpendicular to the projection screen, thereby shortening the distance between the light-emitting side of the lens assembly and the projection screen, thereby reducing the projection system's throw ratio. This arrangement is suitable for use in ultra-short-throw projection systems.

Description

[0001] This application embodiment claims priority to Chinese patent application number 202011025334.6, filed on September 25, 2020, with the invention name “Projection System”, the entire contents of which are incorporated by reference into the present application embodiment. Technical Field

[0002] The present disclosure relates to the field of projection display, and in particular to a projection system. Background Art

[0003] Currently, a projection system may include a lens assembly, a light valve driving board and a display board. The multiple optical lenses included in the lens assembly are arranged in a direction perpendicular to the projection screen, and the light-emitting side of the lens assembly is located on the side of the display board away from the projection screen, and the board surface of the light valve driving board and the board surface of the display board are both parallel to the projection screen.

[0004] However, the arrangement of the lens assembly, light valve drive board and display board results in a large distance between the light-emitting side of the lens assembly and the projection screen, resulting in a relatively large projection of the projection system. The above arrangement is not applicable to ultra-short-throw projection systems. Summary of the Invention

[0005] The present disclosure provides a projection system that can solve the problem in related art that the arrangement of lens assemblies, light valve drive boards, and display boards is not suitable for ultra-short-throw projection systems. The technical solution is as follows:

[0006] In one aspect, a projection system is provided, comprising: a lens assembly, a display panel, and a light valve driving board; wherein the light valve driving board comprises a circuit board and a light valve located on the circuit board;

[0007] The display panel is located on a side of the lens assembly close to the projection screen, and the display panel is electrically connected to the light valve driving board for providing a light valve control signal to the light valve;

[0008] The light valve driving plate and the lens assembly are arranged along a first direction, the first direction being parallel to the projection screen, and the light valve is used to flip under the drive of the light valve control signal and transmit the light beam to the lens assembly;

[0009] The surface of the circuit board is perpendicular to the projection screen, and the surface of the display panel is parallel to the projection screen.

[0010] Optionally, the projection system further comprises: a differential signal line and a bottom plate; the display panel, the light valve driving board and the lens assembly are all located on the bottom plate, and the differential signal line is in contact with the bottom plate;

[0011] The display panel and the light valve driving board are electrically connected through the differential signal line.

[0012] Optionally, the projection system further comprises: a shielding layer;

[0013] The shielding layer is wrapped around the outside of the differential signal line, and the shielding layer is grounded.

[0014] Optionally, the projection system further includes: a magnetic ring, which is sleeved on the outside of the shielding layer, and the length of the magnetic ring is smaller than the length of the shielding layer.

[0015] Optionally, the projection system further includes: a common mode inductor;

[0016] The common-mode inductor is connected in series between the display panel and the light valve driving board through the differential signal line.

[0017] Optionally, the distance between the display panel and the light valve driving board is determined according to a communication rate between a light valve driving component in the display panel and the light valve.

[0018] Optionally, the communication rate between the light valve driving assembly and the light valve is less than or equal to 1.6 gigabits per second, and the distance between the display panel and the light valve driving board is less than or equal to 254 mm.

[0019] Optionally, the projection system further comprises: a light source assembly and a light transmission assembly; the lens assembly comprises a first lens subassembly, a reflection subassembly, and a second lens subassembly, wherein the optical axis of the first lens subassembly intersects the optical axis of the second lens subassembly;

[0020] The light transmission component is located between the light source component and the light valve driving board, and is used to transmit the light beam emitted by the light source component to the light valve driving board;

[0021] The light valve driving board is located on the light incident side of the first lens subassembly and is used to transmit the light beam transmitted by the light transmission assembly to the first lens subassembly under the drive of the light valve control signal;

[0022] The reflection subassembly is located between the first lens subassembly and the second lens subassembly. The first lens subassembly is used to transmit the light beam to the reflection subassembly. The reflection subassembly is used to reflect the light beam to the second lens subassembly. The second lens subassembly is used to project the light beam onto the projection screen.

[0023] Optionally, the optical axis of the first lens subassembly is perpendicular to the optical axis of the second lens subassembly, and the optical axis of the second lens subassembly is perpendicular to the projection screen.

[0024] Optionally, the light transmission component is used to adjust the transmission direction of the light beam emitted by the light source component from the second direction to a third direction, and then adjust the light beam from the third direction to the first direction before transmitting the light beam to the light valve driving board;

[0025] The second direction intersects the third direction, the second direction and the first direction are both parallel to the optical axis of the first lens subassembly, and the first direction and the second direction are opposite.

