Variable sign and display device

Abstract

To provide a variable sign and display device that can reduce the time required to change the display. [Solution] A variable sign according to one embodiment of the present invention comprises a display unit and a display control unit. A plurality of magnetic reversal display elements are arranged in the display unit. When the display of the display unit is changed, the display control unit drives only the magnetic reversal display elements whose display state changes before and after the change, with the target elements being the target elements.

Description

Technical Field

[0001] The present invention relates to a variable sign and a display device using magnetic reversal display elements.

Background Art

[0002] Conventionally, display devices using magnetic reversal display elements have been developed. A magnetic reversal display element is an element that reverses the front and back sides of a display plate by, for example, magnetic reversal. Since the state of the plate is maintained by magnetic force, no current needs to be passed if only the display is to be maintained. This makes it possible to reduce power consumption in variable signs and the like. For example, Patent Document 1 describes a variable speed regulation sign in which a plurality of magnetic reversal display elements are arranged in a grid pattern.

Related Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In general, a relatively large current is required to simultaneously drive a plurality of magnetic reversal display elements. For this reason, for example, in a display device equipped with a plurality of magnetic reversal display elements, the magnetic reversal display elements are driven one by one when changing the display. As a result, it is conceivable that it takes time to complete the display change.

[0005] In view of the circumstances as described above, an object of the present invention is to provide a variable sign and a display device capable of reducing the time required for display change.

Means for Solving the Problems

[0006] A variable sign according to an embodiment of the present invention includes a display unit and a display control section. The display unit has a plurality of magnetic reversal display elements arranged in it. When the display control unit changes the display of the display unit, it drives only the magnetic reversal display element whose display state changes before and after the change, treating the target element as the target element.

[0007] In this variable sign, only the target element, which is a magnetic reversal display element whose display state changes before and after the display unit's display change, is driven. This eliminates the need to drive, for example, a magnetic reversal display element whose display state does not change, and makes it possible to shorten the time required for display changes.

[0008] The display control unit may change the display state of the target element one by one in a predetermined order.

[0009] The display unit may display a number with a predetermined number of digits.

[0010] The display control unit may change the display state of the target element digit by digit.

[0011] The display control unit may change the display state of the target element in an order such that no digit appears to be any other digit.

[0012] The display control unit may determine the target element based on first data representing the display content before the display unit is changed and second data representing the display content after the display unit is changed.

[0013] The first data and the second data may be data that designates the plurality of magnetic reversal display elements constituting the display unit as pixels. In this case, the display control unit may determine the target element by comparing the corresponding pixels between the first data and the second data.

[0014] The variable sign may be configured as a variable speed limit sign that displays the speed limit using the display unit.

[0015] A display device according to one aspect of the present invention includes a display unit and a display control section. A plurality of magnetic reversal display elements are arranged in the display unit. When changing the display on the display unit, the display control section sets the magnetic reversal display elements whose display states change before and after the change as target elements, and drives only the target elements. [Advantageous Effects of Invention]

[0016] According to the present invention, it is possible to reduce the time required for display change. [Brief Description of Drawings]

[0017] [Figure 1] This is a schematic diagram showing an example of a variable speed regulation sign according to one embodiment of the present invention. [Figure 2] This is an exploded perspective view showing a configuration example of the variable speed regulation sign. [Figure 3] This is a block diagram showing a functional configuration example of the variable speed regulation sign. [Figure 4] This is a schematic diagram for explaining the operating principle of the magnetic reversal display element. [Figure 5] This is a circuit diagram showing a connection example of a plurality of magnetic reversal display elements. [Figure 6] This is a schematic diagram showing an example of the display change operation according to the present embodiment. [Figure 7] This is a flowchart showing an example of the display change operation according to the present embodiment. [Figure 8] This is a schematic diagram showing a display change operation given as a comparative example. [Modes for Carrying Out the Invention]

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0019] [Overall Configuration] Figure 1 is a schematic diagram showing an example of a variable speed limit sign according to one embodiment of the present invention. The variable speed limit sign 100 is a road sign that displays a variable speed limit and is placed around the road so that it can be seen by drivers of automobiles, etc. In this embodiment, the variable speed limit sign 100 is an example of a variable sign.

[0020] The variable speed limit sign 100 has a display unit 10 in which a plurality of magnetic reversal display elements 20 are arranged.

[0021] The magnetic reversal display element 20 is a display element that, for example, uses magnetic reversal to switch between a state in which one side of a movable disk is visible and a state in which the other side is visible. In this embodiment, the magnetic reversal display element 20 is configured to display by switching between two colors. This allows one magnetic reversal display element 20 to be used as one pixel.

[0022] The display unit 10 is a unit in which multiple magnetic reversal display elements 20 are arranged in a predetermined pattern. The display unit 10 can change the display content by driving each magnetic reversal display element 20 to change its display state.

