Display panel and display elements therefor

Abstract

 A display panel which is provided with a display surface structure having a large number of display elements rotatably arranged in a vertical plane. The display elements are each formed by a block member having a plurality of display surfaces of different colors and a plurality of magnetic pieces. One of the magnetic pieces is shorter than the others in a vertical direction. By successive movement of head assemblies, each comprised of a first erasing head, a second erasing head and a writing head, one or more of the display elements are turned to bring a predetermined one of their display surfaces to the front of the display surface to erase a display of a character, graph, pattern or the like provided thereon, thereafter bringing a selected one of the display surfaces of a selected display element or elements to the front of the display surface to provide thereon a display of a character, graph, pattern or the like.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] This invention relates to a display panel which has a large number of display elements arranged in the same vertical plane to provide a display of a character, graph, pattern or the like, and display elements for use in the display panel.

Description of the Prior Art

[0002] Display panels of this type are employed for providing a display of a traffic sign, a directional sign, an advertisement, time, dateor like information. Display elements used in the past are usually formed by electrophoto conversion elements, and hence are of large-power consumption. Further, the conventional display elements are readily broken by an external force and short-lived. Also there have been proposed display panels of the type employing display elements, each formed by a block member having a plurality of display surfaces of different colors, but these panels are defective in that the contents of displays cannot easily be changed.

SUMMARY OF THE INVENTION

[0003] Accordingly, this invention is to provide a novel display panel free from the abovesaid defects of the prior art and display elements for use in the display panel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] 

Fig. 1 is a perspective view, partly cut away, schematically showing an embodiment of the display panel of this invention;

Fig. 2 is a front view of an example of a display surface structure of the display panel depicted in Fig. 1;

Fig. 3 is a sectional view taken on the line III-III in Fig. 2;

Fig. 4 is a front view of an example of a display element of this invention;

Fig. 5 is a bottom view of the display element shown in Fig. 4;

Fig. 6 is a sectional view taken on the line VI-VI in Fig. 4;

Fig. 7 is a sectional view taken on the line VII-VII in Fig. 4;

Fig. 8 is an enlarged front view, partly in section, schematically illustrating in detail a portion of the display surface structure depicted in Fig. 2;

Fig. 9 is a sectional view taken on the line IX-IX in Fig. 8;

Fig. 10 illustrates how Figs. 10A and 10B are interconnected;

Fig. 10A and 10B show in elevation an example of a display switching unit and an example of the circuit construction of a drive unit for use in the display panel of this invention;

Fig. 11 is a perspective view schematically showing, by way of example, one of electromagnets forming each of first erasing heads and writing heads;

Fig. 12 is a perspective view schematically showing, by way of example, an electro magnet forming each of second erasing heads;

Fig. 13 is a sectional view taken on the line XIII-XIII in Fig. 10A;

Figs. 14 and 15 are tables showing a sequence of change of the front display surface of each display element during erasing and writing, respectively;

Fig. 16 is a front view schematically illustrating another embodiment of the display panel of the present invention;

Fig. 17 is a plan view of the display panel shown in Fig. 16; and

Figs. 18 and 19 are an enlarged front view schematically illustrating in detail a portion of the display surface structure of the display panel shown in Figs. 16 and 17 and its side view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Fig. 1 illustrates an embodiment of a display panel of this invention, which is composed of a display surface structure 1, a display switching unit 2 and a drive unit 3.

[0006] In the example of the display surface structure 1 such as shown in Figs. 2 and 3, letting N horizontal lines of arrangement spaced a predetermined distance L_A from adjacent ones of them in a vertical direction be represented by a₁, a₂,..... a_N, respectively, M display elements D_i1, ^D_i2' .. ... D_iM are disposed on the horizontal line a_i (i=l, 2, .. ... N) at predetermined intervals L_B in a horizontal direction.

[0007] In this instance, the display element D_ij (j=1, 2, .. ... M) has a construction such, for example, as shown in Figs. 4, 5, 6 and 7 in which a four-sided right prismatic member 4 formed as of a synthetic resin material has a height H a little smaller than the distance L_A and a width W a little smaller than the interval L_B, has two pairs of opposed display surfaces d₁ and d₃ and d₂ and d₄ of different color displays, for instance, in red, blue, white and green, and has a square cross section.