[0026] The beneficial effects of the technical solutions provided by the embodiments of the present disclosure include at least:

[0027] The disclosed embodiments provide a projection system in which a light valve driver board and a lens assembly are arranged parallel to the projection screen. Furthermore, the first circuit board of the light valve driver board is perpendicular to the projection screen, and the display panel is parallel to the projection screen. This arrangement effectively reduces the number of optical lenses in the lens assembly arranged perpendicular to the projection screen, thereby shortening the distance between the light-emitting side of the lens assembly and the projection screen, and lowering the projection system's throw ratio. This arrangement is suitable for use in ultra-short-throw projection systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 is a structural schematic diagram of a projection system provided by an embodiment of the present disclosure;

[0030] Figure 2 is a schematic diagram of a connection between a display panel and a light valve driving board provided by an embodiment of the present disclosure;

[0031] Figure 3 This is a schematic diagram of a differential signal line provided by an embodiment of the present disclosure, in which a shielding layer is wrapped around the shielding layer and a magnetic ring is sleeved on the shielding layer;

[0032] Figure 4 is a schematic diagram of a common-mode inductor provided on a first circuit board according to an embodiment of the present disclosure;

[0033] Figure 5 is a schematic diagram of a second circuit board provided with a common-mode inductor according to an embodiment of the present disclosure;

[0034] Figure 6 is a schematic structural diagram of another projection system provided by an embodiment of the present disclosure;

[0035] Figure 7 is a structural diagram of another projection system provided by an embodiment of the present disclosure;

[0036] Figure 8 is a structural diagram of another projection system provided by an embodiment of the present disclosure;

[0037] Figure 9 is a schematic diagram of the distance between the light-emitting side of a second lens subassembly and a projection screen provided by an embodiment of the present disclosure;

[0038] Figure 10 is a structural diagram of another projection system provided by an embodiment of the present disclosure;

[0039] Figure 11 is a structural diagram of a lighting system provided by an embodiment of the present disclosure;

[0040] Figure 12 This is a partial schematic diagram of the structure of a second circuit board provided by an embodiment of the present disclosure;

[0041] Figure 13 is a partial structural diagram of a second circuit board provided by an embodiment of the present disclosure;

[0042] Figure 14 This is a schematic diagram of the results of a low-frequency radiated disturbance field strength test on a projection system provided by an embodiment of the present disclosure;

[0043] Figure 15 This is an eye diagram of a differential signal transmitted by a light valve driving component received by a light valve according to an embodiment of the present disclosure;

[0044] Figure 16 is a structural diagram of another projection system provided by an embodiment of the present disclosure;

[0045] Figure 17 It is a structural diagram of a projection system provided by the related art. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0047] Figure 1 FIG. 1 is a schematic diagram of a projection system provided by an embodiment of the present disclosure. Figure 1 As shown, the projection system may include a lens assembly 10, a display panel 20 and a light valve driving board 30. Figure 2The light valve driving board 30 may include a first circuit board 301 and a light valve 302 located on the first circuit board 301. Optionally, the first circuit board 301 may be a printed circuit board (PCB).

[0048] The display panel 20 is located on a side of the lens assembly 10 close to the projection screen 40 , and the display panel 20 is electrically connected to the light valve driving board 30 for providing a light valve control signal to the light valve 302 .

[0049] The light valve driving plate 30 and the lens assembly 10 are arranged along a first direction V, which is parallel to the projection screen 40. The light valve 302 is driven by the light valve control signal to flip and transmit the light beam to the lens assembly 10. The lens assembly 10 is used to project the light beam onto the projection screen 40 to display an image.

[0050] The surface of the first circuit board 301 is perpendicular to the projection screen 40 , and the surface of the display panel 20 is parallel to the projection screen 40 .

[0051] In the embodiment of the present disclosure, the projection system may include a housing 00 having a receiving space. The lens assembly 10 , the display panel 20 and the light valve driving board 30 are all located in the housing 00 .

[0052] In summary, the embodiments of the present disclosure provide a projection system in which the light valve driver board and lens assembly are arranged parallel to the projection screen. Furthermore, the first circuit board of the light valve driver board is perpendicular to the projection screen, and the display panel is parallel to the projection screen. This arrangement effectively reduces the number of optical lenses in the lens assembly arranged perpendicular to the projection screen, thereby shortening the distance between the light-emitting side of the lens assembly and the projection screen, thereby reducing the projection system's throw ratio. This arrangement is suitable for ultra-short-throw projection systems.

[0053] refer to Figure 2 and Figure 3 The projection system may further include a differential signal line 50 and a bottom plate 60. The display panel 20, the light valve driving board 30, and the lens assembly 10 are all located on the bottom plate 60. The differential signal line 50 contacts the bottom plate 60, and the bottom plate 60 is grounded. The bottom plate 60 may be made of a metal material, such as iron.