[0023] The variable speed limit sign 100 has a speed display section 11a, an auxiliary display section 11b, and a support section 12 that supports the speed display section 11a and the auxiliary display section 11b. In the example shown in Figure 1, the speed display section 11a and the auxiliary display section 11b are fixed to the columnar support section 12 from top to bottom. Of course, the shape of the support section 12 and the arrangement of the speed display section 11a and the auxiliary display section 11b can be changed as appropriate.

[0024] Both the speed display unit 11a and the auxiliary display unit 11b are constructed using the display unit 10. Hereinafter, the display unit 10 that constitutes the speed display unit 11a may be referred to as display unit 10a, and the display unit 10 that constitutes the auxiliary display unit 11b may be referred to as display unit 10b.

[0025] The speed display unit 11a functions as a speed limit sign that displays the regulated speed. In the speed display unit 11a, a display unit 10a that displays the regulated speed is positioned inside the red circular area. In this way, the variable speed limit sign 100 displays the regulated speed using the display unit 10a.

[0026] The display unit 10a is configured to display a number of a predetermined number of digits. Here, a display unit 10a that displays a two-digit number is provided, and the speed limit specified by the two-digit number is displayed. The speed limit is typically specified in units of 10 km / h. Therefore, the display unit 10a will display two-digit numbers such as "40", "50", "60", "70", "80", and "90". In Figure 1, assuming the speed limit is 50 km / h, the display unit 10a will display "50".

[0027] The auxiliary display unit 11b is positioned together with the speed limit sign and functions as an auxiliary sign indicating the speed limit section. The auxiliary display unit 11b has a display unit 10b that displays a horizontal arrow inside a white rectangular area.

[0028] The display unit 10b is configured to display a left-pointing arrow, a right-pointing arrow, and arrows pointing in both directions. Thus, a display unit 10 capable of displaying images can also be used. In Figure 1, a right-pointing arrow is displayed to indicate the start of a speed-restricted section. A left-pointing arrow is displayed to indicate the end of a speed-restricted section. In addition, arrows pointing in both directions may be displayed to indicate that the vehicle is within a speed-restricted section.

[0029] Figure 2 is an exploded perspective view showing an example of the configuration of a variable speed limit sign. Figure 2 shows an exploded perspective view of the variable speed limit sign 100, specifically the speed display section 11a and the main body section 16 on which the speed display section 11a is provided. The speed display section 11a includes a surface cover 13, a sign plate 14, a display unit 10a, and a unit support section 15.

[0030] The surface cover 13 is a transparent disc member provided to cover the front surface of the speed display unit 11a, and functions as a cover to protect the magnetic reversal display element 20 that constitutes the display unit 10a. A transparent acrylic plate or the like can be used as the surface cover 13.

[0031] The sign board 14 is a board on which a red circle is drawn surrounding the speed limit display area (display unit 10a) in the speed display section 11a, and is positioned behind the surface cover 13. As shown in Figure 2, a rectangular opening is provided inside the red circle for each girder in order to expose the display unit 10a.

[0032] The display unit 10a has multiple magnetic reversal display elements 20 arranged to display a two-digit number as described above, and is positioned behind the sign plate 14. The arrangement pattern of the magnetic reversal display elements 20 will be explained in detail later with reference to Figure 6, etc.

[0033] The unit support portion 15 is a disc-shaped member positioned behind the sign board 14 and supporting the display unit 10a facing forward. Together with the surface cover 13 described above, it functions as a housing for the speed display unit 11a that accommodates the sign board 14 and the display unit 10a.

[0034] The main body 16 is positioned behind the speed display unit 11a (unit support unit 15) and is a housing that contains various devices for driving the speed display unit 11a. The unit support unit 15 is mounted on the front of the main body 16 so that it can be opened and closed. Therefore, the unit support unit 15 functions as a door for the main body 16. The main body 16 includes a power supply unit 17 and a signal control device 40.

[0035] The power supply unit 17 supplies power to each of the magnetic reversal display elements 20 and the indicator control device 40 of the display unit 10. The power supply unit 17 converts power from the commercial power supply to a predetermined power level and outputs it. The power supply unit 17 may also be equipped with a backup battery or the like for use in the event of a power outage.

[0036] Figure 3 is a block diagram showing an example of the functional configuration of a variable speed limit sign. The functional configuration of the sign control device 40 will be described below with reference to Figure 3. The sign control device 40 includes a communication unit 41, a storage unit 42, a controller 43, and a drive circuit 44.

[0037] The communication unit 41 is a communication module that communicates with an external management device (not shown) via wireless or wired communication. The communication unit 41 receives information such as the speed limit to be displayed on the variable speed limit sign 100 transmitted from the management device, and outputs it to the controller 43. The communication unit 41 also transmits information related to the variable speed limit sign 100 (such as information indicating a device malfunction) output from the controller 43 to the management device.