[0008] The display element D_ij has embedded therein magnetic pieces m_l, m₂, m₃ and m₀ at the parralel edges between the display surfaces d₁ and d₄, between d₁ and d₂ , between d₂ and d₃ and between d₃ and d₄, respectively. Each of the magnetic pieces m_l, m₂ and m₃ extends vertically and its length ℓ₁ has a value close to the height H of the member 4. The magnetic piece m₀ also extends vertically but its length ℓ₂ is smaller than the length ℓ₁. The magnetic piece m₀ is disposed centrally of the member 4 in the direction of its height, and consequently it lies opposite only the central portions of the magnetic pieces m₁, m 2₂ and m_3.

[0009] The display element D_ij has a bore 5 extending through the member 4 in the vertical direction. Further, the display element D_ij has grooves 6a and 6b substantially triangular in section which are cut in the bottom 4a of the member 4 to extend across the bore 5 so that they intersect at right angles. In this case, the groove 6a extends, as viewed on the bottom 4a, in the same direction as the direction of extension of the display surfaces of d₁ and d₃, and the groove 6b intends in the same direction as the direction of extension of the display surfaces d₂ and d₄.

[0010] The display surface structure 1 has a frame 7 for arranging the display elements D₁₁ to D_1M, D₂₁ to D_2M, ····· D_N1 to D_NM on the horizontal lines a₁, a₂, ..... a_N, respectively. Between opposing upper and bottom panels 7a and _7b of the frame ₇ are provided fixed shafts B₁, B₂, ..... B_N at regular intervals L_B which extend vertically. Between opposing left-hand and right-hand panels 7c and 7d of the frame 7 are provided laterally extending fixed support plates C_l, C₂,....C_N at regular intervals L_A. In this case, the support plates C₁ to C_N extend through the fixed shafts B₁ to B_N, respectively.. On the support plate C_i are formed projections 9 which extend from the side of the fixed shaft B_j in the direction of extension of the support plate C_i in such a manner that they hold therebetween the fixed shaft B.. The projections 9 each have a width which permits selective reception of the grooves 6a and 6b of the display element D_ij. The display element D_ij is disposed on the support plate C_i with the bore 5 receiving the fixed shaft B_. through a sleeve 8 fixed thereto. The display element D_.. assumes its normal position where it lies on the support plate C_i with either one of the groove 6a and 6b received by the projections 9 on the support plate C_i. However, the display element D_.. thus disposed on the support plate C_. is rotatable about the sleeve 8 fixed to the shaft B.. When the display element D_ij lies in such a rotational position where its groove 6a is received by the projections 9 of the support plate C_i, the display surfaces d₁ or d₃ faces forwardly. When the display element D_ij is turned in this state, the groove 6a disengages from the projections 9 and then the groove 6b engages with the projections 9. In this state, the display surface d₂ or d₄ of the display element D.. faces to the front.

[0011] An example of the display switching unit 2 has first erasing heads E₁ ~ E_N, second erasing heads F₁ ~ F_N and writing heads G₁ ~ G_N, as shown in Figs. 1 and 10A.

[0012] The first erasing head E_i has three electromagnets 101, 102 and 103 arranged laterally in this order at intervals 2×L_B, where L_B is referred to previously in respect of Fig. 2. Each of the electromagnets 101, 102 and 103, as shown in Fig. 11, comprises a magnetic core 12 circular in cross section and having wound thereon a coil 11 and magnetic plates 13U and 13L respectively attached to both ends of the magnetic core 12 so that they coextend in a direction substantially perpendicular to the lengthwise direction of the magnetic core 12. The magnetic core 12 and the magnetic plates 13U and 13L make up each of the electromagnets 101, 102 and 103. In the illustrated case, the magnetic plates 13U and 13L are spaced apart a distance substantially equal to the length ℓ₁ of the magnetic pieces m_l, m₂ and m₃ of the aforesaid member 4 of the display element D_ij in the vertical direction.

[0013] The second erasing head F_i has one electromagnet 104 as shown in Fig. 12. The electromagnet 104 comprises a magnetic core 22 circular in cross section and having wound thereon a coil 21 and magnetic plates 23U and 23L respectively attached to both ends of the magnetic core 22 so that they coextend in a direction substantially perpendicular to the lengthwise direction of the magnetic core 22. The magnetic core 22 and the magnetic plates 23U and 23L make up the electromagnet 104. In the illustrated case, the magnetic plates 23U and 23L are spaced apart a distance substantially equal to the length ℓ₂ of the magnetic piece m₀ of the aforesaid block member 4 of the display element D.. in the vertical direction.

[0014] The writing head G_i has three electromagnets 105, 106 and 107 arranged laterally in this order at this intervals of 2^XL_B. The electromagnets 105, 106 and 107 are each identical in construction with the abovesaid electromagnets 103 to 105 as shown in Fig. 11; therefore, no detail description will be repeated.