[0054] The display panel 20 and the light valve driving board 30 are electrically connected via a differential signal line 50. The display panel 20 can provide a light valve control signal to the light valve 302 in the light valve driving board 30 via the differential signal line 50.

[0055] Optionally, the differential signal line 50 may be a low-voltage differential signaling (LVDS) line. The display panel 20 may transmit a control signal to the light valve 302 in LVDS format. The control signal may include a differential-mode signal and a common-mode signal. The differential-mode signal is the aforementioned light valve control signal, which is used to control the flipping of the light valve 302. The common-mode signal is not used to control the flipping of the light valve 302. Because the base plate 60 is grounded and the differential signal line 50 is in contact with the base plate 60, the common-mode signal transmitted through the differential signal line 50 can be directed to the ground, preventing the common-mode signal from radiating outside the housing and affecting the user.

[0056] refer to Figure 3 The projection system may further include a shielding layer 70 , which is wrapped around the outside of the differential signal line 50 and is grounded.

[0057] Optionally, both ends of the shielding layer 70 may be grounded, or one end may be grounded. The shielding layer 70 may be made of a metal material, for example, red copper or tinned copper. The shielding layer 70 may be a mesh braided layer.

[0058] Because the shielding layer 70 wraps around the differential signal lines 50 and is grounded, the common-mode signal transmitted by the differential signal lines 50 can be conducted to the ground through the shielding layer 70, shielding the common-mode signal within the projection system. This prevents the common-mode signal transmitted by the differential signal lines from being radiated to the outside of the housing 00 and affecting the user, thereby reducing the impact on the user. At the same time, it ensures that the common-mode interference of the projection system meets the electromagnetic compatibility limit requirements, ensuring that the projection system can pass electromagnetic interference (EMI) testing, and thus ensuring that the projection system is qualified.

[0059] refer to Figure 3 , the shielding layer 70 is connected to the bottom plate 60. Since the shielding layer 70 and the bottom plate 60 are both made of metal materials, and the bottom plate 60 is grounded. Therefore, the shielding layer 70 is connected to the bottom plate 60, and the shielding layer 70 can be grounded.

[0060] Optionally, both ends of the shielding layer 70 may be directly connected to the bottom plate 60. Alternatively, both ends of the shielding layer 70 may be connected to the bottom plate 60 via metal wires. Alternatively, one end of the shielding layer 70 may be directly connected to the bottom plate 60, and the other end of the shielding layer 70 may be connected to the bottom plate 60 via metal wires.

[0061] In an optional implementation of the embodiment of the present disclosure, refer to Figure 3The projection system may further include a magnetic ring 80, which is sleeved on the outside of the shielding layer 70. The length of the magnetic ring 80 is less than that of the shielding layer 70, that is, the magnetic ring 80 only covers a portion of the shielding layer 70. By sleeved on the outside of the shielding layer 70, the impedance of the common-mode current transmission path can be increased, that is, the impedance of the differential signal line 50 can be increased, thereby effectively suppressing the common-mode signal, reducing the common-mode current on the differential signal line, and thus reducing the common-mode signal radiated outside the housing.

[0062] In another optional implementation of the disclosed embodiment, the projection system may further include a common-mode inductor, which is connected in series between the display panel 20 and the light valve driving board 30 via a differential signal line 50. By connecting the common-mode inductor in series between the display panel 20 and the light valve driving board 30, the impedance of the common-mode current transmission path can be increased, that is, the impedance of the differential signal line 50 is increased, thereby effectively suppressing the common-mode signal generated by the display panel 20, reducing the common-mode current on the differential signal line, and thus reducing the common-mode signal radiated to the outside of the housing.

[0063] Optional, reference Figure 4 The first circuit board 301 included in the light valve driving board 30 is further provided with a first common mode inductor 303. The first common mode inductor 303 is connected in series between the display panel 20 and the light valve driving board 30 through the differential signal line 50. Alternatively, referring to Figure 5 The display panel 20 may include a second circuit board 201, on which a light valve driving component 202 and a second common-mode inductor 203 may be provided. The second common-mode inductor 203 is connected in series between the display panel 20 and the light valve driving board 30 via the differential signal line 50. Alternatively, the first common-mode inductor 303 may be provided on the first circuit board 301, and the second common-mode inductor 203 may be provided on the second circuit board 201.

[0064] refer to Figure 6 and Figure 7 The distance d1 between the display panel 20 and the light valve driving board 30 can be determined according to the communication rate between the light valve driving assembly 202 and the light valve 302. Optionally, the distance d1 between the display panel 20 and the light valve driving board 30 is the distance between the first circuit board 301 and the second circuit board 201.