[0038] The memory unit 42 is a non-volatile memory device that stores control programs executed by the controller 43, and can be an SSD (Solid State Drive) or HDD (Hard Disk Drive), for example. The memory unit 42 also stores data on the display content shown on the variable speed limit sign 100, and table data for controlling the display unit 10.

[0039] The controller 43 controls the operation of the entire variable speed limit sign 100. In this embodiment, the display unit 10 (display unit 10a and display unit 10b) provided on the variable speed limit sign 100 is controlled by the controller 43. In this embodiment, the controller 43 corresponds to the display control unit.

[0040] The controller 43 has the necessary hardware configuration for a computer, such as a CPU and memory (RAM, ROM). Various processes are executed by the CPU loading the control program stored in the memory unit 42 into the RAM and executing it. As the controller 43, devices such as FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), and ASICs (Application Specific Integrated Circuits) may be used.

[0041] The drive circuit 44 drives each magnetic reversal display element 20 provided in the display unit 10 (display unit 10a and display unit 10b) according to the control signal output from the controller 43. Specifically, it supplies pulse currents for driving the movable disk to a plurality of magnetic reversal display elements 20 specified by the control signal at predetermined intervals. The pulse width of the pulse current is, for example, about 5 ms, and the pulse interval is, for example, about 200 μs. The pulse width and pulse interval are not limited to these values ​​and are set appropriately according to the characteristics of the magnetic reversal display elements 20, etc.

[0042] Figure 4 is a schematic diagram illustrating the operating principle of the magnetic reversal display element. The display state of the magnetic reversal display element 20 is different in Figure 4A and Figure 4B. First, the configuration of each part of the magnetic reversal display element 20 will be explained with reference to Figure 4A. The magnetic reversal display element 20 has a movable disk 21, a permanent magnet 22, a stator pin 23, a set coil 24s, and a reset coil 24r.

[0043] The movable disk 21 is a plate-shaped member that functions as a pixel. The movable disk 21 is configured to be rotatable, for example, around a rotation axis 5 that passes through the center of the movable disk 21 and extends in the planar direction. A stopper (not shown) is provided near the movable disk 21 so as to interfere with the rotating movable disk 21. As a result, the rotation range of the movable disk 21 is approximately ±180° with respect to the position where it interferes with the stopper.

[0044] One side of the movable disk 21 is a display surface 21a for displaying pixels, and the other side is a non-display surface 21b for hiding pixels. A reflective sheet of a different color from the background color of the sign board 14, for example, is attached to the display surface 21a. For example, in the magnetic reversal display element 20 that constitutes the speed display unit 11a (display unit 10a), the display surface 21a is set to blue, and in the magnetic reversal display element 20 that constitutes the auxiliary display unit 11b (display unit 10b), the display surface 21a is set to red. A reflective sheet of the same white color as the background color of the sign board 14 is attached to the non-display surface 21b, for example. Figures 4A and 4B illustrate the state in which the display surface 21a is displayed and the state in which the non-display surface 21b is displayed, respectively.

[0045] The movable disc 21 is made of a relatively lightweight material, such as resin. The planar shape of the movable disc 21 is set to, for example, a square or a circle, but is not necessarily limited to these, and a movable disc 21 with a rectangular or polygonal shape may also be used. Furthermore, the materials and colors that constitute the display surface 21a and the non-display surface 21b are not limited and are appropriately selected so as to enable proper display of the display content of the display unit 10.

[0046] The permanent magnet 22 is embedded in the movable disk 21 and forms magnetic poles facing opposite directions at opposite positions on the outer edge of the movable disk 21. The permanent magnet 22 may be a single magnet, or two permanent magnets 22 may be arranged separately.

[0047] The stator pin 23 is a longitudinal member bent into a U-shape and functions as the core material (electromagnetic core) of the electromagnet. For the stator pin 23, for example, soft ferromagnetic materials such as soft iron or ferrite are used. Two coils (set coil 24s and reset coil 24r) are wound around the center of the stator pin 23. The ends of the stator pin 23, which are bent relative to the center, become the magnetic poles of the electromagnet.

[0048] The set coil 24s and the reset coil 24r are electromagnetic coils that magnetize the stator pins 23 in opposite directions. The set coil 24s is located between the common terminal 25c and the set terminal 25s, and the reset coil 24r is located between the common terminal 25c and the reset terminal 25r. Therefore, the common terminal 25c is a terminal common to both the set coil 24s and the reset coil 24r.

[0049] When a predetermined pulse current 1 is applied to the set coil 24s or the reset coil 24r, a magnetic field is generated in a direction corresponding to each coil, with the ends of the stator pins 23 acting as magnetic poles. Furthermore, due to the residual magnetization of the stator pins 23, the magnetic poles of the stator pins 23 are maintained even when no current is flowing.