[0015] A vertical rod 25 is provided behind the display surface structure 1 in a manner to be movable to right and left in parallel therewith. The first and second erasing heads E_i and F_i and the writing head G_i are mounted on the vertical rod 25 at a position opposite the aforementioned horizontal line a. in such a manner that the front end i faces of the magnetic plates 13U and 13L of the electromagnets 101 to 103 and 105 to 107 of the first erasing head E_i and the writing head G_i and the magnetic plates 23U and 23L of the electromagnet 104 of the second erasing head _Fi may lie adjacent the display surfaces d₁ to d₄ of the display element D_...

[0016] An example of the drive unit 3 has, as shown in Figs. 1, 10A and 13, a belt, chain or like strap member 28 installed between a pair of pulleys 26 and 27 disposed in the horizontal direction, for instance, on the lower side of the display surface structure 1 and spaced a predetermined distance apart and a similar strap member 31 installed between a pair of pulleys 29 and 30 likewise disposed in the horizontal direction on the upper side of the display surface structure 1 and spaced a predetermined distance apart. The vertical rod 25 of the abovesaid display switching unit 2 is secured at both ends to the strap members 28 and 31. A rotary shaft 33 of a motor 32 is coupled, for instance, to the pulley 27 and a shaft 34 is bridged between the pulleys 26 and 29 so that the strap members 28 and 31 may be driven by the rotation of the motor 32 to right or left in synchronism with each other. Accordingly, the vertical rod 25 is moved to right and left while being held vertical.

[0017] The drive unit 3 has, as shown in Figs. l0A and 13, a detecting mechanism 41 for detecting the position of the vertical rod 25. An example of the detecting mechanism 41 has, as shown in Figs. 10A and 13, a position detecting plate 42 which is disposed on the lower side of the display elements D_N1, D_N2, .... D_NM to extend in the horizontal direction and whose front marginal edge has rectangular recesses R₁ to R_M. The recess R_j extends leftwards from the position corresponding to the center of the display element D_Nj in the horizontal direction to a position spaced a distance equal to 1/2 of the interval L_B from the abovesaid position, and a light emitting element 43 and a photo detector 44 which are disposed in opposing relationship to each other with the position detecting plate 42 interposed therebetween. The light emitting element 43 and the photo detector 44 are mounted on the supporting members 16 and 17 respectively planted on the vertical rod 25. The photo detector 44 provides a detected output "1" or "0" in the binary representation depending on whether the recess R_j exists or not between the photo detector 44 and the light emitting element 43. In practice, the position detecting plate 42 has at least the aforesaid recesses R₁ to R_m and similar recesses R_S1 ~ R_S12. The recesses R_S8, R_S7, ......R_S1 are formed in this order at the intervals L_B leftwards of the position spaced the distance L_B from the leftmost recess R1 and the recess R_S9, R_S10, ..... R_S12 are disposed in this order rightwards of the rightmost recess R_M at a position spaced therefrom the distance L_B.

[0018] Further, the drive unit 3 has detecting switches 51 and 52 for detecting the leftmost and rightmost positions of the vertical rod 25, respectively. The detecting switch 51 is adapted to provide an output "1" in the binary representation upon engagement with an engaging piece 53 of the vertical rod 25 when the magnetic plates 13U and 13L of the rightmost electromagnet 101 of the first erasing head E_i mounted on the vertical rod 25 are moved out of the opposing relation with the display element D_il. The detecting switch 52 is similarly adapted to provide an output "1" in the binary representation upon engagement with an engaging piece 53 of the vertical rod 25 when the magnetic plates 13U and 13L of the leftmost electromagnet 107 of the writing head G_i are moved out of the opposing relation with the display element D_iM.

[0019] Moreover, the drive unit 3 has a drive circuit 60 for driving the first and second erasing heads E_i and F_i and the writing head G_i of the display switching unit 2.

[0020] The drive circuit 60 comprises, for instance, memory circuits H and H', address selector circuits I and I', output circuits J and J', a data processing circuit K and shift registers Ql, Q2 and Q3.