[0065] Optionally, the communication rate between the light valve driver assembly 202 and the light valve 302 is less than or equal to 1.6 gigabits per second (Gbits per second), and the distance between the display panel 20 and the light valve driver board 30 is less than or equal to 254 millimeters (mm), that is, the distance between the first circuit board 301 and the second circuit board 201 is less than or equal to 254 mm. This ensures that the differential signal (i.e., the light valve control signal) received by the light valve 302 is of good quality.

[0066] refer to Figure 8 The projection system may further include a light source assembly 90 and an optical transmission assembly 91. The lens assembly 10 may include a first lens subassembly 101, a reflective subassembly 102, and a second lens subassembly 103. The optical axis X1 of the first lens subassembly 101 intersects the optical axis X2 of the second lens subassembly 103. That is, the arrangement direction of the optical lenses included in the first lens subassembly 101 is not parallel to the arrangement direction of the optical lenses included in the second lens subassembly 103. Optionally, the light source assembly 90 is used to emit a laser beam. The reflective subassembly 102 may be a reflector or a prism.

[0067] The light transmission component 91 is located between the light source component 90 and the light valve driving board 30 , and is used to transmit the light beam emitted by the light source component 90 to the light valve driving board 30 .

[0068] The light valve driving board 30 is located at the light incident side of the first lens subassembly 101 and is used to transmit the light beam transmitted by the light transmission assembly 91 to the first lens subassembly 101 under the drive of the light valve control signal.

[0069] The reflective subassembly 102 is located between the first lens subassembly 101 and the second lens subassembly 103. The first lens subassembly 101 is used to transmit the light beam to the reflective subassembly 102. The reflective subassembly 102 is used to reflect the light beam to the second lens subassembly 103. The second lens subassembly 103 is used to project the light beam onto the projection screen 40 to display an image on the projection screen 40. In other words, the light output side of the lens assembly 10 is also the light output side of the second lens subassembly 103.

[0070] In the embodiment of the present disclosure, the reflective subassembly 102 can be located between any two adjacent optical lenses among the multiple optical lenses included in the lens assembly 10. The embodiment of the present disclosure does not limit the specific position of the reflective subassembly 102.

[0071] In the embodiment of the present disclosure, the projection system may be an ultra-short-throw projection system. Figure 9Since the light-exiting side of the lens assembly 10 is the light-exiting side of the second lens subassembly 103, the distance D between the second lens subassembly 103 and the projection screen 40 is the distance between the light-exiting side of the lens assembly 10 and the projection screen 40. Compared with the related art, the optical lenses included in the lens assembly are arranged in a direction perpendicular to the projection screen. Since in the embodiment of the present disclosure, only part of the optical lenses in the lens assembly 10 (i.e., the second lens subassembly 103) are arranged along the X2 direction, and the remaining optical lenses (i.e., the first lens subassembly 101) are arranged along the X1 direction, the number of optical lenses arranged along the X2 direction is effectively reduced, thereby effectively shortening the distance D between the light-exiting side of the second lens subassembly 103 and the projection screen 40. Based on the above analysis, it can be seen that compared with the related art, the arrangement of multiple components in the projection system provided by the embodiment of the present disclosure effectively shortens the distance between the light-exiting side of the lens assembly and the projection screen, reduces the projection ratio of the projection system, and this arrangement can be applied to ultra-short-throw projection systems.

[0072] refer to Figure 10 The second lens subassembly 103 may include a first reflector 1030 in a plurality of optical lenses, and the first reflector 1030 is located at the light-emitting side of the second lens subassembly 103. The first reflector 1030 is used to reflect the light beam to the projection screen 40.

[0073] refer to Figure 10 The optical axis X1 of the first lens subassembly 101 is perpendicular to the optical axis X2 of the second lens subassembly 103 , and the optical axis X2 of the second lens subassembly 103 is perpendicular to the projection screen 40 .

[0074] refer to Figure 10 The optical transmission assembly 91 is used to adjust the transmission direction of the light beam emitted by the light source assembly 90 from the second direction to the third direction, and then from the third direction to the first direction V before transmitting it to the light valve drive board 30. This ensures a short distance between the light source assembly 90 and the lens assembly 10 in the first direction, shortens the length of the optical engine along the optical axis X1, and reduces the size of the projection system. The optical engine may include the light source assembly 90, the optical transmission assembly 91, the lens assembly 10, and the light valve drive board 30.

[0075] The second direction intersects the third direction, the second direction and the first direction V are both parallel to the optical axis X1 of the first lens subassembly 101 , and the first direction V is opposite to the second direction.

[0076] refer to Figure 10The optical transmission assembly 91 may include a first optical transmission subassembly 910 and a second optical transmission subassembly 911. The first optical transmission subassembly 910 is located on the light emitting side of the light source assembly 90, and the second optical transmission subassembly 911 is located between the first optical transmission subassembly 910 and the light valve driving board 30.