[0050] For example, as shown in Figure 4A, when a pulse current 1 is applied to the set coil 24s, the left end of the stator pin 23 in the figure becomes the south pole, and the right end becomes the north pole. In this case, the movable disk 21 is rotated so that the north pole of the permanent magnet 22 approaches the left end of the stator pin 23, and the south pole of the permanent magnet 22 approaches the right end. As a result, the display surface 21a of the magnetic reversal display element 20 becomes visible.

[0051] Furthermore, as shown in Figure 4B, when a pulse current 1 is applied to the reset coil 24r, the left end of the stator pin 23 becomes the north pole and the right end becomes the south pole. In this case, the movable disk 21 is rotated so that the south pole of the permanent magnet 22 approaches the left end of the stator pin 23 and the north pole of the permanent magnet 22 approaches the right end. As a result, the non-display surface 21b of the magnetic reversal display element 20 becomes visible.

[0052] Thus, the magnetic reversal display element 20 is a display device that reverses a movable disk 21 containing a permanent magnet 22 by changing the magnetic poles of the stator pins 23 with a pulse current 1.

[0053] In the following, the rotation operation that displays pixels with the display surface 21a facing outwards, as shown in Figure 4A, will be referred to as the first rotation operation. Similarly, the rotation operation that hides pixels with the non-display surface 21b facing outwards, as shown in Figure 4B, will be referred to as the second rotation operation. For example, if the first rotation operation is considered a forward rotation operation, then the second rotation operation will be a reverse rotation operation. Note that in Figure 4, pixels are displayed by applying a pulse current 1 to the set coil 24s and hidden by applying a pulse current 1 to the reset coil 24r, but the opposite setting is also possible.

[0054] Figure 5 is a circuit diagram showing an example of the connection of multiple magnetic reversal display elements. Figure 5 shows the circuit configuration of the mounting board 26 (display unit 10) on which multiple magnetic reversal display elements 20 are mounted. The mounting board 26 has multiple magnetic reversal display elements 20, multiple set lines 27s, multiple reset lines 27r, and multiple common lines 27c.

[0055] Multiple magnetic reversal display elements 20 are arranged in a grid along the m direction (vertical direction in the figure) and the n direction (horizontal direction in the figure). Here, the magnetic reversal display elements 20 arranged in m rows and n columns are denoted as A(mn), with the upper left magnetic reversal display element 20 in the figure as the reference. Therefore, for example, the reference magnetic reversal display element 20 is A11, and the element below it is A12. Note that the element arrangement on the mounting board 26 does not necessarily have to match the actual element arrangement (the arrangement pattern of magnetic reversal display elements 20 in the display unit 10).

[0056] Each magnetic reversal display element 20 has a set coil 24s, a reset coil 24r, a set terminal 25s, a reset terminal 25r, and a common terminal 25c, as described with reference to Figure 4. Each magnetic reversal display element 20 also has a diode 28s and a diode 28r. Diode 28s is forward connected from the set terminal 25s toward the set line 27s. Diode 28r is forward connected from the reset terminal 25r toward the reset line 27r.

[0057] Multiple set lines 27s and multiple reset lines 27r are provided for every m rows. The set terminals 25s of multiple magnetic reversal display elements 20 arranged in the same row are connected to a common set line 27s via diodes 28s, and the reset terminals 25r of multiple magnetic reversal display elements 20 arranged in the same row are connected to a common reset line 27r via diodes 28r. Multiple common lines 27c are provided for every Y column, and each common line 27c is connected to the common terminal 25c of multiple magnetic reversal display elements 20 arranged in a single column along the X direction.

[0058] To supply a pulse current 1 to the set coil 24s (or reset coil 24r) of the magnetic reversal display element A(mn), one simply selects the set line 27s (or reset line 27r) and common line 27c corresponding to that element. The wiring through which the current flows is appropriately selected by the drive circuit 44 according to the control signal from the controller 43.

[0059] For example, when a pulse current of 1 is passed between the set line 27s in the third row and the common line 27c in the second column, the pulse current of 1 flows through the set coil 24s of the magnetic reversal display element A23, causing the first rotation operation to occur. Similarly, when a pulse current of 1 is passed between the reset line 27r in the third row and the common line 27c in the second column, the pulse current of 1 flows through the reset coil 24r of the magnetic reversal display element A23, causing the second rotation operation to occur.

[0060] Furthermore, attempting to simultaneously reverse the magnetic poles of the stator pins 23 provided on multiple magnetic reversal display elements 20 requires a relatively large current. In this case, increasing the current flowing through the drive circuit 44 would necessitate circuits capable of handling large currents and advanced leakage protection measures, potentially leading to an increase in device size and cost.