[0021] The memory circuits H and H' are designed to store information "0" and "0", "0" and "1", "1" and "0" or "1" and "1", for selecting the display surfaces d_l, d₂, d₃ and d₄ of the display elements D₁₁ to ^D_N1, ^D₁₂ to D_N2, ..... D_1M to D_NM of the display surface structure 1. That is, in each of the memory circuits H and H', N information of the display elements D₁₁ to D_Nl are stored as first parallel information at a first address, N information of the display elements D₁₂ to D_N2 are stored as second parallel information at a second address, ..... and N information of the display elements _DIM to D_NM are.stored as Mth parallel information at an Mth address. The N information making up the jth parallel information stored at the jth address selected by each of the address selector circuits I and I' are read out one by one upon each occurrence of a read control pulse from the data processing circuit K. Each of the address selector circuits I and I' is adapted'to sequentially select the first, second, ..... Mth addresses of each of the memory circuits H and H' for sequentially reading out the M parallel information stored in each of the memory circuits H and H'. The output circuits J and J' receive and output the N jth parallel information read out of the memory circuits H and H', respectively.

[0022] The data processing circuit K has two information input terminals xl and x2 and three information output terminals yl, y2 and y3 and is adapted so tht the information from the output circuits J and J' may be supplied to the information input terminals xl and x2, respectively. Moreover, three shift registers Ql, Q2 and Q3 are provided and information from the information output terminals yl, y2 and y3 of the data processing circuit K are applied to information input terminals of the shift registers Ql, Q2 and Q3, respectively.

[0023] The data processing circuit K receives the sequential information from the output circuits J and J' to generate pulses upon each reception of the information, which pulses are applied as a read control pulse and a shift pulse to the memory circuits H and H' and the shift registers Ql, Q2 and Q3, respectively. The data processing circuit K is also adapted to provide a reset pulse RP for resetting the shift registers Ql, Q2 and Q3. Each of the shift registers Ql, Q2 and Q3 has first to Nth digits'and is designed so that the N information sequentially applied from the data processing circuit K are stored at the N digits, respectively, and are simultaneously read out thereof.

[0024] Further, the drive circuit 60 has input terminals Tl and T2 supplied with the detected outputs from the aforesaid detecting switches 51 and 52, respectively, an input terminal T3 supplied with the detected output from the photo detector 44, output terminals O1 and 02 connected to forward and backward revolution input sides of the motor 32, respectively, output terminals OG₁₁ to OG_1N, OG₂₁ to ^OG_2N and OG₃₁ to OG_3N, an output terminal 03 and a power source switch S.

[0025] The output terminal OG_1i is connected.to the coil 11 of the electromagnet 105 of the writing head G., the output terminal OG_2i to the coil 11 of the electromagnet 106 and the output terminal _OG3i to the coil 11 of the electromagnet 107. The output terminal 03 is connected to the coils 11 of the electromagnets 101 to 103 of the first erasing heads E₁ to E_N and to the coils 21 of the electromagnets 104 of the second erasing heads F₁ to F_N.

[0026] When the vertical rod 25 of the display switching unit 2 lies at its leftmost position to maintain the detecting switch 51 in its ON state, if the power source switch S is turned ON for a very short period of time, output signals are derived from the output terminals 01 and 03. While the output signals are obtained from the output terminals 01 and 03, if the detected output "0" in the binary representation is supplied from the photo detector 44 to the input terminal T3 after counting eight detected outputs "1", then the output "0" in the binary representation is supplied to the input terminal T3 from the photo detector 44 in the state that the address selector circuits I and I', the memory circuits H and H', the data processing circuit K and the shift registers Ql, Q2 and Q3 are controlled so that information stored in the memory circuits H and H' are supplied via the output circuits J and J' to the data processing circuit K. At this time, N pulses CP are sequentially provided from the data processing circuit K and the shift registers Q_l' Q₂ and Q₃ are sequentially shifted upon occurrence of each of the N pulses CP. The data processing circuit K provides at its output terminals yl, y2 and y3 information "0", "0" and "0", respectively, in the case of the information from the memory circuits H and H' being "0" and "0", and information "1", "0" and "0" in the case of the latter information being "0" and "1". When the information from the memory circuits H and H' are "1" and "0", the data processing circuit K provides information "1", "0" and "0" at its output terminals yl, y2 and y3,-respectively, and then if an output "0" in the binary representation is provided twice from the photo detector 44 in the above state, the information "1", "0" and "0" at the output terminals yl, y2 and y3 change to "0", "1" and "0", respectively. In the case of the information from the memory circuits H and H' being "1" and "1", the data processing circuit K provides information "1", "0" and "0" and then, if the output "0" is obtained twice from the photo detector 44 in the above state, the information at the output terminals yl, y2 and y3 change to "0", "1" and "0", respectively, and thereafter, if the output "0" is derived twice from the photo detector 44 in this state, the information at the abovesaid three output terminals change to "0", "0" and "1", respectively. The information thus obtained are successively stored in the shift register Ql, Q2 and Q3. Then, when the output from the photo detector 44 to be supplied to the input terminal T3 becomes "1", the information stored in the shift registers Ql, Q2 and Q3 are derived at the output terminals OG₁₁ to OG_1N, OG21 to ^OG_2N and ^OG₃₁ to OG_3N, respectively. And then, when the output from the photo detector 44 is altered to "0", no outputs are provided at the output terminals OG₁₁ to OG_1N, OG₂₁ to ^OG_2N and ^OG₃₁ to OG_3N. At the same time, the shift registers Ql, Q2 and Q3 are reset and, as described above, the address selector circuits I and I', the memory circuits H and H', the data processing circuit K and the shift registers Ql, Q2 and Q3 are respectively controlled so that information stored at the next address is successively read out of the memory circuits H and H', and, as is the case with the above, the data processing circuit K is actuated and the information therefrom are stored in the shift registers Ql, Q2 and Q3, respectively. Then, when the output from the photo detector 44 is altered again to "1", the information stored in the shift registers Ql, Q2 and Q3 are derived at the output terminals OG₁₁ to OG_1N, OG₂₁ to ^OG_2N and O^G₃₁ to ^OG_3N, ^res- pectively, in the same manner as mentioned above and thereafter such operations are repeated. Further, when the detected output "1" in the binary representation is supplied from the detecting switch 52 to the input terminal T2, no output is obtained from the output terminals O1 and 03.