[0077] refer to Figure 10 The first light transmission subassembly 910 may include a plurality of optical lenses sequentially arranged along the transmission direction of the light beam. Optionally, the plurality of optical lenses may include a reflector, a focusing lens, a collimating lens, etc. The plurality of optical lenses are used to sequentially transmit the light beam emitted by the light source assembly 90 to the second light transmission subassembly 911.

[0078] refer to Figure 11 The second optical transmission subassembly 911 may include a light pipe 9111, a first lens 9112, a second lens 9113, a second reflector 9114, a third lens 9115, and a third reflector 9116, arranged sequentially along the optical axis X1. The light pipe 9111 is used to homogenize the light beam transmitted by the first optical transmission subassembly 910 and sequentially transmit the homogenized light beam to the first lens 9112 and the second lens 9113. The second lens 9113 transmits the light beam to the second reflector 9114, which reflects the light beam to the third lens 9115. The third lens 9115 then transmits the light beam to the third reflector 9116. The third reflector 9226 reflects the light beam to the light valve 302 on the light valve driving board 30.

[0079] Optionally, the first lens 9112 and the third lens 9115 may be spherical lenses, and the second lens 9113 may be an aspherical lens.

[0080] In the embodiment of the present disclosure, the surface of the display panel 20 does not intersect with the optical axis X1 of the first lens subassembly 101 and the optical axis X2 of the second lens subassembly 103, thereby avoiding the problem of the display panel 20 blocking the light beam and ensuring the image display effect.

[0081] Regarding the placement of the display panel, as long as it can be ensured that the display panel does not intersect with the optical axis X1 of the first lens subassembly 101 and the optical axis X2 of the second lens subassembly 103, and the length of the differential signal line 50 is less than or equal to 254 mm, the embodiment of the present disclosure does not limit the position of the display panel.

[0082] In the embodiment of the present disclosure, referring to FIG10 , the distance D0 between the light valve driving board 30 and the display panel 20 along the optical axis X2 is less than a distance threshold, which is equal to a first difference between the first distance and the second distance D1 .

[0083] Among them, the first distance is the distance D between the light-emitting side of the first lens sub-component 101 and the projection screen 40. Refer to Figure 10 , the second distance D1 is the distance between the first lens sub-component 101 in the direction of the optical axis X2 and the first circuit board 301 in the light valve driving board 30. That is, D0 < D - D1.

[0084] Exemplarily, if D = 215 mm and D1 = 197.5 mm, since 215 - 197.5 = 17.5, so D0 < 17.5 mm.

[0085] Alternatively, the distance threshold is equal to the difference between the first difference and the second difference. The second difference is the difference between the thickness w of the housing of the projection system and the safety distance s. That is, D0 < D - D1 - w - s. The safety distance s is the safety distance that needs to be maintained between the display board and the housing.

[0086] Exemplarily, if D = 215 mm, D1 = 197.5 mm, w = 3 mm, and s = 2 mm, since 215 - 197.5 - 3 - 2 = 12.5, so D0 < 12.5 mm.

[0087] In the embodiments of the present disclosure, refer to Figure 12 , the display board 20 may further include multiple pairs of first traces 204 and first sockets 205 located on the second circuit board 201. Each pair of first traces 204 includes two first traces 204. One ends of the multiple pairs of first traces 204 are connected to the light valve driving component 202, and the other ends are connected to the first sockets 205. Among them, the spacing, length, and width of the two first traces 204 included in each pair of first traces 204 are the same, and the spacing, length, and width of adjacent pairs of first traces 204 are the same. The spacing between any one first trace 204 and other traces except the first traces is at least 3 times the line width of one first trace 204.

[0088] The light valve driving board 30 may further include multiple pairs of second traces 304, second sockets 305, and third sockets 306 located on the first circuit board 301. Each pair of second traces 304 includes two second traces 304. One ends of the multiple pairs of second traces 304 are connected to the second sockets 305, and the other ends are connected to the third sockets 306. The third socket 306 is connected to the light valve 302. The spacing, length, and width of the two second traces 304 included in each pair of second traces 304 are the same, and the spacing, length, and width of adjacent pairs of second traces 304 are the same. The spacing between any one second trace 304 and other traces except the second traces 304 is at least 3 times the line width of one second trace 304. In the embodiments of the present disclosure, the first traces and the second traces are both LDVS traces.