[0061] Therefore, the multiple magnetic reversal display elements 20 are basically reversed one by one. Here, reversal control is a control that reverses the movable disk 21 to switch the display state of the magnetic reversal display elements 20 (a state in which pixels are displayed and a state in which they are not displayed). Reversal control is a control that performs either a first rotation operation or a second rotation operation.

[0062] Figure 6 is a schematic diagram showing an example of the display change operation according to this embodiment. Here, we will explain the display change in the variable speed limit sign 100, which is performed by reversing control of the magnetic reversal display element 20. Figure 6A shows the display content before the display change, and Figure 6C shows the display content after the display change. Figure 6B shows the target element 30 that is subject to reversal control.

[0063] First, with reference to Figure 6A, the arrangement patterns of the magnetic reversal display elements 20 in display units 10a and 10b will be explained. Note that the arrangement patterns described here are merely examples, and any other arrangement patterns can be used depending on the display content, etc.

[0064] In the display unit 10a, the section for displaying the tens digit is a rectangular pattern with 12 rows and 7 columns. Various numbers are displayed within this rectangular pattern. The section for displaying the units digit is a ring pattern with an 8x3 space in the center of the 12x7 pattern. This pattern is set because the units digit either displays the digit "0" or is not displayed, and the 8x3 space corresponds to the space inside the digit "0". In addition, a space of about one column is provided between each display section for the tens and units digits where no elements are placed.

[0065] Display unit 10b is a unit for displaying a horizontal arrow. It has a 2x15 axis section. On both the left and right sides of the axis section, three L-shaped blocks are arranged symmetrically to represent the tip of the arrow. In this case, by switching the display / hide status of the six blocks on either side of the axis section, right-facing, left-facing, and bidirectional arrows can be displayed.

[0066] Next, an overview of the display change operation in the variable speed limit sign 100 will be described. In this embodiment, when the controller 43 changes the display of the display unit 10, it drives only the magnetic reversal display element 20, which has a change in display state before and after the change, as the target element 30.

[0067] The target element 30 is, for example, a magnetic flip display element 20 whose display state has changed when comparing the display content before the change with the display content after the change. Therefore, when changing the display of the display unit 10, at least one (typically more) target elements 30 will be generated depending on the display content before and after the change.

[0068] The target element 30 also includes a first target element 30a and a second target element 30b. The first target element 30a is an element that can be switched from non-display to display, that is, an element that is inverted from the non-display surface 21b to the display surface 21a. The second target element 30b is an element that can be switched from display to non-display, that is, an element that is inverted from the display surface 21a to the non-display surface 21b. For example, the inversion control for the first target element 30a is a first rotation operation. The inversion control for the second target element 30b is a second rotation operation.

[0069] For example, in display unit 10a, the speed limit "70" shown in Figure 6A is changed to the speed limit "50" shown in Figure 6C. Figure 6B shows the target elements 30 when the display content of display unit 10a is changed from "70" to "50". For example, in a 12-row, 7-column rectangular pattern representing the tens digit, when the number "7" is changed to "5", the element that changes from white (non-display surface 21b) to blue (display surface 21a) is the first target element 30a, and the element that changes from blue (display surface 21a) to white (non-display surface 21b) is the second target element 30b. Note that in the units digit of display unit 10a, the display does not change, so no target elements 30 are generated.

[0070] In addition, in the display unit 10b, the rightward arrow indicating the start of the speed restriction section shown in Figure 6A is changed to a leftward arrow indicating the start of the speed restriction section shown in Figure 6C. Figure 6B shows the target elements 30 when the display content of the display unit 10b is changed from a rightward arrow to a leftward arrow. In this case, the display of the 2x15 axis section is maintained. Furthermore, the six elements representing the left tip become the first target elements 30a, changing from white (non-display surface 21b) to red (display surface 21a), and the six elements representing the right tip become the second target elements 30b, changing from red (display surface 21a) to white (non-display surface 21b).

[0071] The controller 43 determines which of these target elements 30 are and drives only the target elements 30. Here, driving a magnetic reversal display element 20 means supplying a pulse current 1 to the set coil 24s or reset coil 24r of that element. Therefore, driving only the target elements 30 means supplying a pulse current 1 only to the set coil 24s or reset coil 24r of the target element 30, and not supplying a pulse current 1 to the magnetic reversal display elements 20 other than the target elements 30.

[0072] As a result, in Figure 6B, inversion control is performed only for the first target element 30a and the second target element 30b, and the display state is changed. The display state of the magnetic inversion display elements 20 other than the first target element 30a and the second target element 30b is maintained.

[0073] Thus, in this embodiment, the display unit 10 determines the display state before and after the change, and only the magnetic reversal display element 20 (target element 30) that requires change is driven to perform reversal control.

[0074] This significantly reduces the number of elements performing inversion control compared to, for example, a process in the display unit 10 where the display content before the change is reset before displaying the content after the change. As a result, the time required for display changes can be shortened. Furthermore, by shortening the display change time, it becomes more difficult for drivers to recognize the state during the display change, thus suppressing driver misrecognition.