[0027] The above is the construction of an example of the display panel employing the display elements of the embodiment of this invention. With such a construction, by turning on the power source switch S of the drive circuit 60 of the drive unit 3 for a very short period of time with the vertical rod 25 of the display switching unit 2 being located at its leftmost position to hold the detecting switch 51 in its ON state, the vertical rod 25 is moved to right. While the vertical rod 25 is moved rightwards, the output "1" is yielded at the output terminal 03 of the drive circuit 60, so that the erasing heads E₁ to E_N and F₁ to F_N are energized. By the rightward movement of the vertical rod 25, the electromagnets 101, 102 and 103 of the erasing head E_i are brought to right into opposing relation to the display element D_ij one after another and then the electromagnet 104 of the erasing head F_i is brought to right into opposing relation to the display element D_ij. As a result of this, such operations as described below are selectively carried out depending on which one of the display surfaces d₁ to d₄ of the display element D_ij lies on the front side of the display panel before the electromagnets 101, 102, 103 and 104 are brought to right into opposing relation to the display element D_ij one after another, that is, "Before Erasing"; ultimately, the display surface d₂ of the display element D.. is brought to the front side of the display panel.

[0028] (A) In the case where the display surface d₁ of the display element D_ij lies on the front side of the display panel "before erasing":

The magnetic piece m₀ of the small length ℓ₂ lies near the rear left edge of the display element D_ij. By the way, the electromagnets 101 to 103 each have the pair of magnetic plates 13U and 13L spaced apart the distance corresponding to the length ℓ₁ larger than the length ℓ₂ of the magnetic piece m₀, as described previously in respect of Fig. 11. On the other hand, the electromagnet 104 has the pair of magnetic plates 23U and 23L spaced apart the distance corresponding to the length ℓ₂ of the magnetic piece m₀ and described previously in respect of Fig. 12.

[0029] Accordingly, when the electromagnets 101, 102 and 103 move rightwards along the back of the display element D_ij in succession, the display element D_ij is not turned, whereas when the electromagnet 104 is brought to right across the display element D_ij, the latter is turned through 90° in the clockwise direction in Fig. 13, bringing its display surface d₂ to the front side.

[0030] (_B) In the case where the display surface d₂ of the display element D_ij lies on the front side of the display panel "before erasing":

The magnetic piece m₁ of the length lies near the rear left edge of the display element D_ij. By successive confrontation of the electromagnets 101, 102 and 103 with the display element D_ij, the latter is turned through 90° upon each confrontation with the former, bringing the display surface d₁ of the display element D_ij to the front side, with the magnetic piece m₀ lying near the rear left edge of the display element D_ij. Accordingly, by the confrontation of the electromagnet 104 with the display element D_ij, the latter is turned through 90°, resulting in its display surface d₂ lying on the front side.

(C) In the case where the display surface d₃ of the display element D_ij lies on the front side of the display panel "before earsing":

The magnetic piece m₂ lies near the rear left edge of the display element D_ij. By successive confrontation of the electromagnets 101 and 102 with the display element D_ij, the latter is turned through 90° upon each confrontation, bringing the display surface d_l of the display element D_ij to the front side, with the magnetic piece m₀ lying near the rear left edge of the display elements D... Accordingly, when the electromagnet 103 is moved rightwards across the display element D_ij, the latter is not turned. But when the electromagnet 104 is brought into confrontation with the display element D_ij, the latter is turned through 90°, resulting in its display surface d₂ lying on the front side.