[0089] The differential traces 50 may also include multiple pairs of differential signal lines 50, each pair of differential signal lines 50 comprising two differential signal lines 50. One end of each pair of differential signal lines 50 is connected to the first socket 205, and the other end is connected to the second socket 305, thereby connecting the display panel 20 and the light valve driver board 30. Adjacent pairs of differential signal lines 50 have the same length and cross-sectional area. The two differential signal lines 50 included in each pair of differential signal lines 50 have the same length and cross-sectional area. The spacing between the two differential signal lines 50 is less than half the spacing between the pair of differential signal lines 50 and the shielding layer 70. The differential mode impedance of the two differential signal lines 50 is within the impedance range of [99.9, 100.1].

[0090] refer to Figure 12 The common-mode current transmitted by the light valve driver assembly 202 flows through the first trace 204, the differential signal line 50, and the second trace 304. Therefore, the common-mode signal corresponding to this common-mode current is transmitted through the first trace 204, the differential signal line 50, and the second trace 304. This arrangement of the first trace, the differential signal line, and the second trace effectively reduces the common-mode current, thereby reducing the common-mode signal, and thus reducing the common-mode signal radiated outside the housing. Furthermore, by wrapping the differential signal line with a shielding layer, the common-mode signal is conducted to the base plate 60, and then through the base plate 60 to the ground 01, further reducing the common-mode signal radiated outside the housing.

[0091] In the embodiment of the present disclosure, the differential mode impedance of each pair of first traces 204 and each pair of second traces 304 is within the impedance range, which is [99.9, 100.1]. Each pair of first traces and each pair of second traces can be referred to as microstrip differential lines. Taking the first trace 204 as an example, refer to Figure 13 The second circuit board 201 may include an insulating layer 206 and a conductive layer 207. The first trace 204 is located between the insulating layer 206 and the conductive layer 207. The conductive layer 207 may be made of green oil. The differential mode impedance Z1 of each pair of first traces satisfies the following equation: Z1 = 2 × Z2 × (1-k), where Z2 is the characteristic impedance of a single microstrip line, i.e., the characteristic impedance of one first trace 204, and k is the coupling coefficient of each pair of first traces.

[0092] in, Should

[0093] refer to Figure 13, S1 is the distance between the two first traces 204 included in each pair of first traces 204, W1 is the width of the conductive layer 207 covering one first trace 204 on the side close to the insulating layer 206. Er1 is the dielectric constant of the material of the insulating layer 206, H1 is the thickness of the insulating layer 206. W2 is the width of the conductive layer 207 covering one first trace 204 on the side away from the insulating layer 206, and T1 is the thickness of one first trace 204.

[0094] Assume S1 = 7.5, K ≈ 0.097, H1 = 4.5, Er1 = 4.5, W1 = 5.5, W2 = 4.5, the Then Z1 = 99.19 ohms (Ω) ≈ 100Ω.

[0095] The common mode impedance of each pair of first traces 204 is the parallel approximation of the characteristic impedances of the two first traces. If the common mode impedance Z3 satisfies: N is the coupling degree between the shielding layer and the first trace 204 .

[0096] Assuming N≈1.14, Z2≈54.92, then the

[0097] If the differential signal line 50 is approximately a monopole antenna, the radiation electric field strength E of the common mode current flowing through the differential signal line 50 satisfies: Where I is the common-mode current flowing through the differential signal line 50, in amperes (A). f represents the sinusoidal frequency of the common-mode current component, in hertz (Hz). L is the length of the differential signal line 50, in meters (m). R represents the distance between the test equipment and the differential signal line 50, in meters.

[0098] For example, if the common mode current is 5×10 -3 A, L = 1m, R = 3m, f = 100MHz, then The 2000 μV / m is greater than the quasi-peak threshold of 40 μV / m, so the electromagnetic interference test of the projection system fails.

[0099] In the embodiment of the present disclosure, the radiation electric field intensity E of the common mode current can be reduced by reducing the length of the differential signal line 50, thereby ensuring that the electromagnetic interference test of the projection system is qualified.

[0100] In a scenario where the distance between the display panel 20 and the light valve driving board 30 is less than or equal to 254 mm, a shielding layer 70 is wrapped around the differential signal line 50, a magnetic ring 80 is sleeved on the shielding layer 70, or the projection system includes a common-mode inductor, and the differential-mode impedances of the differential signal line, the first trace, and the second trace are all within the impedance range, a far-field low-frequency radiated disturbance field strength test is performed on the projection system using the test equipment. Figure 14 FIG. 1 is a schematic diagram of the results of a low-frequency radiation disturbance field strength test on a projection system provided by an embodiment of the present disclosure. Figure 14 As shown, the horizontal axis in the result diagram represents the test frequency of the test equipment, that is, the operating frequency of the antenna in the test equipment, and its unit is megahertz (MHz). The test frequency range is 30MHz to 1000MHz. The vertical axis in the result diagram represents the quasi-peak value of the electromagnetic signal, and its unit is μV / m.