[0075] Furthermore, the controller 43 drives the multiple target elements 30, which are to be determined as shown in Figure 6B, one by one in a predetermined order. That is, the controller 43 changes the display state of the target elements 30 one by one in a predetermined order. Even when changing the target elements 30 one by one in this way, the number of target elements 30 is small compared to the total number of elements, so the display change time can be shortened. There are various ways to set the order in which the target elements 30 are driven, but basically any order can be set. For this reason, it is possible to adopt an order that suppresses misrecognition, for example.

[0076] The display unit 10 of the variable speed limit sign 100 changes its display based on instructions from a management device that transmits the speed limit, etc. For example, if the management device receives an instruction that the speed limit is 70 km / h and that the start position of the speed limit section should be displayed, the display content of the display unit 10 will be as shown in Figure 6A. Subsequently, if the management device receives an instruction that the speed limit is 50 km / h and that the end position of the speed limit section should be displayed, the display content of the display unit 10 will change as shown in Figure 6C. During this display change process, the target element 30 is determined as shown in Figure 6B.

[0077] In this embodiment, the controller 43 determines the target element 30 based on first data representing the display content of the display unit 10 before the display is changed, and second data representing the display content of the display unit 10 after the display is changed. That is, the determination of the target element 30 is performed by the controller 43 using data (first data and second data) representing the display content before and after the display change.

[0078] In this embodiment, the first data and the second data are data that designates a plurality of magnetic reversal display elements 20 constituting the display unit 10 as pixels. That is, the first data and the second data are binary pixel data that represent the display content, such as numbers and symbols, corresponding to the arrangement pattern of the magnetic reversal display elements 20. The pixel data stores information that specifies whether to display or not display for each of the plurality of pixels.

[0079] In the variable speed limit sign 100, for example, pixel data corresponding to multiple display contents is stored in the storage unit 42, and the corresponding pixel data is read according to instructions from the management device. For example, when an instruction is received that the speed limit is 50 km / h, pixel data for displaying "50" is read into the display unit 10a. Also, when an instruction is received to display the end position of the speed limit section, pixel data for displaying a left-pointing arrow is read into the display unit 10b. The following will specifically describe the display change operation using this pixel data.

[0080] Figure 7 is a flowchart showing an example of the display change operation according to this embodiment. The process shown in Figure 7 is executed by the controller 43 when, for example, an instruction to change the display is received from the management device.

[0081] First, pixel data before and after the change is acquired (step 101). Data indicating the speed limit and the location of the restricted section before the change is stored in the RAM or storage unit 42 of the controller 43, for example, as the most recent instruction data from the management device. Data indicating the speed limit and the location of the restricted section after the change is received as the latest instruction data from the management device.

[0082] In the controller 43, the pixel data representing the speed limit and the location of the restricted section (70 and a right-pointing arrow in Figure 60A) indicated by the previous instruction data is read from the storage unit 42 as the pixel data before the change (first data). In addition, the pixel data representing the speed limit and the location of the restricted section (50 and a left-pointing arrow in Figure 60C) indicated by the latest instruction data is read from the storage unit 42 as the pixel data after the change (second data).

[0083] Next, the pixels to be compared between the first and second data are determined (step 102). The pixels compared between each data are those located at the same position. Therefore, step 102 determines the pixel positions for comparison. Specifically, all pixels are selected once in a predetermined order.

[0084] The order in which the pixels undergo comparison processing is not particularly limited. For example, in the arrangement pattern shown in Figure 6, the order of blocks is set as follows: the tens digit block of display unit 10a, the ones digit block of display unit 10a, and the block of display unit 10b. Furthermore, for each block, the order within the region is set, for example, that a scan from left to right is performed from top to bottom.

[0085] Next, the pixel values ​​are compared between the first and second data (step 103) to determine whether the display state will change or not (step 104). For example, if both the first and second data have the same display state (No. in step 104), the display state is not changed, and step 102 is executed again, and the comparison process for the next pixel is performed.

[0086] Furthermore, if the first data and the second data have different display states (Yes in step 104), the display state is to be changed, and the rotation direction of the magnetic reversal display element 20 corresponding to that pixel is set (step 105). In this way, the magnetic reversal display element 20 corresponding to the pixel whose display state has been determined to be changed becomes the target element 30.

[0087] For example, when changing a pixel from an emergency state to a display state, the element corresponding to that pixel becomes the first target element 30a. In this case, after the display change, it is necessary to make the display surface 21a visible, as shown in Figure 4A. For this reason, the first rotation operation (in this case, the operation of passing a pulse current 1 through the set coil 24s) is set for the first target element 30a.