(D) In the case where the display surface d₄ of the display element D_ij lies on the front side of the display panel "before erasing":

The magnetic piece m₃ lies near the rear left edge of the display element D_ij. By the confrontation of the electromagnet 101 with the display element D_ij, the latter is turned through 90° to bring its display surface d₁ to the front side, with the magnetic piece m₀ lying near the rear left edge of the display element D_ij. Accordingly, the display element D_ij is turned by successive confrontation therewith of the electromagnets 102 and 103. When the electromagnet 104 is brought to right to the display element D_ij, the latter is turned through 90° to bring its display surface d₂ to the front side.

[0031] The above-described operations are tabulated in Fig. 14.

[0032] By successive confrontation of the photo detector 44 with the recesses R_S1, R_S2' .... R_S8, R₁, R₂, ..... ^R_M ^R_S9' ^R_S8 ..... ^R_S12 after the vertical rod 25 starts its rightward movement, the photo detector 44 yields the outputs "0" in succession, which are provided to the input terminal T3 of the drive circuit 60. As described previously, upon each occurrence of the output "0" after the application of eight outputs "0" to the input terminal T3, the address selector circuits I and I', the memory circuits H and H', the data processing circuit K and the shift registers Ql, Q2 and Q3 of the drive cricuit 60 are controlled to selectively energize the electromagnets 105, 106 and 107 of a selected one or ones of the writing heads G1 to G_N of the display switching unit 2 in accordance with the memory contents of the memory circuits H and H'. The electromagnets 105, 106 and 107 of the writing head G_i are brought to the position opposite the display element D_ij one after another in synchronism with successive generation of the abovesaid output "0" after the electromagnets 101 to 103 and 104 of the erasing heads E_i and F_i are moved across the display element D_ij. In other words, the successive confrontation with the display element D_ij starts with the state in which the display surface d of the display element D_ij lies on the front side and consequently the magnetic piece m₁ stays near the rear left edge of the display element D_ij. Accordingly, the display element D_ij performs such operations as described below in accordance with the contents of the memory circuits H and H', whereby a selected one of the display surfaces d₁ to d₄ of the display element D_ij is brought to the front side according to the contents of the memory circuits H and H'.

[0033] (E) In the case where the contents of the memory circuits H and H' are both "0":

When the electromagnets 105, 106 and 107 confront the display element D_ij one after another, these electromagnets are respectively supplied with outputs "0", and hence they are not energized. Accordingly, the display element D_.. is not turned, in consequence of which its display surface d₂ remains on the front side.

[0034] (F) In the case where the contents of the memory circuits H and H' are "0" and "1", respectively:

[0035] When the electromagnets 105, 106 and 107 sequentially confront the display element D_ij, these electromagnets are supplied with outputs "1", "0" and "0", respectively, and hence only the electromagnet 105 is energized. As a result of this, the display element D_ij is turned through 90°, bringing its display surface d₃ to the front side.

[0036] (G) In the case where the contents of the memory circuits H and H' are "1" and "0", respectively:

When the electromagnets 105, 106 and 107 confront the display element D_ij in a sequential order, these electromagnets are supplied with outputs "1", "1" and "0", respectively, and hence the electromagnets 105 and 106 are energized. Consequently, the display element D_ij is turned through 180° to bring its display surface d₄ to the front side.

[0037] (H) In the case where the contents of the memory circuits H and H' are both "1":

When the electromagnets 105, 106 and 107 confront the display elements D_ij in succession, these electromagnets are all supplied with the outputs "1", and hence they are all energized. In consequence, the display element D_ij is turned through 270° to bring its display surface d_l to the front side.

[0038] The above-described operations are tabulated in Fig. 15.

[0039] When the vertical rod 25 is brought right to its rightmost position to turn on the detecting switch 52 to derive therefrom a detected output "1", the output is no more produced from the output terminal 02, stopping the motor 32 from rotating.

[0040] In accordance with the display panel using the display elements according to the above embodiment of this invention, the display surfaces d₂ of all the display elements D₁₁ to D_N1, ^D12 to D_N2, ..... D_1M to D_NM can be made to face forwardly and a desired one of the display surfaces d_l, d₃ and d₄ of a desired one or ones of the display elements can be made to face forwardly. Accordingly, if the display surfaces d₂, d₁, d₃ and d₄ of the display element D_ij are previously colored, for example, in white, red, green and blue, respectively, a character, symbol, graph or pattern can be displayed in colors as desired. Such a display can be produced with a simple construction as a whole.