[0101] The first curve Y1 in the result diagram is a quasi-peak curve of the electromagnetic signal radiated by the projection system within the test frequency range of 30MHz to 1000MHz. The larger the quasi-peak value of the electromagnetic signal of the projection system, the stronger the electromagnetic signal radiated by the projection system, which includes the common-mode signal mentioned above. The second curve Y2 in the result diagram is a quasi-peak threshold curve of the electromagnetic signal within the test frequency range of 30MHz to 1000MHz, which meets the civilian-grade CISPR22 Class B low-frequency radiated disturbance field strength test.

[0102] If any quasi-peak value in the first curve Y1 is above the second curve Y2, it can be determined that the electromagnetic signal radiated by the projection system is large and cannot meet the use requirements. If the first curve Y1 is below the second curve Y2, it can be determined that the electromagnetic signal radiated by the projection system is small and meets the use requirements.

[0103] from Figure 14 It can be seen that within the test frequency range of 30MHz to 1000MHz, the first curve Y1 lies below the second curve Y2. This means that at any test frequency, the quasi-peak value of the electromagnetic signal radiated by the projection system is less than the corresponding quasi-peak threshold. This indicates that the projection system has passed the civilian-grade CISPR 22 Class B low-frequency radiated field strength disturbance test and meets the requirements for use.

[0104] Table 1 shows the debugging parameters of the test equipment during the test of the projection system, the quasi-peak value of the electromagnetic signal radiated by the projection system, the quasi-peak threshold of the electromagnetic signal, and the difference between the quasi-peak value and the quasi-peak value. The debugging parameters may include the test frequency of the test equipment, the test duration, the height of the test equipment from the bottom surface, the polarity, and the angle of the antenna in the test equipment. The polarity is H, indicating that the antenna of the test equipment is not perpendicular to the projection system. The unit of test duration is milliseconds, and the unit of bandwidth is kilohertz (kHz). The unit of bandwidth is centimeters (cm).

[0105] It can be concluded from Table 1 that if the test frequency of the test equipment is 152.1790 MHz, the quasi-peak value of the electromagnetic signal radiated by the projection system is 32.81, and the quasi-peak threshold value is 40. Since the quasi-peak value 32.81 is less than the quasi-peak threshold value 40, it can be determined that when the test frequency of the test equipment is 152.1790 MHz, the electromagnetic signal radiated by the projection system is small.

[0106] Table 1

[0107]

[0108] In the above scenario, Figure 15 This is an eye diagram of a light valve receiving a differential signal transmitted by a light valve driving component provided by an embodiment of the present disclosure. Figure 15 As shown, the horizontal axis of the eye diagram is time, with the unit being picosecond (ps), and the vertical axis is the voltage of the differential signal received by the light valve 302, with the unit being millivolt (mV).

[0109] from Figure 15 It can be seen that the voltage of the differential signal received by the light valve 302 lies between the first and second thresholds. The maximum voltage of the differential signal has a significant difference from the first threshold, and the minimum voltage of the differential signal also has a significant difference from the second threshold. The first threshold is 400mV, and the second threshold is -400mV. Furthermore, the voltages at intersections P1 and P2 in the differential signal are both low, indicating low jitter. This indicates good quality and a low probability of bit errors. In summary, when the distance between the display panel 20 and the light valve driver board 30 is less than or equal to 254mm, the quality of the differential signal received by the light valve is good.

[0110] In the embodiments of the present disclosure, reference Figure 16 The projection system may further include a heat sink 92 and a conduit 93, one end of the conduit 93 being connected to the heat sink 92 and the other end being connected to the support plate where the light source assembly is located. The heat sink 92 dissipates heat for the light source assembly through the conduit 93.

[0111] refer to Figure 16 The projection system may further include a power supply board 94 , which is located on one side of the second lens subassembly 103 .

[0112] Figure 17 This is a structural diagram of a projection system provided by related technology. Figure 17As shown, the projection system may include a lens assembly 001, a light valve driving board 002 and a display board 003. The multiple optical lenses included in the lens assembly 001 are arranged in a direction perpendicular to the projection screen 004, and the light emitting side of the lens assembly 001 is located on the side of the display board 20 away from the projection screen 004, and the board surfaces of the light valve driving board 002 and the display board 3 are both parallel to the projection screen 004.

[0113] However, the arrangement of the lens assembly 001, light valve drive board 002 and display board 003 results in a large distance between the light-emitting side of the lens assembly 001 and the projection screen 004, resulting in a relatively large projection of the projection system. The above arrangement is not applicable to ultra-short-throw projection systems.

[0114] Moreover, in the related art, if the projection ratio of the projection system is reduced, in order to ensure the display effect of the image, the total length of the lens assembly needs to be increased. However, the increase in the total length of the lens assembly will lead to an increase in the projection ratio of the projection system, and the two cannot be balanced.