[0088] Furthermore, when changing a pixel from visible to invisible, the element corresponding to that pixel becomes the second target element 30b. In this case, after the display change, it is necessary to make the non-display surface 21b visible, as shown in Figure 4B. For this reason, the second rotation operation (in this case, the operation of passing a pulse current 1 through the reset coil 24r) is set for the second target element 30b.

[0089] In this embodiment, the controller 43 determines the target element 30 by comparing the corresponding pixels between the first data and the second data. The direction of rotation for the target element 30 is then set based on the pixel comparison result. By comparing pixels in this way, the target element 30 can be easily determined regardless of what the display content is before or after the change. This makes it possible to easily implement various patterns of display changes, for example.

[0090] Once the rotation direction of the target element 30 is set, it is determined whether processing for all pixels has been completed (step 106). If there are pixels for which the comparison process has not been completed (No in step 106), step 102 is executed again, and the comparison process for the next pixel is performed. If the comparison process has been completed for all pixels (Yes in step 106), the controller 43 drives the target elements 30 in a predetermined order (step 107).

[0091] In step 107, the controller 43 controls the drive circuit 44, and pulse current 1 is sequentially supplied at predetermined intervals to all target elements 30 determined up to step 106. Once all target elements 30 are driven, the display unit 10 (display units 10a and 10b) displays the modified display content indicated by the second data.

[0092] Thus, in this embodiment, all target elements 30 are determined, and then the target elements 30 are actually driven using the determination results. In this case, since information such as the position of each target element 30 can be known in advance, it becomes possible to set, for example, the order in which the target elements 30 are driven according to the arrangement of the target elements 30.

[0093] Here, an example of the sequence in which the target element 30 is driven will be described. In this embodiment, the controller 43 changes the display state of the target element 30 digit by digit. This means that the digits of the speed limit displayed on the display unit 10a are changed one by one. For example, after completely changing the tens digit, the controller 43 changes the ones digit (0) if necessary. The process of changing the ones digit is performed when the speed limit is not displayed, or when the speed limit is displayed from a state of no display. By changing the digits digit by digit in this way, the time it takes for each digit to change, that is, the period during which the state in progress is visible, is shortened. This makes it possible to suppress misrecognition of each digit.

[0094] Furthermore, when changing the display state of each digit, the digits are processed sequentially to suppress misinterpretation. For example, when a variable speed limit sign 100 switches from a no-display state to a display of 50 km / h, if the ones digit is changed first, it may be read as 0 km / h during the switch. Therefore, the tens digit is changed first, and then the ones digit is changed. Also, for example, when switching the display from 50 km / h to a no-display state, changing the ones digit first can suppress misinterpretation that it displays as 0 km / h.

[0095] Furthermore, the controller 43 may change the display state of the target element 30 in an order that prevents any digit from appearing as another digit. In other words, the order in which the target element 30 is changed is set so that the digits from "0" to "9" displayed in each digit do not appear as any digit other than the digit before or after the change. This makes it possible to sufficiently suppress misrecognition of individual digits.

[0096] For example, in the rectangular pattern displaying the tens digit in Figure 6B, suppose each target element 30 is changed according to the order in which a scan from left to right is performed from top to bottom. In this case, the four second target elements 30b in the third and fourth rows are displayed as pixels, and a display state close to the number "9" temporarily occurs in the tens digit. The order in which the target elements 30 are changed is set to avoid such a state.

[0097] For example, the target elements 30 in even-numbered rows may be driven from top to bottom, followed by the target elements 30 in odd-numbered rows. Alternatively, the target elements 30 in even-numbered columns may be driven from left to right, followed by the target elements 30 in odd-numbered columns. This eliminates situations where, for example, only parts of the numbers appear partially connected, making them less likely to resemble other numbers. Other methods may be used, such as driving the target elements 30 in a spiral pattern from the center, or setting the driving order randomly within a rectangular pattern. The order in which the target elements 30 are driven is not limited.

[0098] Figure 8 is a schematic diagram illustrating a display change operation as a comparative example. Figure 8(1) shows the display content before the change, and Figure 8(8) shows the display content after the change. Figures 8(2) to (6) illustrate the intermediate states of the display unit 10's change operation. Here, as in the case of Figure 6, the speed limit is changed from 70 km / h to 50 km / h, and the auxiliary sign is changed from a right-pointing arrow to a left-pointing arrow.

[0099] First, as shown in Figures 8(2), (3), and (4), the tens digit block of display unit 10a, the ones digit block, and the block of display unit 10b are driven to become blank (white) in this order. In this case, each magnetic reversal display element 20 is supplied with a pulse current 1 to drive it in the second rotation operation, regardless of whether the display state has been changed or not. By making the entire display blank once in this way, the display does not become a mixture of numbers before and after the change, thus preventing drivers and others from misinterpreting the numbers.