[0041] Further, since the display element D.. has such a simple construction as shown in Figs. 4, 5, 6 and 7, the distance between adjacent ones of the display elements can be made small; therefore, the overall apparatus can be simplified in construction and reduced in size correspondingly.

[0042] Moreover, as the display element is free from power dissipation, the display panel does not consume much power and, in addition, as the display element is not readily broken by an external force, the display panel can be used without trouble for a long time.

[0043] As will be appreciated from the above, the display element according to the foregoing embodiment of this invention can be applied to construct a display panel which includes a number of such display elements arranged in the same vertical plane and which is capable of providing a character, graph, pattern or like display without much power consumption and with a long life.

[0044] Further, the present invention exhibits the advantages that the content of a display of a character, symbol, graph, pattern or the like can be changed by a single movement of the display switching unit 2 in one direction and that such a change does not take much time.

[0045] In the foregoing embodiment of the present invention it is preferred that the writing heads G₁ to G_N of the display switching unit 2 be constructed so that those magnetic plates 13U or 13L of the electromagnets 105, 106 and 107 of the writing heads G_i-1 and G_i+1 lying on the side of the writing head G_i may be of the same polarity. The advantage by this construction will be briefly described in connection with the electromagnets of the writing heads G_i-1, G_i and G_i+1. Namely, in the case where the electromagnet 105 of the writing head G_i is not energized but the electromagnets 105 of the writing heads Gi-1 and G_i+1 are energized, the electromagnet 105 of the writing head G_i is not exposed to a magnetic field by the electromagnet 105 of the writing head G_i-1 and/or G_i+1. This eliminates the possibility of erroneous activation of the display elements D_il to DiN.

[0046] Next, a description will be given with reference to Figs. 16 to 19, of another embodiment of the display panel of the present invention.

[0047] In Figs. 16 to 19, the parts corresponding to those in Figs. 1 to 15 are identified by the same reference numerals and characters and no detailed description will be repeated. This embodiment is identical in construction with the embodiment described previously in respect of Figs. 1 to 15 except that the display surface structure 1 has such a construction as described below.

[0048] As shown in Figs. 16 and 17, a pair of rotary shafts 74L and 74R are rotatably provided at a predetermined distance on a substrate 72 to extend vertically. On the rotary shafts 74L and 74R are mounted pulleys 73L and 73R, respectively. A carrier member 71, such as an endless belt, is placed on the pulleys 73L and 73R. On the outer surface of the carrier member 71 are arranged the display elements D₁₁ to D_1M, D21 to ^D_2M, ..... D_N1 to ^D_NM in the same manner as described previously with regard to Figs. 1 to 3. In thise case, as will be more apparent from Figs. 18 and 19, the display element D_ij is mounted on the carrier member 71 through a support plate C_ij corresponding to that C_i described previously with respect to Fig. 2. The support plate C_ij has the projections 9 selectively engageable with the grooves 6a and 6b of the display element D_ij.

[0049] On the other hand,.the rotary shaft 74L is adapted to be rotatable by a drive mechanism 75 as desired and, consequently, the carrier member 71 is adapted to be endlessly movable laterally as required. Accordingly, the display surface structure 1 can be endlessly moved laterally.

[0050] Furthermore, this embodiment is identical in construction with the embodiment of Figs. 1 to 15 except that the first erasing head E_i, the second erasing head F_i and the writing head G_i, which constitute the display switching unit 2, are fixedly arranged in the order described previously in respect of Fig. 10A, as shown in Fig. 17.

[0051] Moreover, the drive unit 3 is designed so that, upon moving the display surface structure 1 by the driving mechanism 75 in a lateral direction, the electromagnets 101 to 103 of the first erasing heads E₁ to E_N and the electromagnets 105 to 107 of the second erasing heads F_l to F_N and the writing heads G_l to G_N are energized in synchronism with the movement of the display surface structure 1, though neither illustrated nor described in detail. In consequence, the display surfaces d₁ to d₄ of the display elements D₁₁ to D_1M, D21 to D_2M, ..... ^D_N1 to ^D_NM are selected as desired and face forwardly.