[0115] In the disclosed embodiment, because the optical axes of the first lens subassembly and the second lens subassembly included in the lens assembly of the projection system do not intersect, some of the optical lenses in the lens assembly are arranged along the optical axis of the second lens subassembly, while the remaining optical lenses are arranged along the optical axis of the first lens subassembly. This effectively reduces the number of optical lenses arranged along the optical axis of the second lens subassembly, thereby shortening the distance between the light-emitting side of the second lens subassembly and the projection screen, and reducing the throw ratio of the projection system. This arrangement is suitable for ultra-short-throw projection systems. Furthermore, this arrangement can reduce the throw ratio without increasing the overall length of the lens assembly, ensuring a balance between the two.

[0116] In summary, the embodiments of the present disclosure provide a projection system in which the light valve driver board and lens assembly are arranged parallel to the projection screen. Furthermore, the first circuit board of the light valve driver board is perpendicular to the projection screen, and the display panel is parallel to the projection screen. This arrangement effectively reduces the number of optical lenses in the lens assembly arranged perpendicular to the projection screen, thereby shortening the distance between the light-emitting side of the lens assembly and the projection screen, and reducing the projection system's throw ratio. This arrangement is suitable for ultra-short-throw projection systems.

[0117] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A projection system, characterized in that: The projection system includes: a lens assembly, a display panel, a light valve driving board, a differential signal line and a bottom board; wherein the light valve driving board includes a circuit board and a light valve located on the circuit board; The display panel is located on a side of the lens assembly close to the projection screen, and the display panel is electrically connected to the light valve driving board via the differential signal line, for providing a light valve control signal to the light valve; The light valve driving plate and the lens assembly are arranged along a first direction, the first direction being parallel to the projection screen, and the light valve is used to flip under the drive of the light valve control signal and transmit the light beam to the lens assembly; The lens assembly includes a plurality of optical lenses arranged along the first direction; The display panel, the light valve driving board and the lens assembly are all located on the bottom plate, the differential signal line is in contact with the bottom plate, and the bottom plate is grounded; The board surface of the circuit board is perpendicular to the projection screen and perpendicular to the bottom plate, and the board surface of the display panel is parallel to the projection screen and perpendicular to the bottom plate.

2. The projection system according to claim 1, wherein: The projection system further includes: a shielding layer; The shielding layer is wrapped around the outside of the differential signal line, and the shielding layer is grounded.

3. The projection system according to claim 2, wherein: The projection system further includes a magnetic ring, which is sleeved on the outside of the shielding layer, and the length of the magnetic ring is smaller than the length of the shielding layer.

4. The projection system according to claim 1, wherein: The projection system further includes: a common mode inductor; The common-mode inductor is connected in series between the display panel and the light valve driving board through the differential signal line.

5. The projection system according to any one of claims 1 to 4, characterized in that: The distance between the display panel and the light valve driving board is determined according to the communication rate between the light valve driving component in the display panel and the light valve.

6. The projection system according to claim 5, wherein: The communication rate between the light valve driving assembly and the light valve is less than or equal to 1.6 gigabits per second, and the distance between the display panel and the light valve driving board is less than or equal to 254 millimeters.

7. The projection system according to any one of claims 1 to 4, characterized in that: The projection system further comprises: a light source assembly and a light transmission assembly; the lens assembly comprises a first lens subassembly, a reflection subassembly, and a second lens subassembly, wherein the optical axis of the first lens subassembly intersects the optical axis of the second lens subassembly; The light transmission component is located between the light source component and the light valve driving board, and is used to transmit the light beam emitted by the light source component to the light valve driving board; The light valve driving board is located on the light incident side of the first lens subassembly and is used to transmit the light beam transmitted by the light transmission assembly to the first lens subassembly under the drive of the light valve control signal; The reflection subassembly is located between the first lens subassembly and the second lens subassembly. The first lens subassembly is used to transmit the light beam to the reflection subassembly. The reflection subassembly is used to reflect the light beam to the second lens subassembly. The second lens subassembly is used to project the light beam onto the projection screen.

8. The projection system according to claim 7, wherein: The optical axis of the first lens subassembly is perpendicular to the optical axis of the second lens subassembly, and the optical axis of the second lens subassembly is perpendicular to the projection screen.

9. The projection system according to claim 7, wherein: The light transmission component is used to adjust the transmission direction of the light beam emitted by the light source component from the second direction to the third direction, and then adjust the light beam from the third direction to the first direction before transmitting the light beam to the light valve driving board; The second direction intersects the third direction, the second direction and the first direction are both parallel to the optical axis of the first lens subassembly, and the first direction and the second direction are opposite.

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