[0100] Next, as shown in Figures 8(5), (6), and (7), the tens digit block of display unit 10a, the ones digit block, and the blocks of display unit 10b are driven in this order to display the modified content. In this case, pulse current is supplied to the elements of the magnetic inversion display element 20 that are displayed as pixels to be driven in the first rotational movement. This completes the display change operation.

[0101] As shown in Figure 8, the display change operation in the comparative example suppresses misrecognition by temporarily making the entire display blank, but it takes time to make the entire display blank. In addition, elements that display pixels both before and after the display change are hidden and then displayed again. This results in extra time, increasing the time required for the display change.

[0102] In contrast, in the variable speed limit sign 100 according to this embodiment, only the target element 30, which is a magnetic reversal display element 20 whose display state changes before and after the display unit 10 changes, is driven. This eliminates the need to drive, for example, a magnetic reversal display element 20 whose display state does not change, and makes it possible to shorten the time required for display changes.

[0103] Furthermore, because the time required for the display to change is reduced, it becomes more difficult for drivers to notice the display changing. This effectively prevents drivers from misinterpreting the content of the variable speed limit sign 100.

[0104] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above and can be modified in various ways.

[0105] Figure 7 illustrates an example where all target elements are identified and then driven in a predetermined order. However, the system is not limited to this; for example, the target elements may be driven each time they are identified. This can further shorten the time from receiving a display change instruction to the completion of the display change.

[0106] Furthermore, when driving the target element during determination, the order in which the comparison processing for determining the target element is performed can be such that the state in which each digit appears as another digit, as explained in step 107 of Figure 7, does not occur. This makes it possible to suppress misrecognition of numbers, etc.

[0107] In the above embodiment, an example was described in which pixel data of the display content before and after the display change is compared in order to determine the target element. However, the system is not limited to this, and for example, data (target element specification data) in which the target elements corresponding to the display content before and after the display change are pre-stored may be read. The target element specification data stores the pixel positions and rotation directions of multiple target elements.

[0108] For example, target element specification data corresponding to the combination of the display content before the change and the display content after the change is stored in the memory unit. For example, data storing the target elements when the speed limit changes from 50 km / h to 70 km / h, or data storing the target elements when it changes from 50 km / h to 80 km / h, etc., are created and stored in advance as target element specification data. This makes it possible for the controller to easily determine the target element by reading the corresponding target element specification data in accordance with the display change instruction received from the management device.

[0109] The above embodiment describes a case where a two-digit speed is displayed, but the present invention is not limited to this, and it is also possible to apply the present invention to signs and the like that display a three-digit speed (e.g., 100 km / h).

[0110] Although the above embodiment described a variable speed limit sign, the present invention may also be applied to variable signs that switch between displaying priority lanes for route buses, etc., and the direction of travel for each lane depending on the time of day. In addition, the types of variable signs to which the present invention is applied are not limited.

[0111] Furthermore, the present invention can be applied to various display devices that use magnetic reversal display elements, in addition to variable signs. For example, the present invention may be used in scoreboards that display game scores, etc., in baseball fields and stadiums. This makes it possible to switch score numbers, etc., in a short amount of time. In addition, the types of display devices to which the present invention can be applied are not limited. [Explanation of Symbols]

[0112] 10, 10a, 10b… Display Units 20…Magnetic reversal display element 30…Target element 30a...First target element 30b...Second target element 40... Traffic Sign Control Device 42...Storage section 43…Controller 44…Drive circuit 100... Variable speed limit sign

Claims

1. A display unit with multiple magnetic reversal display elements arranged in a grid, When changing the display of the display unit, the magnetic reversal display element whose display state changes before and after the change is selected as the target element, and a display control unit drives only the target element. A variable sign equipped with the following features.

2. A variable sign according to claim 1, The display control unit changes the display state of the target element one by one in a predetermined order. Variable sign.

3. A variable sign according to claim 1, The display unit displays a number of a predetermined number of digits. Variable sign.

4. A variable sign according to claim 3, The display control unit changes the display state of the target element digit by digit. Variable sign.

5. A variable sign according to claim 3, The display control unit changes the display state of the target element in an order such that no digit appears to be any other digit. Variable sign.

6. A variable sign according to claim 1, The display control unit determines the target element based on first data representing the display content before the display unit's display was changed and second data representing the display content after the display unit's display was changed. Variable sign.

7. A variable sign according to claim 6, The first data and the second data are data that designates the plurality of magnetic reversal display elements constituting the display unit as pixels. The display control unit determines the target element by comparing the corresponding pixels between the first data and the second data. Variable sign.

8. A variable sign according to claim 1, The variable sign is configured as a variable speed limit sign that displays the speed limit using the display unit. Variable sign.

9. A display unit with multiple magnetic reversal display elements arranged in a grid, When changing the display of the display unit, the magnetic reversal display element whose display state changes before and after the change is selected as the target element, and a display control unit drives only the target element. A display device equipped with the following.

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