[0052] In accordance with the embodiment described above with reference to Figs. 16 to 19, it is also possible to obtain the same advantages as those of the embodiment of Figs. 1 to 15. That is to say, the display surfaces d₂ of all the display elements D₁₁ to D_N1, D12 to D_N2, ..... D_1M to ^D_NM can be made to face forwardly and a desired one of the display surfaces d_l, d₃ and d₄ of a desired one or ones of the display elements can be made to face forwardly. Accordingly, a character, symbol, graph or pattern can be displayed in colors as desired. Such a display can be produced with a simple construction as a whole.

[0053] Further, since the display element D_ij has such a simple construction as described previously, the distance between adjacent ones of the display elements can be made small; therefore, the overall apparatus can be simplified in construction and reduced in size correspondingly.

[0054] Moreover, as the display element is free from power dissipation, the display panel does not consume much power and, in addition, as the display element is not readily broken by an external force, the display panel can be used without trouble for a long time.

[0055] The foregoing description should be construed as merely illustrative of the present invention and should not be construed in limiting, sense. For example, the display element D_ij need not be limited specifically to the four-sided right prismatic block member 4 with the four display surfaces d₁ to d₄ but may be a multi-sided prismatic block member with plural (P) display surfaces of different colors. In this case, the magnetic pieces responsive to the first erasing head and the writing head are disposed in the block member near its (P-l) edges and a magnetic piece responsive to the second erasing head is disposed near the remaining one edge and (P-l) electromagnets are disposed in the first erasing head and the writing head correspondingly.

[0056] Moreover, the length ℓ₂ of the magnetic piece m₀ of the display element D_ij need not always be selected smaller than the lengths ℓ₁ of the other magnetic pieces m₁ to m₃.

[0057] Besides, the structures of the heads E_i, F_i and G_i and the magnetic pieces m₀ and m₁ to m₃ of the display element D_ij can be modified from those employed in the foregoing embodiment if the first erasing head E. and the writing head G_i have such construction that acts on only the magnetic pieces m₁ to m₃ of the display element D_ij. Also it is possible to substitute the first and second erasing heads with permanent magnetic heads.

[0058] It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

Claims

1. A display panel comprising:

a display surface structure;

a display switching unit; and

a drive unit;

in which, letting N horizontal lines of arrangement spaced a predetermined distance from adjacent ones of them in a vertical direction be represented by a₁, a₂, ..... a_N, respectively, the display surface structure has M display elements Dill ^D_i2' .... D_iM disposed on the horizontal line a_i (i=l, 2, ..... N) at predetermined intervals in a horizontal direction;

in which the display element D_ij (j=l, 2, ..... M) is formed with a block member with uniform cross section having an outer periphery forming a plurality of display surfaces of different colors to form a plurality of edges parallel to and around the axis extending in the vertical direction, a first magnetic piece disposed near each of the edges except one of them and second magnetic piece disposed near the remaining edge, the display element D_ij being supported by supporting means in a manner to be rotatable about the axis and to permit a selected one of the display surfaces to lie in a vertical plane;

in which the display switching unit has a first erasing head E_i, a second erasing head F. and a writing head G_i disposed to be movable along the horizontal line a_i in the horizontal direction, the first erasing head E_i having electro- or permanent-magnets less than the edges of the block member by one, the second erasing head F_i having an electro- or permanent-magnet, the writing head G_i having electromagnets of the same number as the electro- or permanent-magnets of the first erasing head; and

in which the drive unit has means for simultaneously moving laterally the first erasing heads E₁ to E_N, the second erasing heads F₁ to F_N and the writing heads G₁ to G_N and the display surface structure relative to each other, and means for energizing the electromagnets of the writing heads G₁ to G_N in synchronism with the movement of the writing control heads G₁ to G_N.

2. A display panel according to claim 1 wherein the block member forming the display element D_ij is a four- sided right prismatic member, and hence four parallel edges and four display surfaces and has three first magnetic pieces, wherein the writing head G_i has three electromagnets, and wherein the first erasing head E_i has three electro- or permanent-magnets.

3. A display panel according to claim 1 wherein the first magnetic pieces of the block member forming the display element D_ij differ in length from the second magnetic piece.

4. A display element for a display panel, which is formed with a block member with uniform cross section having an outer periphery forming a plurality of display surfaces of different colors to form a plurality of edges parallel to and around the axis extending in the vertical direction, a first magnetic piece disposed in each of the edges except one of them and a second'magnetic piece disposed near the remaining edge.

5. A display element according to claim 4 wherein the block member is four-sided right prismatic member, and hence has four-parallel edges and four display surfaces and has three first magnetic pieces.

6. A display element according to claim 4 wherein the first mangetic pieces differ in length from the second magnetic piece.

Drawing